Stable Photocatalyst Research Articles

An organic visible-photocatalytic-adsorbence mechanism to high-efficient removal of heavy metal antimony ions

Purification of emerging heavy metal antimony contaminated water based on advanced ingenious strategies. An activated modified coconut shell charcoal (CSC) was synthesized and evaluated as a substrate-supported loaded organic photovoltaic material, PM6:PYIT:PM6-b-PYIT, to prepare a surprisingly highly efficient, stable, environmentally friendly, and recyclable organic photocatalyst (CSC–N–P.P.P), which showed excellent effects on the simultaneous removal of Sb(III) and Sb(V). The removal efficiency of CSC-N-P.P.P on Sb(Ⅲ) and Sb(V) reached an amazing 99.9% in quite a short duration of 15 min. At the same time, under ppb level and indoor visible light (∼1 W m−2), it can be treated to meet the drinking water standards set by the European Union and the U.S. National Environmental Protection Agency in 5 min, and even after 25 cycles of recycling, the efficiency is still maintained at about 80%, in addition to the removal of As (III), Cd (II), Cr (VI), and Pb (II) can also be realized. The catalyst not only solves the problems of low reuse rate, difficult structure adjustment and high energy consumption of traditional photocatalysts but also has strong applicability and practical significance. The pioneering approach provides a much-needed solution strategy for removing highly toxic heavy metal antimony pollution from the environment.

Investigating the Z-scheme mechanism on the optimized oxygen vacancies ZnO/Co3S4 photocatalyst for the efficient photocatalytic removal of ciprofloxacin

The waste of human and animal antibiotics is an inescapable problem and a severe threat to the continuation of human life. A logical strategy to face the challenge of antibiotic contamination is to design active, stable, environmentally friendly, and economical photocatalysts. Hence, oxygen vacancies ZnO/Co3S4 (ZnO-OV/Co3S4) photocatalyst was successfully fabricated for the first time and used for the photocatalytic removal of ciprofloxacin (CIP) as a widely used antibiotic under visible light. Several techniques were engaged in exploring the crystallinity, morphology, structure, chemical and elemental composition, and electrochemical and optical properties of the constructed nanocomposites. The band gap of ZnO-OV and Co3S4 nanoparticles was determined at 2.95 and 1.58 eV by evaluating the optical properties and using the Tauc plots. To optimize the conditions of the photocatalytic process, factors such as the weight percentage of the nanocomposite components, the photocatalyst dosage, the initial concentration of CIP, the pH of the test solution, and the presence of bubbled oxygen were varied. The optimal degradation rate constant (0.0720 min−1) was obtained for ZnO-OV/Co3S4 (15 %) nanocomposite at pH 9, nanocomposite dosage of 1.5 g/L, and 10 mg/L of CIP in the visible spectrum. The experimental and characterization outcomes indicated that the significantly boosted photocatalytic activity of the ZnO-OV/Co3S4 composite was chiefly attributed to the oxygen vacancies, retard charge carriers recombination by the construction of heterojunction between the ZnO-OV and Co3S4. Finally, the possible Z-scheme mechanism was proposed to illuminate the migration of charge carriers.

Enhanced Photocatalytic Degradation by the Preparation of a Stable La-Doped FeTiO3 Photocatalyst: Experimental and DFT Study.

The rapid photocarrier recombination limits the photocatalytic activity of iron titanate (FeTiO3) to be further improved. Developing novel approaches to inhibit the rapid recombination rate of the FeTiO3 photocatalysts is crucial for efficiently degrading pollutants in wastewater. Rare earth ions, with unique electron dispositions and large ion radii, could effectively inhibit photocarrier recombination. Herein, novel lanthanum (La)-doped FeTiO3 photocatalysts were designed and successfully synthesized. The photocatalytic performance of the 12 mol % La/FeTiO3 photocatalyst was superior in degrading tetracycline hydrochloride (TCH), methylene blue (MB), and brilliant blue (BB). These degradation rate constants (k) were 0.12358, 0.01357, and 0.03064 L mg-1 min-1, respectively, which were 12.83, 1.61, and 7.78 times that of pure FeTiO3. The photoelectronic tests and density functional theory (DFT) calculations revealed that the La 4f orbital forms an impurity energy level in the conduction band of FeTiO3. This level narrows the bandgap and acts as an electron acceptor, capturing photoexcited electrons and inhibiting the rapid recombination of photoexcited electron-hole pairs in FeTiO3. This work enhances the potential of FeTiO3 in the photocatalysis field and provides important insights into the efficient degradation of organic pollutants in wastewater.

InVO4-Decorated Ti3C2 MXene for Efficient Photocatalytic Hydrogen Evolution.

The generation of hydrogen through photocatalysis is a fascinating technology for addressing environmental concerns and the energy crisis. Nevertheless, the quest for cost-effective, stable, and efficient photocatalysts in the realm of energy conversion remains a significant challenge. Herein, we designed novel InVO4/Ti3C2 MXene (IVTC) heterostructures by employing acid etching to produce Ti3C2 MXene with an accordion-like morphology, using the hydrothermal technique for the production of orthorhombic InVO4 nanoparticles (NPs), and integrating them through a self-assembly approach. Both field-emission scanning electron microscopy and HRTEM analyses revealed a consistent distribution of InVO4 NPs with an average size of 43.4 nm on both surfaces and between the sheets of Ti3C2 MXene. The intimate interface between the Ti3C2 MXene nanosheet and InVO4 suppressed carrier recombination and promoted charge transfer, thereby boosting photocatalytic H2 production. Under visible light exposure, the rate of hydrogen evolution is enhanced in IVTC heterostructures containing an optimized 10% loading of InVO4, exhibiting over a 3-fold increase compared to pristine InVO4 NPs, maintaining efficiency across four cycles. This research presents a promising method for designing and creating high-efficiency heterostructures possessing excellent visible-light-driven photocatalytic activity for H2 evolution.

Monodisperse silver nanocubes composite Ag@C/SrTiO3 photocatalytic decomposition of water for hydrogen reduction

Metal-induced photocatalysis has been a relatively effective strategy for the efficient use of solar energy. In this paper, highly efficient and stable Ag@C/SrTiO3 photocatalysts were prepared by compounding silver nanocubes wrapped with few layers graphite with strontium titanate materials. We obtained silver nanocubes with a uniformly dispersed size of about 35 nm by varying the surface energy of silver and inducing the preferential binding of PVP on the (100) crystal plane with the help of selective adsorption of chloride ions on the different crystal planes of silver. As obtained under the characterisation of UV–visible absorption spectra, the material has a broad visible light absorption (450–900 nm). The Ag@C/SrTiO3 has a hydrogen reduction rate of up to 457.5 μmol g−1·h−1 under simulated sunlight, which is ∼200 % higher than the SrTiO3 and ∼900 % higher than the sliver. Moreover, the catalyst was stable, still producing 93.5 % hydrogen after three cycles of testing, and the photocatalyst structure did not change as known from the XRD data of the material before and after testing. The present work demonstrates the feasibility of rational design of efficient and stable silver-based photocatalysts.

Investigation of ZnO@CdS nanocomposite with amplified photocatalytic H2 production under visible light irradiation

Researchers are trying to develop an efficient solar-powered catalytic water splitting system to solve the energy dilemma and generate green hydrogen. In this study, ZnO@CdS nano-heterostructures were synthesized using sol-gel and co-precipitation techniques. The pristine ZnO, CdS, and their heterostructures were characterized through various characterization tools such as XRD, SAED, XPS, FTIR, EDX, SEM, FE-TEM, UV–vis, Mott-Schottky, GCG, EIS, and PL, to know the crystal structure, chemical state, elemental composition, morphology, band gap, scheme mechanism, hydrogen production and charge transfer resistance characteristics of the samples, respectively. The SEM, FE-TEM, confirm that CdS NPs are well decorated on hexagonal ZnO rods. The efficient H2 production of 587.86 μmolg−1 h−1 were measured for the optimized sample which is 3.91 times greater than pure ZnO rods and 3.22 times than CdS NPs. Strong photo-cyclic stability test was carried out for 20 h in four cycles while, PL spectroscopy confirms the suppressed charge recombination. All of the above characterization prove that (ZC-20) optimized sample, has a potential to be used as an efficient and stable photocatalyst for H2 production via photocatalytic water splitting.

Engineering single-atom rhodium-C3N sites on covalent organic frameworks for boosting photocatalytic hydrogen evolution

Developing efficient and stable photocatalysts for solar hydrogen (H2) energy conversion is meaningful but challenging. Herein, a novel photocatalyst with Rh single atoms (Rh SAs) anchoring in β-ketoimine-linked covalent organic frameworks (TpPa-1) via RhC3N sites is proposed for achieving highly efficient H2 production in phosphate buffer saline (PBS) solution with sodium ascorbate (SA) as sacrificial agent under visible light. TpPa-1 with abundant N and C-chelate sites provides a reliable basis for anchoring Rh single atoms. The optimized Rh SAs/TpPa-1 exhibits an outstanding hydrogen evolution activity (1836.81μmol h−1 g−1), 9.34 and 2.27 folds enhancement than that of pristine TpPa-1 and Rh NPs/TpPa-1. X-ray absorption fine structure (XAFS) combined with density functional theory (DFT) calculations reveal that the significant improvement in H2 evolution performance on Rh SAs/TpPa-1 originates from the unique RhC3N coordination environment, promoting the charge separation and migration at the atomic interface, and thus decreasing the energy barrier for H* formation. Notably, in situ Raman technique confirmed Rh SAs was the main active sites (RhH) for proton reduction.

Reactive oxygen boosts photocatalytic oxytetracycline degradation and H2O2 production by K, O and cyano co-modified carbon nitride

Engineering photocatalysts to enhance the production of reactive oxygen species holds great importance in realizing effective water purification and hydrogen peroxide (H2O2) generation. Herein, the K, O, and cyano co-modified carbon nitride (KOCN) was constructed using thermal polymerization. Under visible light irradiation, KOCN showed excellent oxytetracycline hydrochloride (OTC) degradation efficiency and H2O2 generation rate. During the photocatalysis, rich reactive oxygens involving ·O2-, 1O2, H2O2, and ·OH were detected. Additionally, the production of H2O2 was attributed to a two-step single-electron oxygen reduction reaction (ORR). DFT and characterization analyses confirmed that the doping of K and O as well as the formation of cyano groups expanded the visible light response range, adjusted the band structure, and improved the separation of photogenerated carriers. This study presents a novel approach for developing efficient, stable, and reusable photocatalysts to address contemporary environmental challenges.

UVA light assisted activation of sulfite by metal–organic framework-derived FeOx@C catalyst for organic degradation: Formation and role of non-radical species

Advanced oxidation processes (AOPs) based on sulfite (S(IV)) activation are gaining recognition as a promising Fenton-like strategy, primarily due to their ability to generate potent radicals (e.g., SO4− and HO). However, the existence and role of a non-radical-driven oxidation pathway in the S(IV)-mediated degradation of contaminants remain under debate. Herein, a magnetic iron-carbon composite (FeOx@C) was fabricated using the MOF-templated method and utilized as a stable photocatalyst to activate S(IV) under UVA light, achieving >93.6 % degradation of 20 μM ofloxacin (OFL) with a high degradation rate constant of 0.073 min−1 within 45 min. The catalyst’s porous carbon structure facilitated the transport of substrates to active sites and shortened the diffusion distance between reactive species and contaminants. Adsorbed S(IV) donated one electron to photo-generated holes and exposed Fe(III) sites with the formation of SO5−, which then followed two distinct pathways to produce radicals (SO4−) and non-radicals (Fe(IV) and 1O2) responsible for OFL degradation. By leveraging the synergy of both radicals and non-radicals, this innovative oxidative system showcased robust anti-interference capacities and exceptional performance in degrading contaminants from complex water matrices. This study provides new insights into the significant role of non-radical species in S(IV)-mediated decontamination processes.

Improving the Photoactivity of Porphyrin-Based Metal-Organic Frameworks via Constructing [Ce-O] Active Site and Vacancy.

Defect engineering of metal-organic frameworks (MOFs) is a versatile approach to tailoring their electronic structures and photocatalytic performance. Herein, Ce-based porphyrin MOFs (CMFs) featuring controlled structural defects were successfully prepared using a simple acid modulation strategy to drive the photocatalytic H2 generation. The [Ce-O] unit serves as the active site via a ligand-to-metal charge transfer process, which has been confirmed by in situ XPS analysis. Abundant exposed coordinatively unsaturated Ce-O centers are beneficial for the adsorption and activation of water molecules, which is an important factor for improving the photocatalytic performance of the synthesized defective MOFs. In addition, optical and electrochemical experiments indicate that CMFs with more oxygen vacancies possess higher charge separation efficiency. As a result, the optimized CMF(Zn)-200 sample afforded high stability and activity in the H2 generation (up to 1603.3 μmol·g-1·h-1 under cocatalyst-free conditions) and tetracycline hydrochloride removal efficiency (97%), which was 8.45 and 97 times higher than that of pure meso-tetra(4-carboxyphenyl)porphine. This study demonstrates that effective structural modulation and defect introduction can improve the activity and stability of PMOF-based photocatalysts.

Effect of Nitrogen Doping on the Photocatalytic Properties and Antibiofilm Efficacy of Reduced TiO2 Nanoparticles.

Nanomaterial-mediated antibacterial photodynamic therapy (aPDT) emerges as a promising treatment against antibiotic-resistant bacterial biofilms. Specifically, titanium dioxide nanoparticles (TiO2 NPs) are being investigated as photosensitizers in aPDT to address biofilm related diseases. To enhance their photocatalytic performance in the visible spectral range for biomedical applications, various strategies have been adopted, including reduction of TiO2 NPs. However, despite improvements in visible-light photoactivity, reduced TiO2 NPs have yet to reach their expected performance primarily due to the instability of oxygen vacancies and their tendency to reoxidize easily. To address this, we present a two-step approach to fabricate highly visible-light active and stable TiO2 NP photocatalysts, involving nitrogen doping followed by a magnesium-assisted reductive annealing process. X-ray photoelectron spectroscopy analysis of the synthesized reduced nitrogen-doped TiO2 NPs (H:Mg-N-TiO2 NPs) reveals that the presence of nitrogen stabilizes oxygen vacancies and reduced Ti species, leading to increased production of reactive oxygen species under visible-light excitation. The improved aPDT efficiency translates to a 3-fold enhancement in the antibiofilm activity of nitrogen-doped compared to undoped reduced TiO2 NPs against both Gram-positive (Streptococcus mutans) and Gram-negative (Porphyromonas gingivalis, Fusobacterium nucleatum) oral pathogens. These results underscore the potential of H:Mg-N-TiO2 NPs in aPDT for combating bacterial biofilms effectively.

AB-INITIO CALCULATIONS OF THE RHODIUM-DOPED (001) SURFACE OF THE RHOMBOHEDRAL PHASE BaTiO<sub>3</sub>

The advancement of effective, durable, and economically viable photocatalytic systems aimed at solar-driven water splitting into hydrogen and oxygen represents a strategically vital pathway for future fuel and chemical production from renewable sources. Water splitting is a promising strategy for the sustainable production of renewable hydrogen and for addressing the global energy and environmental crisis. However, the large-scale application of this method is limited by the low efficiency and high cost of solar water splitting systems. The search for economical, efficient, and stable photocatalysts is crucial in the development of solar water splitting technologies. Perovskite-based photocatalysts have recently attracted considerable attention for use in solar water splitting processes due to their simple structure and flexible composition. BaTiO3 is a promising photocatalyst because of its adjustable electronic structure. Initially considered a poor photocatalyst due to its wide band gap, this material has become the focus of various strategies aimed at reducing the band gap. In this paper, we study the effect of Rh doping on the electronic structure of the (001) BaTiO3 perovskite surface. Theoretical results show that Rh atoms can occupy both sites simultaneously, or only Ti sites, or Ba sites. The electronic structure was modeled for two conditions. When Rh atoms occupy one Ba position and one Ti position, the electronic structure shows the presence of an acceptor level within the band gap above the Fermi level, effectively reducing the band gap of the material.

Photothermal Effect of Cu NCs on CdS Homojunction Boosting Hydrogen Evolution in Alkaline Seawater

AbstractDeveloping photocatalysts with desired activity and stability toward hydrogen evolution reaction (HER) in alkaline seawater is of prime significance but still pressingly challenging. Herein, cuprum nanoclusters (CuNCs) are anchored on the surface of cadmium sulphide homojunctions (CdS‐H) with unsaturated edge sulphur (S) by an in situ photoreduction technique, which promotes the stability and hydrogen evolution of photocatalyst in the process of alkaline seawater hydrogen (H2) evolution (15.5 mmol g−1 h−1) with an apparent quantum yield of 11.0% at 450.0 nm. It is comprehensively confirmed that the unsaturated edge S not only effectively anchored Cu NCs but also promoted the adsorption of chloride ion (Cl−) ions, which suppressed the oxidation of lattice S and modulated the stability of the photocatalyst in alkaline seawater. The photothermal effect induced by the anchored Cu NCs accelerated the reaction kinetics, and the directional migration of the photocarrier at the metal‐semiconductor interface is demonstrated via the in situ method. This work affords a new perspective to rational design photocatalysts with high stability and superior performance in alkaline seawater.

Application of Quantum Dots for Photocatalytic Hydrogen Evolution Reaction

There is increased interest in the conversion of solar energy into green chemical energy because of the depletion of fossil fuels and their unpleasant environmental effect. Photocatalytic hydrogen generation from water involves the direct conversion of solar energy into H2 fuels, which exhibits significant advantages and immense promise. Nevertheless, photocatalytic efficiency is considerably lower than the standard range of industrial applications. Low light absorption efficiency, the rapid recombination of photogenerated electrons and holes, slow surface redox reaction kinetics and low photostability are well known to be key factors negatively affecting photocatalytic hydrogen production. Therefore, to construct highly efficient and stable photocatalysts is important and necessary for the development of photocatalytic hydrogen generation technology. In this review, quantum dots (QDs)-based photocatalysts have emerged with representative achievements. Due to their excellent light-harvesting ability, low recombination efficiency of photogenerated electrons and holes, and abundant surface active sites, QDs have attracted remarkable interest as photocatalysts and/or cocatalyst for developing highly efficient photocatalysts. In this review, the application of QDs for photocatalytic H2 production is emphatically introduced. First, the special photophysical properties of QDs are briefly described. Then, recent progress into the research on QDs in photocatalytic H2 production is introduced, in three types: semiconductor QDs (e.g., CdS, CdMnS, and InP QDs), metal QDs (e.g., Au, Pt and Ag QDs), and MXene QDs and carbon QDs (CDQs). Finally, the challenges and prospects of photocatalytic H2 evolution with QDs in the future are discussed.

Construction of 2D/2D ZnIn2S4/Nb2CTx (MXene) hybrid with hole transport highway and active facet exposure boost photocatalytic hydrogen evolution

In this study, leveraging the tunable surface groups of MXene, the two-dimensional (2D) Nb2CTx with OH terminal (NC) was synthesized. 2D ZnIn2S4 (ZIS) nanosheets were prepared with the aid of sodium citrate, enhancing the exposure ratio of active (110) facet. On this basis, 2D/2D ZnIn2S4/Nb2CTx heterojunctions were fabricated to improve photocatalytic hydrogen evolution reaction (HER) performance. The optimized 6 wt%Nb2CTx/ZnIn2S4-450 (6NC/ZIS-450) photocatalyt exhibits a remarkable HER rate of 3603 μmol g−1h−1, which is 10 times superior to that of the original ZnIn2S4. Its apparent quantum efficiency (AQE) at 380 nm reaches 14.9 %. Meanwhile, even after 5 rounds of HER, the activity of 2D/2D ZnIn2S4/Nb2CTx heterojunction remained at 90 %, far superior to that of pure ZnIn2S4 (34 % and 31 %). Energy band structure analysis and density functional theory (DFT) calculation indicate that Nb2CTx adsorbed with OH exhibit a low work function. By serving as a hole cocatalyst, it effectively boosts the photocatalytic HER rate of ZnIn2S4/Nb2CTx heterojunction and inhibits the photocorrosion of ZnIn2S4. This unique insight, via hole transport highways and increased exposure of active facets, effectively enhances the activity and stability of sulfides photocatalysts.

Insights into the PMS activation towards phenol removal mechanism by a Ti3C2-MXene doped BiVO4 photocatalyst

In the field of water treatment, photocatalysis and the peroxomonosulfate (PMS) deep oxidation process have emerged as potential solutions for the degradation of refractory organic pollutants. In this study, a novel BiVO4/Ti3C2 composite photocatalytic material was successfully synthesized using a hydrothermal method. The energy band structure of this material was utilized to establish Schottky barriers, enhancing the separation of photogenerated carriers. This, in turn, facilitated the activation of PMS under visible light, generating reactive species that effectively degraded phenol. The results demonstrate that in the BT-3/PMS system, the degradation rate of phenol reached 87.2 % within 60 min, with a maximum degradation rate constant of 0.02537 min−1. This represents an 8.8-fold improvement compared to pure BiVO4 and a 5.2-fold improvement compared to pure PMS. Free radical tests indicated that SO4·- was the primary reactive species involved in the degradation process. This study offers a promising approach for the design of efficient and stable Schottky junction photocatalysts that can be activated by visible light and PMS to effectively degrade organic pollutants.

One-step thermal polymerization synthesis of P and K co-doped two-dimensional porous g-C3N4 photocatalyst with enhanced visible light photocatalytic activity for RhB

To improve the reaction rate of g-C3N4 for the photocatalytic degradation of RhB, we have synthesized P and K co-doped porous g-C3N4 using a simple one-step thermal polymerization technique. The 3-P/K-CN-N sample showed the highest photocatalytic activity for RhB degradation under visible light irradiation. The first-order kinetic equation for 3-P/K-CN-N had a reaction rate constant of 0.10601 min−1, which was 13.59 times higher than that of pure g-C3N4. The internal reasons for improving the catalytic activity of the 3-P/K-CN-N are the synergistic effects of heteroatom doping and morphology regulation. The co-doping of P and K reduces the band gap, broadens the response range of visible light, and promotes the separation efficiency of photogenerated carriers. The decomposition of NH4Cl and KH2PO4 together at high temperatures promotes the formation of porous g-C3N4 with a large specific surface area and numerous surface active sites. This effectively shortens the distance of photogenerated carriers migrating from the bulk phase to the surface. Furthermore, the stability and repeatability were examined. After four cycles, the catalyst degrading efficiency decreased by only 5 %. This research provides a new reference for the preparation of highly efficient and stable photocatalysts.

Construction of novel BiOI/CuInS2/ZnO dual S-scheme charge transfer pathway for efficient antibiotic degradation

The present work explored the photocatalytic activity of BiOI–CuInS2–ZnO ternary heterojunction for the photodegradation of the tetracycline (TCl). The bare photocatalysts were prepared via hydrothermal method while the ternary heterojunction was synthesized using simple physical mixing route. The ternary heterojunction of BiOI, CuInS2 and ZnO followed the S-scheme charge transfer pathway exhibiting superior photodegradation ability compared to other synthesized photocatalysts. The attained degradation efficiency of BiOI–CuInS2–ZnO S-scheme ternary heterojunction was 96.75 % within 90 min of light illumination which was much higher than other photocatalysts. Electron spin resonance (ESR) investigations and scavenging experiment indicated that •O2−, and •OH radicals plays an important role in photodegradation of TCl. Furthermore, the structural analysis of synthesized bare photocatalysts was also done via density functional theory (DFT) calculations. The results showed that after the formation of S-scheme heterojunction, the ternary heterojunction showed lower recombination rate (validated via PL analysis) with boosted charge carriers separation rate (confirmed through EIS and TPR analysis) and light absorption ability. This had led to upgradation in photodegradation efficiency of ternary BiOI–CuInS2–ZnO photocatalyst. The reusability test of the photocatalysts confirmed excellent stability of ternary photocatalysts with 90.25 % degradation rate up to five catalytic cycles.

Magnetically separable Z-scheme ZnFe2O4/MoS2 photocatalyst for boosting photo-Fenton degradation activity by a hole-mediated mechanism

The development of high-efficiency and robust photocatalysts is imperative and challenging in advanced oxidation processes (AOPs). Herein, magnetically separable ZnFe2O4/MoS2 photocatalyst was prepared by a simple hydrothermal method. The degradation characteristics of several organic pollutants (rhodamine B (RhB), methyl orange, methylene blue, and antibiotic tetracycline) were investigated with/without the addition of H2O2 under visible light irradiation. It is found that the synergistic effect of Z-scheme ZnFe2O4/MoS2 photocatalyst and photo-fenton-like reaction promotes the decomposition of H2O2, accelerates the separation efficiency of photogenerated electrons and holes, and thus improves the photocatalytic activity. The RhB photo-degradation of the constructed Z-scheme ZnFe2O4/MoS2 (96.3%) photocatalyst in the absence of H2O2 for 100min is better than that of MoS2 (74.8%) and ZnFe2O4 (6.2%), with a rate constant of 0.0332min-1. The slight amount of H2O2 boosts the photocatalytic performance significantly. Its degradation rate is 98.6% within 8min with the rate constant of 0.396min-1, 12 times higher than that of ZnFe2O4/MoS2 photocatalyst without H2O2. The magnetic separation, recycling stability and neutral solution process are also confirmed in ZnFe2O4/MoS2 system, indicating the enormous potential of this photocatalyst in environmental remediation and waste water treatment. The hole-mediated oxidation mechanism has been proposed instead of conventional active radicals of •OH based on the free radicals capture and electron spin resonance experiments. MoS2 plays a crucial role in facilitating the H2O2 decomposition and realizing the conversion circulation from Fe3+ to Fe2+ by the redox cycling as a co-catalyst. This study provides insights into the photocatalytic mechanism of Z-scheme photo-Fenton heterojunction photocatalysts, conducive to the development of high-efficient and stable photocatalysts in AOPs.

Building metal-thiolate sites and forming heterojunction in Hf- and Zr-based thiol-dense frameworks towards stable integrated photocatalyst for hydrogen evolution

Building metal-thiolate sites and forming heterojunction in Hf- and Zr-based thiol-dense frameworks towards stable integrated photocatalyst for hydrogen evolution