Separation Of Photoinduced Charge Carriers Research Articles

Engineering sulfur doped flower-like BiOBrxI1-x solid solutions for strengthened photocatalytic activities

In this work, a series of S-doped BiOBrxI1-x solid solutions are fabricated via a simple and rapid solvothermal process. Various characterization techniques are used to thoroughly investigate the as-fabricated solid solutions. Interestingly, compared to BiOBrxI1-x, S-doped BiOBrxI1-x solid solutions exhibit a loose flower-like structure comprised of thinner nanosheets, which contributes to the enhanced specific surface area, as assessed by Brunauer-Emmett-Teller analysis. Furthermore, S-doped BiOBrxI1-x solid solutions reveal boosted visible-light response and rapid separation of photoinduced charge carriers, as verified by optical, photo-electrochemical, and electrochemical analysis. These lead to superior visible-light photocatalytic properties of S-doped BiOBrxI1-x solid solutions on pollutant removal, N2 fixation, and microplastic degradation. The crystal structure, morphology, and photocatalytic stability of the prepared samples are demonstrated by comparing their X-ray diffraction patterns, scanning electron microscopy images, and photocatalytic degradation as well as nitrogen reduction performance before and after six catalytic recycles. Furthermore, based on Density Functional Theory simulations, significant modifications in the band gap of BiOBrxI1-x solid solutions occur as iodine content increases while sulfur doping further refines the electronic features, which aligns with the results of Tauc plots. This research proves that S doping is a viable strategy for modulating the electronic structures of BiOBrxI1-x solid solutions for improving its photocatalytic performance, and provides a new route for optimizing the bandgaps of semiconductors via the non-metallic doping strategy.

Z-scheme driven charge transfer in g-C3N4/α-Fe2O3 nanocomposites enabling photocatalytic degradation of crystal violet and chromium reduction

In this study, we demonstrated the design and fabrication of iron oxide-embedded protonated graphitic carbon nitride (α-Fe2O3/p-g-C3N4) nanocomposites for photocatalytic dye degradation and heavy metal reduction applications under sunlight irradiation. The developed nanocomposites, with varying weight percentages of α-Fe2O3, were characterized for their structural (XRD, FTIR, XPS), optical (absorption and photoluminescence), morphological (FE-SEM, TEM), and electrochemical (EIS) properties to elucidate their structure-property relationships. The synthesis method ensures the uniform dispersion of α-Fe2O3 nanoparticles, with a particle size range of 50–60 nm, onto p-g-C3N4. XPS analysis suggests the formation of an electrical layer at the interface of α-Fe2O3/p-g-C3N4, facilitating the formation of a Z-scheme heterojunction. The photoluminescence and EIS spectra of the nanocomposite indicated effective separation and transfer of photo-induced charge carriers, aided by a reduced bandgap energy of ∼2.63 eV. Notably, the optimized 10 wt% α-Fe2O3/p-g-C3N4 nanocomposite exhibited superior photocatalytic activity, degrading nearly 100 % of crystal violate dye and reducing 98 % of Cr(VI) ions, compared to bare p-g-C3N4, which degraded around 43 % of the dye and reduced 39 % of Cr(VI) ions under sunlight irradiation. Scavenger studies indicated that α-Fe2O3/p-g-C3N4 nanocomposites produce adequate superoxide anions and hydroxyl radicals for dye degradation and heavy metal ion reduction. The composite also demonstrated consistent recyclability up to 5 cycles with around 100 % cyclical efficiency. The pH-dependent photoreduction and cyclic dye degradation by the 10 wt% α-Fe2O3/p-g-C3N4 photocatalyst indicated excellent stability, making it suitable for the treatment of multi-pollutant wastewater.

Fabrication of double S-scheme Sr2MgSi2O7:Eu2+,Dy3+/ZnIn2S4/UiO-66-NH2 heterojunctions with photon storage effect for enhanced round-the-clock photocatalysis

Persistent light-emitting materials (PLMs), which have the potential to store and release light energy after light irradiation, are receiving increasing attention for their role in prolonging the lifetime of photogenerated electrons for the development of photocatalysts with round-the-clock applications. In this paper, a double S-scheme Sr2MgSi2O7:Eu2+,Dy3+/ZnIn2S4/UiO-66-NH2 (SZU) heterojunction with round-the-clock catalytic activity was prepared by hydrothermal self-assembly method. The photocatalytic performance of the SZU heterojunction for RhB(MB) degradation was significantly improved compared with the pristine ZnIn2S4 and UiO-66-NH2. The SZU heterojunction has excellent catalytic degradation performance for RhB (MB), and the removal rate of RhB (MB) reaches 72.2 % (81.7 %) after visible light irradiation for 40 (60) minutes. After the end of light, the total removal rate of RhB (MB) reached 86.7 % (96.8 %) when the catalysis continued for several hours under dark conditions, which was 14 % and 15 % higher than that under visible light irradiation, respectively. Based on the characteristics of SMS photoluminescence, combined with a large number of photocatalytic experiments, The sustained photocatalytic activity was enhanced under both daytime and darkness conditions, not only because of the production of SZU complexes, which prolonged the visible light response of ZnIn2S4, but also because of the construction of double S-scheme heterojunctions, which facilitates the light storage capacity, charge transfer, and the separation of photo-induced charge carriers and effectively promoted the photocatalytic activity of the photocatalysts. This work contributes to a deeper understanding of the design of round-the-clock photocatalysts, and provides a useful exploration for the practical application of photocatalytic technology.

Fabrication of CoTiO3/MgIn2S4 S–scheme heterojunctions with efficient charge separation to enhance the photocatalytic activities of hydrogen generation and formaldehyde removal

The efficient separation of photoinduced charge carriers is a primary factor in the catalytic performance of photocatalysts. Constructing S-scheme heterojunctions is a prospective strategy to efficiently and spatially separate photoinduced charges while retaining strong oxidation and reduction capacities of the catalyst system. Herein, CoTiO3/MgIn2S4 (abbreviated x% CTO/MIS, where x% represents the mass ratio of CTO-to-MIS; x = 5, 10, 15, 20, and 25) heterojunctions were successfully synthesized using a hydrothermal method. These heterojunctions exhibited highly efficient and reusable visible-light photocatalytic properties for hydrogen (H2) generation and formaldehyde (HCHO) degradation. Notably, the 15 % CTO/MIS demonstrated an admirable H2 evolution activity of 631.77 μmol·g−1·h−1, with AQE = 2.25 % at λ = 420 nm, and an HCHO degradation rate of 67.18 %. The intermediate products generated during HCHO removal were identified applying in situ diffuse reflectance infrared Fourier transform spectroscopy. The exceptional catalytic performance of the synthesized materials was attributed to the boosted light absorption and utilization, rapidly separation, and transfer of photoproduced charge carriers, which resulted from the internal electric field of the S-scheme mechanism. Moreover, the S-scheme electron transfer pathway for the CTO/MIS catalyst system during the photocatalytic process was confirmed using electron spin resonance spectroscopy, free-radical capturing tests, density functional theory calculations, in situ X-ray photoelectron spectroscopy, and semiconductor energy band theory. The study offers an innovative perspective for establishing S-scheme heterojunctions with highly efficient and stable photocatalytic activity for H2 generation and HCHO removal.

Heterointerface engineering in mesoporous g-C3N4@MnFe2O4 photocatalysts for superior hydrogen (H2) evolution

Surfaces and interfaces play a pivotal role in heterostructures-based photocatalysts, which regulate the transfer, separation, and migration of photogenerated charge carriers. In this study, p-type MnFe2O4 nanoparticles (NPs) with complementary band structures were purposefully integrated with n-type porous g-C3N4 nanosheets (NSs) through precise interface engineering. The synergies in the g-C3N4@MnFe2O4 nanocomposites (NCs), leading to performance enhancement and functionalities, arise from their optimized mass fractions within the composite. The heterojunction interface formed in NCs possesses uniformly distributed mesopores (<4 nm), abundant active sites, and a high specific surface area (116 m2/g). Mesoporous heterojunctions improve photocatalytic activity by promoting the transfer of photogenerated electrons and holes to the photocatalyst surface. Notably, the optimized NCs, containing 20 wt% MnFe2O4, display the highest hydrogen evolution rate of 3.17 mmol g⁻¹ h⁻¹ (with methanol) and 5.77 mmol g⁻¹ h⁻¹ (with triethanolamine), which is many folds higher than bare MnFe2O4 and porous g-C3N4, using 1.0 wt.% of Pt as co-catalyst. The enhanced performance is corroborated by the efficient separation of photoinduced charge carriers, facilitated by an induced internal electric field arising from the Fermi level differences between the semiconductors. This study provides new insights into the advantages of designing and constructing mesoporous Z-scheme heterojunction photocatalysts for hydrogen evolution.

Construction of Visible light Driven Z-Scheme 1D/1D p-CuBi2O4/n-CdWO4 Heterojunction Nanocomposite for Effective Degradation of Organic Pollutants

The effective separation and harnessing of photoinduced charge carriers in photocatalysis are significant challenges. The present study aims to overcome this obstacle by developing a Z-Scheme heterojunction between a p-type CuBi2O4 (CBO) and a n-type CdWO4 (CWO) through a straightforward heat treatment method. The powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and High-resolution transmission electron microscopy (HRTEM) results revealed the successful formation of heterostructures. The photocatalytic efficiency of the materials was assessed by selecting an anionic methyl orange (MO) and cationic Rhodamine-B (Rh-B) dyes under visible light irradiation. Among all the materials, 85 wt.% CBO+ 15 wt.% CWO (CBO/CWO-15) heterostructure exhibited superior photocatalytic activity (90%) corresponding to 90 and 45 times higher than the pristine CBO and CWO, respectively. The positively charged photocatalyst surface attracts a greater number of MO dye molecules than Rh-B, thereby enhancing the degradation of MO over Rh-B. The scavenger results confirmed the involvement of hydroxy ( and superoxide () radicals in the degradation of MO. The rate constant of CBO/CWO-15 (0.01061 min-1) was 64 and 39 times higher than those of CBO (0.00016 min-1) and CWO (0.00027 min-1), respectively. The photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) analyses substantiated the improved charge separation in the CBO/CWO-15 composite, establishing the Z-scheme mechanism. Cycling experiments over four cycles demonstrated consistent stability of the CBO/CWO-15 composite. The study provides an in-detail plausible mechanism of MO degradation. This type of Z-scheme composite material has potential applications in environmental remediation for the effective removal of organic pollutants and antibiotics from wastewater.

Exploring the formation of S-scheme heterojunctions in CuFe2O4/Bi2MoO6 porous cubes for photocatalytic removal of tetracycline

Exploring highly active and noble metal-free photocatalysts for the efficient photocatalytic degradation of antibiotics is of great significance. The CuFe2O4 nanostructured cube is synthesized by using a self-sacrificial template strategy, and two-dimensional Bi2MoO6 nanosheets are grown on the surface of CuFe2O4 through a solvothermal method to construct CuFe2O4/Bi2MoO6 S-scheme heterostructure. The CuFe2O4/Bi2MoO6 composite material exhibits eminent photocatalytic activity for the degradation of TC under simulated sunlight, with the optimal ratio CFO/BMO-2 achieving a degradation rate of 98.54 % within 30 min (initial concentration of TC: 50 mg L−1). In addition, CFO/BMO-2 also has excellent magnetic recyclability and cycling ability. Rice cultivation tests demonstrate that the biotoxicity of TC is effectively removed. Density functional theory calculations and in-situ irradiated X-ray spectroscopy deeply reveal the mechanisms of charge separation and transfer of S-scheme heterojunctions in CuFe2O4/Bi2MoO6. The construction of S-scheme heterojunctions promotes the separation of photo-induced charge carriers and improves photocatalytic degradation performance by retaining holes and electrons with strong redox ability. The work provides a practicable method for constructing efficient spinel photocatalysts to drive wastewater treatment reactions, and the constructed magnetically recyclable photocatalysts have certain practical application potential.

Ultrasound-assisted synthesis of a novel type-II Bi12O15Cl6/CTF-1 heterojunction for visible-light-driven photocatalytic degradation of levofloxacin: Reaction kinetics, degradation pathways, and toxicity assessment

Fluoroquinolones (FQL) are ubiquitous in aquatic environments due to their widespread use, posing a serious environmental threat. In this regard, a novel Bi12O15Cl6/CTF-1 (BTF) photocatalyst was prepared by integrating a covalent triazine framework (CTF-1) with Bi12O15Cl6 by a simple wet-impregnation method for removing levofloxacin (LFX), an FQL-based antibiotic, from an aqueous solution. Under optimal conditions, BTF (III) (comprising 20 % CTF-1) showed the highest photocatalytic activity, achieving approximately 94 % LFX (10 mg/L) degradation in 120 min under visible light with a pseudo-kinetic rate constant of 0.02072 min−1. This can be attributed to the reduced recombination rate and efficient transfer and separation of photoinduced charge carriers. The photocatalyst demonstrated remarkable stability and reusability. The radical trapping experiment revealed O2•− and h+ to be the primary active species facilitating the photocatalytic degradation of LFX. Furthermore, the seed germination test affirmed treated effluent to be non-phytotoxic and suitable for irrigation.

Constructing type II heterojunction of 2D/1D Pg-C3N4/Ag3VO4 nanocomposite with high interfacial charge separation for boosting photocatalytic CO2 reduction under solar energy

The well-designed, template-free synthesis of 2D protonated g-C3N4 nanosheets (Pg-C3N4) coupled with novel 1D Ag3VO4 nanorods has been investigated to construct 2D/1D interface heterostructures with strong electrostatic interactions between the positively charged 2D Pg-C3N4 nanosheets and the negatively charged 1D Ag3VO4 nanorods. The coupling of Pg-C3N4 and Ag3VO4 with desirable characteristics resulted in a 2D/1D interface heterojunction with a type II charge carrier transfer mechanism, effectively maintaining and utilizing charge carriers. The 2D/1D Pg-C3N4/Ag3VO4 exhibited remarkable photocatalytic performance for CO2 conversion with H2O, resulting in maximum CH4 and dimethyl ether (DME) production of 352.3 and 130.9 µmol/g-cat, respectively. A quantum yield of 0.23 % for CH4 generation was achieved over the 2D/1D Pg-C3N4/Ag3VO4, which was 2.9 and 1.4 times higher than that of the Pg-C3N4 and Ag3VO4 samples, respectively. The improvement in photocatalytic performance primarily stems from the effective interaction between Pg-C3N4 and ternary Ag3VO4, leading to enhanced transfer and separation of photoinduced charge carriers through the creation of a type II heterojunction. The findings of this study are useful in designing template-free heterojunctions for photocatalytic CO2 conversion and other solar energy applications.

One-Step Self-Assembled WO3/rGO Microspheres Photoanode Assembled Efficient Photocatalytic Fuel Cells for Simultaneous Organic Pollutant Degradation and Electricity Generation.

Photocatalytic fuel cells (PFCs) present a promising and environmentally friendly approach to simultaneously treat organic pollutants in wastewater and electricity generation. The development of photoanodes with high light absorption and carrier mobility is essential for enhancing the performance of PFCs but remains challenging. Herein, a one-step self-assembly strategy was adopted to develop flower-like WO3/rGO microspheres for PFC devices. Attributed to the abundant surface-active sites, enhanced light harvesting, and efficient separation of photogenerated charge carriers, the WO3/rGO photoanode demonstrated superior rhodamine B (RhB) degradation rate (90% in 2 h), maximum power density (4.74 μW/cm2), and maximum photocurrent density (0.096 mA/cm2), 1.4, 2.4, and 4.0 times higher than the corresponding pure WO3 photoanode, respectively. Density functional theory (DFT) calculations reveal that the built-in electric field formed between the interface of WO3 and rGO promotes the transfer of photogenerated electrons from WO3 to rGO, thus exerting a significant impact on improving the migration and separation of photoinduced charge carriers. Moreover, by combining experimental and theoretical results, a complete PFC operation mechanism for the PFC system was proposed. This study focuses on the strategy of constructing rGO-doped photocatalysts to enhance the interfacial charge transfer mechanism, providing a promising approach for the development of high-performance photoanodes in PFC systems.

Trimetallic alloy nanoparticles as cocatalyst for improving the photocatalytic performance of graphitic carbon nitride for H2 production

Trimetallic alloy nanoparticles (NPs) hybridized with graphitic carbon nitride (g-C3N4) nanosheets show potential as photocatalysts owing to their multicomponent interactions, increased catalytic efficiency, and enhanced stability. Herein, a NiCoAg–CN nanocomposite comprising NiCoAg alloy NPs deposited on g-C3N4 nanosheets was synthesized via photoreduction using simulated solar light. X-ray photoelectron spectroscopy revealed the metallic properties of Ni, Co, and Ag within the NiCoAg–CN nanocomposite, and the high-resolution transmission electron microscopy image showed alloy NPs on the surface of g-C3N4. The as-formed Schottky junction accelerated the separation and transfer of photoinduced charge carriers in NiCoAg–CN. NiCoAg–CN exhibited a remarkable photocatalytic hydrogen (H2) yield of 4896 μmol/g, surpassing the performance of NiAg–CN and CoAg–CN by 1.9- and 1.8-fold, respectively. This is attributed to the enhanced catalytically active sites, facilitating rapid charge carrier transfer between the NiCoAg alloy and the g-C3N4 nanosheets. Photoluminescence spectra indicated that NiCoAg NPs served as efficient electron conduits, suppressing charge carrier recombination and promoting direct electron transfer. Alloy NPs synthesized via the proposed strategy efficiently harness solar radiation, facilitate charge carrier transfer, and mitigate recombination, thus advancing efficient photocatalytic H2 generation.

Fabrication of novel N-rich g-C3N5 decorated cubic spinel Co2SnO4 hybrids: Studies on morphology, degradation efficacy, pathway and mechanism

Managing interfacial charge transfer is a crucial and challenging problem in promoting the migration/separation of photogenerated carriers for heterojunction photocatalysts. The innovative dual Z-scheme heterojunction is crucial in effectively removing organic pollutants by enhancing the separation of charge carriers. A novel Co2SnO4/g-C3N5 (CoSn/CN) nanocomposite heterojunction is synthesized using a simple hydrothermal approach. The resulting nanocomposite is then studied in terms of its crystal phases, optical characteristics, surface morphologies, and compositions. The charge separation efficiency is significantly enhanced, resulting in a high-efficiency photocatalytic degradation performance. The CoSn/CN photocatalyst exhibits a degradation efficiency of 99.11 % and 98.08 % for Congo red (CR) and Rose Bengal (RB) respectively, within 75 minutes and 50 minutes under visible light conditions. In addition, scavenging tests demonstrated the generation of active radical species, specifically •OH, h+, and •O2−. The hypothesized CR and RB degradation process and potential pathways were derived from the proper experimental study. The primary objective of this project is to create a novel photocatalytic material that can effectively degrade dyes. Additionally, the study aims to construct a larger-scale photocatalytic system, determine the cost of the wastewater treatment unit, and analyze the life cycle of the entire process. In addition, the Co2SnO4/g-C3N5 heterojunction also demonstrates the expected stability as no substantial drop was observed after 5 cycles. The exceptional degrading performance and stability of the system can be attributed to the enhanced separation of photo-induced charge carriers and the strong contact at the interface, achieved through the formation of a Z-Scheme charge transfer.

Lattice Strain in High Entropy Oxides Promote CO2 Photomethanation.

Lattice strain is widely investigated to improve the performance of heterogeneous catalysts, however, the effect of lattice strain is under-explored in high-entropy oxide based photocatalyst. In this study, noble-metal-free (CoCrMnFeNi)Ox with lattice strain is synthesized using a temperature-controlled, template-free and salt-assisted strategy. In the presence of lattice strain, an intensive internal electric field is formed in (CoCrMnFeNi)Ox, promoting the separation of photoinduced charge carriers. The size of the (CoCrMnFeNi)Ox can be tuned by varying the calcination temperature. Specifically, (CoCrMnFeNi)Ox prepared at a higher temperature possesses a smaller grain size exposing more active sites, resulting in an enhanced CO2 photomethanation performance. This work provides valuable insights for the rational design of the photocatalysts and highlights the promising role of high-entropy oxides in heterogeneous photocatalysis.

High-efficient separation of photoinduced charge carriers in CoFe2O4-ZnO magnetic heterostructures mediated by oxygen vacancies

In this work, magnetic heterostructures were obtained by the in-situ growth of various ZnO amounts on the preformed CoFe2O4 nanoparticles. The X-ray diffraction characterization shows the presence of both ZnO and CoFe2O4 crystalline phases, and the crystallite size is about 13–14 nm for both components. X-Ray Photoelectron Spectroscopy (XPS) analysis revealed a CoFe2O4 inversion degree of 0.7. The composite samples demonstrated an extended absorption edge into the visible range. The sample’s magnetic properties were investigated by vibrating-sample magnetometer (VSM) and correlated with Electron Paramagnetic Resonance (EPR) results. The magnetic behavior was attributed to the combination of CoFe2O4 and ferromagnetic ZnO. The emergence of a ferromagnetic phase within ZnO was elucidated to originate from charge/spin transfer of spin-up polarized states from the CoFe2O4 Fermi level into empty oxygen vacancies of ZnO. High efficiency in Rhodamine B (RhB) degradation under visible light was observed in the prepared composite materials, particularly with an optimal CoFe2O4-ZnO ratio of 1:5, achieving an 81 % degradation rate within 6 h. The proposed photodegradation mechanism, based on various spectroscopic and magnetic investigations, highlights the role of spin transfer and oxygen vacancies in facilitating reactive oxygen species (ROS) generation for pollutant degradation.

Asymmetric Charge Distribution in One-dimensional Metal-Organic Assemblies to Promote Photocatalytic Hydrogen Evolution.

The local charge distribution of photocatalyst is crucial to the catalytic activity due to its influence on the charge separation process. Herein, we report two one-dimensional Ni-based metal-organic assemblies for efficient photocatalytic hydrogen evolution without using noble-metal cocatalysts. By adjusting the aromatic ring in the center of the tricarboxylic ligand, the photocatalytic hydrogen evolution activity was increased from 1715 to 2652 μmol h-1 g-1. The detailed mechanism study shows that the introduced nitrogen atoms in the ligands of the metal-organic coordination assembly could modulate the local charge distribution, and yielding a significant enhancement of the molecular dipole moment which engenders a propulsive force for the effective separation and transport of photoinduced charge carriers. This work provides insights into the local charge distribution via ligand modulation for enhancing the activity of photocatalysts.

Carbon dots-loaded cellulose nanofibrils hydrogel incorporating Bi2O3/BiOCOOH for effective adsorption and photocatalytic degradation of lignin

A novel photocatalytic adsorbent, a cellulose nanofibrils based hydrogel incorporating carbon dots and Bi2O3/BiOCOOH (designated as CCHBi), was developed to address lignin pollution. CCHBi exhibited an adsorption capacity of 435.0 mg/g, 8.9 times greater than that of commercial activated carbon. This enhanced adsorption performance was attributed to the 3D porous structure constructed using cellulose nanofibrils (CNs), which increased the specific surface area and provided additional sorption sites. Adsorption and photocatalytic experiments showed that CCHBi had a photocatalytic degradation rate constant of 0.0140 min−1, 3.1 times higher than that of Bi2O3/BiOCOOH. The superior photocatalytic performance of CCHBi was due to the Z-scheme photocatalytic system constructed by carbon dots-loaded cellulose nanofibrils and Bi2O3/BiOCOOH, which facilitated the separation of photoinduced charge carriers. Additionally, the stability of CCHBi was confirmed through consecutive cycles of adsorption and photocatalysis, maintaining a removal efficiency of 85 % after ten cycles. The enhanced stability was due to the 3D porous structure constructed by CNs, which safeguarded the Bi2O3/BiOCOOH. This study validates the potential of CCHBi for high-performance lignin removal and promotes the application of CNs in developing new photocatalytic adsorbents.

Novel cocatalyst MnCo2S4 based on Zn3In2S6 for enhanced photocatalytic hydrogen production and ranitidine degradation

Photocatalysis offers a sustainable method for producing hydrogen and degrading harmful substances such as ranitidine. In this research, metal-like properties of MnCo2S4 nanoparticles were synthesized using a glycerol precursor and integrated into Zn3In2S6 floral microsphere via a low-temperature hydrothermal method to function effectively as a cocatalyst. The catalyst not only exhibits excellent hydrogen production efficiency but also demonstrates outstanding performance in degrading ranitidine. Under visible light irradiation, the MnCo2S4/Zn3In2S6 composite material reached a maximum hydrogen production rate of 4471.7 µmol·g−1·h−1 within 6 h, which is 10.6 times higher than that of pure Zn3In2S6. After 24 h of reaction over 4 continuous cycles, the hydrogen evolution activity maintained 94.86 % of its initial performance. Additionally, after 60 min of visible light exposure, the composite achieved a ranitidine degradation rate of 94.7 %, significantly surpassing the performance of pure Zn3In2S6. This exceptional photocatalytic activity is attributed to the synergistic interactions between Zn3In2S6 and the conductive cocatalyst MnCo2S4, which facilitate interfacial charge transfer. A potential reaction mechanism was proposed, supported by a series of experiments and characterization techniques. The formation of a Schottky junction at the MnCo2S4/Zn3In2S6 interface enables rapid electron transfer to the MnCo2S4 nanoparticles, preventing electron backflow and thus promoting effective separation of photo-induced charge carriers. Therefore, this study introduces a novel approach for designing metal-semiconductor photocatalysts for efficient hydrogen production and ranitidine degradation.

In-situ construction of the novel In2S3/BiOIO3 heterojunction with boosted visible-light photodegradation performance for diverse persistent organic pollutants

Designing rational heterojunctions to achieve efficient separation and transmission of photoinduced charge carriers is one of the effective strategies to improve the activity of semiconductor photocatalysts. In this study, the novel In2S3/BiOIO3 binary heterojunctions were facilely synthesized at room temperature using a simple in-situ growth method. The physicochemical properties of the fabricated In2S3/BiOIO3 heterojunction catalyst were investigated using various techniques including XRD, FT-IR, BET, XPS, TEM, UV–vis DRS, PL, EIS, and PC analysis. The In2S3/BiOIO3 composite catalyst possesses suitable band position and bandgap energy and therefore is capable of degrading organic contaminants under visible light irradiation. The optimized composite catalyst with In2S3/BiOIO3 molar ratio of 0.5 (In2S3/BiOIO3-5) exhibited superior photocatalytic activity, achieving 98.6 % degradation rate for Rhodamine B (RhB), far surpassing the performance of the individual components. In addition, In2S3/BiOIO3-5 showed broad-spectrum photocatalytic activity in the decomposition of various organic pollutants including methyl orange (MO), methylene blue (MB), tetracycline (TC) and bisphenol A (BPA). The improved photocatalytic activity of the prepared composite catalysts can be ascribed to the formation of type-II heterojunction, which facilitates the separation and migration of e–/h+ pairs. The excellent photocatalytic properties and favorable structural stability make In2S3/BiOIO3-5 a viable material for degrading various persistent organic pollutants.

Removal of mixed pollutants of perfluorooctanoic acid and 2,4,6-trichlorophenol via adsorption-photocatalysis using Ga2O3-Bi4O7 combining with fluorine-doped covalent triazine framework: Role of different active species

Perfluorooctanoic acid (PFOA) and 2,4,6-trichlorophenol (2,4,6-TCP) are significant pollutants found in textile wastewater, posing severe threats to ecological environments. The construction of an adsorption-photocatalytic system enables the efficient removal of mixed pollutants by harnessing their synergistic effect, thereby overcoming the limitations of removing mixed pollutants with single water treatment technologies. Herein, fluorine-doped covalent triazine framework (F-CTF) was combined with Ga2O3-Bi4O7 heterojunction to obtain Ga2O3-Bi4O7/F-CTF (GaBi/CTF). F-CTF greatly facilitates the adsorption process and provides convenience for photocatalysis. Simultaneously, the excellent conductivity of F-CTF promoted the separation of photoinduced charge carriers in Ga2O3-Bi4O7. GaBi/CTF5 (5 is the mass percentage of F-CTF) showed excellent degradation performance, and the removal rates of PFOA and 2,4,6-TCP reached 93.0 % and 100.0 % within 90 min, respectively. Mechanistic analysis revealed that 2,4,6-TCP and PFOA were attacked by distinct active species because of the disparate characteristics. The presence of phenolic hydroxyl groups makes 2,4,6-TCP more vulnerable to superoxide radicals (·O2–) and hydroxyl radicals (·OH), whereas PFOA is oxidized by holes (h+). The coexistence of mixed pollutants with diverse characteristics enables optimal utilization of active species generated within photocatalytic system. Moreover, the good stability of GaBi/CTF5 provides a feasible solution for efficient treatment of mixed pollutants in textile wastewater.

Fabrication of two-dimensional FePS3 nanosheets for promising photo/electrocatalytic applications

Transition metal phosphorus trisulfides, namely sulfides composed of three elements, stand out within 2D nanomaterials due to the unique layered structure, distinctive bonding, and electronic configurations. However, the preparation of ultrathin nanosheets encounters significant challenges due to the inherent properties of the material itself and the complexity of the synthetic process. In this work, we successfully fabricated ultrathin FePS3 nanoflakes with lateral dimensions of 500–800 nm and an average thickness of 5 nm utilizing mechanically assisted liquid-phase exfoliation in N-Methyl-2-pyrrolidone solution. The unique few-layer structure of FePS3 may increase the number of active sites, facilitating the rapid separation and migration of photo-induced charge carriers. Consequently, this enhancement leads to an increase in photogenerated current and a substantial reduction in resistance. This study presents an effective approach for optimizing light absorption and charge separation processes of 2D nanostructure, thereby providing valuable insights for the rational design of efficient photocatalysts based on ultrathin FePS3 nanosheet as a co-catalyst.