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Simple preparation, favorable price and environmental protection have been a long-term challenge in the field of electrochemistry. Herein, we studied and prepared a bifunctional Mo-doped Co3O4 ultrathin nanosheets, which has been validated as an effective binder-free electrode material for electrocatalytic water splitting and supercapacitors. The material has a large specific surface area, high electrical conductivity and exposure to more active sites, breaking down the limited performance and range of use of transition metal oxides. Benefiting from intriguing ultrathin property and conductivity, OER and HER process of 0.4Mo-Co3O4 have a small Tafel slope of 83.7 and 98 mV dec−1, respectively. The current density at 10 mA cm−2 show a low overpotential of 315 and 79 mV and significant stability. The water electrolytic device requires a potential of 1.64 V to reach 10 mA cm−2, and the potential change is negligible after 12 h of continuous electrolysis. In addition, the manifest improved electrochemical performance of 0.3Mo-Co3O4 as supercapacitor electrode material shows high areal capacitance 2815 mF cm−2 at 1 mA cm−2, excellent rate performance (85% at 10 mA cm−2) and retains 90% of the initial capacitance by cycling 5000 at a current density of 10 mA cm−2. Moreover, 0.3Mo-Co3O4||0.3Mo-Co3O4 symmetrical supercapacitor has a maximum volumetric energy density of 1.25 mW h cm−3 at a power density of 7.1 mW cm−3 and superior cycle life. The influence of doping on electrochemical performance was studied by changing the content of doped metal ions, which is of great significance for the exploration of supercapacitor and electrocatalytic hydrolysis of bifunctional electrode materials.

Reasonable hollow structure design and oxygen vacancy defects control play an important role in the optimization of electrochemical energy storage and electrocatalytic properties. Herein, a plant polyphenol tannic acid was used to etch Co-based zeolitic imidazolate framework (ZIF-67) followed by calcination to prepare a porous Co3O4@Co/NC hollow nanoparticles (Co3O4@Co/NC-HN) with rich oxygen vacancy defects. Owing to the metal-phenolic networks (MPNs), rich oxygen vacancy defects and the synergistic effect between Co3O4 and Co/NC, the box-like Co3O4@Co/NC-HN nanomaterials with large specific surface areas exhibit excellent supercapacitor performance and electrocatalytic activity. As expected, Co3O4@Co/NC-HN shows high specific capacity (273.9 mAh g−1 at 1 A g−1) and remarkable rate performance. Moreover, the assembled Hybrid supercapacitor (HSC, Co3O4@Co/NC-HN//Active carbon) device obtained a maximum energy density of 57.8 Wh kg−1 (800 W kg−1) and exhibited superior cycle stability of 92.6% after 4000 cycles. Notably, as an electrocatalyst, the nanocomposites exhibit small overpotential and Tafel slope. These results strongly demonstrate that both unique hollow structure and abundant oxygen vacancies designed from plant polyphenols provide superiorities for the synthesis of efficient and green multifunctional electrode materials for energy storage and conversion.

Photocatalytic materials have been widely used to remove dyes from printing and dyeing wastewater. However, difficulty in recycling of photocatalysts is the great concern in the real catalytic applications, which significantly raises the application cost. This study developed a low-cost catalyst by loading magnetic Ni onto filter paper (FP) via an easy going in-situ reaction. The characterization results displayed that the Ni particles were uniformly anchored onto the FP. The Ni@FP material presented a strong magnetic ability which was evidenced by a saturation magnetization (Ms) of 5.014 emu·g−1, a remanent magnetization (Mr) of 2.067 emu·g−1 and a coercivity (Hc) of 133.868 Oe. Meanwhile, the magnetic Ni@FP material displayed a recyclable advantage in photocatalytic degradation of methyl orange (MO) via an external magnetic field. There existed an optimal photocatalytic degradation rate of 93.40% within 5 min when MO concentration was 15 mg·L−1 at pH 8.0. Three cycle experiments confirmed that the Ni@FP possessed a satisfied stability and recycling ability. Moreover, the Ni@FP material presented a strong antibacterial activity which can prevent it from being contaminated by microorganisms. The versatility of the newly proposed photocatalyst in this study demonstrated its great application prospect in dyeing wastewater treatment.

The incorporation of zeolitic imidazolate framework-8 (ZIF-8) into interfacial polymerized thin film nanocomposites (TFNs) has been extensively reported to enhance their membrane performance. However, the traditional membrane synthesis strategy suffers from the poor dispersity of hydrophobic ZIF-8 in an aqueous phase. Moreover, the exact structure of this TFN membrane is still a subject of scientific debate since only few studies of the visualization of ZIF-8 in PA layers by TEM or SEM characterization have been reported. Herein, a novel strategy for the synthesis of TFN membranes containing ZIF-8 (TFN–ZIF-8) was developed via an in situ conversion of ZnO in a polyamide layer into ZIF-8. Due to the hydrophilic nature of ZnO, it can be well dispersed in the aqueous phase of interfacial polymerization. More importantly, SEM and TEM characterizations clearly revealed the presence of ZIF-8 crystals in the polyamide layer. The as-prepared TFN–ZIF-8 membrane shows a pure water permeance of 20.4 L m−2 h−1 bar−1, which is 423% higher than that of the pristine TFC membrane, and meanwhile, has 97.4% Na2SO4 rejection. The novel TFN–ZIF-8 membrane synthesis strategy provided in this study can provide a new incentive to develop advanced ZIF-8 membranes applicable to various separation processes for further sustainable use.

The low cost, high energy density, high theoretical capacity and environmental friendliness of manganese dioxide (MnO2) make it a promising electrode material for aqueous zinc-ion batteries. However, poor conductivity and insufficient active sites of MnO2 hinder its further development. In this study, a molten salt method and plasma technology are proposed to synthesize an amorphous layer and oxygen vacancies on the surface of MnO2, promoting enhanced charge transport and increased exposed active sites. Originating from its unique electronic structure, the as-prepared MnO2-3 possesses a high discharge capacity of 252 mA h g−1 at a current density of 0.1 A g−1, and the capacity retention rate is 81% after 100 cycles. In addition, the sample shows lower polarization and charge transfer resistance. The results of this study show that the molten salt method combined with the plasma treatment technology has a promising prospect in the field of electrochemical energy storage.

Metallic 1T phase molybdenum disulfide(1T MoS2) is an excellent catalyst due to the abundant active sites and good conductivity. However, complex synthesis and unstable nature of 1T MoS2 still limit its practical application. Herein, we propose a simple method to trigger the phase transition of MoS2. This phase transition is first predicted by density functional theory(DFT) calculations and then confirmed by Raman spectroscopy and high-resolution transmission electron microscopy(HRTEM). 1T MoS2/Cu2O heterostructure catalyst is then developed, showing enhanced photocatalytic hydrogen evolution.

Fabrication of membranes with high antifouling and self-cleaning ability is a long-term pursuit of research community. For this purpose, the current work proposed a strategy to use an external magnetic field to arrange the magnetic TiO2@Ni particles (MNPs) onto the polymeric polyether sulfone (PES) membrane surface. The characterization results clearly indicated that the MNPs were successfully embedded onto the membrane surface instead of uniformly distributing into the membrane bulk. Because of this superficial distribution, the prepared composite membrane exhibited a flux of 871.2 ± 2.9 L·m−2·h−1·bar−1, which was 5 times flux of the pristine PES membrane. Meanwhile, it remained a rejection of 95.85% bovine serum albumin (BSA), which was also better than that of the pristine PES membrane. The cycle filtration experiments verified that the composite membrane possessed promoted antifouling ability for filtrating BSA, yeast extract fermentation (YEF), ammonium alginate (SA) and humic acid (HA) solutions. The antifouling mechanism was analyzed by the total interaction energies (ΔGTotal), which were quantitatively evaluated by using the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory. Moreover, it was interestingly found that the composite membrane possessed a self-cleaning property under radiation of UV light and sunlight. The optimal membrane after self-cleaning presented flux recovery ratio (FRR) of 75.4%, 99.56%, 92.11% and 98.26% for BSA, YEF, SA and HA solutions, respectively. This work demonstrated a novel way to fabricate membranes with high antifouling and self-cleaning ability for water treatment.

While electroless nickel plating is considered as a promising candidate for fabrication of metallized polymer composite membranes with high performance, it suffers from problems of complex and high-cost pretreatment procedure, hindering its large-scale implementations. It is hypothesized that, inkjet printing integrated with electroless plating (ELP) can serve as a facile and economical membrane fabrication method to overcome above problems. The new method proposed in this study was processed by inkjet printing silver ions and pyrrole inks as catalytic layer followed by electroless Ni deposition on polypropylene (PP) membrane surface. Successful modification was verified by characterizing the surface morphology and elemental compositions of the membranes. In comparison to the pristine PP membrane, the PPy-Ag/Ni modified membrane demonstrated lower surface resistance (2.3 Ω), better hydrophilicity (44.9°) and higher pure water flux (1135.1 L m−2 h−1). When applying an external electric field (10.0 V cm−1), the average flux of the PPy-Ag/Ni membrane for yeast filtration increased from 107.8 to 137.7 L m−2 h−1, which was about 2.0 times higher than that of the pristine PP membrane. Meanwhile, the PPy-Ag/Ni membrane possessed a maximum flux recover rate when applied with an external electrical field. This work provided a facile and efficient approach for fabrication of composite conductive membranes.

Inspired by the mussel adhesion mechanism, plant polyphenol tannic acid (TA) with abundant catechol groups and hydrophilic Jeffamine (JA) containing amino groups were used in a layer-by-layer (LBL) process to fabricate composite nanofiltration (NF) membranes in this study. Alternately immersing a polyacrylonitrile substrate into individual TA and JA buffer solutions could readily construct a NF membrane selective layer without any pre-treatment to the substrate. The optimised membrane showed a high pure water permeance of 37 L m−2 h−1 bar−1 whilst maintaining rejections higher than 90% towards various dyes with molecular weights ranging from 269 to 1017 g mol−1. Particularly, the obtained membrane exhibited excellent anti-fouling and long-term performance attributed to the hydrophilic membrane surface and covalent bonds in the selective layer. The novel strategy inherited the advantages of a mussel-inspired dopamine material but overcame its disadvantages. The results disclosed in this study not only provide a novel strategy to prepare composite NF membranes, but also facilitate the mussel-inspired LBL design of advanced materials for environmental applications.

N-Doped carbon-incorporated Ni2P/Ni was reasonably designed and synthesized from nickel-based metal organic framework (Ni-MOF) precursors via a novel simultaneous carbonization and phosphatization process. Interestingly, subtle phosphating significantly improves the energy storage performance of supercapacitors (SCs). Ni2P/Ni/C composites exhibit a good energy storage performance with a specific capacitance of 257.2 C g−1 at 1 A g−1. The corresponding hybrid supercapacitor achieves an energy density of 25.4 W h kg−1 at a power density of 750 W kg−1, ultrahigh electrochemical cyclic stability (98.2% retention after 4000 cycles) and nearly 100% coulombic efficiency with a Ni2P/Ni/C-100 positive electrode and a porous carbon negative electrode, respectively. These can be attributed to the synergetic effects of N-doped carbon and metal phosphates, which ensure good electrical conductivity and provide rich reactive sites as well as stable architecture. These results indicate that the controlled pyrolysis of MOFs is an effective method to design a kind of high-performance electrode material for hybrid supercapacitors.

It is of great significance to develop novel membranes with dual-function of simultaneously separating oil/water emulsion and degrading the contained water-miscible toxic organic components. To meet this requirement, a dual-functional Ni nanoparticles (NPs)@Ag/C-carbon nanotubes (CNTs) composite membrane was fabricated via electroless nickel plating strategy in this study. The as-prepared composite membrane possessed superhydrophilicity with water contact angle of 0° and splendid underwater oleophobic property with oil contact angle of 142°. When the membrane was applied for separation of surfactant stabilized oil-in-water emulsion, high permeate flux (about 97 L m−2·h−1 under gravity), oil rejection (about 98.8%) and antifouling property were achieved. Benefitting from the NiNPs@Ag/C-CNTs layer on membrane surface, the composite membrane exhibited high catalytic degradation activity for water-miscible toxic organic pollutant (4-nitrophenol) with addition of NaBH4 in a flow-through mode. Meanwhile, the NiNPs@Ag/C-CNTs composite membrane possessed excellent durability, which was verified by the good structural integrity even under ultrasonic treatment. The cost-efficiency, high separation and degradation performance of the prepared membrane suggested its great potential for treatment of oily wastewater.

Reasonable structural design and metal-doping play significant roles in the optimization of electrochemical energy storage and conversion. Herein, in situ growth of Molybdenum-doped amorphous cobalt acid nickel nanoneedles on Ni foam (Mo-NiCo2O4/NF) has been successfully synthesized by a simple hydrothermal-annealing strategy. Benefiting from the unique hierarchical nanostructures and doping-optimized electronic structural configuration, the cross-link network structure of Mo-doped amorphous NiCo2O4 with large specific surface areas exhibit excellent supercapacitor performance and electrocatalytic activity. As expected, the optimized Mo-doped NiCo2O4 samples possess a specific capacitance of 3970 mF cm−2 at 1 mA cm−2 and remarkable rate performance. The assembled hybrid supercapacitor obtains a maximum energy density of 35 Wh kg−1 (420 W kg−1) and keeps a capacitance retention of 107% after 5000 cycles. As an electrocatalyst, Mo-NiCo2O4/NF shows a rapid self-reconstruction process during oxygen evolution reaction (OER) that produces rich oxygen vacancies and thus exhibits remarkable long-term stability. The nanocomposites exhibit small overpotential (280 mV at 10 mA cm−2) and Tafel slope (43 mV dec-1). These results strongly demonstrate that both local amorphous phase and porous hierarchical structure design from Mo dopant provide superiorities for the synthesis of efficient and stable multifunctional electrode materials for energy storage and conversion.

While surface morphology is the key parameter affecting membrane performance, its exact roles on membrane fouling have not well unveiled. In this study, effects of membrane surface roughness on fouling caused by alginate adhesion were investigated by thermodynamic techniques of the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach and density functional theory (DFT). The energy of a single typical alginate chain adhering to rough membrane surface was figured out to be 0.5–3.0 kJ/mol for the first time. Whereas, the related bending energy at typical bending angle was calculated to be over 13.0 kJ/mol based on DFT calculations. The big energy gap suggested that the alginate chain in solution would not change its configuration to fit membrane surface morphology, and tended to directly adhere to membrane surface. The thermodynamic analyses predicted that the direct adhesion pathway was favorable in energy when an alginate chain approaching to rough membrane surface. As a result, as compared to the smooth membrane, rough membrane corresponds to less alginate adhesion and adhesive fouling. Combination of XDLVO and DFT techniques provided not only molecular insights into membrane fouling, but also a new way for fouling research.

Ultrafiltration (UF) membrane has recently drawn interest in textile and dyeing wastewater treatment due to its unique advantages of low-cost and large flux. However, its low rejection to dyes and developing appropriate membrane materials remain the major hurdles for its large-scale application. Herein, we developed a novel conductive polyvinylidene fluoride (PVDF)-Ni membrane combined with an external electric field to treat typical dyes. The membrane could be fabricated by a facile and low-cost method. The conductive PVDF-Ni membrane showed favorable rejection rate of Congo red (CR) (100%) and extremely high permeance (137.5 ± 6.8 L m−2 h−1 bar−1). To our knowledge, the permeance has exceeded the maximal literature record for the membranes with similar rejection rates of CR. The novel membrane combined with external electric field also provided a unique aeration mode: in-situ aeration, due to its good electrocatalytic activity for hydrogen evolution reaction (HER) (overpotential of 157 mV at the current density of 10 mA cm−2). Benefit from the in-situ aeration, the PVDF-Ni membrane showed 94% flux recovery after filtration of bovine serum albumin (BSA). Additionally, the PVDF-Ni membrane exhibited evident resistance to dye absorption and antibacterial activity. These versatile proprieties, together with the facile fabrication process, indicated the tremendous application prospect of the fabricated PVDF-Ni membrane for textile and dyeing wastewater treatment.

Due to potential toxicity of the dyes and their visibility even at the very low concentration, treatment of dye wastewater has been a matter of considerable interest. Membrane technology is an emerging technology that offers a promising way to remove dyes from wastewater. However, the membrane fouling and trade-off effect severely hinder the removal efficiency. In view of this, the conductive polyvinylidene fluoride (PVDF)-graphene oxide (GO)‑nickel (Ni) composite membrane was firstly developed and implanted into the dead-end filtration cell as the cathode in the sandwich-like electrode. Under the assistance of electric field, the conductive PVDF-GO-Ni membrane displayed 98.02% Congo red (CR) rejection with the flux of 38.39 L·m−2·h−1·bar−1, which was an encouraging result comparing to most previous reports. Moreover, PVDF-GO-Ni membrane possessed certain antibacterial ability and super anti-adhesion ability to CR molecules. The underlying mechanism of super anti-adhesion of CR molecules was investigated by quantitatively calculating the interfacial interaction energy according to the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory. XDLVO theory indicated that the repulsive acid-based (AB) interaction energy between CR molecules and membrane surface predominantly facilitated the super anti-adhesion ability of the hydrophilic PVDF-GO-Ni membrane. The present study not only supplied a novel PVDF-GO-Ni membrane for high-efficient treatment of dye waste water, but also built an approach to quantitatively calculate interfacial interaction energy which should have a wide applications in forecasting and directing the modifications of separation membranes.

While polyacrylonitrile (PAN) has been widely used to prepare membranes, it is still not handy to prepare PAN integrally skinned asymmetric (ISA) nanofiltration (NF) membrane via direct immersion precipitation phase inversion method. Herein, a low-cost and commercial polyacrylonitrile-co-methylacrylate, P(AN-co-MA), was demonstrated to prepare ISA NF membranes via a one-step immersion precipitation phase inversion process. It was found that increasing P(AN-co-MA) concentration in NMP can shift the membranes from ultrafiltration (UF) to NF range. The addition of a co-solvent in dope could further improve dye rejection. Effects of solvent (NMP or DMF)/co-solvent (THF and 1,4-dioxane) type and mass ratio in dope solution on membrane separation performance were further investigated. The membrane prepared from a 20% polymer concentration and a NMP/1,4-dioxane ratio of 3:1 showed 87.4% methyl orange (MO) rejection and 98.3% rose bengal (RB) rejection, and simultaneously a relatively high water permeance of 55.22 L m−2 h−1 bar−1. Increase in the content of co-solvent in solvent/co-solvent mixture would depress the formation of macrovoids, lead to a dense top layer and contribute to high dye rejections. The low-cost and one-step process to prepare P(AN-co-MA) ISA NF membranes disclosed in this study paved a new way for sustainable molecular separation.

The development of highly efficient Pt-based alloy nanocatalysts is important but remains challenging for fuel cells commercialization. Here, a new class of zigzag-like platinum-zinc (Pt-Zn) alloy nanowires (NWs) with rough surface and controllable composition is reported. The merits of anisotropic one-dimensional nanostructure, stable high-index facets and coordinatively unsaturated Pt sites endow the composition-optimal Pt94Zn6 NWs with a mass activity of 7.2 and 6.2 times higher than that of commercial Pt black catalysts toward methanol/ethanol oxidation, respectively. Alloying-induced d-band electron modulation and lattice strain effects weaken the adsorption strength of poisoning species, which originally enhances the catalytic activity of Pt-Zn NWs. This study provides a new perspective of Pt-Zn electrocatalysts with intrinsic mechanism for enhanced catalytic performance.

The permeability-selectivity trade-off remains the major drawback limiting application of membrane technology. This study provided a new strategy to break through this trade-off. A novel conductive membrane prepared by electroless Ni plating of the polyvinylidene fluoride (PVDF) membrane was used for dyeing wastewater treatment by applying an electric field. Series analyses demonstrated success of immobilizing a Ni/NiO layer on the pristine PVDF membrane. The conductive membrane possessed improved hydrophilicity indicated by the water contact angle decrease from 75.5° to 45.0°. Moreover, the conductive PVDF membrane integrating electric field voltage of 20 V simultaneously possessed high selectivity (97.93% rejection) and extremely high permeability (202.51 ± 9.63 L m−2 h−1 at 0.1 MPa) for filtration of Congo red (CR) solution, significantly breaking through the permeability-selectivity trade-off. The filtration performance was quite stable even after 6 filtration cycles, indicating the feasibility of the conductive membrane for long-term treatment of CR wastewater. In addition, the conductive membrane showed high antifouling ability to methylene blue (MB), rhodamine B (RB), CR and microorganisms. The conductive membranes, together with the new strategy, offered in-depth insights into membrane fabrication.

Although electrode materials based on metal organic frameworks (MOFs) were widely studied in the electrochemistry field, the origin of poor conductivity is still a bottleneck restricting their development. Herein, we constructed a conductive circuit by growing a layer of hydroxide on the surface of the Fe-MOF, and composite materials (Fe-MOF@Ni(OH)2) are applied in the fields of supercapacitor, OER, and electrochemical sensing. Fe-MOF@Ni(OH)2 not only maintains the intrinsic advantages of Fe-MOF, but also improves the electrical conductivity. Fe-MOF@Ni(OH)2 exhibits a high specific capacity of 188 mAh g−1 at 1 A g−1 . The energy density of the asymmetric supercapacitor (Fe-MOF@Ni(OH)2–20//AC) reaches 67.1 Wh kg−1. During the oxygen evolution reaction, the overpotential of the material is 280 mV at 10 mA cm−2, and the Tafel slope is 37.6 mV dec−1. The electrochemical sensing tests showed the detection limit of BPA is 5 μM. Hence, these results provide key insights into the design of multifunctional electrode materials.

Effects of calcium ions and polyaluminum chloride (PACl) on membrane fouling in coagulation-ultrafiltration (UF) process were investigated in this study. Filtration tests demonstrated three interesting filtration behaviors: 1) high specific filtration resistance (SFR) of alginate solution with low CaCl2 or PACl addition (e. g. 3.51×1015 m·kg -1 under the condition of 1.5 mM CaCl2 addition); 2) unimodal pattern of alginate SFR with PACl or CaCl2 addition alone; 3) synergistic effects between CaCl2 and PACl on alginate SFR. It was found that, the foulant morphological changes driven by the thermodynamic mechanisms based on Flory-Huggins lattice theory take the critical roles in these filtration behaviors. Density functional theory (DFT) calculations showed that initial coordination of Ca2+ and Al3+ ions with alginates tended to form tetrahedron geometry and geometry of coordinating three terminal carboxyl groups, respectively, which facilitated to elongate the alginate chains (without clustering the flocs) and form more stable gel, increasing SFR. Improving Ca2+ and Al3+ dosages triggered transition to other geometries for clustering polymeric network and flocculation, reducing SFR. Due to the higher binding affinity of Ca2+ over Al3+, Ca2+ and Al3+ sequentially take roles of enlarging polymeric network and clustering the coordination compounds, and then facilitate to form large size flocs and reduce SFR, causing the synergistic effects between CaCl2 and PACl additions. The proposed thermodynamic mechanisms satisfactorily explained these interesting fouling behaviors, allowing to further optimize coagulation-UF process.

A series of in-situ grown bimetallic Metal-organic frameworks (MOFs) self-supporting electrodes with an easy one-step strategy have been designed, which meet many requirements for high-performance electrode materials. The presence of iron and the increase in redox active sites, the material exhibits astonishing electrochemical activity for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The prototype electrolytic unit for overall water splitting with Ni/Fe3-MOF electrode displays similar catalytic performance to the benchmark precious metal-based catalysts. Moreover, Ni/Fe3-MOF showed an excellent specific capacitance of 6377.6 mF cm-2.

Due to the far cheaper price than polydopamine, plant polyphenol and amine have been widely used for mussel-inspired chemistry. However, co-deposition of them still suffers the problem of long co-deposition time owning to the slow dissolution and diffusion of oxygen in solution. Herein, we reported an interesting strategy regarding addition of AgNO3 as both oxidant and Ag precursor into co-deposition of tannic acid and diethylenetriamine for nanofiltration (NF) membrane preparation. It was found that, AgNO3 addition not only shortened co-deposition time, but also in-situ generated Ag nanoparticles and rendered membrane surface antibacterial activity. The effect of AgNO3 addition on co-deposition behavior, physicochemical properties, separation and antibacterial performance of the as-prepared NF membrane were systematically investigated. The results showed that, when 0.15 wt% AgNO3 was added, the prepared NF membrane possessed a pure water flux of 5.36 L m−2h−1 bar−1, a MgCl2 rejection of 86.5% and an excellent antibacterial activity. This study not only provided a facile and effective strategy to prepare antibacterial NF membrane, but also offered new insights into co-deposition of polyphenol and amine for more widespread applications.

While membrane technology emerges as one of the promising candidates for printing and dyeing wastewater treatment, it still suffers problems of “trade-off” effect and membrane fouling. It is therefore highly desired to fabricate high-performance membranes. This study reported a new functional polyvinylidene fluoride (PVDF)-Ni-Co membrane fabricated via an in-situ reduction method. The PVDF-Ni-Co membrane displayed conductive property, magnetic property and special in-situ micro-aeration function under assistance of electric field. Benefiting from in-situ micro-aeration function, the membrane showed excellent decoloration efficiency to Rhodamine B (RB), Congo red (CR) and methylene blue (MB) solutions. Particularly, the PVDF-Ni-Co membrane possessed 98.33% rejection to CR solution with flux up to 69.30 L m−2 h−1·bar−1, which is far better than the data reported in the literature. Moreover, in-situ micro-aeration was confirmed to be critical to enhance membrane antifouling performance. Cycling filtration results revealed that flux recovery rate (FRR) of PVDF-Ni-Co membrane reached to 90% and 94% for sodium alginate (SA) and bovine serum albumin (BSA) solutions, respectively. Thermodynamic calculation suggested that attractive energy of interaction between PVDF-Ni-Co membrane and foulants was largely reduced so that the foulants could hardly adhere onto membrane surface. This study simultaneously provided interesting findings regarding functional PVDF-Ni-Co membrane as well as its fabrication strategy, and new membrane fouling mitigation method of in-situ micro-aeration.

Metallic phase molybdenum disulfide (1T-MoS2), with its fast carrier mobility and highly abundant active sites, plays a vital role in the field of catalysis. However, the development of a simple and efficient strategy for the preparation of stabilized 1T-MoS2 remains a great challenge. Herein, we report the spontaneous phase transformation of MoS2 from the 2H to the 1T phase, caused by the strong metal–support interaction during iridium (Ir) adsorption. The resulting Ir/MoS2 heterostructures show higher catalytic activity for overall water splitting than those of commercial Pt/C and IrO2 in alkaline media. We believe that the spontaneous phase transformation of this material not only opens up a new perspective for developing advanced catalysts for alkaline water splitting but also presents an efficient and intriguing method for the phase engineering of two-dimensional materials.

It is of importance to develop earth-abundant, low-cost and efficient catalysts for oxygen evolution reaction (OER). Herein, we prepare Ti3C2Tx-FeOOH heterostructure that exhibits excellent electrochemical performance with a potential of 1.65 V at 10 mA cm−2, a Tafel slope of 31.7 mV dec−1 and outstanding stability for OER in alkaline medium. The superior catalytic activity is attributed to the synergistic coupling between amorphous FeOOH QDs and Ti3C2Tx. This study offers a new pathway for MXene-based materials toward OER in alkaline media.

A novel mussel-inspired sticky catechol-functionalized poly (ethylene glycol) (Cate-PEG) was synthesized and deployed as an additive to modify the hydrophobic poly (vinylidene fluoride) (PVDF) ultrafiltration (UF) membrane for reducing the leakage of poly (ethylene glycol) (PEG) from membrane matrix towards practical water treatment applications. By the interesting surface segregation, the sticky Cate-PEG polymer could migrate from matrix onto the membrane surface and internal pores, endowing the modified membrane with excellent hydrophilicity. In addition, the PVDF/Cate-PEG UF membrane exhibited a high water flux, good BSA rejection and a satisfactory antifouling performance after the BSA solution cycling tests. Most importantly, a wonderful stability of Cate-PEG in membrane matrix was discovered by the XPS analysis in the incubation treatment with hot water due to the strong sticky property of catechol structure in Cate-PEG. Therefore, the new sticky material has great potential not only for membrane surface modification but also for multifunctional manipulations of materials for diverse applications.

This study aims to investigate influences form zinc oxide on glasses in xZnO-(100-x) (54P2O5-36Fe2O3-10CaO) (x = 3,6,9,12,15,18 mol%). Structure analyses were carried by FTIR, and chemical durability tests were introduced to study changes in dissolution rate and weight losses. Thermal stability properties were measured and discussed through DSC. Results from structure changes indicate that glass network turns less compact with more ZnO, the building units gradually evolving into Q0 groups from Q1 tetrahedra, even the whole glass system locates in orthophosphate glasses. Higher melting temperature results in more Fe2+ that would lead to octahedral and disordered octahedral in the prepared glasses also contributing to open glass network in glass structure. The resistance in both alkali and acid solution were deteriorated for the sake of the open network, accompanied with the less strong P-O-Zn bonds when compared with the P-O-P bonds. Reasons accounting for the weak resistance also refer to the transition from [ZnO6] to [ZnO4], larger volume of [ZnO4] than that of [PO4], small particle size in ternary phosphate glasses. Drops in weight loss for each test span with corrosion time might be owing to the formation of alter layer on the surface of glass samples during corrosion. The phenomenon in water also follow the similar trend as those in the other two solutions for the same reasons. The glass transition and crystalline temperatures of all glasses drop as the degree of polymerization in glass becomes small, with four glass stability parameters falling as the amount of ZnO rises.

In order to prepare a synergetic flame retardant, the magnesium hydroxide (MH) and hexaphenoxycyclotriphosphazene (HPCTP) were blended with ethylene–vinyl acetate copolymer (EVA). The EVA–MH–HPCTP composite materials were characterized by various tests including Fourier transform infrared spectroscopy, X-ray diffractometer and scanning electron microscopy (SEM). The SEM images indicated that the compatibility of EVA–MH–HPCTP composite materials was significantly promoted due to the bridging effect of HPCTP. Therefore, the EVA–MH–HPCTP composite materials possessed better processability which was evidenced by the melt flow rate tests. Comparing to the traditional addition dosage (over 50%) of MH in previous reports, the EVA–MH–HPCTP composite materials showed significant flame-retardant efficiency even when the dosage of MH was lowered to 20 parts per hundred resins. The experimental results suggest that the prepared EVA–MH–HPCTP composite material may be a potential candidate in various industrial applications due to its excellent flame retardant.

Engineering the interfacial structure of bimetallic nanocrystals is an effective method to improve their electrocatalytic performances. Here, we design a facile strategy for controlling the surface morphology evolution of Au@Pd core-shell nanorods by adjusting the solution supersaturation. The Pd shell of the as-prepared Au@Pd bimetallic nanorods can be modulated from a (111) facet-exposed island to a (100) facet-exposed conformal shell. The conformal shell structure exhibited enhanced catalytic performance toward the ethanol oxidation reaction, while the core-island structure possessed better catalytic stability. This work provides a facile method for interfacial engineering of bimetallic nanocrystals with desired morphology and properties.

While composite membranes with two-dimensional (2D) lamellar materials (e.g., graphene and MXene) have recently attracted increasing attention, fabrication of high-performance 2D membrane still faces a serious challenge. In this study, 2D TiO2@MXene nanomaterial was prepared and introduced to fabricate polyethersulfone (PES)-TiO2@MXene composite membrane. The composite membrane displayed superior separation and antifouling performance. When filtrating 1.0 g L−1 bovine serum albumin (BSA) solution, the flux of the optimal membrane (BSA rejection 95%) reached to 756.8 L m−2 h−1·bar−1, which is 185% higher than that of the original membrane (BSA rejection 70%). Moreover, the PES-TiO2@MXene composite membrane possessed excellent self-cleaning function under UV irradiation, which was verified by the flux recovery rate (FRR) values of 80.2%, 100%, 100% and 99.56% for BSA, sodium alginate (SA), humic acid (HA) and yeast (YE) solution, respectively. The excellent self-cleaning ability can be put down to the special 2D TiO2@MXene structure where there exists a synergy between MXene and TiO2 for self-cleaning. The composite membrane demonstrated a significant superiority in filtration performance over those in the literature. According to extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach, the PES-TiO2@MXene composite membrane displayed an optimal interface condition, significantly reducing the attractive interactions with foulants. The facile fabrication method, together with the efficient membrane performance, indicated good application prospects of the PES-TiO2@MXene composite membrane proposed in this study.

Surface metallization of membrane via electroless plating for improvement of permeation flux and anti-fouling performance has attracted extensive attentions in recent years. However, high activation cost and poor stability have always been the obstacles to its practical application. It is urgently desired to explore economical and stable membrane modification methods. Herein, a novel strategy for fabrication of a hydrophilic and conductive separation membrane with low cost, excellent filtration performance, and high chemical stability was ingeniously proposed. A nickel-tin/cobalt-polypyrrole (NiSn/Co-PPy) coating was deposited onto the PP membrane through successive three-step route including in-situ vapor-phase polymerization, cobalt activation and electroless plating. The successful formation of NiSn/Co-PPy coating on membrane surface was confirmed by a series of characterizations. Driven by self-gravity, the optimum modified membrane (NiSn4-15/Co-PPy) applied with an external electric field (9.0 V) had prominent permeation flux (189 L m-2 h-1), impressive separation efficiency (100%) and outstanding cycle stability for separation of n-hexane/water emulsion. Under the micro-electric field (2.0 V), the average flux of the NiSn4-15/Co-PPy membrane for yeast suspension filtration reached 22.3 L m-2 h-1, which is approximately 3 and 9 times higher than that of the modified membrane without electric field and the original membrane, respectively. Meanwhile, the external electric field also endowed the NiSn4-15/Co-PPy membrane with a maximum flux recovery rate of 82.7%. In addition, the modified membrane was confirmed to have brilliant stability and acid resistance. This study provided a new strategy and novel insights into fabrication of composite hydrophilic conductive membrane for water treatment.

Polyvinylidene fluoride (PVDF) is rarely used as substrate membrane for thin film composite polyamide (PA) nanofiltration (NF) membrane due to its hydrophobic surface pushes water away during interfacial polymerization. According to Jurin's law, the pressure of membrane surface pushed water away is inversely proportional to the radius of membrane pore. In this study, a series of commercial PVDF membranes with pores ranging from 25 to 450 nm were used as substrates in a traditional interfacial polymerization. This preparation process does not need any pre-modification on substrate or specific equipment. It was found that the PVDF substrate pore size greatly influences the morphologies and surface properties of the corresponding TFC PA NF membrane. Only when a PVDF substrate has moderate pore size, such as 50 and 100 nm, could a continuous and defect-free PA layer will be formed, as verified through SEM characterization. The TFC membrane prepared with the PVDF substrate of 100 nm exhibits a 27.0 L m-2 h-1 bar-1 pure water permeance, and a 96.2% Na2SO4 rejection. The facile and effective method demonstrated in this study provides a new thought for the preparation of PVDF substrate supported PA NF membrane.

Efficient separation of oil/water emulsion is still a worldwide challenge. Herein, a new conception/strategy of in-situ electroflotation driven by hydrogen evolution reaction (HER) combining with a polypyrrole (PPy)-Ni-modified fabric membrane was proposed for efficient oil/water separation. To realize this new conception, nickel-decorated polyester fabric membrane was successfully fabricated via facile electroless Ni plating process on the polypyrrole (PPy)-modified surface. The Ni-decorated fabric membrane processed superhydrophilicity, underwater superoleophobicity and excellent electrical conductivity (electrical resistance of ~14.1 Ω), which could serve as cathode for HER. The fabric membrane itself couldn't separate oil/water emulsion, but achieved extremely high permeation (above 12526.5 L m−2 h−1) and oil rejection (above 98.6%) for separating stratified oil/water mixtures under gravity force. By applying an extra electric field on the conductive fabric membrane, an in-situ electroflotation process driven by HER can be produced. Under the optimized electroflotation conditions (20.0 V cm−1 electric field intensity, 20 g L−1 electrolyte concentration and 30 min electroflotation time) in this study, this new process could efficiently separate oil/water emulsion with high permeation flux (840.6 L m−2 h−1) and oil rejection (98.5%). The present work provided a new conception of in-situ electroflotation-membrane separation process for treatment of oily wastewater, showing strong application significance.

Effects of iron(III) ion level and ionic strength on membrane fouling in coagulation-ultrafiltration (UF) process were explored in this study. Two interesting filtration phenomena during the filtration process were observed: extremely reduced specific filtration resistance (SFR) of alginate solution complexed with iron (III) ions level from 0.1 to 2.0 mM (phenomenon I), and different change trends of alginate SFR with ionic strength between two iron(III) ion levels (remarkable increase trend of alginate SFR with ionic strength at 0.1 mM ions level while almost remaining unchanged trend at 2.0 mM ions level) (phenomenon II). Experimental characterizations indicated that the two phenomena were closely linked to changes of zeta potential, viscosity and morphology of the related foulants. It was proposed that iron(III) ions at low level (0.1 mM) preferentially coordinate the terminal carboxyl groups of alginate chains and form gel layer. The chemical potential gap described by Flory-Huggins lattice theory is responsible for the extremely high SFR of gel layer. Coordinating the non-terminal carboxyl groups at high iron(III) ion level (2.0 mM) causes transition from gel layer to cake layer formation during filtration, and lots of interstices in cake layer correspond to low SFR, well interpreting phenomenon I. Meanwhile, electrostatic double layer compression caused by the increased ionic strength makes the gel layer shrunk and denser for low iron(III) ion level, but less affects the number and size of interstices in the cake layer for high iron(III) ion level, reasonably explaining phenomenon II. This study revealed essential and comprehensive thermodynamic fouling mechanisms and facilitated to optimize coagulation-UF/MF process.

Herein, a mussel-inspired polydopamine (PDA) coating layer has been first explored as a separating layer for organic solvent nanofiltration (OSN). A PDA based separating layer was constructed on polyimide (PI) support via dopamine coating. The subsequent membrane was then treated with 1,6-hexanediamine for cross-linking on both the PDA layer and PI support. Fourier transform infrared (ATR-FTIR) and X-ray photoelectron (XPS) results indicated the deposition of PDA on support and the cross-linked structures of both PDA and PI. Scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle, and surface energy measurements were further employed to characterize the morphologies and surface properties of the composite membranes. After an optimized coating time of 4 h, the resultant membrane showed an EtOH permeance of 0.91 L m–2 h–1 bar–1 and a RB rejection of 99%. More importantly, the composite membrane also exhibited good performance for dyes separation from a wide range of solvents i...

Nanofiltration (NF) membranes with tannic acid (TA) based selective layers have been intensively studied in recent years, but they still suffer from poor inorganic salt rejection. This study provided a first report on mussel-inspired co-deposition of TA and amine to obtain high-performance NF membranes. The inorganic salt separation performance of the as-prepared NF membrane was significantly improved by optimising the amine molecular weight. The membranes prepared by TA and various amines were characterised by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR), scanning electron microscopy (SEM), zeta potential, and water contact angle measurement. It was found that amines with low molecular weight, such as ethylenediamine (EDA) and diethylenetriamine (DETA) facilitated the co-deposition onto the membrane surface, while polyethylene polyamine (PEPA) and branched polyethylenimine 600 (PEI600) enhanced the precipitation in solution. The TA/DETA co-deposited membrane showed an MgCl2 rejection of 83.5% and a pure water permeance of 4.5 L m−2 h−1 bar−1. The rejection was higher than the reported TA based NF membranes in the literature. In addition to demonstrating a TA based NF membrane with the improved inorganic salt rejection, this study provided new insights into the mussel-inspired co-deposition for material surface engineering towards various applications.

Multiple wall carbon nanotubes (MWCNTs), as an excellent material, have been used in various applications including preparation of polymer-MWCNTs composite membranes. However, few reports have combined the magnetic Ni@MWCNTs with polyether sulfone (PES) membrane to improve its antifouling performance to humic acid (HA), sodium alginate (SA), bovine serum albumin (BSA) and yeast (YE) solutions. In this study, the Ni@MWCNTs was generated by immersing MWCNTs into Ni2+ solution where in-situ reduction reaction was launched by the adsorbed Ag+ on MWCNTs. Since the loaded Ni endowed magnetism to MWCNTs, the Ni@MWCNTs can be easily attracted onto the membrane surface by an external magnetic field during the phase inversion process. The morphology measurements confirmed that the Ni@MWCNTs headed out of the PES-Ni@MWCNTs membrane surface. Because the MWCNTs played a role of free channels for water molecules, the composite membrane water flux reached to threefold flux of the pristine membrane. Moreover, the PES-Ni@MWCNTs membranes displayed the obviously enhanced antifouling ability during all the three alternative filtration cycles of water and BSA, SA, YE and HA solutions. In addition, the optimal PES-Ni@MWCNTs membrane demonstrated a flux recovery rate (FRR) of 67.89%, 85.53%, 60.28 and 90.12% for BSA, SA, YE and HA, respectively, which were not only much higher than that of the pristine membrane, but also exhibited significant improvements comparing with the previous studies. Further results of extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory indicated that the modified membrane possessed advantageous interaction energies with contaminant molecules over the pristine membrane.

A chemical-epigenetic method was used to enhance the chemodiversity of a marine algicolous fungus. Apart from thirteen known compounds, (+)-brevianamide R ((+)-3), (‒)-brevianamide R ((‒)-3), (+)-brevianamide Q ((+)-4), (‒)-brevianamide Q ((‒)-4), brevianamide V ((+)-5), brevianamide W ((‒)-5), brevianamide K (6), diorcinol B (7), diorcinol C (8), diorcinol E (9), diorcinol J (10), diorcinol (11), 4-methoxycarbonyldiorcinol (12), two new compounds, (+)- and (‒)-brevianamide X ((+)- and (‒)- 2)), as well as a new naturally occurring one, 3-[6-(2-methylpropyl)-2-oxo-1H-pyrazin-3-yl]propanamide (1), were isolated from chemical-epigenetic cultures of Aspergillus versicolor OUCMDZ-2738 with 10 µM vorinostat (SAHA). Compared to cultures in the same medium without SAHA, compounds 1–4, 8, 9, 11, and 12 were solely observed under SAHA condition. The structures of these compounds were elucidated based on spectroscopic analysis, specific rotation analysis, ECD, and X-ray crystallographic analysis. (±)-3, (±)-4, and (±)-5 were further resolved into the corresponding optically pure enantiomers and their absolute configurations were determined for the first time. Compounds 11 and 12 showed selective antibacterial against Pseudomonas aeruginosa with a minimum inhibitory concentration (MIC) of 17.4 and 13.9 μM, respectively. Compound 10 exhibited better α-glucosidase inhibitory activity than the assay control acarbose with IC50 values of 117.3 and 255.3 μM, respectively.

Manganese Dioxide (MnO2) as an efficient cathode material for zinc-ions battery (ZIBs) and water oxidation has always been a research emphasis because of its rich crystal phases, tunnel and layered structure, which is conducive to the deintercalation / intercalation of zinc ions. However, the key bottleneck of MnO2 electrode materials are their poor rate capability and electrochemical stability. Herein, we successfully obtained oxygen vacancy-rich K-birnessite MnO2 (KxMnO2) by plasma etching strategy. K+ intercalation in MnO2 can adjust the interlayer distances, which improves the structural stability of material, and constructs a tunable Zn2+ channel. Meanwhile, the oxygen vacancy is not only contribute to the fast adsorption and diffusion of electrolytic ions, but also to the rapid transfer of charges. In addition, the nano-structure could provide abundant reaction sites and short diffusion pathways. Remarkably, the KxMnO2 is used cathode material of ZIBs after plasma optimization treatment presents reversible specific capacity of 272 mAh g−1 at 1 mA cm−2, and then it could reach an admirable capacity of 310 mAh g−1 after 100 cycles. As the oxygen evolution reaction (OER) electrocatalysts, the overpotential to reach 10 mA cm−2 of KxMnO2 is 1.47 V of versus RHE. The Tafel slope is 36 mV dec−1, which is lower than that of the KxMnO2 without plasma treatment (244 mV dec−1). This study provides a new opportunity to design low-cost and high-performance electrode materials for rechargeable zinc-ion batteries and OER catalyst by using plasma processing technology.

In this study, magnetic Ni@MXene nanoparticles were firstly developed and then elevated to the upper layer of polyether sulfone (PES) membrane by an external magnetic field during the wet phase inversion process. Flux of the prepared PES-Ni@MXene membrane was 2.5 times of that of the control PES membrane. Moreover, PES-Ni@MXene membranes showed a significant promotion of antifouling ability, evidenced by the flux recovery rates (FRR) of 64.6% and 99.8% for bovine serum albumin (BSA) and humic acid (HA) solutions, respectively. The antifouling performance of the PES-Ni@MXene membrane was comparable or better than those in the literature studies. Meanwhile, the optimal PES-Ni@MXene membrane possessed an efficient decoloration ability for Congo red (CR) solution and colored emulsion. To analyze the anti-fouling mechanism, the interaction energies between the membrane surface and pollutants (BSA and HA) were computed via the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. The results showed that the total attraction energy between PES-Ni@MXene membrane and pollutant interface was smaller than that between the control PES membrane and pollutant interface. This study provided a new incentive to development of high-efficient Mxene-based membranes.

A continuous and ultra-thin metal-phenolic network top layer on a polyethersulfone substrate surface was used as metal precursor for a metal-organic framework (MOF) membrane synthesis. A plant polyphenol tannic acid (TA) and Zn2+ based network top layer prepared by a layer-by-layer (LBL) self-assembly process was immersed into a 2-methylimidazole aqueous solution, and then a ZIF-8 top layer was facilely formed due to the partial self-conversion of TA-Zn2+ network to ZIF-8. The LBL process provides sufficient controllability of preparing a continuous and ultra-thin ZIF-8 top layer, which are crucial factors for nanofiltration membrane separation performance. The optimized ZIF-8 membrane exhibited a pure water permeance (PWP) of 5.1 L m−2 h−1 bar−1, a 55.2% NaCl rejection and a 93.6% Na2SO4 rejection. This is one of the few MOF membranes that possesses a divalent inorganic salt rejection higher than 90%. The novel zinc source of ZIF-8 synthesis disclosed in this study can provide a new incentive to not only MOF membrane preparation but also engineering MOFs towards a wide energy and environmental applications.

Mussel-inspired polydopamine (PDA) modification of membrane is an effective alternative for improving permeation flux and anti-fouling performance. Meanwhile, efficient method for oil-water emulsions separation is still highly desired. However, problems, such as time-consuming process and low utilization ratio of expensive raw material, have always been stumbling block to application of this strategy. In this study, inkjet printing of dopamine (DA) followed by UV light irradiation to modify mussel-inspired polyvinylidene fluoride (PVDF) membrane was proposed. Accordingly, PVDF membrane was inkjet printed by alternately using DA inks and alkaline tris (hydroxymethyl) aminomethane (Tris) ink. The resultant membrane was then subjected to photopolymerization under UV irradiation to form a PDA layer. Successful formation of PDA layer on membrane surface was verified by series of physical and chemical methods. The optimized membrane (DA80-60/PVDF) exhibited superior oil/water separation performance with 1.5 times permeate flux higher than that of the pristine PVDF membrane and above 99% oil rejection rate. Meanwhile, the modified membranes showed satisfactory stability in aqueous solution with wide pH range (pH 2.0–7.0). The novel membrane modification method proposed in this study is facile, cost-saving and environment-friendly, serving as a competitive candidate for fabrication of efficient membranes for oil-water emulsion separation.

Synthesis of a continuous and intergrown metal-organic framework (MOF) membrane remains a challenging issue due to the grain boundary defects and intercrystalline cracks in MOF thin film. In this study, a ZIF-8 membrane was fabricated by using a plant polyphenol tannic acid (TA) layer as an intermediate layer to overcome this issue. Specifically, a TA layer was constructed on a polyethersulfone substrate via a facile and environmentally friendly aqueous coating process. Thereafter, the above modified membrane was immersed into a Zn(Ac)2 and Hmim mixture solution for in-situ growing a ZIF-8 thin film on membrane surface. It was found that the abundant pyrogallol groups in TA layer could coordinate with Zn2+ ions, promote heterogeneous nucleation and contribute to a continuous and intergrown ZIF-8 thin film. The as-prepared ZIF-8 membrane showed a pure water permeance of 3.6 L m−2 h−1 bar−1 with NaCl and Na2SO4 rejections of 64.7% and 92.2% respectively, overwhelming the controlled ZIF-8 membrane without TA as intermediate layer in both permeability and selectivity. This membrane is one of few MOF membranes that have a divalent salt rejection higher than 90%, demonstrating its great potential application in efficient desalination.

Transition metal oxide, α-Fe2O3, has attracted great interest as a kind of potential battery-type electrode material due to its high theoretical specific capacity. However, α-Fe2O3 still suffers from poor conductivity and large volume expansion during charge and discharge process. Herein, for the first time, the oxygen vacancies-modifying α-Fe2O3 are prepared via a novel two-step calcination of MIL-88-Fe (Fe-MOF) template. Note that the incorporation of oxygen vacancies into α-Fe2O3 nano-octahedron will promote faster charge storage kinetics and enables the α-Fe2O3 structure to be retained during the Li-ions. The oxygen vacancies-modifying α-Fe2O3 nano-octahedron exhibits high specific capacity (250.2 mAh g−1), and an activated carbon (AC)//α-Fe2O3 hybrid supercapacitor is constructed, delivering a high energy density of 63 W h kg−1 at a power density of 900 W kg−1. This finding underlines the importance of incorporating oxygen vacancies into battery-type electrode materials for promoting the practical application.

Herein, a novel positively charged nanofiltration (NF) membrane has been facilely fabricated via a highly efficient one-step mussel-substance-simulated co-deposition of low-cost catechol and branched polyetheylenimine (PEI) onto substrates. The co-deposition behaviour, physicochemical properties and separation performances of resultant membranes can be readily tailored by varying PEI molecular weight. In particular, the catechol/PEI600 co-deposited NF membrane shows good removals toward dyes, common salts and heavy metal ions for textile wastewater treatment. Our membranes exhibit high removal efficiency toward cationic dye and metal ions due to the Donnon effect. In addition, EtOH activation process can greatly enhance the membrane permeance with a factor of 1.8–2.4 without compromising rejection. Especially, the novel membranes show stable long-term separation performance toward MgCl2 removal, and the dye-fouled co-deposited membranes can be facilely regenerated and reused with a simple static immersion operation. The co-deposited membrane can perform well in alcohols solvents, indicating its excellent performance for practically environmentally-friendly usages. The facile strategy disclosed in our study can provide new opportunities to not only nanofiltration membrane modification but also the surface engineering of vast kinds of materials towards energy and environmental applications.

The main drawback of polyimide (PI) based OSN membrane capable to separate molecules is the declined solvent permeance after crosslinking. In this study, the hydrophilic monoamine named as Tris(hydroxymethyl) aminomethane (Tris) was first utilized to modify polyimide OSN membranes by adding Tris into the dope solution before phase inversion and diamino crosslinking for improving membrane-solvent mutual affinity so as to obtain high-performance OSN membranes. Such Tris modified membranes were proved by chemical characterizations, and the further contact angles and surface energy measurements revealed that the hydrophilicity and surface energy of the novel membranes increased with the Tris loading. Interestingly, the morphological observation demonstrated that the macrovoids shown in the pristine membranes can be completely displaced by sponge-like pores in Tris modified membranes. Surprisingly, the isopropanol (IPA) permeance of 10% Tris modified crosslinked membranes increased to 270% of the original value with only slight decline in dyes rejections. Besides, the fundamental study on the relationship between IPA or N,N-dimethylformamide (DMF) permeance and the membrane-solvent solubility parameter distance were performed. Our novel monoamine modification strategy can provide a new incentive to develop advanced membranes applicable to aqueous solution separation, gas separation and pervaporation for future sustainable usages.

Membrane fouling problem is the bottleneck for commercial applications of separation membranes. The current study offered a first report on preparation and performance of the magnetic and photocatalytic poly (vinylidene fluoride) (PVDF)-Ni-ZnO composite membranes for the antifouling purpose. Magnetic Ni–ZnO particles (NZPs) was firstly prepared via an in-situ reduction reaction. Thereafter, the NZPs were attracted onto a PVDF membrane surface through a magnetic force effect. The PVDF-NZPs composite membrane displayed magnetic property, photocatalytic property and obviously higher antifouling performance than that of bare PVDF membrane. Particularly, the flux recovery rates (FRR) of the optimal PVDF-NZPs membrane reached to 100%, 100%, 83% and 83% for filtration of humic acid (HA), sodium alginate (SA), bovine serum albumin (BSA) and yeast solutions, respectively, which are comparable or much better than most of the literature data. In addition, it was found that acid-based (AB) interaction of the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) results played the predominant role during the fouling process. The ultrahigh FRR of the modified PVDF-NZPs membrane mainly stemmed from its in-situ and persistent photocatalytic activities. The current work not only offered a novel membrane modification method, but also presented the modified membranes with enhanced performance for water treatment.

Though sludge foaming often occurs and thus causes serious membrane fouling in membrane bioreactors (MBRs), the fouling mechanisms related with the foaming phenomenon have not been well addressed, hindering better understanding and solving foaming problem. In this work, it was interestingly found that, the foulants during the foaming period possessed extremely high specific filtration resistance (SFR) (over 1016 m kg−1) and strong adhesion ability to membrane surface. Chemical characterization showed that the proteins (178.57 mg/L) and polysaccharides (209.21 mg/L) in the foaming sample were about 6.4 times and 5.4 times of those in the supernatant sample, suggesting existence of a mechanism permitting continuous production of these foulants in the MBR during the foaming period. It was revealed that the fouling caused by foams was associated with gel layer filtration process, and the extremely high SFR can be interpreted by chemical potential change in the gel filtration process depicted in Flory-Huggins theory. Meanwhile, analyses by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory showed that the strong adhesion ability stemmed from the high interaction energy between the foaming foulants and membrane surface. In addition, 16S rDNA gene sequencing identified that the abundance of the foaming related bacteria species in the sludge suspension during the foaming period was more than 10 times of that during the non-foaming period. This study offered new mechanism insights into foaming fouling in MBRs.

Co-deposition between plant polyphenol tannic acid (TA) and Fe3+ has been reported to be a facile way to construct nanofiltration (NF) membranes. However, this strategy suffers the problems of low atom economy and generating a large amount of environment-harmful aggregate wastes in solution. This work proposed a novel method based on layer-by-layer (LBL) self-assembly for preparation of TA-Fe3+ complex based NF membrane. The proposed method was facile and environmental-friendly because it did not require any chemical or solvent involved pretreatment nor generated any aggregate waste. A series of characterizations proved the successful formation of TA-Fe3+ complex based top layer on polyacrylonitrile (PAN) support surface. The resultant membrane showed superhydrophilicity property with water contact angle as low as 8°. Meanwhile, the optimized membrane showed a high water permeance of 40.9 L m−2 h−1 bar−1 whilst simultaneously maintained rejections higher than 93.9% towards various dyes with the molecular weight (MW) ranging from 320 to 1017 Da. Moreover, the as-prepared NF membranes showed stable long-term separation performance and good ion/organic selective separation performance. This study not only proposed a facile fabrication process for TA-Fe3+ complex based NF membrane, but also provided great potentials for sustainable molecular separation by the prepared membranes.