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Biomass-derived nanocarbons with natural intramolecular N,S frameworks are impressively used to fabricate DACs with pairwise-dual-atoms on a gram-scale for highly efficient oxygen reduction reaction.

A simple, efficient, and environmentally friendly electro-Fenton (EF) process is highly demanded for EF practical application. Herein, a highly practical double-cathode EF system has been developed...

Field-effect transistors (FETs) receive growing attention for gas detection owing to their superior sensing performance over traditional techniques. The sensitivity and selectivity of FET sensors can be enhanced by tuning the structure of channel materials via doping, surface functionalization, hybridization, etc. However, the intrinsic semiconductor characteristics of the channel material and its gas adsorption capacity largely determine the sensing performance. In this work, we compared the room-temperature sensing performance of FET sensors with few-layer graphene, black phosphorous (BP), and MoS2 with mixed polymorphic phases (metallic 1T phase and semiconducting 2H phase), and 2H-MoS2 as a channel material for formaldehyde. The sensing results indicate that 1T/2H-MoS2 exhibits the best sensitivity, response time as well as selectivity for formaldehyde detection. The theoretical calculation demonstrates that 1T/2H-MoS2 yields the optimum semiconducting properties and gas adsorption capability for formaldehyde over other 2D channels. Moreover, by investigating the sensing performance under humid conditions, it was discovered that high humidity enhances the sensing response. This study demonstrates that the regulation of the intrinsic electronic structures of the 2D semiconducting channel directly affects the gas detection performance.

Two-dimensional (2D) Ti3C2Tx MXene has shown great potential in the energy storage field, and its performance strongly depends on the intercalation of cations. Therefore, engineering its interlayer...

Removal of uranium from groundwater is of great significance as compared to in situ bioimmobilization technology. In this study, a novel direct electro-reductive method has been developed to efficiently remove and recover uranium from carbonate-containing groundwater, where U(VI)O

Metallic 1T phase molybdenum disulfide (1T-MoS2) holds great promise in energy storage applications due to its excellent conductivity and hydrophilicity. However, free 1T-MoS2 nanosheets are prone to agglomeration and convert to 2H-MoS2, resulting in a decrease in electrochemical performance. In this study, metallic 1T phase MoS2 nanosheets are confined among TiO2 nanotube arrays (1T-MoS2@TiO2/Ti) via a facile hydrothermal process. The architecture in the glory of ultrathin 1T-MoS2 nanosheets and highly ordered pore tunnel of TiO2 nanotube arrays benefits fast electrolyte diffusion and electron transfer. As a result, the 1T-MoS2@TiO2/Ti composite shows a high specific capacitance of 428.1F g−1 at 0.2 A g−1, high energy density of 48.2 Wh kg−1, high power density of 2481.7 W kg−1 and 97% capacitance retention after 10,000 cycles. This study proves an artful thought for designing electrode materials to enhance their electrochemical performances.

Mercury ions (Hg2+) are the dominant mercury species in water, and have severe toxic effects on human health and the ecosystem. Due to the limitations of traditional analytical methods for mercury determination, e.g., complex pretreatment, costly instruments, and being unsuitable for low-level online sensing, numerous efforts have been made to develop rapid, low-cost, and portable sensors for Hg2+ determination. The excellent characteristics of graphene, i.e., a unique two-dimensional structure, large surface area, high conductivity and carrier mobility, and good optical and electrochemical properties, lead to intense studies on graphene-based Hg2+ sensors with desirable performance and broad application prospects. The scope of this review is recent advances in graphene Hg2+ sensors with a special focus on optical, electrochemical, and electronic sensors. The working principles and advantages of representative graphene Hg2+ sensors are introduced and compared with traditional methods. Moreover, challenges as well as potential solutions and research directions of mercury sensors are discussed, which will guide future research of Hg2+ sensors in biomedical and environmental monitoring applications.

Heat dissipation is a critical issue in high-performance electronics, which needs to be solved, and an electronic paste is a good choice to solve this issue. In this paper, silver nanoparticles/multi-walled carbon nanotube (Ag-NPs/MWCNT) composites were prepared by the chemical process for the modification of electronic pastes. The micromorphology and spectral analysis of the as-prepared Ag-NPs/MWCNT composites indicated that Ag-NPs were uniformly distributed on the MWCNT surfaces with high distribution densities; the average size of Ag-NPs was estimated to be 8.29 nm. The as-obtained Ag-NPs/MWCNT composites were then added to a silver-epoxy paste. Field emission scanning electron microscopy (FESEM), thermogravimetry (TG) and thermal conductivity analyses suggested the incorporation of Ag-NPs/MWCNT composites in the silver-epoxy paste; Ag flakes were better connected by Ag-NPs/MWCNTs, which improved the thermal conductivity of the paste from 0.73 to 0.96 W m−1 K−1. However, more weight loss was observed when Ag-NPs/MWCNTs were incorporated in the silver-epoxy paste. Overall, the addition of Ag-NPs/MWCNTs into the silver-epoxy paste increased the thermal conductivity, which can be applied to high-performance electronics.

Integration of oxidation and adsorption of adsorbents is highly desired to deep remove As(III) in groundwater. In this study, a superparamagnetic Fe3O4@SiO2@Fe2O3- CuO/TiO2 (Mag@Fe-Cu/TiO2) adsorbent was synthesized using step-by-step precipitation process. The TiO2 nanoparticles were rationally positioned onto the shell of Fe2O3-CuO for oxidization of As(III). The Fe2O3-CuO binary oxide significantly improved As(III, V) adsorption compared to individual oxide (Fe2O3 or CuO). The ingenious design of the adsorbent could give full play to oxidation and adsorption functions. As a result, Mag@Fe-Cu/TiO2 showed much better As(III) removal performance than Mag@Fe-Cu-TiO2 prepared by co-precipitation. The maximal adsorption capacity of Mag@Fe-Cu(7)/TiO2(8.74) for As(III) reached to 17.49 mg/g under UV irradiation. The removal of As(III) in groundwater was tested using Mag@Fe-Cu/TiO2 adsorbent. Almost all the As(III) were removed under UV irradiation (t = 24 h for C0 = 1–5 mg/L or 12 h for C0 = 20–1000 μg/L, adsorbent dose = 1 g/L, pH = 7.0, T = 25 °C). Moreover, it could be easily separated from treated water with an external magnet and well reused maintaining a high As(III) adsorption capacity. Furthermore, the adsorbent could effectively treat arsenic spiked natural groundwater. The adsorption followed the inner-sphere complex mechanism via the chemical interactions between metal (M: Fe and Cu) and arsenic species (As) forming M O As bonds.

Prednisolone (PDNN) as an emergent micropollutant directly influences the regional ecological security. In this study, the degradation of PDNN by ultraviolet activated chlorine (UV/chlorine) oxidation process was comprehensively evaluated. The quenching experiment suggested that the PDNN degradation in UV/chlorine process was involved in the participation of hydroxyl radical ( OH) and reactive chlorine species (RCS). Influence factors including chlorine dosage, pH, common anion and cation, fulvic acid (FA) on PDNN degradation via UV/chlorine process were investigated. A low chlorine (≤7.1 mg L−1) promoted the PDNN degradation, while a high chlorine dosage (>7.1 mg L−1) was adverse. The pH (4.0–10.0) showed negligible effect, while the investigated anions (Cl−, Br−, HCO3− and SO42−), NH4+ and FA exerted negative impact on PDNN degradation. An efficient process to minimize pharmaceutical micropollutants was the disposal of human urine containing a high concentration of pharmaceutical and potential toxic metabolites. An inhibitory effect was observed in the synthetic urine (fresh urine and hydrolyzed urine). The intermediates/products were identified and the mechanism of PDNN degradation was proposed. PDNN gone through three degradation routes, involving the direct addition of α, β-unsaturated ketone at C1 or C5, the photolysis of C17 and H-abstraction of C11. The main reactive sites were further determined by comparison of the frontier orbitals calculation and the proposed mechanism. Based on the toxicological tests for PDNN degradation, TP396 (TP396-C1Cl and TP396-C5Cl) and TP414-2-1 (TP414-C1Cl C5OH) exhibited much higher toxicity than PDNN, and prolonging reaction time was necessary to achieve PDNN detoxification.

Narrow pH application range and tepid reaction kinetics greatly hinder the efficacy of heterogeneous Fenton and electro-Fenton technologies. Herein, a hollow sea-urchin-shaped carbon-anchored single-atom iron (SAFe@HSC) derived from metal organic framework has been developed as a dual-functional electro-Fenton catalyst for O2 reduction to H2O2 followed by in situ activation to •OH. Benefited by the unique structure and atomically dispersed iron, the electro-Fenton system exhibits fast reaction kinetics in a wide pH range from 3 to 11. For instance, 120.7 mmol gcatalyst−1 (7.5 mol gFe−1) H2O2 and 50.7 mmol gcatalyst−1 (3.1 mol gFe−1) •OH can be detected simultaneously at 60 min (20 mA cm−2 and pH 7). As a result, the mass kinetic constants of refractory thiamphenicol (TAP) degradation are as high as 4506 min−1 gFe−1 (pH 3), 4099 min−1 gFe−1 (pH 5), 4037 min−1 gFe−1 (pH 7), 2974 min−1 gFe−1 (pH 9), and 2595 min−1 gFe−1 (pH 11). The TAP removal efficiency in static flow process achieves nearly 100% within 40 min, showing a high total organic carbon (TOC) removal of 85% in 2 h (pH 7, 20 mA cm−2, C0 = 20 mg L−1, 1.5 mg of catalyst). It is the highest electro-Fenton activity among the reported catalysts for pollutant degradation at pH above 5. Furthermore, the TAP removal keeps 97% and the TOC removal reaches as high as 82.2% in the continuous-flow process (C0 = 20 mg L−1, pH 7, 20 mA cm−2, flow rate = 2 mL min−1). Moreover, only 1.5% Fe is leaked within 6 h. This study develops a highly efficient electro-Fenton catalyst for the treatment of organic wastewater.

Iron oxide-modified biochars are increasingly recognized as a promising arsenic adsorbent. However, most of them face serious challenges in the rapid and efficient removal of As(III). Herein, we integrated the iron oxide nanoneedles vertically covered biochar fibers (Fe-BFs) with H2O2 and Hydroxylamine (HA) to construct a heterogeneous catalytic system for the rapid oxidation and deep removal of As(III) from water. The system oxidized the As(III) to As(V) with high efficiency, and then the generated As(V) could be rapidly removed by adsorption onto Fe-BFs. The removal efficiency of As(III) by Fe-BFs/H2O2/HA at 120 min reached up to 98.93%, which is much higher than that of by Fe-BFs (69.20%) and Fe-BFs/H2O2 (92.32%). The system could work reliably in a wide pH range (4–10). Moreover, fixed-bed column experiments demonstrated that the addition of H2O2 and HA could increase the effective treatment volume from ~350 bed volume (BV) to ~700 BV to meet the drinking water standard ( OH. The OH played a very important role in promoting the removal of As(III). This study offers a new strategy to enhance the applicability of Fe modified biochar for As(III) removal.

Phenicol antibiotics (PABs) degradation by UV/H2O2 is important because we need to determine the reduction in toxicity and disinfection byproducts for post-chlorine. In this study, the degradation of PABs, including florfenicol (FLO), chloramphenicol (CAP) and thiamphenicol (THA), was examined. The pseudo-first order degradation rate constants of PABs were 3 times higher in ultrapure water (UW) than that in synthetic wastewater (SW) for these conditions: [PABs]0 = 1 μM, [H2O2] = 0.1 mM, and I0 = 1.985 × 10−6 E L−1 s−1. Fulvic acid (FA) and HCO3– inhibited PABs degradation, Cl− and NO3– concentrations of up to 5 mM and 10 mM had a negligible impact. The impact of water matrix on PABs degradation was successfully predicted using pseudo-steady-state kinetic model. The degradation of PABs was triggered via hydroxylation and/or hydrogen abstraction. The treatment of PABs via UV/H2O2 could decrease their antimicrobial properties, while the byproducts of FLO and THA showed higher acute toxicity in Vibrio fischeri. In addition, two identification products (TP-276 and TP-354) of FLO had higher ecotoxicity toxicity (using ECOSAR) in fish, daphnid and green algae. The trichloromethane formation potential (TCMFP) for PABs with post-chlorination in UW and SW can be reduced after UV/H2O2 compared to UV, and is related to the corresponding decrease of dissolved organic carbon (DOC).

Although UV/chlorine advanced oxidation process has been employed to treat contaminants, the roles of secondary radicals are generally negligible. The comprehensive evaluation of secondary radicals on contaminants degradation remains deficient. In this study, two typical neonicotinoid insecticides, imidacloprid (IMD) and thiacloprid (THIA), were degraded via UV/chlorine process. It is for the first time found that the existence of Cl− significantly promoted THIA degradation during UV/chlorine process, attributed to the formation of Cl2 −. In addition, the effects of pH, fulvic acid (FA), and bicarbonate (HCO3–) on the degradation of IMD and THIA were evaluated. Low pH was in favor of the degradation of IMD and THIA, while both FA and HCO3– had slight inhibition effects. Meanwhile, the degradation of IMD and THIA via UV/chlorine process was inhibited in real matrices. The existence of Br− heavily suppressed the degradation of THIA via UV/chlorine process. The initial transformation pathways of IMD and THIA involved electron transfer, H-abstraction, and then disproportionation or the methylene bridge cleavage, yielding hydroxyl and keto derivatives as well as free amine. Although the mineralization for IMD (29%) and THIA (35%) was low, the acute toxicity to Vibrio fischeri for the treated samples was lower than that for corresponding parent compounds. This study comprehensively evaluated the degradation of IMD and THIA via UV/chlorine process, highlighting Cl2 − as an important reactive species for THIA elimination.

A systematic study of the interaction between adsorbents and potentially toxic metal ions in multicomponent systems is of great significance due to the coexistence of multiple potentially toxic metal ions in the real water environment. In this study, a new humic substance-based double network hydrogel (PAA/HS gel) was produced by a radical polymerization method and applied to Pb(II), Cu(II) and Cd(II) removal in both individual and multicomponent systems under various conditions. The macroporous network structure (aperture ≈ 10 μm) and high water permeability of the PAA/HS gel could fully facilitate the active site exposure and increase the potentially toxic metal ion diffusion rate. The PAA/HS gel exhibited high theoretical adsorption capacities of 360.50, 151.00 and 412.76 mg g−1 for Pb(II), Cu(II) and Cd(II) in individual systems. Noticeably, both interference and promotion of adsorption behaviors were identified in multicomponent systems. In binary systems, the adsorption capacity and rate were decreased for Pb(II) and Cu(II), while increased for Cd(II). In ternary systems, the adsorption capacity and rate for Pb(II), Cu(II) and Cd(II) were decreased. The adsorption isotherms and kinetics were well fitted by Langmuir–Freundlich and Elovich models, respectively, indicating that the PAA/HS gel possessed a heterogeneous surface and various types of binding sites. The FTIR and XPS studies confirmed that both nitrogen- and oxygen-containing functional groups (i.e., amino, phenolic hydroxyl and carboxyl groups) were involved in the adsorption process, while the interactions between functional groups and Pb(II), Cu(II) and Cd(II) were different.

The azole fungicide fluconazole (FLC) is persistent in conventional wastewater treatment plants, thus posing potential threats to human and ecosystem health. This study investigated the oxidation of FLC in aqueous solution by thermally activated persulfate (TAP) under different operation conditions. Higher temperature greatly improved the removal rate of FLC (0.057 h−1 for 30 °C and 0.223 h−1 for 60 °C) and the relationship between pseudo-first-order rate constant (kobs) and temperature fit the Arrhenius equation, with a comparatively low activation energy of 37.8 kJ mol−1. The degradation rate constants were enhanced with the increase of PS concentration during FLC oxidation (0.072 h−1 for 1.0 mM PS and 0.50 h−1 for 20 mM PS). Solution pH influenced the kobs of FLC degradation and the highest and lowest degradation rates were obtained at pH 3 (0.51 h−1) and pH 5 (0.23 h−1), respectively. Increasing the level of natural water constituents (HCO3−, Cl−, and humic acid) significantly inhibited FLC degradation. Geometry optimization of FLC was performed using density functional theory (DFT) and the data indicated that the C3 atom in the benzene ring was the most reactive site. SPE-HPLC/MS/MS analysis showed that intermediate products could form during FLC oxidation by PS and the total organic carbon (TOC) results indicated that FLC could be mineralized into CO2 and H2O. Accordingly, a plausible pathway for the degradation of FLC by the thermally activated PS could be proposed. The results of this study suggested that TAP is an applicable approach for the removal of azole fungicides in water.

In this study, a paper spray ionization mass spectrometric (PS-MS) method was developed for the rapid in situ screening and simultaneous quantitative analysis of bisphenol A and its analogues, i.e., bisphenol S, bisphenol F, and bisphenol AF, in food packaging products. At the optimal PS-MS conditions, the calibration curves of bisphenols in the range of 1-100 μg/mL were linear. The correlation coefficients were higher than 0.998, and the LODs of the target compounds were 0.1-0.3 μg/mL. After a simple treatment by dichloromethane on the surface, the samples were analyzed by PS-MS in situ for rapid screening without a traditional sample pretreatment procedure, such as powdering, extraction, and enrichment steps. The analytical time of the PS-MS method was less than 1 min. In comparison with conventional HPLC-MS/MS, it was demonstrated that PS-MS was a more effective high-throughput screening and quantitative analysis method.

The metallic 1T-MoS2 has attracted considerable attention as an effective catalyst for hydrogen evolution reactions (HERs). However, the fundamental mechanism about the catalytic activity of 1T-MoS2 and the associated phase evolution remain elusive and controversial. Herein, we prepared the most stable 1T-MoS2 by hydrothermal exfoliation of MoS2 nanosheets vertically rooted into rigid one-dimensional TiO2 nanofibers. The 1T-MoS2 can keep highly stable over one year, presenting an ideal model system for investigating the HER catalytic activities as a function of the phase evolution. Both experimental studies and theoretical calculations suggest that 1T phase can be irreversibly transformed into a more active 1T′ phase as true active sites in photocatalytic HERs, resulting in a "catalytic site self-optimization". Hydrogen atom adsorption is the major driving force for this phase transition.

Transition metal phosphides (TMPs) have been one of the ideal candidates as low-cost and high-efficiency catalysts for hydrogen evolution reactions (HERs). We report herein a novel TMP architecture, Fe2P nanoparticles/reduced graphene oxide (rGO) nanosheets/Fe2P nanoparticles (Fe2P@rGO) sandwich-structured (Fe2P@rGO) nanowall arrays on a Ti plate. This nanostructure was easily prepared via one-step electrodeposition followed by a low-temperature phosphidation reaction. The Fe2P@rGO nanowall array film is featured with maximally exposed catalytic sites, fast electron and mass transport, and robust structure stability, and therefore it behaves as an excellent HER electrocatalyst. The Fe2P@rGO shows a low overpotential of 101 mV at a current density of 10 mA cm−2 and a small Tafel slope of 55.2 mV dec−1 with a large exchange current density of 0.146 mA cm−2. Furthermore, the catalyst exhibits superior durability evidenced by about 87% catalytic activity retention against about 55% for the commercial Pt/C catalyst after a 12 h test. The study presents a new nanoengineering strategy for high-performance TMP-based HER catalysts.

A ethylenediaminetetra-acetic acid (EDTA) cross-linked chitosan and N,N-methylenebis(acrylamide) (MBA) cross-linked polyacrylamide based double network hydrogel was successfully synthesized via a two-step method and then employed for heavy metal ion adsorption. Various adsorption conditions, such as pH, ionic strength, adsorbent dosage, and contact time were investigated. CTS/PAM gel have a theoretical maximum Cd(II), Cu(II), and Pb(II) sorption capacities of 86.00, 99.44, and 138.41 mg/g, respectively, at experimental conditions. The adsorption process of CTS/PAM gel on the heavy metal ion was identified to be endothermic and follows an ion-exchange reaction. The application of this gel adsorbent was demonstrated using practical industrial effluent. We found that it could effectively treat practical wastewater with all kinds of heavy metals. At an adsorbent dosage of 8 g/L, the total metal ions concentration declined from 448.5 to 5.0 mg/L. Simultaneously, the CTS/PAM gel exhibited remarkable mechanical ...

Photoelectrocatalytic (PEC) process is a rising approach to simultaneous removal of heavy metals and organic pollutants. However, electric field plays a dual role in the reduction of negatively charged metal species (e.g., Cr 2 O 7 2− ): Reduction driving force makes metal species move to cathode; electric field force pulls negatively charged species to anode. The reduction reaction of Cr(VI) (Cr 2 O 7 2− ) strongly depends on the concentration of both Cr 2 O 7 2− and H + on the surface of cathodes. The reduction of Cr(VI) in conventional PEC process must enhance proton concentration with a mass of strong acid or prolong reaction time. A highly effective PEC system was constructed with amino-modified carbon cloth as cathode and reduced graphene oxide functionalized TiO 2 nanotube arrays as photo-anode. The amino groups could concentrate protons to form quaternary ammonium cations which could adsorb Cr 2 O 7 2− ions through electrostatic interaction. The graphene functionalized anode greatly accelerated the mass transfer of organic pollutants onto photo-anode. Resultantly, Cr(VI) and 2,4-dichlorophenoxyacetic acid (2,4-D) could be removed faster at lower cell voltage compared with conventional PEC process and the electric energy consumption decreased by at least 50%. Furthermore, the proposed PEC process could be repeatedly utilized with highly stable working performance. This work would give a new insight into the development of cost-effective PEC process for treatment of Cr(VI)-containing wastewater.

Efficient elimination of antibacterial activity of halogenated antibiotics by dehalogenation pretreatment is desired for a biochemical treatment process. In this study, crystalline cobalt phosphide nanosheet arrays on a Ti plate (C-CoP/Ti) are fabricated by a simple electrodeposition and phosphorization process. The crystalline structure greatly promotes atomic hydrogen (H*) generation. Moreover, the nanosheet arrays can provide abundant active sites and accelerate electron transfer and mass transport. As a result, the dehalogenation rate of florfenicol (FLO, an emerging organic pollutant) on C-CoP/Ti is 11.1, 2.97, and 13.6 times higher than that on amorphous CoP/Ti, Pd/Ti, and bare Ti, respectively. The C-CoP/Ti electrode achieves 97.4% dehalogenation of FLO (20 mg L-1) within 30 min at -1.2 V (vs Ag/AgCl). Nearly 100% of Cl and 20% of F are broken away within 120 min, showing the highest electrocatalytic defluorination efficiency reported so far. Both experimental results and theoretical calculations reveal that the dehalogenation of FLO on C-CoP/Ti is synergistically accomplished via direct reduction of electron transfer and indirect reduction of H*. This study develops a highly efficient non-noble metal electrode material for dehalogenation of halogenated organic compounds.

Highly efficient planar heterojunction perovskite solar cells (PHJ–PSCs) with a structure of ITO/PEDOT:PSS/CH3NH3PbI3–xClx/PCBM/C60/Ag was fabricated, in which the compact and pinhole-free CH3NH3PbI3–xClx perovskite thin film was obtained using a mixture of precursors containing lead iodide (PbI2), lead chloride (PbCl2), and methylammonium iodide (CH3NH3I) at an optimized ratio of 1:1:4. The morphology and formation process of CH3NH3PbI3–xClx thin film was closely related to the annealing temperature and time, which would result in the controllable performance for the PHJ–PSC devices. The morphology, crystallization process, and element analysis suggested that the chlorine gradually diffused and sublimated from the film surface while the iodine moved to the surface, together with the removal of the pinholes in the film. The PHJ–PSCs with the as-prepared CH3NH3PbI3–xClx thin film showed good performance and excellent repeatability. The power conversion efficiency (PCE) up to 14.03% was achieved without obv...

Interface is one of the most important factors to influence the device stability, which directly determines the commercialization of perovskite solar cells (PSCs). The research disclosed the degradation process and mechanism of planar heterojunction (PHJ) PSCs with a structure of ITO/PEDOT:PSS/CH 3 NH 3 PbI 3 /PCBM/Al using in-situ experiments. The degradation of PHJ-PSCs is mainly attributed to the interface decay of perovskite/cathode. Large amount of bubbles formed quickly at the interface and grew up as PHJ-PSCs exposed to air. The cathode electrode easily peeled off from the devices that led to lose the efficiency completely after only 1 h exposure to air. On the other hand, the degradation driven by intrinsic decomposition of perovskite itself under atmosphere (humidity ∼ 45 RH%) was not obvious and the power conversion efficiency ( PCE ) could retain almost the same when only the perovskite layer was exposed to air for 200 h. Furthermore, annealing-free TiO 2 nanocrystalline particles (TiO 2 NPs) as an interface modification layer was inserted into PHJ-PSCs and dramatically improved the stability, of which the PCEs retained over 75% of its initial values after exposure to air for 200 h. The results provide important information to understand the degradation of PSCs and the improvement of the stability, which may potentially accelerate the development and commercialization of PSCs.

At the bedrock section of the auxiliary shaft of the Tong-ting coal mine, the sidewall has varying degradation degrees in different parts. The part on which water flowed is barely corroded, whereas the moist part near the pouring joints is seriously corroded. We first studied the mechanism of this phenomenon by chromatography, X-ray diffraction, and energy-dispersive X-ray spectroscopy. We then used simplified models built by particle flow code software (i.e., particle flow code in three dimensions, PFC3D) to analyse how increasing degradation depth affects compressive strength and failure patterns. The results were as follows. (1) Gypsum and calcite in corrosive water were supersaturated. The part on which water flowed was protected by the crystallized precipitation on the concrete. By contrast, the degradation of the part where water flowed through pouring joints was aggravated by internal crystallization and dissolution. (2) PFC3D numerical simulation indicated that decreases in vertical ultimate stress were strongly linearly correlated with degradation depth. As for the −355.5 m damaged part, reinforcement should be conducted before degradation depth reaches 250 mm. (3) No obvious signs were observed prior to the failure of the corroded sidewall. Therefore, the development of degradation depth should be monitored before degradation parts are reinforced.

It is challenging to prepare monolayer MoS2 with activated basal planes in a simple and efficient way. In this study, an interlayer spacing expanded counterpart, ammonia-intercalated MoS2, was obtained by a simple hydrothermal reaction of ammonium molybdate and elemental sulfur in hydrazine monohydrate solution. Then, the ammonia-intercalated MoS2 could be easily exfoliated by ultrasonication to get monolayer MoS2. Importantly, this monolayer MoS2 possessed rich S vacancies. The produced MoS2 demonstrated a proliferated active site density as well as low-loss electrical transport for efficient electrochemical hydrogen production from water. As expected, the monolayer MoS2 with S vacancies exhibited an excellent electrocatalytic hydrogen evolution reaction performance with a low overpotential (at 10 mA cm−2) of 160 mV (V vs. RHE) in acid media and a small Tafel slope of 54.9 mV dec−1. Furthermore, the catalyst displayed a good long-term stability and chemical stability during the electrochemical hydrogen production process. Computational studies prove that the S vacancies enabled the inert basal planes by introducing localized donor states into the bandgap and lowered the hydrogen adsorption free energy. This study could open new opportunities for the rational design and a better understanding of structure–property relationships of MoS2-based catalysts for water splitting or other applications.

Nitrogen-rich carbon material derived from carbon self-repairing g-C3N4 is self-assembled with graphene oxide (GO) to form a porous structure. Different from the pristine g-C3N4, which has scarcely been employed in supercapacitors because of its low charge mobility, the carbon self-repairing g-C3N4 (C-C3N4) shows an improved electrochemical activity. After carbon-repairing, a delocalized big π-bond can be formed by the homogeneous C-substitution for N atoms or the formation of new interstitial C–N bond. The extending π-conjugation planar layer of C-C3N4 possesses a closer contact with GO to form a three-dimensional (3D) pore structure, which ensures good mobility for electrons and quick access for electrolytes. Under the optimum C-repairing content of 5.99 at%, the C-C3N4@rGO exhibited high specific capacity of 379.7 F g−1 and energy density of 52.7 W h kg−1 at a current density of 0.25 A g−1. Moreover, the electrode kept 85% capacity retention after 10 000 cycles at a high constant current density of 10 A g−1. The active sites of pseudocapacitance can be confirmed in the oxygen-containing groups and the carbon atoms close to the nitrogen by the XPS results.

Three-dimensional (3D) network-like graphitic carbon nitride nanobelts (g-C3N4 NBs) were facilely achieved by the hydrothermal treatment of bulk g-C3N4 in a medium strong oxalic acid solution (1 M, pH 0.89). The positions of the conduction band (CB) and valence band (VB) were upraised from −0.90 and +1.86 eV for bulk g-C3N4 to −0.92 and +1.92 eV for g-C3N4 NB networks with enhanced redox ability, respectively. With an optimized Pt loading of 3%, the g-C3N4 NB networks showed excellent visible-light photocatalytic H2 production activity (1360 μmol g−1 h−1), which was 10.9 times higher than that of optimized 2% Pt@bulk g-C3N4 (124.7 μmol g−1 h−1) using triethanolamine as a sacrificial agent. Furthermore, Pt@g-C3N4 NBs exhibited a considerable rate of H2 evolution of 33.3 μmol g−1 h−1, much higher than 1.79 μmol g−1 h−1 for Pt@bulk g-C3N4 in distilled water without any sacrificial agents, revealing a great potential for photocatalytic overall water splitting. This outstanding performance not only originates from its unique 3D nanostructure and prolonged electron lifetime, but also from the electronic structure modulation and improved redox capacities of the CB and VB. The pH effect of hydrothermal conditions on the g-C3N4 molecular structure, chemical elements, optical properties and catalytic performance is also expounded. This study demonstrates a facile and environmentally friendly strategy to design highly efficient g-C3N4 catalysts for potential applications in solar energy driven photocatalytic water splitting.

Cathode materials with high activity, selectivity and stability are essential to efficient electrochemical H2O2 generation. Herein, nitrogen-doped porous carbon (NPC) is synthesized via direct calcination of nitrogen-containing metal organic framework. The N doping into porous carbon boosts H2O2 generation, thus enhancing electro-Fenton activity. The NPC cathode exhibits a highly selective reduction of O2 to H2O2 (96.4% at pH 1 and −0.1 V vs SCE) and H2O2 production rate reaches 52.3 mmol·L−1 h−1 (pH 1, −0.6 V vs SCE). Moreover, NPC achieves a high current efficiency of 87.7% for H2O2 production (pH 1, −0.5 V vs SCE). The removal efficiency of oxcarbazepine antibiotics achieves 100% in 10 min ([Fe2+] = 1.0 mmol L−1, C0 = 12.61 mg L−1 (50 μmol L−1), pH 1–5, −0.5 V vs SCE), and total organic carbon (TOC) removal efficiency reaches 90.7% in 60 min. Additionally, the removal efficiency of other antibiotics of prednisolone, chloramphenicol and thiamphenicol reaches 97.0–98.8% in 10 min and the TOC removal efficiency achieves 70.8–92.0% in 60 min. Moreover, NPC shows an excellent electrochemical stability. This work is valuable for designing electro-Fenton catalysts with high activity, selectivity and stability.

Flexible all-solid-state supercapacitors (ASSSs) have caught the scientific attention to meet the explosive demand for portable and wearable electronic devices. However, it is difficult for flexible electrode materials to obtain a high areal capacitance at a high mass loading, which limits their commercial applications. In this study, vanadium oxide (V2O5) nanoparticles are introduced into Ti3C2 flakes with the aid of cetyltrimethylammonium bromide (CTAB). The intercalation of V2O5 particles in the interlayer of Ti3C2 establishes a hierarchical structure and facilitates the electrolyte penetration. As a result, the prepared CT-Ti3C2@V2O5 composite electrode achieves a high areal capacitance of 2065 mF cm-2 at 3 mA cm-2 and superior active mass loading (15 mg cm-2). Meanwhile, over 93% capacitance is maintained after 6000 cycles at 18 mA cm-2. The ASSS based on CT-Ti3C2@V2O5 delivers a high areal capacitance of 477 mF cm-2 at 1 mV s-1 and exhibits stable performance at different bending states, which reaches to the advanced level for the ASSSs based on MXenes.

Lithium ion sieves (LIS) have gained great interest in lithium recovery. However, the synthesis of high stability, selectivity, and adsorption capacity of LIS is still a great challenge. Here, a general strategy combining electrospinning and calcination techniques is developed to fabricate a series of porous titanium-based LIS nanofibers. The porous structure created by calcination increases the exposure of the adsorption sites, which significantly accelerates the deintercalation and intercalation of Li+ from and into the vacancies in the framework. All of samples have good Li+ adsorption capacity and high selectivity for Li+. As a proof of concept, porous H4Ti5O12 nanofibers (P-HTO-NF) transformed from the electrospun porous Li4Ti5O12 nanofibers (P-LTO-NF) are systematically investigated in lithium recovery. P-HTO-NF possesses a superior adsorption capacity (59.1 mg/g), which is nearly close to the theoretical value (63.77 mg/g). The Freundlich isotherm model can well describe the adsorption isotherm data. The adsorption equilibrium can reach within 30 min (C0 = 300 mg/L, pH = 11, S/L = 60 mg/60 mL). The equilibrium distribution coefficient (Kd, mL/g) for Li + (232) is extremely higher than that for competing ions (1.41 for Na+, 1.17 for K+, 0.88 for Mg2+, 0.58 for Ca2+) (C0 = 40 mg/L for Li+, pH = 8), indicative of a highly selective recovery of lithium from brine water. The LIS show excellent stability with a low Ti dissolution and the adsorption capacity for Li+ remains 86.5% after 6 cycles. Our work provides a universal strategy for the synthesis of porous LIS.

Low cost, high adsorptivity, fast regeneration and excellent reusability are strongly recommended for a qualified adsorbent used in removing heavy metals from practical wastewater. A sponge-like polysiloxane-graphene oxide (PS-GO) gel adsorbent for removing lead and cadmium from wastewater has been prepared by simple one-step sol-gel method. The maximum sorption capacity of Pb(II) achieves as high as 256 mg/g. PS-GO gel adsorbent exhibits an excellent reusability because of its remarkable mechanical strength and highly efficient desorption/regeneration. In the static treatment process, after five cycles, Pb(II) in actual industrial effluent at 3.225 mg/L could be reduced to below 0.01 mg/L, still holding over 99% removal efficiency. Significantly, in the dynamic treatment process using a fixed-bed column packed with PS-GO gel, the treatment volume of wastewater is as high as 720 bed volume (BV) (8143 mL) for Pb(II) and 480 BV (5429 mL) for Cd(II) with producing only 11.31 mL eluent in each cycle. It should be stressed that the in situ regeneration of PS-GO gel adsorbent in fixed-bed column is operationally feasible and the treatment technology has the advantage of producing “zero” amount of sludge. This work has taken a key step closer to the treatment of actual heavy metals wastewater based on adsorption technology in large scale.

Highly efficient and non-hysteresis organic/perovskite planar heterojunction solar cells was fabricated by low-temperature, solution-processed method with a structure of ITO/PEDOT:PSS/CH 3 NH 3 PbI 3 /PCBM/Al. The high-quality perovskite thin film was obtained using a solvent-induced-fast-crystallization deposition involving spin-coating the CH 3 NH 3 PbI 3 solution followed by top-dropping chlorobenzene with an accurate control to induce the crystallization, which results in highly crystalline, pinhole-free, and smooth perovskite thin film. Furthermore, it was found that the molar ratio of CH 3 NH 3 I to PbI 2 greatly influence the properties of CH 3 NH 3 PbI 3 film and the device performance. The equimolar or excess PbI 2 was facile to form a flat CH 3 NH 3 PbI 3 film and produced relatively uniform perovskite crystals. Perovskite solar cells (PSCs) with high-quality CH 3 NH 3 PbI 3 thin film showed good performance and excellent repeatability. The power conversion efficiency ( PCE ) up to 13.49% was achieved, which is one of the highest PCEs obtained for low-temperature, solution-processed planar perovskite solar cells based on the structure ITO/PEDOT:PSS/CH 3 NH 3 PbI 3 /PC 61 BM/Al. More importantly, PSCs fabricated using this method didn’t show obvious hysteresis under different scan direction and speed.

A poly(sodium acrylate)–graphene oxide (PSA–GO) double network hydrogel adsorbent was facilely prepared in mild conditions. The chemical composition of the hydrogel adsorbent was characterized by FITR, Raman spectra and XPS analysis. The uniaxial compression tests proved extraordinary mechanical strength of PSA–GO gel, benefiting to practical application. The PSA–GO hydrogel was used as an adsorbent for heavy metal ions such as Cd(II) and Mn(II). The adsorption behaviors in different conditions (e.g., pH, contact time, ionic concentration and existence of fulvic acid) as well as the adsorption mechanism were studied. The maximum sorption capacities were found up to 238.3 mg/g and 165.5 mg/g at pH = 6 and T = 303 K, for Cd(II) and Mn(II), respectively, estimating from the Langmuir model. After experiencing four cycles, this adsorbent kept high removal efficiencies of Cd(II) and Mn(II), indicating a good reusability. Cost analysis reveals that the adsorbent is relatively low-cost. Meanwhile, its satisfactory performance in practical industrial effluent test demonstrates that PSA–GO gel can be a potential candidate for practical application.

Twenty four sesquiterpenoids, 1–24, including 11 new sesquiterpenoids, jambolanins A–K, and two new norsesquiterpenoids, jambolanes A and B, along with six known triterpenoids, were isolated from the seeds of Eugenia jambolana fruit. Their structures were elucidated on the basis of NMR and MS spectrometry data analysis. Among the isolates, compound 13 possessed a rare 6,7-seco-guaiene skeleton, and compounds 14 and 15 were norsesquiterpenoids containing a spiro[4.4]nonane skeleton. Antimicrobial assay evaluation revealed that sesquiterpenoids, 4, 5/6, 17, 19, 21, 23, and 24 inhibited the growth of the Gram-positive bacterium, Staphylococcus aureus. The current study advances scientific knowledge of E. jambolana phytochemicals and suggests that its sesquiterpenoids may contribute, in part, to the anti-infective effects attributed to the edible fruit of this plant.

In2S3 nanoparticle (NP) decorated self-organized TiO2 nanotube array (In2S3/TiO2 NT) hybrids were fabricated via simple successive ionic layer adsorption and reaction (SILAR) technique. The In2S3 NPs in a size of about 15 nm were found to deposit on the top surface of the highly oriented TiO2 NT while without clogging the tube entrances. The loading amount of In2S3 NPs on the TiO2 NT was controlled by the cycle number of SILAR deposition. Compared with the bare TiO2 NT, the In2S3/TiO2 NT hybrids showed stronger absorption in the visible light region and significantly enhanced photocurrent density. The photocatalytic activity of the In2S3/TiO2 NT photocatalyst far exceeds that of bare TiO2 NT in the degradation of typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) under simulated solar light. After 160-min irradiation, almost 100% 2,4-D removal is obtained on the 7-In2S3/TiO2 NT prepared through seven SILAR deposition cycles, much higher than 26% on the bare TiO2 NT. After 10 successive cycles of photocatalytic process with total 1,600 min of irradiation, In2S3/TiO2 NT maintained as high 2,4-D removal efficiency as 95.1% with good stability and easy recovery, which justifies the potential of the photocatalytic system in application for the photocatalytic removal of organic pollutants such as herbicides or pesticides from water.

Graphene is a promising support for nanosized electrocatalysts, however the conventional stacking arrangement of its graphene sheets substantially decreases the catalytic sites on the catalyst. We report here the fabrication of a graphene/Cu electrocatalyst by the simple cyclic voltammetric electrolysis of graphene oxide (GO) and copper ethylenediamine tetraacetate (Cu–EDTA), and find that the electrochemically reduced GO (RGO) and Cu nanoparticles can be sequentially self-assembled into layer-by-layer, 3D sandwich-type, and homogenous architectures as the concentration ratio of Cu–EDTA/GO increases. The 3D sandwich-type RGO/Cu composite (S-RGO/Cu) shows RGO sheets decorated with Cu nanoparticles which stand nearly perpendicular on the electrode, leading to a significant increase in the electrochemically accessible surface area (0.685 cm2) relative to those of the horizontal layer-by-layer RGO/Cu composite (0.147 cm2) and the homogenous RGO/Cu composite (0.265 cm2). Stemming from its high electrochemical surface area, the S-RGO/Cu composite exhibits a high electrocatalytic activity in hydrazine oxidation in terms of current density and overpotential. Mechanistic analysis of the electrode reactions reveals the reaction pathways of hydrazine on RGO/Cu are closely related to the electrochemical surface area of the RGO/Cu electrocatalyst. The correlation between the architectures and their performances in electrocatalysis presented here can guide the design of novel structures with enhanced properties.

Refractory herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) can be efficiently removed by photocatalytic degradation when using reduced graphene oxide (RGO) and CuInS2 nanoparticles (NPs) co-decorated TiO2 nanotube arrays (NTs) (RGO/CuInS2–TiO2 NTs) as a photocatalyst prepared by successive pulse electrodeposition of CuInS2 and RGO film onto the top surface of TiO2 NTs. The new catalyst exhibits significant photocatalytic activity and good removal efficiency of 2,4-D. The photodegradation rate toward 2,4-D over RGO/CuInS2–TiO2 NTs under simulated solar light (or visible light) irradiation is 96.2% (or 87.7%), much higher than 68.0% (or 58.4%) over CuInS2–TiO2 NTs, 50.1% (or 38.1%) over RGO–TiO2 NTs and 36.0% (or 26.3%) over bare TiO2 NTs, respectively, meaning that the photocatalytic performance of TiO2 NTs could be greatly enhanced by the synergetic effect of RGO and CuInS2. This work could provide new insights into the design and fabrication of advanced photocatalysts.

The aim of this work was to evaluate effects of endophytic bacterium inoculation on plant growth and assess the possible mechanism of endophyte in heavy metal phytoremediation. Seeds of Solanum nigrum L. were inoculated with endophyte Serratia nematodiphila LRE07 and were subjected to Cd in the growing medium. Cd produced a significant inhibition on plant growth and a reduction in the content of photosynthetic pigments. The inoculation of endophytic bacterium alleviated the Cd-induced changes, resulting in more biomass production and higher photosynthetic pigments content of leaves compared with non-symbiotic ones. The beneficial effect was more obvious at relatively low Cd concentration (10 μM). Based on the alteration of nutrient uptake and activated oxygen metabolism in infected plants, the possible mechanisms of endophytic bacterium in Cd phytotoxicity reduction can be concluded as uptake enhancement of essential mineral nutrition and improvement in the antioxidative enzymes activities in infected plant.

Graphene film was formed on the surface of titanium dioxide nanotube (TiO2 NT) arrays through in situ electrochemical reduction of a graphene oxide dispersion by cyclic voltammetry. The residual oxygen-containing groups and other structural defects such as sp3-hybridized carbons in the electrodeposited graphene were further removed by photo-assisted reduction of the underlying TiO2 NTs, thus achieving the maximum restoration of π-conjugation in the graphene planes. Spectroscopic, electrochemical, and photoelectrochemical techniques were used to characterize the graphene films, and the use of the resulting graphene–TiO2 NT material in photocatalysis was investigated. The results showed that the graphene–TiO2 NT material exhibited a greatly improved photocatalytic activity compared with unmodified TiO2 NTs.

This study investigates the heavy metal-resistant bacterial endophytes of Cd-hyperaccumulator Solanum nigrum L. grown on a mine tailing by using cultivation-dependent technique. Thirty Cd-tolerant bacterial endophytes were isolated from roots, stems, and leaves of S. nigrum L. and classified by amplified ribosomal DNA-restriction analysis into 18 different types. Phylogenetic analysis based on 16S rDNA sequences showed that these isolates belonged to four groups: Actinobacteria (43%), Proteobacteria (23%), Bacteroidetes (27%) and Firmicutes (7%). All the isolates were then characterized for their plant growth promoting traits as well as their resistances to different heavy metals; and the actual plant growth promotion and colonization ability were also assessed. Four isolates were re-introduced into S. nigrum L. under Cd stress and resulted in Cd phytotoxicity decrease, as dry weights of roots increased from 55% to 143% and dry weights of above-ground from 64% to 100% compared to the uninoculated ones. The total Cd accumulation of inoculated plants increased from 66% to 135% (roots) and from 22% to 64% (above-ground) compared to the uninoculated ones. Our research suggests that bacterial endophytes are a most promising resource and may be the excellent candidates of bio-inoculants for enhancing the phytoremediation efficiency.

New multifunctional PEG-grafted chitosan copolymers possessing both amino and carboxyl (4) or formyl (5) groups were synthesized by the grafting reaction method between chitosan and heterobifunctional PEG from anionic polymerization of ethylene oxide. Completion of the reactions and characterization of the resulting polymers were demonstrated by 1H NMR, FT-IR and GPC studies. The multifunctional polymers may have potential utility in gene/drug co-delivery or heterogeneous catalysis.

In the absence of Cu(I), the catalytic coupling of haloaryl carboxylic acids or unactivated aryl bromides with terminal alkynes are shown to occur in the presence of 10 equiv. piperidine at 85 °C within 20 min using PdCl 2 (PPh 3 ) 2 as catalyst in good to excellent yields. This procedure avoids the carboxy group protection/deprotection steps and enhances the total yield to simplify the synthesis of acetylenic retinoids. It is noteworthy that this protocol employs direct, mild and efficient copper-free reaction conditions.

2,5-bis-(4-biphenyl)-yl-1,3,4-oxadiazole (1a), 2,5-bis-(4-(6,8-difluoro)-biphenyl)-yl-1,3,4-oxadiazole (1b) and 2,5-bis-(4-(spiro-fluorenyl)-phenyl)-yl-1,3,4-oxadiazole (1c) were designed, synthesized and characterized. 1a–c were easily obtained from Suzuki reactions between 2,5-bis-(4-bromo-phynyl)-[1,3,4]oxadiazole (2) and aromatic boronic acids (3). They were characterized by 1H-NMR, DSC, TGA, UV-Vis, photoluminescence (PL) spectrometry and CV. The melting temperatures (T m) of 1a–c are 237, 208 and 370 °C, respectively, much higher than that of 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD, T m = 136 °C). The oxidation potentials of 1a–c are 1.86, 1.94 and 1.18 V, and their reduction potentials are −2.31, −2.22 and −2.27 V, respectively, indicating that the introduction of electronegative oxadiazole unit lowers the electron density in molecules and enhances their stabilities. The LUMO/HOMO energy levels of 1a–c are as low as −2.39/−6.56, −2.48/−6.69 and −2.43/−5.88 eV, respectively. The good thermal stabilities and low orbital levels of 1a–c make them promising electron-transporting or hole-blocking materials for organic optoelectronic devices.