A novel 2D/1D core-shell heterostructures coupling MOF-derived iron oxides with ZnIn2S4 for enhanced photocatalytic activity

Insights into the function of metallic 1T phase tungsten disulfide as cocatalyst decorated zinc indium sulfide for enhanced photocatalytic hydrogen production activity

Improving the separation efficiency of carriers is an important part of enhancing photocatalytic activity. Herein, we successfully decorated metallic 1T phase tungsten disulfide (1T-WS2) on the surface of zinc indium sulfide (ZnIn2S4) and investigated the synergistic effect of 1T-WS2 on ZnIn2S4. The characterization results show that 1T-WS2 improves the light absorption capacity and utilization efficiency, increases the catalytic active site, improves the photogenerated charge separation efficiency, and optimizes the reduction potential of ZnIn2S4. Theoretical calculations show that compared with ZnIn2S4, 1T-WS2/ZnIn2S4 has a smaller adsorption Gibbs free energy of the intermediate state H*, which is conducive to the catalytic reaction. Under simulated solar irradiation, the hydrogen (H2) production rate of 1T-WS2/ZnIn2S4 with a loading of 12 wt% reaches 30.90 mmol h-1 g-1, which is 3.38 times higher than that of single ZnIn2S4 (9.13 mmol h-1 g-1). In addition, the apparent quantum efficiency of 1T-WS2/ZnIn2S4 with a loading of 12 wt% reaches 21.14 % under monochromatic light at a wavelength of λ = 370 nm. This work analyzes the light absorption and carrier separation to the catalytic site, and elucidates the mechanism for the enhancement of the photocatalytic hydrogen production performance.

Metal-Organic Frameworks-Derived Nanocarbon Materials and Nanometal Oxides for Photocatalytic Applications

Harnessing low-density solar energy and converting it into high-density chemical energy through photocatalysis has emerged as a promising avenue for the production of chemicals and remediation of environmental pollution, which contributes to alleviating the overreliance on fossil fuels. In recent years, metal-organic frameworks (MOFs) have gained widespread application in the field of photocatalysis due to their photostability, tunable structures, and responsiveness in the visible light range. However, most MOFs exhibit relatively low response to light, limiting their practical applications. MOFs-derived nanomaterials not only retain the inherent advantages of pristine MOFs but also show enhanced light adsorption and responsiveness. This review categorizes and summarizes MOFs-derived nanomaterials, including nanocarbons and nanometal oxides, providing representative examples for the synthetic strategies of each category. Subsequently, the recent research progress on MOFs-derived materials in photocatalytic applications are systematically introduced, specifically in the areas of photocatalytic water splitting to H2, photocatalytic CO2 reduction, and photocatalytic water treatment. The corresponding mechanisms involved in each photocatalytic reaction are elaborated in detail. Finally, the review discusses the challenges and further directions faced by MOFs-derived nanomaterials in the field of photocatalysis, highlighting their potential role in advancing sustainable energy production and environmental remediation.

Construction of two-dimensional zinc indium sulfide/bismuth titanate nanoplate with S-scheme heterojunction for enhanced photocatalytic hydrogen evolution

Improving the separation efficiency of photogenerated carriers plays an important role in photocatalysis. In this study, two-dimensional (2D)/2D zinc indium sulfide (ZnIn2S4)/bismuth titanate (Bi4Ti3O12) nanoplate heterojunctions were synthesized to alter the Bi4Ti3O12 morphology, modulate the bandgap of Bi4Ti3O12, and enhance the utilization of light. Meanwhile, the construction of the S-scheme heterojunction establishes an internal electric field at the ZnIn2S4/Bi4Ti3O12 heterojunctions interface and achieves the spatial separation of photogenerated charges. The hydrogen production rate of ZnIn2S4/Bi4Ti3O12 nanoplate with the optimal ratio reaches 27.50 mmol h-1 g-1, which is 1.5 times higher than that of ZnIn2S4/Bi4Ti3O12 nanoflower (18.28 mmol h-1 g-1) and 2.4 times higher than that of ZnIn2S4 (11.69 mmol h-1 g-1). The apparent quantum efficiency of ZnIn2S4/Bi4Ti3O12 nanoplate reached 57.9 % under a single wavelength of light at 370 nm. This work provides insights into the study of new materials for photocatalytic hydrogen production.

Rational Photodeposition of Cobalt Phosphate on Flower-like ZnIn2S4 for Efficient Photocatalytic Hydrogen Evolution

The high electrons and holes recombination rate of ZnIn2S4 significantly limits its photocatalytic performance. Herein, a simple in situ photodeposition strategy is adopted to introduce the cocatalyst cobalt phosphate (Co-Pi) on ZnIn2S4, aiming at facilitating the separation of electron-hole by promoting the transfer of photogenerated holes of ZnIn2S4. The study reveals that the composite catalyst has superior photocatalytic performance than blank ZnIn2S4. In particular, ZnIn2S4 loaded with 5% Co-Pi (ZnIn2S4/5%Co-Pi) has the best photocatalytic activity, and the H2 production rate reaches 3593 μmol·g-1·h-1, approximately double that of ZnIn2S4 alone. Subsequent characterization data demonstrate that the introduction of the cocatalyst Co-Pi facilitates the transfer of ZnIn2S4 holes, thus improving the efficiency of photogenerated carrier separation. This investigation focuses on the rational utilization of high-content and rich cocatalysts on earth to design low-cost and efficient composite catalysts to achieve sustainable photocatalytic hydrogen evolution.

Dual Z-scheme BiOI/Bi2S3/MgIn2S4 composite photocatalyst for effective photocatalytic degradation of Congo red

The demand and use of dyes in modern life are increasing, and dye pollution has become a widespread concern worldwide; therefore, it is essential to develop novel environmentally friendly materials to deal with dye wastewater. Herein, a novel visible-light-driven ternary catalyst (BiOI/Bi2S3/MgIn2S4) was fabricated by employing the hydrothermal method. Compared to BiOI, the synthesized ternary catalyst exhibited better photocatalytic performance to decompose Congo red under visible light. Congo red was completely degraded after 0.5 h (0.5 g/L photocatalyst BiOI/Bi2S3/MIS-1) in the presence of visible light, which was 16.83 and 9.94 times of that of pure BiOI and MgIn2S4, respectively. A repetitive experiment showed that the BiOI/Bi2S3/MIS-1 could be reusable to degrade Congo red, demonstrating that it has excellent mechanical properties. The enhanced photocatalytic capability was due to addition of BiOI and Bi2S3, which increased the charge separation as well as suppressed the recombination of photo-induced holes and electrons. Electron paramagnetic resonance technique and free radical trapping tests were employed to determine the radicals produced in BiOI/Bi2S3/MgIn2S4 in the presence of visible light, indicating that ·O2- and h+ were major active species to decompose Congo red under photocatalytic process. Seventeen main intermediates or reaction products were identified by UPLC-MS. The tentative degradation pathway of Congo red was also proposed.

Facile Synthesis of P-Doped ZnIn2S4 with Enhanced Visible-Light-Driven Photocatalytic Hydrogen Production

ZnIn₂S₄ (ZIS) is widely used in the field of photocatalytic hydrogen production due to its unique photoelectric properties. Nonetheless, the photocatalytic performance of ZIS usually faces problems of poor conductivity and rapid recombination of charge carriers. Heteroatom doping is often regarded as one of the effective strategies for improving the catalytic activity of photocatalysts. Herein, phosphorus (P)-doped ZIS was prepared by hydrothermal method, whose photocatalytic hydrogen production performance and energy band structure were fully studied. The band gap of P-doped ZIS is about 2.51 eV, which is slightly smaller than that of pure ZIS. Moreover, due to the upward shift of its energy band, the reduction ability of P-doped ZIS is enhanced, and P-doped ZIS also exhibits stronger catalytic activity than pure ZIS. The optimized P-doped ZIS exhibits a hydrogen production rate of 1566.6 μmol g^-1 h^-1, which is 3.8 times that of the pristine ZIS (411.1 μmol g^-1 h^-1). This work provides a broad platform for the design and synthesis of phosphorus-doped sulfide-based photocatalysts for hydrogen evolution.

Integrating Ultrasmall Pd NPs into Core-Shell Imidazolate Frameworks for Photocatalytic Hydrogen and MeOH Production

The construction of photoactive units in the proximity of a stable framework support is one of the promising strategies for uplifting photocatalysis. In this work, the ultrasmall Pd NPs implanted onto core-shell (CS) metal organic frameworks (MOFs), i.e., CS@Pd nanoarchitectures with tailored electronic and structural properties are reported. The all-in-one heterogeneous catalyst CS@Pd3 improves the surface functionalities and exhibits an outstanding hydrogen evolution reaction (HER) activity rate of 12.7 mmol g^-1 h^-1, which is 10-folds higher than the pristine frameworks with an apparent quantum efficiency (AQE) of 9.02%. The bifunctional CS@Pd shows intriguing results when subjected to photocatalytic CO₂ reduction with an impressive rate of 71 μmol g^-1 h^-1 of MeOH under visible-light irradiation at ambient conditions. Spectroscopic data reveal efficient charge migrations and an extended lifetime of 2.4 ns, favoring efficient photocatalysis. The microscopic study affirms the formation of well-ordered CS morphology with precise decoration of Pd NPs over the CS networks. The significance of active Pd and Co sites is addressed by congruent charge-transfer kinetics and computational density functional theory calculations of CS@Pd, which validate the experimental findings with their synergistic involvement in improved photocatalytic activity. This present work provides a facile and competent avenue for the systematic construction of MOF-based CS heterostructures with active Pd NPs.

Dual cocatalysts and vacancy strategies for enhancing photocatalytic hydrogen production activity of Zn3In2S6 nanosheets with an apparent quantum efficiency of 66.20

Converting solar energy into hydrogen energy is a feasible means to solve the current energy crisis. However, developing an excellent photocatalyst with high light utilization and stability for hydrogen production remains a great challenge. In this work, CoS₂ nanoparticles as cocatalysts are growth on Zn₃In₂S₆ nanosheets with abundant sulfur vacancies for hydrogen evolution, and the optimal rate of hydrogen evolution is as high as 5.69 mmol h^-1 g^-1 in the absence of noble metal co-catalyst Pt, which is 2.87 and 2.29 times that of CoS₂/Zn₃In₂S₆ (with few sulfur vacancies) and Zn₃In₂S₆ (with rich sulfur vacancies). In addition, the hydrogen production rate of CoS₂/Zn₃In₂S₆ composite (with rich sulfur vacancies and 1 wt% Pt) is 24.17 mmol h^-1 g^-1, which is 4.25 and 1.90 times that of CoS₂/Zn₃In₂S₆ (with rich sulfur vacancies) and 1%-Pt/Zn₃In₂S₆ (with rich sulfur vacancies), respectively. The apparent quantum efficiency (AQE) of CoS₂/Zn₃In₂S₆ composite (with rich sulfur vacancies and 1 wt% Pt) reaches 66.20% under light irradiation at the wavelength of 370 nm. Above all indicate that dual cocatalysts (CoS₂ and Pt) and sulfur vacancies can promote the efficient hydrogen evolution activity of Zn₃In₂S₆ nanosheets. This work will provide new ideas and insights for the development of photocatalytic hydrogen production technology.

Construction of a p-n heterojunction based on magnetic Mn0.6Zn0.4Fe2O4 and ZnIn2S4 to improve photocatalytic performance

To improve the photocatalytic performance of Mn_0.6Zn_0.4Fe₂O₄ (MZFO) and ZnIn₂S₄ (ZIS) for organic pollutants, the p-n MZFO@ZIS heterojunctions with different weight percentage (10 ~ 40%) of MZFO are constructed from spent batteries and added indium ion via a green bioleaching and hydrothermal method. Structural, optical, and photocatalytic properties for the heterojunctions are investigated systematically by XRD, FT-IR, SEM-EDX, TEM, BET, VB-XPS, UV-vis DRS, PL, etc. The results confirm that p-n junction significantly improves the visible light adsorption and the separation efficiency of photogenerated carriers. Specifically, MZFO-25%@ZIS shows the highest photodegradation performance toward Congo red (CR), and its reactive kinetic constant is about 9.6, 7.8, and 7.0 times higher than that of P25 TiO₂, MZFO, and ZIS, respectively, and MZFO-25%@ZIS still possesses a high reusability and simple magnetic separation after 5 cycles of reuse. The radical trapping experiments and electronic paramagnetic resonance (EPR) tests show that ·O₂^-, ·OH, and h⁺ are the most important active substance for degrading CR. The pathways for the CR degradation are further proposed based on the intermediate analysis. DFT + U calculations confirm that the high charge density of Zn-O, Fe-O, and Zn-S bonds in the MZFO and ZIS molecules provides the electrons for the sufficient production of free radicals. This work also provides a novel high value-added strategy for the green utilization of spent batteries.

Simple preparation of a CuO@γ-Al2O3 Fenton-like catalyst and its photocatalytic degradation function

We designed a photocatalyst and developed sustainable wastewater purification technology, which have significant advantages in effectively solving the global problem of drinking water shortage. In this study, a new nanocomposite was reported and shown to be a catalyst with excellent performance; CuO was coated successively onto functionalized nano γ-Al₂O₃, and this novel structure could provide abundant active sites. We evaluated the performance of the CuO@γ-Al₂O₃ nanocomposite catalyst for polyvinyl alcohol (PVA) degradation under visible light irradiation. Under optimized conditions (calcination temperature, 450 °C; mass ratio of γ-Al₂O₃:Cu(NO₃)₂·3H₂O, 1:15; pH value, 7; catalyst dosage, 2.6 g/L; reaction temperature, 20 °C; and H₂O₂ dosage, 0.2 g/mL), the CuO@γ-Al₂O₃ nanocomposite catalyst presented an excellent PVA removal rate of 99.21%. After ten consecutive degradation experiments, the catalyst could still maintain a PVA removal rate of 97.58%, thus demonstrating excellent reusability. This study provides an efficient and easy-to-prepare photocatalyst and proposes a mechanism for the synergistic effect of the photocatalytic reaction and the Fenton-like reaction.

Cl-based functional group modification MIL-53(Fe) as efficient photocatalysts for degradation of tetracycline hydrochloride

MIL-53(Fe) catalyst has been widely used to treat the pollutants in water. However, the limited number of electrons in MIL-53(Fe) catalyst has always affected the rate at which Fe³⁺ can be reduced to Fe²⁺. We modulated iron-based metal-organic frameworks (MOFs) using organic ligands modified with chlorine functional groups. The characterization results indicate that the 2Cl-MIL-53(Fe) catalyst exhibited the optimal photoelectric properties while maintaining the original structural characteristics. The experimental analyses and the first-principles study suggest that the introduction of a chlorine functional group not only reduced the band gap width and enhanced the visible-light absorption capacity, but also significantly enhanced the electron cloud density of Fe-O clusters. This could further accelerate the redox cycle of Fe(III)/Fe(II), beneficial for H₂O₂ activation. The constructed Cl-MIL-53(Fe) catalyst exhibited a 3.8 times higher reaction rate constant than pure MIL-53(Fe) catalyst. The specific TCH degradation pathway and mechanism of 2Cl-MIL-53(Fe) treatment are proposed. This study provides a new strategy for iron-based MOFs as a heterogeneous photo-Fenton catalyst to degrade pollutants in water.

Fabrication of a ternary NiS/ZnIn2S4/g-C3N4 photocatalyst with dual charge transfer channels towards efficient H2 evolution

As a renewable green energy, hydrogen has received widespread attention due to its huge potential in solving energy shortages and environment pollution. In this paper, a one-step solvothermal method was applied to grow ultra-thin g-C₃N₄ (UCN) nanosheets and NiS nanoparticles on the surface of ZnIn₂S₄ (ZIS). A ternary NiS/ZnIn₂S₄/ultra-thin-g-C₃N₄ composite material with dual high-speed charge transfer channels was constructed for the advancement of the photocatalytic H₂ generation. The optimal ternary catalyst 1.5wt.%NiS/ZnIn₂S₄/ultra-thin-g-C₃N₄ (NiS/ZIS/UCN) achieved a H₂ evolution yield reached to 5.02 mmolg^-1h^-1, which was 5.23 times superior than that of pristine ZnIn₂S₄ (0.96 mmolg^-1h^-1) and even outperform than that of the best precious metal modified 3.0 wt%Pt/ZnIn₂S₄ (4.08 mmolg^-1h^-1). The AQY at 420 nm could be achieved as high as 30.5%. The increased photocatalytic performance of NiS/ZIS/UCN could be ascribed to the type-I heterojunctions between intimated ZIS and UCN. In addition, NiS co-catalyst with large quantity of H₂ evolution sites, could result in efficient photo-induced charges separation and migration. Furthermore, the NiS/ZIS/UCN composite exhibited excellent H₂ evolution stability and recyclability. This work would also offer a reference for the design and synthesis of ternary co-catalyst with heterojunction composite for green energy conversion.

In Situ Self-Assembled ZIF-67/MIL-125-Derived Co3O4/TiO2 p-n Heterojunctions for Enhanced Photocatalytic CO2 Reduction

Photocatalytic CO₂ reduction to carbon fuels is regarded as an ideal and sustainable way to provide clean energy and solve environmental crisis. Herein, a p-n Co₃O₄/TiO₂ heterojunction photocatalyst was synthesized by one-step pyrolysis of self-assembly ZIF-67/MIL-125, which was used in photocatalytic CO₂ reduction for the first time. Co₃O₄ nanocages were highly dispersed on the surface of TiO₂ nanoplates with an intimate contact. The optimal Co₃O₄/TiO₂ exhibited a significantly enhanced CO evolution rate of 1256 μmol g^-1 h^-1 under simulated solar light, which was 2.4 times higher than that of pure Co₃O₄. The high photocatalytic performance of Co₃O₄/TiO₂ was attributed to its enriched active sites and formed p-n heterojunctions. According to the electrocatalytic measurements, the possible mechanism and photoinduced charge transfer process were discussed in detail. We believe that this research provides a facile and efficient approach to fabricate MOF-derived heterojunction photocatalysts for CO₂ reduction.

Micro/macrostructure and multicomponent design of catalysts by MOF-derived strategy: Opportunities for the application of nanomaterials-based advanced oxidation processes in wastewater treatment

Advanced oxidation processes (AOPs) have demonstrated an effective wastewater treatment method. But the application of AOPs using nanomaterials as catalysts is challenged with a series of problems, including limited mass transfer, surface fouling, poor stability, and difficult recycling. Recently, metal-organic frameworks (MOFs) with high tunability and ultrahigh porosity are emerging as excellent precursors for the delicate design of the structure/composition of catalysts and many MOF-derived catalysts with distinct physicochemical characteristics have shown optimized performance in various AOPs. Herein, to elucidate the structure-composition-performance relationship, a review on the performance optimization of MOF-derived catalysts to overcome the existing problems in AOPs by micro/macrostructure and multicomponent design is given. Impressively, MOF-derived strategy for the design of catalyst materials from the aspects of microstructure, macrostructure, and multicomponent (polymetallic, heteroatom doping, M/C hybrids, etc.) is firstly presented. Moreover, important advances of MOF-derived catalysts in the application of various AOPs (Fenton, persulfate-based AOPs, photocatalysis, electrochemical processes, hybrid AOPs) are summarized. The relationship between the unique micro/macrostructure and/or multicomponent features and performance optimization in mass transfer, catalytic efficiency, stability, and recyclability is clarified. Furthermore, the challenges and future work directions for the practical application of MOF-derived catalysts in AOPs for wastewater treatment are provided.

Rational synthesis of isomorphic rare earth metal–organic framework materials for simultaneous adsorption and photocatalytic degradation of organic dyes in water

Two isomorphic rare earth metal–organic frameworks (MOFs) were synthesized by a solvothermal method. These MOFs have good removal effects on cationic and neutral dyes through simultaneous adsorption and photocatalysis.

ZnIn2 S4 -Based Photocatalysts for Energy and Environmental Applications

As a fascinating visible-light-responsive photocatalyst, zinc indium sulfide (ZnIn₂ S₄ ) has attracted extensive interdisciplinary interest and is expected to become a new research hotspot in the near future, due to its nontoxicity, suitable band gap, high physicochemical stability and durability, ease of synthesis, and appealing catalytic activity. This review provides an overview on the recent advances in ZnIn₂ S₄ -based photocatalysts. First, the crystal structures and band structures of ZnIn₂ S₄ are briefly introduced. Then, various modulation strategies of ZnIn₂ S₄ are outlined for better photocatalytic performance, which includes morphology and structure engineering, vacancy engineering, doping engineering, hydrogenation engineering, and the construction of ZnIn₂ S₄ -based composites. Thereafter, the potential applications in the energy and environmental area of ZnIn₂ S₄ -based photocatalysts are summarized. Finally, some personal perspectives about the promises and prospects of this emerging material are provided.

Core-shell ZIF-8@MIL-68(In) derived ZnO nanoparticles-embedded In2O3 hollow tubular with oxygen vacancy for photocatalytic degradation of antibiotic pollutant

Developing a novel core-multishelled metal oxide hollow tube with rich oxygen vacancy is highly attractive in photocatalytic degradation of antibiotic pollutant. Herein, ZnO@In₂O₃ core-shell hollow microtubes were synthesized via one-step calcination of ZIF-8@MIL-68(In) formed by an in-situ self-assembly. TEM images demonstrate that 0D ZnO quantum dots (QDs) shell with 0.2 µm were well coated on the surface of 1D In₂O₃ hollow tube as the core with 1.2 µm. The synthesized heterostructure indicates the enhanced photocatalytic performance in tetracycline (TC) degradation compared with single ZIF-derived ZnO and MIL-68(In)-derived In₂O₃ under simulated solar irradiation. Besides, organic pollutants including malachite green (MG), methylene blue (MB) and rhodamine B (RhB) are further used to evaluate the photocatalytic activity of ZnO@In₂O₃, and the effect of weight ratios between ZnO and In₂O₃ on degradation efficiency is also studies. The ZnO@In₂O₃ heterojunction can provide higher specific surface area, expose more active sites, possess appropriate number of oxygen vacancies, enhance light absorption and further effectively boost the transfer and separation of photoinduced charge carriers. In addition, the proposed photocatalytic mechanism and degradation pathway are discussed in detail based on active species trapping test, electron spin resonance (ESR) and LCMS.

In Situ Growth of ZnIn2S4 on MOF-Derived Ni-Fe LDH to Construct Ternary-Shelled Nanotubes for Efficient Photocatalytic Hydrogen Evolution

A rational design of a novel ternary-shelled nanotube is attractive in photocatalytic water splitting. Herein, ZnIn₂S₄ nanosheets were in situ grown on the surface of MIL-88A-derived Ni-Fe layered double hydroxide (LDH) to fabricate ternary-shelled nanotubes (ZIS@Ni-Fe LDH) via a self-assembly strategy. Characterization indicates that the ZIS@Ni-Fe LDH heterostructure exhibits a high surface area and a well-defined ternary-shelled hollow structure. The optimal heterostructure presents a remarkably improved photocatalytic hydrogen production rate (2035.81 μmol g^-1 h^-1) compared with bare ZnIn₂S₄ and MIL-88A-derived Ni-Fe LDH under visible light illumination. The effect of ZnIn₂S₄ loading on the photocatalytic performance and stability of ZIS@Ni-Fe LDH is systematically studied. The ZIS@Ni-Fe LDH heterostructure can make better use of the inner space, provide abundant reactive sites, improve light harvesting, accelerate interfacial electron transfer, and further promote photocatalytic hydrogen evolution. Based on the electrocatalytic performance, the probable photocatalytic mechanism and the electron transfer pathway can be proposed. Our work provides a facile and efficient strategy to construct ternary-shelled heterojunction photocatalysts.

Experimental studies on water matrix and influence of textile effluents on photocatalytic degradation of organic wastewater using Fe-TiO2 nanotubes: Towards commercial application

The application of photocatalysis for the effective removal of textile dyes is dependent on various parameters related with both water quality and different chemicals discharge during the dying process. Because the oxidation rates of the particular mixtures mainly influenced by the elements of the water matrix. These elements comprised of organic, inorganic salts, heavy metals, and ions. The impact of water matrices (Tap water, DI water, seawater, surface water, and ultra-pure water) on the Congo red decolorization, total organic carbon, and chemical oxygen demand removal efficacy has been assessed using Fe-TiO₂ nanotubes as a photocatalyst. The photocatalytic degradation rate decreased in unclean water due to the interferences of dissolved organics and minerals. However, all the environmental water matrices depict the significant decrease in turbidity and conductivity after treating with photocatalytic process. The photoactivity and capacity for decantation are the two crucial elements that have an impact on the "practical efficiency" of photocatalysts. Moreover, the textile wastewater contains a large quantity of dyes mixed with number of detrimental chemicals and other effluents discharged into the water which consequently pollute ecosystem and cause serious risks to human health. For environmental applications, we investigated individually the impact of various harmful chemicals commonly discharged from each step of textile wet processing which can have inhibiting or promoting effect on the azo dye photocatalytic degradation.

Recent advances on preparation and environmental applications of MOF-derived carbons in catalysis

Carbon materials derived from metal organic frameworks (MOFs) have excellent properties of high surface area, high porosity, adjustable pore size, high conductivity and stability, and their applications in catalysis have become a rapidly expanding research field. In this review, we have summarized the synthesis strategies of MOF-derived carbons with different physical and chemical properties, obtained through direct carbonization, co-pyrolysis and post-treatment. The potential applications of derived carbons, especially monometal-, bimetal-, nonmetal-doped and metal-free carbons in organo-catalysis, photocatalysis and electrocatalysis are analyzed in detail from the environmental perspective. In addition, the improvement of catalytic efficiency is also considered from the aspects of increasing active sites, enhancing the activity of reactants and promoting free electron transfer. The function and synergy of various species of the composites in the catalytic reaction are summarized. The reaction paths and mechanisms are analyzed, and research ideas or trends are proposed for further development.

Efficient degradation of perfluorooctanoic acid by electrospun lignin-based bimetallic MOFs nanofibers composite membranes with peroxymonosulfate under solar light irradiation

Perfluorooctanoic acid (PFOA) has demonstrated potential toxicity to human health and has been detected in different environmental matrices due to its stable physical and chemical properties. To degrade PFOA under solar light irradiation, we fabricated a lignin/polyvinyl alcohol (PVA)/Co/Fe metal-organic frameworks (lignin/PVA/bi-MOFs) composite membrane via a typical electrospinning and in-situ solvothermal method for the catalytic degradation of PFOA. In the peroxymonosulfate (PMS)/membranes/solar light system, Electron paramagnetic resonance analysis (EPR) demonstrated the sulfate radicals (SO₄^-) and hydroxyl radicals (OH) were generated by activating PMS with transition metal and solar light irradiation. Lignin/PVA/bi-MOFs showed outstanding performance in that 89.6% of PFOA was degraded within 3 h under optimal conditions. Compared with that in solar light, only 59.6% PFOA was degraded in the dark, and the rate constant of PFOA degradation decreased from 0.0150 min^-1 to 0.0046 min^-1. Moreover, lignin/PVA/bi-MOFs were reused after simply rinsing with ultra-pure water and the degradation capacity of lignin/PVA/bi-MOFs remained at 77% after 4 cycles. The results might provide a new concept for the design of bimetallic MOFs for applications in organic pollutant removal.