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[Display omitted] • S-doped ultra-microporous wood carbon (SUMW) composite was prepared by one-step chemical activation. • We proposed E pzc -based ion-selective electro-adsorption mechanism. • The selective coefficient of SUMW electrode of NO 3 – over SO 4 2− was reached 32, • The adsorption capacity of the designed material reached up to 637 μmol/g. Capacitive deionization (CDI) technology is promising for selective removal of target ions from various sewages. However, the low electro-adsorption capacity and poor selectivity in the complex sewage system highly restrict its practical application. Potential of zero charge (E pzc) is the external circuit applied potential as the electrode material exhibiting no ion electro-adsorption from the electrolyte. Although E pzc shows a great prospect for regulating the electro-adsorption performance of the electrode, how to use it to achieve selective electro-sorption remains challenging. Herein, we demonstrate a Sulphur (S) doped ultra-microporous (∼0.7 nm) free-standing wood carbon electrode by one step chemical activation, which exhibits different E pzc values in nitrate or sulphate solution due to the unique S-doped ultra-microporous structure. Accordingly, a fantastic selectivity for NO 3 – over SO 4 2− (S N O 3 - / SO 4 2 - =32) was achieved as the applied voltage window ranges from 0.12 V (E pzc -NO 3 –) to 0.43 V (E pzc -SO 4 2−). In addition, the adsorption capacity of the designed material reached up to 637 μmol/g, which is much higher than the maximum value ever reported (∼200 μmol/g). 2000 mL Yellow River water was treated by our tandem CDI cell device through recycling charge and discharge ten times. As expected, the concentrations of NO 3 – ions in the Yellow River water were dramatically reduced from 152 mg/L to about ∼ 35 mg/L after treated with the tandem CDI cell device, which demonstrates the excellent practical application prospect. [ABSTRACT FROM AUTHOR]

• Easy electrochemical activation enables performance improvement of Fe-MnO 2. • Activation process induces structure reconstruction of Fe-MnO 2. • Fe-MnO 2 reconstructs into Fe-doped and oxygen-deficient nanosheet and nanowire. • The reconstructed Fe-MnO 2 displays favorable electron and ion transfers. • Supercapacitor with the reconstructed Fe-MnO 2 electrode shows high energy density. Monitoring and understanding of materials reconstructed under working conditions are vital to accurately identify active sites, clarify reaction mechanism and reasonably design advanced electrodes. Here, a Fe doped MnO 2 (Fe-MnO 2) nanosheet with unique features is demonstrated, unfolding dynamic reconstruction on both morphology and defect structures toward self-optimized pseudocapacitive storage, which can be easily controlled by galvanostatic charge/discharge activation. The results show that the Fe-MnO 2 after activation is reconstructed from nanosheets to a composite structure of Fe-doped and oxygen-deficient nanosheets and nanowires. This composite structure endows the reconstructed Fe-MnO 2 with accelerated electron and ion transfers and high electrochemical active surface area. Density functional theory (DFT) calculation and finite element simulation reveal that the co-existence of Fe doping and oxygen defects arouses more delocalized charges, and the nanowires on nanosheets display tip-enhanced electric field effects for attracting more ions, which effectively improves electron and ion transfer kinetics. The reconstructed Fe-MnO 2 delivers a specific capacitance of 500.1 F g−1 at 1 A g−1, a significant self-optimized energy storage compared with Fe-MnO 2 with 379.2 F g−1. These observations demonstrate active morphology and crystallinity for outstanding pseudocapacitive storage of the Fe doped MnO 2 electrode, offering a guidance to design the electrode materials with superior performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Energy stored in bipolar MCDI is recovered via direct connection manner. • Direct connection of two bipolar MCDI induce their partial adsorption and desorption. • By using this phenomenon, operation with direct connection reduced energy up to 47% • Appropriate time combination can reduce energy with the same desalination performance. In the practical implementation of capacitive deionization (CDI), membrane CDI with a bipolar electrode (bipolar MCDI) is emerging as one of the alternative CDI platforms due to its favorable cell configuration for scale-up and low current originating from the serial connection of electrodes. Nevertheless, one obstacle to practical use is that there are few studies about the energy recovery process for the high energy efficiency of bipolar MCDI, requiring further research. Therefore, in this study, we propose a bipolar MCDI process with energy recovery and assess its potential by analysis of a lab-scale module with a single stack and nine stacks of the bipolar electrode (i.e., 2.4 V and 12 V system, respectively) and a pilot-scale module with 250 stacks (i.e., 300 V system). As a result, the energy consumption of the bipolar MCDI systems was reduced by 43% and 41% in the lab-scale modules with 2.4 V and 12 V systems, respectively, via energy recovery. Furthermore, the energy recovery led to a 40% reduction in the energy consumption of bipolar MCDI, even in the pilot-scale modules of the 300 V system. The results suggest that energy recovery in bipolar MCDI can be one of the essential processes and it has a strong potential for implementation in real industrial and environmental applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The terephthalic acid intercalated carbon nanotube composite was developed for phosphate removal by CDI. • ZnZr-COOH/CNT electrode showed greatest phosphate adsorption capacity. • Phosphate adsorption occurred via the electrostatic attraction, inner sphere complexation and coordination exchange. • The energy consumption of CDI dephosphorization was sixteenth of that of chemical phosphate removal process. The discharge of phosphate from sewage water can lead to water eutrophication and endanger the aquatic ecosystem. Capacitive deionization (CDI) has displayed great potential for salt removal and nutrient recovery due to its excellent performance such as environmental friendliness and energy efficient. In this study, the terephthalic acid intercalated carbon nanotube composite material (ZnZr-COOH/CNT) was developed as an anode and its selective removal of phosphate in CDI was investigated. At a applied voltage of 1.2 V, ZnZr-COOH/CNT electrode exhibited great adsorption capacity of phosphate with low concentration (∼10 mg/L) at a wide range of pH (3 – 10), with the equilibrium concentration as low as 0.3 mg/L which was less than the national first-class emission standard (0.5 mg/L). Moreover, the adsorption of phosphate by ZnZr-COOH/CNT composite electrode was mildly disturbed by the coexisting ions (Cl−, NO 3 –, SO 4 2− and HCO 3 –). X-ray Photoelectron Spectroscopy (XPS) analysis indicated that the zirconium and zinc were coordinated with phosphate to form inner sphere complex, and the hydrogen bond was formed between the hydroxyl group of phosphate and the carboxyl group of electrode material, which enhanced the selective adsorption of phosphate. Furthermore, the energy consumption of CDI dephosphorization was calculated as low as 0.0075 kWh/g P and 0.043 kWh/m3 water at 1.2 V. This study was expected to provide the potential electrode materials and theoretical basis for the application of CDI dephosphorization. [ABSTRACT FROM AUTHOR]

• The presence of coordinated water was beneficial for ion diffusion within CuHCF. • Chelators and Na+ in precursors reduced zeolitic and/or coordinated water in CuHCF. • Lower water content increased Na+ removal capacity but sacrificed stability. • CuII/CuI redox couple activation increases when controlling chelators in precursors. • Activation of reversible CuII/CuI redox couple contributed to BDI cycling stability. Prussian blue analogues are being explored as electrode materials for electrochemical desalination of saline water in battery-type electrode deionization systems and hybrid capacitive deionization systems due to their open framework crystal structure that provides selective adsorption of multiple cations, high theoretical sodium adsorption capacities, and low costs. However, poor electronic conductivity and instability (dissolution) prevents the use of these materials for long-term desalination applications. To understand how synthesis conditions might improve the properties of copper hexacyanoferrate (CuHCF) powders relative to sodium ion adsorption capacity and cycle life, the co-precipitation process was investigated using multiple common synthesis strategies that included addition of chelators and sodium salts as well as different concentrations and oxidation states of precursors. Smaller crystallite sizes (<35 nm) and lower structural water contents increased the initial sodium removal capacity to 53.2 mAh/g from 40.4 mAh/g (control), but also reduced cycling stability in long-term operation (20–55% retention over 100 cycles). The trade-off in stability is thought to be a consequence of structural water facilitating ion diffusion within the material. Adding chelators as precursors led to a highly reversible CuII/CuI redox couple that increased the stability of the FeIII/FeII redox couple in BDI cycling performance (79.4% retention over 100 cycles). [ABSTRACT FROM AUTHOR]

• An in-depth overview of MXene applied to capacitive deionisation for desalination. • Performances of MXene are compared to current best performing faradaic electrodes. • MXene salt desalination mechanisms and its stability in water are addressed. • Challenges and prospects of MXene capacitive deionisation are highlighted. Due to the continually growing world population, water desalination has played a vital role for many countries with a shortage of clean water services. A relevant process for brackish water desalination is capacitive deionization (CDI) with the potential of producing clean water via low energy consumption electrochemical interactions. Due to the recent availability of layered and nanostructured materials to fabricate faradaic electrodes acting as pseudocapacitors to increase the salts' storage capacity, CDI-like desalination methods have gained renewed interest. As a way of improving the desalination performance and energy efficiency of CDI, faradaic deionization (FDI) based on faradaic electrodes such as Ti-MXene (Ti 3 C 2 T x) have been proposed for brackish water desalination. This paper provides a review of the theoretical and experimental framework underpinning CDI and FDI using MXene as electrodes, discussing the actual unique role of MXene in CDI-like desalination methods and its prospects. We will examine MXene's current achievements in the broader area of faradaic and hybrid capacitive deionization if compared with other materials and with various architectures and determine the research gaps in the use of MXene for these applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • First attempt to remove salt from the anaerobic OMBR sludge by FCDI. • The hybrid FCDI-OMBR obtained a higher net energy gain. • Desalination performance of AC, CB, CNT as FCDI electrode material were compared. • Synergistic desalination between different electrode materials was found. Osmotic membrane bioreactors (OMBRs) for anaerobic digestion of waste sludge have many advantages, but salt accumulation in the feed solution is a major problem. In this study, the feasibility of using flow-electrode capacitive deionization (FCDI) to mitigate salinity buildup was investigated. Three types of carbon materials, i.e., activated carbon (AC), carbon black (CB), and carbon nanotubes (CNTs), were tested as flow-electrode materials in desalination via FCDI. The results showed that, the salt removal efficiency (SRE) of CNTs was 110% higher than that of AC. Addition of CB and CNTs to 5.0 wt% AC as conductive additives at concentrations of 0.5 or 1.0 wt% synergistically enhanced the FCDI desalination performance. Cyclic voltammetry, galvanostatic charge–discharge, and electrical impendence spectroscopy showed that use of a combination of 5.0 wt% AC and 1.0 wt% CNTs gave an excellent capacitive performance, and the highest SRE, fastest average salt adsorption rate (0.84 μg cm−2 s−1), and the highest charge efficiency (85.0%) were achieved. The optimal voltage and sludge flow rate for FCDI of real OMBR sludge were 1.5 V and 80 mL min−1, respectively. In comparison with a control OMBR, a hybrid FCDI-OMBR system showed many advantages such as slower salinity buildup, alleviation of inhibition by ammonia, lower production of soluble microbial products, greater volumetric methane production, and higher net energy gains. The proposed hybrid FCDI-OMBR system provides a novel and cost-effective approach to recovering resources and energy from waste sludge or other types of biomass. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel submerged photocatalytic membrane reactor is presented. • Membrane distillation is used for separation of TiO2 and feed components. • Removal of ketoprofen from various feed matrices is discussed. • The feed composition influences consumption of dissolved oxygen. • Distillate is non-toxic regardless of feed matrix. The removal of ketoprofen from simulated sea, brackish and surface water as well as secondary effluent of a municipal wastewater treatment plant in a submerged photocatalytic membrane reactor (SPMR) coupling photocatalysis and direct contact membrane distillation was investigated. TiO 2 photocatalyst was suspended in a feed. The investigations revealed almost complete photooxidation of ketoprofen (initial concentration of 10 mg·L−1) after 5 h, regardless of the matrix, and mineralization ranging from 19 to 56%. For comparison, ketoprofen mineralization in deionized water reached about 86%. No ketoprofen was found in distillate, however, the type of the feed affected the amount of total organic carbon (TOC) and total inorganic carbon (TIC). The highest TOC content in distillate was observed for the secondary effluent. The type of the aqueous matrix affected the concentration of dissolved oxygen in feed, which decreased to the highest extent in the case of surface water (61% after 5 h). The analysis of toxicity towards Aliivibrio fischeri revealed that regardless of the feed type the distillate was non-toxic. A slight increase of permeate flux was observed during the process compared to pure water flux which was explained in terms of thermal conductivity of the TiO 2 layer on a membrane surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • Charging activated carbon (AC) tunes adsorption of ionic but not nonionic compounds. • Defunctionalized AC allows better electro-assisted trap&release performance. • Combine surface modification and electric polarization for promoted removal. • Long-term (20 d) stable electro-assisted trap&release with high enrichment effects. • Electro-assisted trap&release promising for on-site AC regeneration. Highly water-soluble, persistent, and mobile organic compounds (PMOCs) are more and more often detected in surface and groundwater, evoking potential threats to the environment and human health. Traditional water treatment strategies, including adsorption by activated carbon materials, fail to efficiently remove PMOCs due to their hydrophilic nature. Electro-assisted sorption processes offer a clean, facile, and promising solution to remove PMOCs on activated carbon-based electrodes and potentially allow an easy on-site sorbent regeneration (trap&release). In this work, the electrosorption of five selected PMOCs, that is, tetrapropylammonium (TPA+), benzyltrimethylammonium (BTMA+), p -tosylate (p -TsO-), p -toluenesulfonamide (p -TSA), and methyl- tert -butyl ether (MTBE), were investigated on two comprehensively characterized activated carbon felt (ACF) types carrying different surface functionalities. Significant enrichment factors in ranges of 102 to 103 for charged PMOCs were expected by our first estimation for electro-assisted trap&release on ACFs in flow systems applying potentials in the range of −0.1 V/+0.6 V vs. SHE for ad-/desorption, respectively. Defunctionalized ACF carrying larger density in surface π-systems and lower O-content promises a higher capability in electrosorption processes than the pristine material in terms of better material stability (tested for 5 cycles over 500 h) and better removal efficiency of ionic PMOCs. To improve ACFs adsorption performance for cationic and anionic PMOCs, permanent chemical surface modification and reversible electric polarization as alternative strategies are compared. Our findings explore future electrode and process design of electrosorption for applications to treat water contaminated by emerging PMOCs. [ABSTRACT FROM AUTHOR]

• A porous nanofiber membrane with dense distribution of La nanorods was prepared. • Exceptional high utilization ratio of La (0.98). • LPS was easily separated from solution. • The LPS can reduce total phosphorus to less than 10 μg/L in natural lake water. • Phosphate was effectively captured in a wide pH range of 4–10. As phosphate is one of the key causes of water eutrophication, its removal from aquatic ecosystems is essential. Adsorption methods have been widely used to remove phosphate from water bodies. However, most of the adsorbents are unstable and difficult to separate from solution. In this paper, we used a simple electrospinning method to prepare a new, well-dispersed, lanthanum (La)-based porous polyacrylonitrile nanofiber (LPS) with more active sites, which improve its phosphate removal efficiency. The maximum phosphate adsorption capacity on LPS was 218.5 mg P/g (La) (50.4 mg P/g). After complete adsorption, the P/La molar ratio on LPS was 0.98. After 48 h of oscillation, the leakage of La from LPS in deionized water was only 74 μg/L, effectively ruling out secondary pollution of the water-body. Moreover, unlike most adsorbents, LPS has the advantage that it can be readily isolated from water. After treatment with LPS, the total phosphorus (TP) of a water sample from Yangzonghai Lake (Yunnan, China) was reduced to 4.2 μg/L, a value lower than the concentration threshold of eutrophication (10 μg/L) set by the United States Environmental Protection Agency (USEPA) and the first category of the surface water environmental quality standard (10 μg/L) set by China for lakes and reservoirs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Waste pomelo peel converted into a novel adsorbent for use in CDI. • Removal of Pb and Cu ions strongly enhanced by functionalizing with pyrrolic-N. • Strong selectivity of Pb2+ from water containing multiple competing ions. • Easy regeneration of adsorbent on no loss in performance over 300 cycles. Water is not only a valuable resource that is needed to sustain life, but also an essential ingredient in many engineering processes, which unavoidably leads to large volumes of water being contaminated. To achieve safe discharge and also recover valuable "pollutants", better performing sorbents are needed to rapidly and efficiently decontaminate water while generating minimal secondary wastes. Bio-sorbents derived from pomelo peel were functionalized with pyrrolic-N (BNC-5 electrode) and pyridinic-N (BNC-6 electrode) to enhance electroadsorption and selectivity of Pb2+ and Cu2+. The interaction between soft acid ions (Pb2+) and soft base sites (pyrrolic-N) contributed to a strong chemisorption that elevated the electroadsorption capacity to 2.0 mmol g−1 for Pb2+ at an applied voltage of 1.2 V. With fast removal kinetics (0.077 g mg−1 min−1 of Pb2+), the BNC-5 sorbent performed comparably to other N-doped sorbents prepared using graphene. The large adsorption–desorption hysteresis of BNC-5 in responding to the applied electric voltage confirmed the nature of chemisorption. The results showed only 32.4% of the adsorbed ions being desorbed from the sorbent by reducing the applied voltage to 0 V, but reached almost complete desorption (98.5% of adsorbed ions) at –0.8 V. When operated in adsorption–desorption cycle mode, BNC-5 after ∼ 400 cycles maintained a capacity retention ≥ 80%. After 400 cycles, the electrode capacity was almost fully restored (98.7%) by only mild chemical washing (0.1 M HNO 3) of the sorbent and the cycling performance maintained. The study demonstrated the robustness of the sorbent over 1200 cycles and hence the potential to successfully convert waste into high-performance materials for large-scale remediation strategies of contaminated wastewater using CDI. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of cation-induced Ti 3 C 2 T x hydrogels were fabricated successfully. • The morphology of Ti 3 C 2 T x hydrogel was determined by the charge of cations. • Interlayer spacing was influenced by hydrated radii and cation content. • A promoted capacitance was realized in cation-induced Ti 3 C 2 T x electrode. • The outstanding rate-capability was obtained in H-Ti 3 C 2 T x electrode. To date, Ti 3 C 2 T x MXene has been a promising candidate for energy storage field, however the construction of 3D MXene hydrogel with their inherent hydrophilicity and high conductivity remains a challenge. Herein, a series of Ti 3 C 2 T x MXene hydrogel was fabricated successfully via a facile and fast cation-induced strategy. Typically, the formation of hydrogel is stem from the quick cross-linking of Ti 3 C 2 T x nanosheets, accompanying with the intercalation of high-concentration cation between the layers. Characterization analyses have demonstrated that the cation-induced Ti 3 C 2 T x hydrogel possesses 3D porous structure and controllable basal spacing, which could synergistically facilitate fast diffusion of electrolyte ions and accessibility of electrochemical active sites. Density functional theory (DFT) calculation shows that larger hydrated radii and more intercalated cation are favorable for the expansion of basal spacing thermodynamically. As a result, the excellent capacitance and high rate-capability are both realized in cation-induced Ti 3 C 2 T x hydrogels. Especially, as-synthesized Al-Ti 3 C 2 T x hydrogel delivery a remarkable capacitance of 675F/g at 1 A/g, along with a specific energy density of 46 Wh/kg when the power density is 349 h/kg, which is superior to the previous reported Ti 3 C 2 T x electrodes. Besides, the well-designed H-Ti 3 C 2 T x hydrogel still achieves 206F/g capacitance when the scan rate is up to 1 V/s, and it could withstand 5000 cycles with only 8% loss of capacitance. This work not only illuminates a straightforward way to construct high-performance MXene electrode for capacitive energy storage, but also provides a new guideline over the manipulation of interlayer spacing and morphology of 2D colloid materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • An ammonia-rich solution of purity ∼ 70% were attained. • Ca scaling was effectively alleviated by coupling with MCEM when operating FCDI. • High charging voltage (4.5 V) improved performances without sacrificing stability. • Simultaneous efficient removal of ammonia and TOC were achieved. The conventional technologies for ammonia recovery from wastewaters usually requires high chemicals and energy input. And if the wastewater contains hardness, there is a risk of scaling with increasing in cost. Flow electrode capacitive deionization (FCDI) coupled with monovalent cation exchange membrane (MCEM) was employed to solve abovementioned problem. Our method was an effective strategy for the selective production of an ammonia-rich solution from coal gasification gray water by simply adjusting the charging and discharging processes. During the charging process, both NH 4 + and Na + were transported to the cathode due to electrosorption of the electrical double layers (EDLs) on charged carbon particles and electrodialysis of potential gradient, while Ca 2+ was retained by the MCEM. The Faradaic reactions induced the generation of OH - and led to the conversion of charged NH 4 + into uncharged NH 3. When the electrode polarity was reversed, charged species such as Na + would be mostly pushed back into the spacer chamber, yet NH 3 was more likely to be trapped in the cathode due to sluggish pH variations, thereby producing an ammonia-rich solution. Under optimal operating conditions (i.e., a carbon content of 5 wt%, charge and discharge voltages of 4.5 and 0.2 V, respectively, charge 80 min and discharging 15 min, and six continuous cycles), a stable recovery efficiency (∼205 mg/L per cycle) and product purity of 70.4% were attained at a relatively low electrical energy consumption (11.1 kWh/kg N). Additionally, Ca scale was effectively avoided by MCEM. These results demonstrated that FCDI coupled with MCEM could be a promising technology for efficient NH 4 + removal, recovery as an ammonia-rich solution and TOC removal from industry wastewaters with alleviation of scaling. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fungal hypha activated carbon pad (FhACPad) is a promising electrode for desalination. • FhACPad is a freestanding electrode readily prepared from the fungus suspension for CDI. • The continuous and porous structure of FhACPad facilitates both electron and ion transfer. • FhACPad with hierarchical pores exhibits a high desalination capacity of 35.6 mg NaCl /g. Capacitive deionization (CDI) is an emerging technology for water desalination, especially low-salinity water. Freestanding porous carbon-based electrodes with rapid electron transfer rate and effective ion diffusion features are desired to achieve high desalination performance. Here, a porous carbon pad derived from the fungal hyphae of Aspergillus niger was prepared as a precursor of the electrode. After carbonization and activation, the intertwined and hierarchical porous structure of the fungal hypha pad was well-preserved, producing a freestanding fungal hypha activated carbon pad (FhACPad) electrode for MCDI. The interconnected carbon fibers and open pore structure of the FhACPad yielded an electrode with high electrical conductivity and rapid ion transport properties. The novel FhACPad exhibited a gravimetric salt adsorption capacity of 35.6 ± 2.3 mg NaCl /g with an average desalination rate of 1.2 mg NaCl /g electrode /min from a 585 mg/L NaCl aqueous solution at a cell voltage of 1.2 V and a flow rate of 1 mL/min. As a result, the FhACPad outperformed conventional powdered activated carbon (PAC) electrodes and the most recently reported porous carbon electrodes under similar desalination conditions. This work also provides insights into the structure-performance relationships of CDI electrodes and shows a great potential of fungal biomass-derived porous carbon electrodes for high-performance MCDI applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel technology of coupling DBD and UV was investigated to degrade ENRO. • Approximately 93.9% of the ENRO was removed in the DBD/UV system. • OH played an important part in the ENRO degradation. • The DBD/UV system decreased H 2 O 2 concentration, and increased ·OH concentration. • Twelve degradation products were determined by HPLC-MS. Enrofloxacin (ENRO) as a highly toxic antibiotic poses great threats to human health and environmental safety. In this study, a novel technology of coupling dielectric barrier discharge (DBD) and ultraviolet (UV) was investigated to efficiently degrade ENRO in aqueous, and had a higher degradation rate. The ENRO degradation rate achieved approximately 93.9% at 30 min, and approximately 1.20 g kWh−1 of energy yield (G 50) was observed for the combined system. The addition of H 2 O 2 and K 2 S 2 O 4 improved the ENRO degradation due to the generation of ·OH and ·SO 4 2-. In the presence of NO 3 –, the ENRO degradation played a tendency to promote first and then decrease, and the presence of SO 4 2- resulted in the positive effect, while the negative effect was shown in the presence of Cl- and CO 3 2–. The trapping experiment indicated that ·OH played an important part in the ENRO degradation. The addition of UV into the DBD system decreased H 2 O 2 concentration in deionized water, and increased ·OH concentration. The DFT analysis showed the degradation mechanisms of ENRO at a molecular level. The degradation of ENRO mainly involved the oxidation of the piperazine group, the removal of ethyl acetate and the substitution of the F atom. The toxicity of ENRO and its degradation intermediates was evaluated. [ABSTRACT FROM AUTHOR]

[Display omitted] • As a hydrophobic modifier, rGO makes CGA stably float on the water–vapor interface. • The porous structure promotes the supply of bulk water to the water interface. • The effect of ambient factors on water evaporation is dominant in open system. • Clean water recycling from actual seawater and heavy metal wastewater is achieved. • Purification of heavy metal sewage is achieved mainly for interfacial evaporation. Solar-driven water evaporation plays an important role in the recycling of low-energy water resources. Here, we have prepared porous hydrophilic/hydrophobic cellulose graphene aerogel (CGA) to achieve efficient water recycling in solar-driven desalination and purification of heavy metal wastewater. The aerogel can reach water evaporation of 7.2 kg·m−2 for 4 h from simulated or actual seawater under 1 sun irradiation, which meets the daily water demand of two adults. Due to the interfacial evaporation and the formation of hydrogen and chelating bonds between heavy metal ions and oxygen-containing functional groups, CGA can effectively reduce the amount of heavy metal sewage to obtain water without biotoxicity. The efficient water recycling of aerogel is mainly attributed to the photothermal conversion of hydrophobic reductive graphene oxide (rGO), the interconnected porous structure formed by random stacking and cross-linking of hydrophilic cellulose sheets as well as holes in it serve as supply channel of water evaporation. In addition, ambient factors such as wind, humidity and ambient temperature boost the water evaporation of CGA in open system, while in closed system reducing the light reflection of condensed water and the relative humidity of the space is more conducive to improving evaporation efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • CO 2 hydrate dissolution rate was in situ determined experimentally. • The diffusion-controlled mechanism for hydrates dissolution was demonstrated. • The factors controlling CO 2 hydrate stability were discussed. Measuring the dissolution rates of CO 2 hydrates in marine environments is urgently needed because CO 2 hydrate is a powerful means in CO 2 ocean sequestration as well as a product of CO 2 -CH 4 gas replacement in hydrate exploitation. The stability of CO 2 hydrates is a significant index to evaluate the feasibility of gas hydrate technologies. It is generally agreed that the dissolution of hydrates is diffusion-controlled rather than reaction-controlled. In this work, the dissolution rates of CO 2 hydrates in sediments under a variety of experimental conditions were calculated by the CO 2 fluxes and mass balance. The in situ CO 2 concentrations in static and flowing water layers were measured by Raman spectroscopy. Firstly, the dissolution rates of CO 2 hydrate in sediments in different diffusion stages were 314 to 3.5 cm/year and 194 to 1.2 cm/year in static deionized water and brine layer, respectively. The CO 2 hydrate underwent a rapid dissolution stage in the beginning of the experiment. Then the dissolution rate slowed down because of the decreasing concentration gradients. The difference of dissolution rates between deionized water and brine is related to the CO 2 solubility in different solutions. CO 2 hydrates covered with sediments dissolved much slower than hydrates dissolved in direct contact with water layers due to the increased diffusion boundary layers and the decreased diffusion coefficients. Additionally, the dissolution rates of CO 2 hydrate that exposed to a variety of flow rates showed a strong velocity dependency. In this work, the dissolution rates of CO 2 hydrate under flowing water layers ranged from 5.6 to 365 cm/year with volume flow rates ranged from 1.01 to 8.57 ml/min. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel electrochemical reactor is developed for direct synthesis of H 2 O 2 on-site. • Porous solid electrolyte and gas diffusion electrode improve H 2 O 2 production. • H 2 O 2 production efficiency and reactor stability was investigated. • The exhibited a good performance in odor compounds removing combining with UV. The on-site generation of hydrogen peroxide (H 2 O 2) attracts much attention for advanced oxidation processes (AOPs) in water treatment. In this work, we reported a novel on-site H 2 O 2 generation reactor combined with ultraviolet (UV) for taste and odor (T&O) compounds removal in drinking water purification systems. The reactor is equipped with a gas diffusion electrode (GDE) accompanied by a proton-conducting solid electrolyte. In this reactor, GDE is used to improve the oxygen transfer efficiency. The porous solid electrolyte is selected for the proton and electron conduction instead of an electrolyte solution, which is crucial for producing pure H 2 O 2 solution. The production rate and concentration of H 2 O 2 can be controlled through adjusting the applied current efficiency and the flow rate of deionized water in a solid chamber. Meanwhile, this system exhibits long-term stability during a continuous operation for 96 h. For the application of the system, the single-cell was assembled into cell stacks, which improved the H 2 O 2 concentration from 780.9 to 2301.3 mg·L−1, along with the energy consumption reduced from 23.81 to 6.67 kWh·kg−1 under the applied current density of 30 mA·cm−2. To evaluate the water purification performance of this system, the oxidation degradation of 2,4,6-trichloroanisoles (TCA) was conducted using the on-site H 2 O 2 generation process under both static and dynamic flow conditions combined with UV light. The degradation rate of TCA was >95% with its initial concentration of 1 μg·L−1 under the hydraulic retention time from 10 to 40 min−1 and H 2 O 2 dosage from 10 to 100 mg·L−1. Meanwhile, almost no residual H 2 O 2 was detected after the degradation process. This study proposed a promising device for drinking water purification. [ABSTRACT FROM AUTHOR]

In this study, hierarchical porous cellulose/alginate/carbon black hydrogel (CACH) was successfully manufactured by 3D printing method. The 3D-printed CACH can be an effective evaporator in solar steam generation and has great application prospects in seawater desalination and wastewater purification. [Display omitted] • Design of cellulose based solar steam generation through 3D printing. • 3D-printed hierarchically porous structure for customizable solar evaporator. • Macroscopic pore and inherent pore synergistically promoted evaporation efficiency. • Evaporation rate of 1.33 kg m-2h−1 and efficiency of 90.6% was gained. • Seawater desalination and dye wastewater purification using hybrid hydrogel evaporators. Solar steam generation (SSG) has great application prospects in seawater desalination and dye wastewater treatment. However, it is still a challenge to realize a low-cost, rapid evaporation, high water quality and sustainable solar-driven water purification system. Three-dimensional (3D) structural design of evaporator is conducive to promoting evaporation efficiency, which has great potential in SSG field. In this study, 3D hierarchical porous hybrid hydrogel evaporators with embedded carbon black (CB) for SSG are built through 3D printing method. The 3D hierarchically porous cellulose/alginate/carbon black hydrogel (CACH) shows a super-hydrophilic wettability, and excellent light absorption (97%) within the wavelength range from 300 to 2500 nm, which can dramatically improve water transportation capacity and photothermal performance in the evaporator. The evaporation rate of the evaporator is as high as 1.33 kg m-2h−1 and the conversion efficiency of solar energy at 1 kW m−2 (one-sun) solar illumination is up to 90.6%. Moreover, the evaporation also exhibits superior salt resistant performance, and collected water meets World Health Organization (WHO) drinking water standards after purification from seawater. In addition, a small amount of photothermal material (1 wt% CB) is required in this system, which is beneficial to reduce the cost of the system. The 3D-printed hierarchically porous hydrogel evaporator has great application prospects in seawater desalination and wastewater purification. [ABSTRACT FROM AUTHOR]

[Display omitted] • Developed a carbonized MIP-202/MXene (CMM) for selective electrosorption of U(VI). • MXene provides pseudocapacitance/intercalation effect and conductive base. • Two composite structures were observed during preparation of CMMs. • The CMM electrode exhibited excellent adsorption capacity and selectivity for U(Ⅵ). As the key element in the nuclear industry, uranium (U) has been widely concerned for its stable acquisition and efficient recycling. Capacitive deionization (CDI), which known as a seawater desalination technology, has shown great potential for uranium-adsorption. However, the poor selectivity restricts the application of CDI in uranium extraction. In this work, a carbonized MIP-202/MXene (CMM) composite was developed for highly efficient selective electrosorption of U(VI) from multi-ionic water. The uniformly decorated MIP-202 can prevent MXene from aggregation and provide rich pore structures, large specific surface area and additional nitrogen source for the efficient electrosorption of U(VI). With the addition of MXene nanosheets, a conductive network was introduced into the CMM and improved mechanical robustness of material to facilitate rapid charge transfer at the interface. As a result, the CMM electrode exhibited a maximum adsorption capacity of 582.46 mg g−1 calculated from Langmuir model and a removal ratio of 89.1% at 1.2 V in UO 2 2+ solution. The selectivity adsorption of CMM for UO 2 2+ can reach 92.3% when treated with multi-ionic solution. Besides, there is an interesting fact that the decreased ratio of added MXene can got a higher adsorption capacity, which may cause by the two composite structures formed when the mixing ratio changed. Overall, the excellent conductivity, high adsorption capacity and selectivity make CMM a promising electrode in CDI for efficient extraction of uranium from water. [ABSTRACT FROM AUTHOR]

• Noble-metal free catalysts for overall water splitting reactions are investigated. • First principle calculations confirm that the remarkable HER and OER at the Co site is due to the doping of V species. • The VCoCO x @NF catalyst shows excellent AAEMWE cell performance with a low overpotential and good stability. • The VCoCO x @NF catalyst exhibits a low overpotential of 63 mV for HER and 240 mV for OER at 10 mA cm−2. Large scale, cost-efficient, durable, and non-noble metal catalysts for overall water splitting in alkaline-anion-exchange-membrane-water-electrolyzer (AAEMWE) are highly demanded for the clean hydrogen economy. Meanwhile, V- and Co-based bimetallic oxide materials were rarely reported for overall water splitting in AAEMWE. Herein, we demonstrate that the self-supported oxovanadate-doped cobalt carbonate (VCoCO x @NF) on nickel foam (NF) is a high-performance overall water-splitting catalyst in AAEMWE. The as-prepared VCoCO x @NF catalyst demonstrates high activity for both hydrogen and oxygen evolution reactions (HER and OER) in alkaline media, with a current density (j) of 10 mA cm−2 at overpotentials of 63 mV and 240 mV, respectively. Assembled as a conventional electrolyzer for overall water splitting, VCoCO x @NF as both anode and cathode in 1 M KOH operates at low cell voltages of 1.54 and 1.74 V at 10 and 100 mA cm−2, respectively, superior to the Ir/C−Pt/C@NF electrolyzer (1.59 and 1.86 V, respectively). First principle calculations show that the remarkable HER and OER at the Co site are due to the doping of V species, which reduces the overpotential by shifting the d-electron states of Co towards the Fermi-level. Besides, an AAEMWE cell fabricated with the VCoCO x @NF catalyst delivers j = 200 mA cm−2 at 2.01 V in deionized water, lower than the expensive commercial IrOx-Pt/C@Au/Ti electrolyzer (2.06 V). This finding provides the stage for large-scale hydrogen production by utilizing the V- and Co-based bimetallic oxide materials. [ABSTRACT FROM AUTHOR]

A self-supported MoS 2 /CoS 2 @TiO 2 nanotube (TNT) hybrid electrode was fabricated by an in-situ hydrothermal process-assisted growth strategy, which achieved a significantly high gravimetric Na+ adsorption capacity and excellent regeneration performance. It also demonstrated amazing removal efficiencies close to 90% for various heavy metal ions (i.e., Fe3+, Cr3+, Cd2+, Pb2+, Cu2+ and Ni2+), revealing its great potential for wastewater purification. [Display omitted] • A self-supported MoS 2 /CoS 2 @TNT hybrid electrode was constructed. • The electrode achieved a gravimetric Na+ adsorption capacity of 44.22 mg g−1. • The electrode exhibited excellent regeneration performance and removal rates. • The electrode also realized removal efficiencies up to 90% for heavy metal ions. Recently, the rational design and construction of graphene-like layered transition-metal disulfides (TMDs) with chemical and physical superiorities to act as capacitive desalination (CDI) electrodes for water purification have attracted increasing interest worldwide. Herein, an advanced self-supported MoS 2 /CoS 2 @TiO 2 nanotube (TNT) hybrid electrode was grown on a TNT scaffold by a hydrothermal process-assisted in-situ growth strategy, and an asymmetric CDI cell was constructed with the as-fabricated MoS 2 /CoS 2 @TNT and commercial AC electrodes as cathode and anode, respectively. Benefiting from the effective structural feature (i.e., fully open nanosheet-assembled flowers and hierarchical pore alignment) and synergy effect of metal-like CoS 2 , state-of-the-art MoS 2 and TNTs with an efficient charge "superhighway", the MoS 2 /CoS 2 @TNT electrode achieved a significantly high gravimetric Na+ adsorption capacity of 44.22 mg g−1 in a 600 mg L−1 NaCl solution at 1.2 V. Moreover, the hybrid electrode possessed excellent regeneration performance with a capacity retention of nearly 100% even after 20 cycles. Most notably, such electrode also demonstrated amazing removal efficiencies close to 90% for various heavy metal ions (i.e., Fe3+, Cr3+, Cd2+, Pb2+, Cu2+ and Ni2+), revealing its great potential for wastewater purification. [ABSTRACT FROM AUTHOR]

[Display omitted] • A porous structured carbon electrode reactor was designed for wastewater treatment. • Mass and electron transfer were significantly enhanced. • Radical and nonradical oxidation jointly contributed to the degradation of MNZ. • With reactive species confined inside the electrodes, organics were vastly removed. • This technology remained a high efficacy in complicated water matrixes. The co-activation of persulfate (PS) using electricity and carbon is a novel method used in sulfate radical-based advanced oxidation processes. However, the full utilisation of the synergistic effects between diverse reactions on both electrodes to achieve high PS activation and efficient removal of contaminants remains challenging. In this study, we designed porous graphite to serve as two electrodes and a continuous-flow reactor; this system resulted in internal PS activation and the degradation of organics within a specified "confined space". With the enhancement of mass and electron transfer in the reactor, the model contaminant metronidazole (MNZ) was successfully degraded with a removal efficiency of 94.79%. The flow-through design remarkably outperformed the flow-by design, which reflected the stronger restrain of side reactions, larger electrochemical active surface area, higher active-site exposure, lower charge-transfer resistance, and higher diffusion coefficient of porous graphite electrodes. Kinetic experiments, radical scavenging experiments, and electron paramagnetic resonance tests carried out in split cells demonstrated that direct electron transfer, ∙OH oxidation, and non-radical oxidation with active PS* and 1O 2 collectively contributed to the degradation of MNZ in the anode; SO 4 −∙ oxidation played the most significant role in the cathodic cell. Finally, the broad applicability of the reactor was confirmed by the treatment of diverse water matrixes and wastewater containing various persistent organic contaminants, showing great potential for practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Schiff base reaction is developed to build two-dimensional nanocomposites. • In-situ formed FeS nanocrystals are half-embedded in N,S-doped carbon nanosheets. • Robust connection between FeS and carbon reduces diffusion resistance of Na+/Li+. • Charge/discharge process is dominated essentially by pseudocapacitive behavior. • Intrinsic pseudocapacitive feature enables nanocomposites high rate capability. Combining electrode materials with low-dimensional carbonaceous materials such as graphene is an effective way to improve the electrochemical performance of sodium/lithium-ion batteries (SIBs/LIBs). A common drawback of these recombinant hybrids is the weak interaction between the active component and graphene, resulting in poor structural stability and high resistance to diffusion of Na+/Li+ and electrons diffusing between phase boundaries during charging and discharging, thus leading to capacity decay and low rate capability of these hybrids. Here, a facile integrated construction strategy based on Schiff base reactions is developed to build a nitrogen and sulfur co-doped flexible lotus-leaf-like carbon and FeS nanosheets (FeS@N,S-CNSs). This structure takes full advantage of the high conductivity and mechanical flexibility of carbon nanosheets, and the high theoretical capacity of FeS. Together with the co-doping effects, the nanoscale size of FeS, and the robust connection between the in-situ generated FeS nanocrystals and carbon nanosheets, the FeS@N,S-CNSs outputs excellent electrochemical performance in both of SIBs and LIBs. Impressively, experimental results and Density functional theory (DFT) calculations indicate that the charging/discharging process is essentially dominated by pseudocapacitive behavior, this intrinsic feature gives FeS@N,S-CNSs electrode exceptional rate capability (∼50% capacity retention even at 100 A g−1 in SIBs). [ABSTRACT FROM AUTHOR]

[Display omitted] • Crude glycerol from biodiesel was used to obtain a new sustainable activated carbon. • The polyglycerol activated carbon electrodes successfully desalinate brackish water. • Operation within the potential stability window ensured the long-term stability. • Asymmetric configurations (CDI) and MCDI improved the charging efficiency. • The best stable desalination performance was achieved using the membrane CDI at 1.6 V. Capacitive deionization (CDI) is a promising electrochemical technology for water desalination that can contribute to reducing water scarcity. At the same time, appropriate routes for the disposal or reuse of liquid wastes are also a major current concern. Based on the water-waste nexus concept, this work demonstrates that crude glycerol from biodiesel plants can be successfully used to obtain a new sustainable activated carbon. After polymerization, the crude glycerol was carbonized and activated to obtain polyglycerol activated carbon (PGAC), which was employed as an electrode for CDI desalination of brackish water. Evaluation was made of the electrode performance and stability over cycles of electrosorption/desorption, using different cell configurations (symmetric, asymmetric, and membrane CDI) and cell voltages (E cell). It was observed that maintaining the potential of zero charge of the negative and positive electrodes outside their working domains during the cycles enabled minimization of that part of the applied potential deviated to co-ion repulsion, consequently improving the salt adsorption capacity (SAC) and charge efficiency (Q E). Furthermore, maintaining the potential of the positive electrode below the oxidation potential by controlling the applied E cell could ensure electrode stability. The best desalination performance using the PGAC electrode was achieved using the membrane CDI configuration (at 1.6 V), resulting in stable SAC (∼ 27.1 mg g−1) and Q E (∼100%) over 50 cycles. The low cost and high SAC and Q E values suggested that the PGAC electrode could be considered a potential candidate for use in CDI desalination. [ABSTRACT FROM AUTHOR]

This work constructed a kind of high-quality CdSe/CdS@ZnO QDs for the first time that enabled by inorganic ZnO sol as surface ligands with the improved PL stability and gain performance. The CdSe/CdS@ZnO QDs exhibited stable amplified spontaneous emission process, and finally as gain medium achieved high-performance single-mode lasing output with an ultralow threshold of ~3.3 μJ cm−2. [Display omitted] • High-quality CdSe/CdS@ZnO QDs enabled by inorganic ZnO sol as surface ligands. • ZnO sol possesses effective surface passivation capability and deionization effect. • CdSe/CdS@ZnO QDs exhibit the enhanced optical gain performance and PL stability. • All-inorganic CdSe/CdS@ZnO QDs lasers achieve high-performance lasing output. Colloidal semiconductor quantum dots (QDs) have attracted great attention in field of optoelectronic devices. However, the surface organic ligands of QDs involving in optical instability and limited passivation remain challenging, thus bringing additional difficulties in practical application. Here, the high-performance CdSe/CdS@ZnO QDs were successfully prepared by ZnO sol as surface ligands. Importantly, this kind of CdSe/CdS@ZnO QDs maintained the typical advantages of conventional QDs, such as superior monodispersity and long-term storage stability in solution. Because of the effective surface passivation provided by inorganic sol ligands and the deionization effect that electron transferring from surface state of QDs to ZnO acceptor, CdSe/CdS@ZnO QDs showed the remarkably enhanced photostability and biexciton lifetime, as well as further suppressed Auger process and PL blinking. Meanwhile, the CdSe/CdS@ZnO QDs demonstrated PL thermal stability much higher than that of pristine CdSe/CdS QDs under heating to 100 °C, which was efficiently improved 3 times that from ~20% to ~63% of their initial emission intensity. Moreover, a stable amplified spontaneous emission process was observed in CdSe/CdS@ZnO QDs film and still retained a lower ASE threshold (~28 μJ cm−2). Finally, we successfully fabricated a high-performance vertical cavity surface-emitting laser based on CdSe/CdS@ZnO QDs, which presented spatially directional single-mode lasing output with an ultralow threshold of ~3.3 μJ cm−2. We believe that this work could not only enrich the family of surface ligands passivated semiconductor QDs but also provide a novel strategy towards constructing stable and functionalized colloidal nanomaterials for all-inorganic optoelectronic devices. [ABSTRACT FROM AUTHOR]

• Lipophilic solute dissolved more in plasmon-activated water (PAW). • PAW forming stronger intermolecular hydrogen bonds with hydrophilic alcohol. • Decreased evaporation rate observed on PAW/alcohol solution. Liquid water, as the most environmentally friendly polar solvent, is popularly used in physical processes and chemical reactions. Its unique properties and activities come from the presence of intermolecular hydrogen bonds (HBs) with itself and other species. Scientists have been discussing properties other than known bulk water for a long time. However, the particular application of water being researched is limited today. Mass-produced active and stable plasmon-activated water (PAW) with a reduced HB network based on hot electron transfer (HET) from resonantly illuminated gold (Au) nanoparticles (NPs) was first created in 2014. In this work, we report its distinct intermolecular HBs with water-soluble alcohols and the solubility of hydrophobic solutes. Interestingly, the densities of PAW in methanol, ethanol, and propanol at various ratios all increased due to stronger HBs between PAW and the alcohols, particularly seen with propanol, compared to deionized water (DIW)-based systems. Moreover, these results reflect the decreased evaporation rates of PAW/alcohol solutions, especially observed for the solution with the maximum increased density, compared to DIW-based systems. Compared to DIW, the solubilities of hydrophobic antioxidants of curcumin and melatonin in PAW increased by ca. 240% and 120%, respectively. Moreover, sunflower oil was more soluble in the more-lipophilic PAW compared to conventional DIW. The distinct increased density of the alcohol/PAW solution lasted for at least 1 week. Innovative PAW has emerged as a promising green active solvent applicable for both hydrophilic and hydrophobic solutions. [ABSTRACT FROM AUTHOR]

• PAW significantly increases the solubility of melatonin that endows lipophilic property. • Melatonin dissolved in PAW displays greater anti-viral activity against dengue infection. • PAW plays synergetic effects with melatonin to raise melatonin's anti-oxidative function. • Melatonin dissolved in PAW greatly improves hepatic bioenergetics after sleep deprivation. • PAW may act as a powerful medium to greatly enhance melatonin's therapeutic efficiency. Melatonin is a lipophilic antioxidant generally dissolved in organic solvent before delivery. However, the presence of organics may severely depress the functional effects of melatonin. By rendering deionized water (DIW) flow through gold nano-particles under localized surface plasmon resonant illumination, we developed plasmon-activated water (PAW) which successfully increases the solubility of melatonin to 150.325%. Melatonin dissolved in PAW also exhibits stronger anti-viral and anti-oxidative activities than that dissolved in DIW in which the percentage of dengue virus infected human hepatocellular carcinoma cells is remarkably decreased (14.7% vs. 20.6%) whilst the clearance rate of hydroxyl radical is significantly enhanced (11.9% vs. 6.69%), respectively. Moreover, in vivo approaches further show that following chronic sleep deprivation, the level of oxidative stress, hepatic bioenergetics, anti-oxidative enzyme activity, and metabolic function are all significantly improved in rats received melatonin prepared in PAW than that in DIW. As the bio-activity of melatonin depends largely on its solubility, utilizing PAW as a non-organic solvent will not only enhance the anti-viral and anti-oxidative function of melatonin, but also offer great potential for clinical use of melatonin as a therapeutic strategy to depress virus infection and counteract oxidative damage in a more natural, more economic and more efficient way. [ABSTRACT FROM AUTHOR]

[Display omitted] • Superelastic and versatile cellulose aerogel was prepared by Schiff base cross-linking and freeze-drying assembly. • Porous water channels with reverse transportation achieved long-term desalination without salt accumulation. • This solar steam generator realized efficient purification of seawater and wastewater. • As a proof of concept, a simple device that can adsorb the dye pollutant was designed. Solar steam generators (SSGs) that continuously supply clean water resources under solar radiation have been recognized as a sustainable approach to mitigate the global water and energy crisis. However, most SSGs currently face the accumulation of salt on the surface during long-term seawater desalination, which hinders the water supply and vapor escape and significantly reduces the evaporation efficiency. Inspired by the porous water channels of reverse transportation, the SSG (PPy@PEI@A-CNF aerogel) with superelastic and photothermal properties was obtained by the Schiff base reaction of aldehyde-based cellulose nanofibers (A-CNF) and polyethyleneimine (PEI) and freeze assembly, and further in-situ polymerized with polypyrrole (PPy). This aerogel with porous hierarchical structure performed outstanding mechanical robustness (89.9% strain remaining after 100 compress-release cycles), ultra-low density (0.021 g cm−3) and thermal conductivity (0.042 W m−1 K−1), high porosity (97.72%) and full spectrum solar energy absorption (98.4%). Moreover, the aerogel could be used for solar-driven water evaporation, and its evaporation rate and efficiency were as high as 1.66 kg m–2h−1 and 94.62% under 1.0 sun. Owing to the rapid re-dissolution of the salt in the reverse transport of macroporous structure, the aerogel exhibited excellent salt-resistant and self-desalting properties during long-term seawater desalination, and also showed superior purification effects and reusability. These findings provide a new method for designing reusable macroporous SSGs to meet eco-friendly, efficient and sustainable fresh water access. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous hydrogel sponge has been realized via in-situ growth of hydrogel on sponge. • Hydrogel layer can be readily controlled to reserve the porosity of the sponge. • The "porous hydrogel sponge" can be arbitrarily compacted, folded, and twisted. • Water evaporation rate is up to 2.8 kg m-2h−1 under one sun with 332 g h−1 $−1. • Long-term cycling stability (>6 months), as large as 7500 cm2. Hydrogel evaporator is becoming an excellent platform for solar-driven water purification. However, the cost effectiveness and scalability of hydrogel-based evaporate materials is still a great challenge due to the high energy-consuming and time-consuming freeze drying process, as well as limited black hydrogel materials. Herein, inspired by porifera, "porous hydrogel sponge" has been proposed and realized via in-situ growth of novel adhesive/black hydrogel on polyurethane (PU) sponge without freeze drying process for durable and highly efficient solar-driven water evaporation. The in-situ generated hydrogel can firmly adhere on the sponge skeleton just like a skin, and the thickness of the hydrogel layer can be readily controlled to reserve the high porosity of the sponge, while the sponge skeleton can endow the evaporator with desirable mechanical stability (can be arbitrarily compacted, folded, and twisted). The water evaporation rate of the resultant hydrogel evaporator can reach up to 2.8 kg m-2h−1 under one sun with excellent cost-effectiveness at 332 g h−1 $−1. Moreover, the resultant hydrogel evaporator possesses outstanding long-term cycling stability (at least 6 months), and can be as large as 7500 cm2 (can be readily enlarged further). This study represents a new avenue for fabrication and design of high performance hydrogel evaporator toward practical application, and will contribute to the global effort in addressing world water and energy issues. [ABSTRACT FROM AUTHOR]

Highlights: [•] Charge efficiency is directly related to flow rate and applied voltage. [•] 30–35% Of the energy consumed by CDI is for desorption of co-ions. [•] CDI electrosorption is driven by a physisorption according to thermodynamics. [•] The isotherm results were well represented by the Langmuir model. [Copyright &y& Elsevier]

Abstract: Giant reed (GR) was modified into giant reed quaternary amino anion exchanger (GR-QE) for the removal of phosphate by reacting with epichlorohydrin, ethylenediamine (EDA) and triethylamine in the presence of N,N-dimethylformamide (DMF). Factors like GR dosage, temperatures and volumes of organic liquid chemicals were used in single-factor experiments and orthogonal experiments for determining optimal conditions, with phosphate removal efficiency and zeta potentials as indicators. The results indicated that the optimal conditions obtained in the orthogonal experiments were consistent with those in the single-factor experiments. The GR utilization on a large-scale was realized, and the dosage of EDA was considered as the key influential factor in the preparation of GR-QE. Under these conditions, the nitrogen content in GR-QE was about 7.78%, while it was 0.9% in GR. The phosphate removal was about 82.1%, zeta potential was 23.2mV. [Copyright &y& Elsevier]

Abstract: The ability of saw dust and neem bark as low-cost natural adsorbents were investigated for adsorptive removal of Zn(II) and Cd(II) ions from aqueous solutions. Various physico-chemical parameters such as pH, initial metal ion concentration, and adsorbent dosage level and equilibrium contact time were studied. The optimum pH for adsorption was found to be 5 for Zn(II) and 6 for Cd(II). Kinetics data were best described by pseudo-second-order model. Mass transfer coefficients were also determined for individual adsorbents for removal of Zn(II) and Cd(II) ions from aqueous solutions. The equilibrium adsorption data were fitted to Langmuir and Freundlich isotherm models for Zn(II) and Cd(II) adsorption respectively. The adsorption capacities (q max) for individual metal ions in terms of monolayer adsorption were compared with the other reported values. The sorption energy calculated by using Dubinin–Radushkevich isotherm for different system indicated that the adsorption process is physical in nature. The thermodynamic equilibrium constant and the Gibbs free energy were determined for each system and results indicated the spontaneous nature of the adsorption process. FT-IR studies were carried out to understand the type of functional groups in saw dust and neem bark responsible for metal binding process. [Copyright &y& Elsevier]

• Comprehensively active condensed plasmon-activated water (PAW) • Condensed PAW with electron-doping and reduced hydrogen bonding. • Condensed PAW enhancing hydrogen evolution reaction and oxygen evolution reaction. Water is the most environmentally friendly solvent, but bulk water is conventionally considered to be a bystander in reactions performed in it. For decades, scientists have been discussing the characteristics of water that differ from bulk water in special environments. Recently, various small amounts of treated water were developed to create specific applications. In 2014, comprehensively active and stable plasmon-activated water (PAW), which was mass-produced and innovatively created by utilizing hot electron transfer (HET) from gold nanoparticles (AuNPs), was first reported. In this work, we report the maintenance of activity of purified Au-free PAW collected from water condensed from PAW vapor (PAW-V). Interestingly, the metastable PAW-V was still active with a structure of electron-doping and reduced hydrogen bonding (HB), which were confirmed by zeta potentials and the nuclear magnetic resonance (NMR) relaxation time (T 1). Like PAW, PAW-V enhanced hydrogen evolution reactions (HERs) and oxygen evolution reactions (OERs), compared to deionized water (DIW). The PAW-V itself exhibited the ability to more rapidly evaporate due to reduced HBs between homogeneous molecules, while a PAW/isopropanol solution evaporated more slowly due to enhanced HBs between heterogeneous molecules. Also, PAW-V could scavenge free 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and reduce the strong KMnO 4 oxidant. The unique properties of PAW-V were maintained after storage for 3 days at room temperature in the dark. The condensed Au-free PAW has emerged as a promising green active solvent applicable in various fields of physics, chemistry and biomedicine. [ABSTRACT FROM AUTHOR]

• The bio-CFC obtained 42 ± 2 W/m2 power density using seawater and wastewater. • The power density was three times higher than the 10.6 ± 0.1 W/m2 of the control CFC. • The bioelectrochemical currents developed an extra capacitive potential on CuHCF electrodes. • Na+ intercalation/deintercalation processes on CuHCF electrodes were enhanced. • Cl− transfer across the anion exchange membrane in the bio-CFC was also improved. An enormous source of clean energy, called salinity gradient (SG) energy, exists from mixing waters with different salinities. Harvesting SG energy has attracted lots of attentions to develop efficient technologies. However, the power output is still limited. In this study, a concentration flow cell (CFC) powered by a bioelectrochemical system, defined as a bio-CFC, was proposed to recover SG energy from synthetic seawater (30 g/L NaCl) and river water (1 g/L NaCl) efficiently. The maximum power density of the bio-CFC reached 42 ± 2 W/m2, which was three times higher than that of a single CFC (10.6 ± 0.1 W/m2). The significant improvement was attributed to the additionally developed capacitive potential, which was formed by the bioelectrochemical currents from degradation of the organics in wastewater. The capacitive potential enhanced the Na+ intercalation/deintercalation on the electrodes and accelerated the Cl− transfer across the anion exchange membrane. This new strategy provides a promising way to recover energy from seawater and wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ion sorption on EDL and pseudocapacitor was studied at constant potential. • α-MnO 2 was the best in diffusive capacitance among polymorphs. • Effects of ion solvation and valence on sorption of inert ions were studied. • Monolayer capacity as affected by electrode polarity was estimated via Langmuir model. • Isoelectric point of the reversible MnO 2 /AC composite was modified. The capability of manganese dioxide (MnO 2) supported on loofah-derived activated carbon (AC) in the electrosorptive removal of common inert ions was studied in constant potential mode. Four MnO 2 polymorphs were prepared by redox chemical precipitation and characterized by XRD, SEM, BET and XPS. The pseudocapacitance property of the MnO 2 /AC electrode, significantly affected by the surface- and diffusion-controlled charge storage mechanism, was assessed via voltammetry and modified Langmuir adsorption isotherm. Batch electrosorption experiments were then performed at constant potential in the range of −1.5 V to + 1.5 V (vs. Ag/AgCl) using AC and α-MnO 2 /AC electrodes in the presence of common simple electrolytes, including NaNO 3 , Li 2 SO 4 , and Ca(ClO 4) 2. Consequently, the applied working potential (E app) positively affected the ion electrosorption rate and capacity. Faradaic processes occurred on MnO 2 , i.e., Mn(III)/Mn(IV) transition, increased the diffusion capacitance of AC, thus enhancing the first-order rate and monolayer capacity, mainly for the electrosorption of cations. Results showed that ion solvation, controlled by the ionic radius and valence of an ion, which impacted ion intercalation in MnO 2 and affected ion adsorption characteristics. The cation sorption capacity of α-MnO 2 /AC followed the order of Na+ (2.8 × 10-4 mol g−1) > Ca2+ (2.1 × 10-4 mol g−1) > Li+ (0.76 × 10-4 mol g−1) at E app = -1.5 V. The differential capacitance as affected by polarized potential and the shift of zero net charge or IEP toward more positively charging potential further highlighted the contribution of pseudocapacitance to ion adsorption on α-MnO 2 /AC electrode. [ABSTRACT FROM AUTHOR]

[Display omitted] • QRAC electrodes selectively adsorb NO 3 – due to the difference in binding energy. • The selectivity coefficient of QRAC-5 to NO 3 – reaches 2.7 at 0.4 V. • The electrosorption behavior of QRAC depends on physical adsorption and ion exchange adsorption. Nitrate pollution has become an increasingly serious water pollution problem worldwide. Capacitive deionization (CDI) technology is an emerging water treatment technology that can efficiently remove nitrate in water with advantages of simple process, high water recovery rate, low cost and energy consumption. In this work, we engineer a covalently bonded quaternized activated carbon (QRAC) material by silanization and investigate its selective adsorption of nitrate in mixed solution with extended voltage capacitive deionization (eV-CDI) mode. The results show that (1) the QRAC electrodes achieve selective adsorption due to the different adsorption binding energies of the quaternary ammonium group with Cl- and NO 3 –. The selectivity coefficient of QRAC-5 to NO 3 – reaches 2.7 at 0.4 V and the electrosorption capacity is 140% higher than that of AC in 5/5 mM KCl/KNO 3 solution. (2) The electrosorption of QRAC electrodes are dominated by two aspects: physical adsorption by external electric field which occurs in the incipient stage and ion exchange adsorption by quaternary ammonium groups occurring in the following stage. (3) CDI experiments in simulated municipal wastewater show that SO 4 2- had a negative effect on the adsorption capacity of NO 3 –, but QRAC electrode can still achieve separation effect in Cl-/NO 3 – solution system. These results show that covalently bonded quaternized activated carbon can achieve the effective separation and removal of NO 3 – in polluted water, and our work provides new insights into the selective electrosorption of CDI technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polysaccharides-bound porous graphene electrodes were rationally designed. • Oppositely charged groups at cathode and anode weakened the co-ions exclusion effect. • The asymmetrical configuration gave rise to 97.9% removal ratio for U(VI). • The mechanism involves improved EDL, extra micro electric field and complexation. As an energy-saving and facile technology, the potential of capacitive deionization (CDI) starts to surface in enrichment and recovery of uranium (U(VI)) from aqueous solutions. However, co-ion expulsion effect and poor surface wettability of electrode materials limit the eletrosorption performance. Here, polysaccharides xanthan gum (XG)- and chitosan (CS) -bound porous reduced graphene (RGH) electrodes were rationally designed, and then assembled into asymmetrical electrode configuration for U(VI) eletrosorption. Owing to the introduction of polysaccharide binders, the oppositely charged groups on the surface of cathode and anode weaken the co-ions exclusion effect as well as endow their superior surface hydrophilicity and electroconductivity, which facilitates the electrosorption for U(VI). Meanwhile, the negatively charged carboxylate groups could act as extra micro electric fields to attract U(VI) cations, and form stronge complexation between them. As a consequence, asymmetrical polysaccharide-bound RGH configuration gave rise to a larger removal ratio of 97.9% within 4 h at 1.2 V, as well as 2.5 times faster kinetics than symmetrical PVDF-bound RGH electrode configuration. Moreover, the accumulated adsorption capacity in six adsorption–desorption cycles of the former is up to 1413.0 mg g−1, 75% higher than the latter, which is of practical significance and economic benefit for electrosorption application. [ABSTRACT FROM AUTHOR]

[Display omitted] • CM-CNT/graphene electrode was directly constructed by core-sheath 3D printing. • Electrode features hierarchical pores and highly interconnected conductive network. • Electrode enables adequate channel and pathway for ultrafast ion/electron transport. • Pseudocapacitor exhibits prominent stability and electrochemical performance. Pseudocapacitance holds great promise for energy density improvement of supercapacitors. However, how to enable a pseudocapacitor with combined feature of high mass loading of pseudocapacitive material, efficient ion/electron transport, as well as facile and scalable manufacturing, still remains a significant challenge. Herein, we demonstrated an efficient and scalable extrusion-based core-sheath 3D printing strategy for directly and controllably constructing pseudocapacitive carbon nanotube (CNT)- MoS 2 (CM)-CNT/graphene electrode, with high mass loading up to 55% and uniform distribution of MoS 2 , hierarchically porous configuration and highly interconnected conductive network framework built by coupling graphene scaffold located in shell layer and CNTs situated in core layer. The unique architecture featuring adequate channels and pathways can act as a "superhighway" for ultrafast ion diffusion and electron transport throughout the entire device, thereby enabling fast kinetics of Faradaic reactions and abundant availability of electrochemical active sites. A symmetric pseudocapacitor assembled with 3D-printed electrode and in situ electrospun poly(vinylidene fluoride) (PVDF) nanofiber separator delivered high specific capacitance (558 mF cm−2) and energy density (49 µWh cm−2), remarkable cycling stability (87% after 8000 cycles), and superior capacity even at large electrode thickness. This work has shed light on new strategies for designing and fabricating high-performance pseudocapacitors toward future uses. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ion removal performance of FCDI was greatly enhanced via cathodic iodide redox couple. • A similar positive effect noticed during desorption upon polarity reversal. • The system exhibited a stable behavior over multi-cycle consecutive runs. • The approach holds great promise in treatment of iodide-containing saline wastewater. Flow-electrode capacitive deionization (FCDI) is attracting growing attention owing to its advantages such as effective ion removal capacity and easy management of the electrodes. Optimization of the flow-electrode comprising carbon materials and aqueous electrolyte is always a research hotspot aimed at improving FCDI performance. Herein, we innovatively introduced appropriate amount of KI 3 into the cathodic flow-electrode to provide a highly efficient means of enhancing FCDI desalination performance with a stable behavior in salt electrosorption and desorption over multi-cycle consecutive runs. The accelerated salt removal rate originated from the reversible redox reaction of I 3 −/I− and the maintenance of the electro-neutrality of the global electrolyte. Although possible minor release or leakage of I−/I 3 − through the cation-exchange membrane and into the treated water occurred, which makes the proposed approach not quite suitable for potable water production, we demonstrated that this system has great application prospects in treatment of iodide-containing saline wastewater without causing secondary pollution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemical capture and release of Cd2+ were conducted using Cu-MOF-74. • Selective removal of Cd2+ (>95%) was feasible under Na/Cd ~ 2 × 104 in molar ratio. • Redox of Cu within the MOF enables energy-efficient electrosorption/regeneration. • Excellent electrosorption (>100 mg/g) and regeneration (>90%) were achieved. An electrochemically-assisted wastewater treatment using Faradaic materials offers a promising technique for the selective removal of hazardous substances. Here, we demonstrate the reversible capture and release of cadmium ions in aqueous solutions, using a redox-active metal-organic framework (MOF) electrode. As-synthesized copper-based MOF (Cu-MOF-74; copper 2,5-dihydroxyterephthalate) is a highly attractive candidate for Faradaic electrosorption due to its large surface area, water stability, and redox-active metal nodes. Our work demonstrates the reversible capture and release of Cd2+ ions assisted by the electrochemical redox reaction of Cu2+/Cu+ within the MOF structure. Combined material characterization and electrosorption tests were carried out to determine the operational conditions for maximizing adsorption capacity, energy efficiency, and material stability, thus leading to excellent electrosorption (>100 mg g−1) and regeneration efficiency (>90%). This study demonstrates the feasibility of leveraging MOFs containing redox-active metal nodes for the selective separation of toxic cations, and paves the way for promising future applications of these 3-D porous structures for wastewater treatment and environmental remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simultaneous and precise recovery of lithium and boron from salt lake brine. • Capacitive deionization with oxygen vacancy-rich CoP-graphene aerogel as electrode. • Adsorption capacity of Li+ and B(OH) 4 − is 37 mg/g and 70 mg/g (Mg/Li = 24, Cl/B = 70) • A good and stable performance of CDI system with >92% of recovery after 10 cycles. • Synergy of oxygen vacancy, hydrophilicity, P-metal interaction and low resistance. Lithium and boron recovery from salt lake brine is highly important for resource utilization and environmental risk reduction, particularly as an alternative source of the critical raw lithium materials for lithium ion batteries. This study develops a novel capacitive deionization (CDI) method to simultaneously and precisely extract Li+ and B(OH) 4 − ions from salt lake brine with high Mg/Li ratio. Using oxygen vacancy-rich CoP/Co 3 O 4 -graphene aerogel (GA/CoP/Co 3 O 4) as the bifunctional anode and cathode, the effective adsorption capacity of Li+ and B(OH) 4 − ions reached 37 mg/g and 70 mg/g, respectively at the Mg/Li ratio of 24:1 and Cl/B ratio of 70:1. The excellent selectivity and efficiency could be attributed to the synergistic effect of rich oxygen vacancy, better hydrophilicity, flexible P-metal interaction and low internal resistance. The CDI system also has a good and stable performance of electrochemical adsorption-desorption, reaching >92% of recovery after 10 cycles. This paper provides a green and efficient method for recovery of valuable elements from salt lake brine and reduction of environmental risk. [ABSTRACT FROM AUTHOR]

[Display omitted] • Diprophylline modifies the work function of ITO and increases the transmittance of P3CT-Na HTL. • The doped diprophylline could simultaneously interact with ITO and P3CT-Na. • The diprophylline could fix P3CT-Na onto the ITO substrate and enhancing the durability of HTL. • Inverted PSCs utilizing diprophylline doped P3CT-Na HTL yield a remarkable efficiency of 20.87%. • The device fabricated with ultrasonically cleaned doped HTL showed an efficiency of 18.77%. Poly[3-(4-carboxybutyl) thiophene-2,5-diyl] (P3CT) is extensively used as hole transport layers (HTL) for efficient inverted perovskite solar cells (PSCs). However, some drawbacks of P3CT-Na such as strong aggregation tendency and unwell-matched energy alignment restrict the application of P3CT-Na-based devices. Here, diprophylline is first used to modify the P3CT-Na HTL in inverted PSCs. Diprophylline modifies work function of ITO (indium tin oxide) by self-assembling onto the ITO surface. Meanwhile, it could interact with P3CT-Na through hydrogen bonding interaction, thus inducing ordered arrangement of P3CT-Na molecules, and increasing transmittance of the HTL. In addition, diprophylline could partially dissolve into the upper perovskite layer, and facilitate the perovskite crystallization. As a result, inverted PSCs utilizing diprophylline added P3CT-Na as HTL yield a remarkable efficiency of 20.87% and excellent long-term stability. Notably, the fill factor (FF) is approaching 84%, representing one of the highest results in inverted PSCs. More interestingly, when the diprophylline treated P3CT-Na layer undergoes ultrasonic cleaning in deionized water for 10 mins, the as-fabricated PSCs still show a high efficiency of 18.77%, manifesting good durability of the HTL. Thus, the recyclability and cost-effectiveness of the HTL makes it more applicable in future commercialization. This work provides a new strategy of improving efficiency and long-term stability of inverted PSCs through HTL engineering. [ABSTRACT FROM AUTHOR]

[Display omitted] Ion electrosorption in sub-nanometer carbon micropores enables ion separation. • Studies ion selectivity in nanoconfinement applying online chemical monitoring. • Ion selectivity based on pore size effect, charge effect, and desolvation energy effect. • Observed ion sieving effect and the influence on ion selectivity. Subnanometer pores of carbon discriminate against ions based on their size. Capitalizing on such nuanced differences enables ion separation via charge/discharge cycling during ion electrosorption. Different ion uptake capacities in aqueous media with multiple, competing ions are also of high importance to understand capacitive deionization of surface water or industrial process water. In our experiments, we observed divalent cations sieving in pores smaller than 0.6 nm. By applying this phenomenon, a desalination cell with online concentration monitoring was used to study the ion-selectivity. We concluded that in pores below 0.6 nm, divalent Mg2+ and Ca2+ are entirely blocked, and the K+ over Na+ selectivity corresponds with their size ratio. Larger micropores show a preference for divalent cations with higher charge numbers. In both materials, a dynamic monovalent cation and divalent cation replacement dependent on the potential variation is observed. [ABSTRACT FROM AUTHOR]

[Display omitted] • CDI hybrid systems are more promising than standalone CDI technology. • Current developments and challenges are extensively discussed. • MFC powered CDI systems are a suitable solution for sustainable water treatment. • Technical and economic barriers need to be overcome to make hybrid systems practical. The collective negative impact of both energy depletion and freshwater scarcity has inspired the researchers to develop effective water treatment approaches with lower energy consumption. Capacitive deionization (CDI), an emerging technology for water treatment and desalination is gaining global interest because of its ion selectivity, high water recovery and energy efficiency. Over the last two decades, CDI has gone through several modifications and advancements in terms of module configuration, electrode material and its applicability. For further enhancement in practicability and commercialization of CDI, researchers have shown a broad range of interest in CDI hybrid systems over the past few years. CDI modules have been integrated with photochemical, membrane separation, ion exchange, electrochemical oxidation and bioelectrochemical processes for desalination, wastewater treatment, energy recovery, resource recovery and performance enhancement. These integrated systems are more promising compared with standalone CDI technology. This comprehensive and state of the art review examine different CDI hybrid systems on the basis of working mechanism, module configuration, operating parameters and their effects on system performance. Moreover, synergetic effects, limitations and challenges of these hybrid systems towards their large scale implementation also have been addressed in this review paper. [ABSTRACT FROM AUTHOR]

This work provides a new synthetic conception for the synergistic effect of ZIF and LDH on the construction of unique hollow nanoarrays, simultaneously proposes a feasible means for designing dual-functional catalysts for efficient overall water splitting. [Display omitted] • Ordered self-supported CuO@CoZn-LDH nanoarrays have been successfully prepared. • The hollow structure with defect-rich pores facilitates electrocatalytic. • The CuO@CoZn-LDH exhibits outstanding electrocatalytic activity and stability. Driving the electrochemical water splitting is considered as a green and sustainable method to produce hydrogen energy. Herein, a novel strategy to fabricate the dual-metal zeolitic imidazolate framework (CoZn-ZIF) nanocrystals on Cu(OH) 2 nanowires supported by Cu foam (CF) as a precursor to change the conventional LDH growth has been proposed. It can obtain highly ordered hollow CuO@CoZn-LDH nanoarrays with defect-rich porous surface for efficient overall water splitting. Specifically, the appropriate adjustment of Co/Zn metal ratios in the ZIF precursor could lead to a well-defined morphology to create the defect-rich porous surface, which exposes more active sites and the accessibility of electrolyte to promote the electrocatalytic efficiency. The obtained hollow CuO@CoZn-LDH/CF nanoarrays catalyst exhibits an excellent activity in alkaline media with the low overpotentials of 194 mV and 124 mV at the current density of 10 mA cm−2 for OER and HER, respectively. Remarkably, as bifunctional electrodes for overall water splitting, it displays an alkali-electrolyzer with a low cell voltage of 1.55 V at the current density of 10 mA cm−2, and can be comparable to commercial the IrO 2 @CF||Pt/C@CF couple catalyst. The work provides a new prospect for the rational design and fabrication of advanced hierarchical multifunctional electrocatalysts in electrochemical energy device application. [ABSTRACT FROM AUTHOR]

The ZIF-9(III)/Co LDH layered composite was successfully synthesized by a one-step controllable phase transition from ZIF-9(I). ZIF-9(III)/Co LDH nanosheets shows great OER electrocatalytic activity and exhibits a low overpotential of 297 mV at the current density of 10 mA cm−2 in 1.0 M KOH due to the high surface area, abundant metal sites and synergistic effect. [Display omitted] • A novel ZIF-9(III)/Co LDH was prepared by controllable phase transition of ZIF-9(I). • The fascinating structures and compositions of ZIF-9(III)/Co LDH are reported. • The optimized ZIF-9(III)/Co LDH exhibits efficient electrocatalytic performance. The quest for desirable two-dimensional (2D) materials and facile strategies to construct 2D layered composites with fascinating structures and compositions for high-performance electrocatalysis is still a major challenge. In the present research, novel nanocomposites of 2D zeolitic imidazolate framework-9 (ZIF-9) combined with Co-layered double hydroxide (Co LDH) were successfully synthetized through a controllable phase transition from ZIF-9(I). The 3D to 2D structural transformation of ZIF-9 was induced by deionized water, and the formation of 2D Co LDH was simultaneously realized during the one-step fabrication of ZIF-9(III)/Co LDH nanocomposites. Due to the high surface area, the presence of abundant metal sites, and the interactions between 2D ZIF-9(III) and 2D Co LDH, the as-optimized ZIF-9(III)/Co LDH nanocomposite exhibits great electrochemical activities for oxygen evolution reaction (OER) (η = 297 mV at 10 mA cm−2) in 1.0 M KOH solution. The electrochemical performance of the ZIF-9(III)/Co LDH nanocomposite was superior to those of the pure Co LDH, ZIF-9(III), and commercial RuO 2. The present work demonstrates that the proposed strategy can effectively boost catalytic activities and also design new routes to synthesize advanced MOF nanohybrids for various applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanically combined Na 2 S 2 O 8 and ZVI (PSZVIbm) was developed using ball milling. • Rapid destruction of the passive layer was found in PSZVIbm at neutral pH. • Surface-combined Na 2 S 2 O 8 showed different effects on oxidation and reduction. • Main radical species were different depending on the persulfate injection method. Persulfate (S 2 O 8 2−; PS) has been used with zerovalent iron (ZVI) for the remediation of various contaminants. However, the passive layer of commercial ZVI limitates the corrosion of ZVI and reaction with PS. In our initial attempt, we mechanically combined Na 2 S 2 O 8 and micro-sized ZVI by simple ball milling to improve the reaction of PS and ZVI. The synthesized composite (PSZVIbm) was compared to the system in which Na 2 S 2 O 8 was separately injected with ball-milled ZVI (ZVIbm/PS). The reaction in ZVIbm/PS depended on surface-bound Fe(II) to initiate PS consumption. Conversely, the PS immediately destroyed the passive layer and enhanced the corrosion of ZVI in PSZVIbm. Therefore, PSZVIbm reduced nitrobenzene rapidly with higher efficiency in deionized water (94.2%) compared to that of ZVIbm/PS (73.1%). Furthermore, PSZVIbm was less affected by the real groundwater matrix and removed nitrobenzene with higher efficiency (64.7%) than ZVIbm/PS (10.3%). Due to the different PS consumption rates and radical species, PSZVIbm removed phenol with lower efficiency (22.7%) than ZVIbm/PS (61.5%), showing the different effects of surface-bound Na 2 S 2 O 8 on the reduction/oxidation capacities of ZVI. This study suggests a new scalable method to control the reactivity of ZVI without the use of toxic chemicals and wastewater generation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-supported electrocatalysts are prepared via solid-state diffusion. • Effective mass-transfer between carbon-layers and Ni endowing electrocatalyst with ultrahigh activity. • The district confinement of CNTs and heteroatomic doping collaboratively promotes kinetics. To satisfy the practical requirements of electrochemical water splitting, developing a flexible, effective and sustainable approach for scalable production of bifunctional electrocatalyst for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is a tremendous issue to be rationally addressed. Herein, a solid-state diffusion strategy with Ni foam and N-doped carbon layers is applied to prepare multi-interfacial, self-supported and N-doped carbon nanotube (NCNT) encapsulated Ni nanoparticles (NPs) array bifunctional electrocatalyst (NCNT-NP@NF). Prominently, this NCNT-NP@NF is scalable to meet the application requirements and can be used as a binder-free electrode for direct the water splitting. The optimal sample demonstrate outstanding HER/OER performance in 1.0 M KOH, with low overpotential (η 10) at 10 mA cm−2 during HER (96.1 mV) and OER (240 mV) process, which is extremely superior to the most reported metal-based electrocatalysts and even better than commercial IrO 2 (400 mV at 10 mA cm−2 for OER). Strikingly, when these bifunctional electrocatalysts are employed in a dual-electrode electrolyzer for water splitting, the NCNT-NP@NF only needs cell voltage of 1.54 V to drive overall water splitting in 1.0 M KOH, and displays excellent long-term stability (150 h for water splitting). Moreover, experiments combined with density functional theory (DFT) calculations clarify that the remarkable electrochemical activity and stability are mainly attribute to the synergistic effect of the uniform distribution of Ni NPs, heteroatomic doping, as well as district confinement effect of NCNT leading to enhanced electronic multi-interfacial transmission, all these factors co-accelerate electrocatalytic kinetics. Accordingly, this solid-state diffusion method possesses a favorable potential to construct a multi-interfacial and self-supported electrocatalysts in the fields of sustainable supply of clean energies. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZIF-8 has antibacterial properties superior to ZnO, a benchmark nanomaterial. • ZIF-8 displays variable antibacterial performance in different liquid environments. • Degradation pathways and by-products affect MOFs' antibacterial performance. • ZIF-8 degrades more in culture media than in deionized water, and faster than ZnO. • MOFs' aqueous stability must be fully understood for their application development. The stability and degradation characteristics of metal–organic frameworks (MOFs) in liquid media dictate their use in biomedical engineering applications. In this study, the antibacterial property of a zinc-based MOF, zeolite imidazolate framework-8 (ZIF-8), against gram-negative Escherichia coli (E. coli) is studied in comparison with ZnO, a widely-used antimicrobial agent. Superior antibacterial property of ZIF-8 was demonstrated and the reason was elucidated by new insights on the stability of ZIF-8 in bacterial culture media. Contrary to the widely held notion that ZIF-8 is stable in aqueous media, inductively coupled plasma-optical emission spectrometry and UV–Vis adsorption spectroscopy revealed the release of zinc ions and 2-methyilimidazolate molecules in the culture media. Electron microscopy and X-ray diffractometry revealed that the degradation of ZIF-8 is enhanced by the reaction of released zinc ions with phosphate ions in phosphate-buffered saline (PBS) or with organic moieties in Luria Bertani (LB) media, resulting in stronger antibacterial properties of ZIF-8 than that of ZnO. In fact, due to the affinity of ions and organic constituents in the cell media towards the building block of ZIF-8 structure, a higher amount of ZIF-8 degrades in LB and PBS media (70–80 wt%) than in pure water (22 wt%) after 24 h of immersion. The results of the present investigation strongly advocate the importance of stability study on MOFs in developing their biomedical applications, in terms of its efficacy, biosafety and eco-safety. [ABSTRACT FROM AUTHOR]