Hierarchical ZnIn2 S4 /MoSe2 Nanoarchitectures for Efficient Noble-Metal-Free Photocatalytic Hydrogen Evolution under Visible Light

Tuning Electrons Migration of Dual S Defects Mediated MoS2-x/ZnIn2S4-x Toward Highly Efficient Photocatalytic Hydrogen Production

Photocatalytic hydrogen production is a prevalent method for hydrogen synthesis. However, high recombination rate of photogenerated carriers and high activation energy barrier of H remain persistent challenge. Here, the two-step hydrothermal method is utilized to prepare dual S-defect mediated catalyst molybdenum sulfide/zinc indium sulfide (MSv/ZISv), which has high hydrogen production rate of 8.83 mmol g-1h-1 under simulated sunlight. The achieved rate is 21.91 times higher than pure ZnIn2S4 substrate. Defects in ZIS within MSv/ZISv modify the primitive electronic structure by creating defect state that retaining good reducing power, leading to the rapid separation of electron-hole pairs and the generation of additional photogenerated carriers. The internal electric field further enhances the migration toward to cocatalyst. Simultaneously, the defects introduced on the MoS2 cause electron rearrangement, leading to electron clustering on both S vacancies and edge S. Thereby MSv/ZISv exhibits the lowest activation energy barrier and |ΔGH*|. This work explores the division of synergies between different types of S defects, providing new insights into the coupling of defect engineering.

Advances in Hierarchical Inorganic Nanostructures for Efficient Solar Energy Harvesting Systems

The urgent need to address the global energy and environmental crisis necessitates the development of efficient solar-power harvesting systems. Among the promising candidates, hierarchical inorganic nanostructures stand out due to their exceptional attributes, including a high specific surface area, abundant active sites, and tunable optoelectronic properties. In this comprehensive review, we delve into the fundamental principles underlying various solar energy harvesting technologies, including dye-sensitized solar cells (DSSCs), photocatalytic, photoelectrocatalytic (water splitting), and photothermal (water purification) systems, providing a foundational understanding of their operation. Thereafter, the discussion is focused on recent advancements in the synthesis, design, and development of hierarchical nanostructures composed of diverse inorganic material combinations, tailored for each of these solar energy harvesting systems. We meticulously elaborate on the distinct synthesis methods and conditions employed to fine-tune the morphological features of these hierarchical nanostructures. Furthermore, this review offers profound insights into critical aspects such as electron transfer mechanisms, band gap engineering, the creation of hetero-hybrid structures to optimize interface chemistry through diverse synthesis approaches, and precise adjustments of structural features. Beyond elucidating the scientific fundamentals, this review explores the large-scale applications of the aforementioned solar harvesting systems. Additionally, it addresses the existing challenges and outlines the prospects for achieving heightened solar-energy conversion efficiency.

All-inorganic lead halide perovskites for photocatalysis: a review

Nowadays, environmental pollution and the energy crisis are two significant concerns in the world, and photocatalysis is seen as a key solution to these issues. All-inorganic lead halide perovskites have been extensively utilized in photocatalysis and have become one of the most promising materials in recent years. The superior performance of all-inorganic lead halide perovskites distinguish them from other photocatalysts. Since pure lead halide perovskites typically have shortcomings, such as low stability, poor active sites, and ineffective carrier extraction, that restrict their use in photocatalytic reactions, it is crucial to enhance their photocatalytic activity and stability. Huge progress has been made to deal with these critical issues to enhance the effects of all-inorganic lead halide perovskites as efficient photocatalysts in a wide range of applications. In this manuscript, the synthesis methods of all-inorganic lead halide perovskites are discussed, and promising strategies are proposed for superior photocatalytic performance. Moreover, the research progress of photocatalysis applications are summarized; finally, the issues of all-inorganic lead halide perovskite photocatalytic materials at the current state and future research directions are also analyzed and discussed. We hope that this manuscript will provide novel insights to researchers to further promote the research on photocatalysis based on all-inorganic lead halide perovskites.

Construction of core-shell CoSe2/ZnIn2S4 heterostructures for efficient visible-light-driven photocatalytic hydrogen evolution

The use of photocatalysts based on semiconductor heterostructures for hydrogen evolution is a prospective tactic for converting solar energy. Herein, visible-light-responsive three-dimensional core-shell CoSe2/ZnIn2S4 heterostructures were successfully fabricated via in situ growth of ZnIn2S4 ultrathin nanosheets on spherical CoSe2. Without any noble metal co-catalysts, the as-prepared CoSe2/ZnIn2S4 composite achieved attractive photocatalytic hydrogen evolution activity under visible light illumination. Optimal CoSe2/ZnIn2S4 achieved a hydrogen evolution rate of 2199 μmol g-1 h-1, which was 7 times higher than that of pristine ZnIn2S4 and even exceeded that of ZnIn2S4 loaded with platinum. In this distinctive core-shell heterostructure, the presence of CoSe2 could considerably improve the ability to harvest light, quicken the charge transfer kinetics, and avoid the agglomeration of ZnIn2S4 nanosheets. Meanwhile, the experimental results demonstrated that the strong interaction between CoSe2 and ZnIn2S4 at the compact interface could appropriately boost the photogenerated electron-hole pair migration and relieve charge recombination, thus improving photocatalytic hydrogen evolution activity. This work has bright prospects in constructing noble-metal-free core-shell heterostructures for solar energy conversion.

Construction of a transition-metal sulfide heterojunction photocatalyst driven by a built-in electric field for efficient hydrogen evolution under visible light

Photocatalytic H2 evolution is of prime importance in the energy crisis and in lessening environmental pollution. Adopting a single semiconductor as a photocatalyst remains a formidable challenge. However, the construction of an S-scheme heterojunction is a promising method for efficient water splitting. In this work, CdS nanoparticles were loaded onto NiS nanosheets to form CdS/NiS nanocomposites using hollow Ni(OH)2 as a precursor. The differences in the Fermi energy levels between the two components of CdS and NiS resulted in the formation of a built-in electric field in the nanocomposite. Density functional theory (DFT) calculations reveal that the S-scheme charge transfer driven by the built-in electric field can accelerate the effective separation of photogenerated carriers, which is conducive to efficient photocatalytic hydrogen evolution. The hydrogen evolution rate of the optimized photocatalyst is 39.68 mmol·g-1 h-1, which is 6.69 times that of CdS under visible light. This work provides a novel strategy to construct effective photocatalysts to relieve the environmental and energy crisis.

Janus Z-scheme heterostructure of ZnIn2S4/MoSe2/In2Se3 for efficient photocatalytic hydrogen evolution

Artificial manipulation of charge separation and transfer are central issues dominating hydrogen evolution reaction triggered via photocatalysis. Herein, through elaborate designing on the architecture, band alignment, and interface bonding mode, a sulfur vacancy-rich ZnIn₂S₄-based (Vs-ZIS) multivariate heterostructure ZnIn₂S₄/MoSe₂/In₂Se₃ (Vs-ZIS/MoSe₂/In₂Se₃) with specific Janus Z-scheme charge transfer mechanism is constructed through a two-step hydrothermal process. Steering by the Janus Z-scheme charge transfer mechanism, photogenerated electrons in the conduction band of MoSe₂ transfer synchronously to the valence band of Vs-ZIS and In₂Se₃, resulting in abundant highly-active photogenerated electrons reserved in the conduction band of Vs-ZIS and In₂Se₃, therefore significantly enhancing the photocatalytic activity of hydrogen evolution. Under visible light irradiation, the optimized Vs-ZIS/MoSe₂/In₂Se₃ with the mass ratio of MoSe₂ and In₂Se₃ to ZnIn₂S₄ at 3 % and 30 %, respectively, performs a high hydrogen evolution rate of 124.42 mmol·g^-1·h^-1, about 43.5-folds of the original ZIS photocatalyst. Besides, an apparent quantum efficiency (AQE) of 22.5 % at 420 nm and favorable durability are also achieved over Vs-ZIS/MoSe₂/In₂Se₃ photocatalyst. This work represents an important development in efficient photocatalysts and donates a sound foundation for the design of regulating charge transfer pathways.

Constructing Z-scheme 1D/2D heterojunction of ZnIn2S4 nanosheets decorated WO3 nanorods to enhance Cr(VI) photocatalytic reduction and rhodamine B degradation

Photocatalysis has been vastly employed as a feasible and efficient strategy for the removal of environmental pollutants. In this study, a well-designed core-shell heterojunction of WO3 decorated with ZnIn2S4 nanosheets were fabricated under mild in-situ conditions, and fabricated processes were systematically investigated with different fabrication durations. The coupling of WO3 and ZnIn2S4 (ZIS) resulted in a Z-scheme mechanism for charge carrier transfer, holding the respective redox capacity. The as-prepared 1D/2D WO3@ZIS heterostructure displayed the highest removal efficiency within 30 min for 25 mg L-1 Cr(VI), 89.3 and 29.7 times higher than pure WO3 and ZnIn2S4. 1D/2D WO3@ZIS remained excellently stable after 5 cycling experiments. Moreover, 40 mg L-1 RhB could be degraded within 50 min. The broad and short photogenerated electron transportation path is guaranteed by the 1D/2D and Z-scheme charge separation mechanism. It efficiently prevented photo-generated charge carriers from recombination, resulting in a longer carrier lifespan and better photocurrent responses than that of pure ones. This photocatalytic system showed promising results and also provides a framework for an efficient system for photocatalysis with potential for environmental application.

Review on 2D Molybdenum Diselenide (MoSe2) and Its Hybrids for Green Hydrogen (H2) Generation Applications

Hydrogen (H₂) is a green and economical substitute to traditional fossil fuels due to zero carbon emissions. Water splitting technology is developing at a rapid speed to sustainably generate H₂ through electro- and photolysis of water without the harmful emissions associated with steam methane reforming. Development of efficient catalysts for the hydrogen evolution reaction (HER) is pertinent for economical green H₂ generation. In this regard, 2D transition metal dichalcogenides (TMDCs) are considered to be excellent alternatives to noble metal catalysts. Among other TMDCs, 2D MoSe₂ is preferred due to the low Gibbs free energy for hydrogen adsorption, good electrical conductivity, and more metallic nature. Moreover, the physicochemical and electronic properties of MoSe₂ can be easily tailored to suit HER application by simple synthetic strategies. Herein, we comprehensively review the application of 2D MoSe₂ in the electrocatalytic HER, focusing on recent advancements in the modulation of the MoSe₂ properties through nanostructure design, phase transformation, defect engineering, doping, and formation of heterostructures. We also discuss the role of 2D MoSe₂ as a cocatalyst in the photocatalytic HER. The article concludes with a synopsis of current progress and prospective future trends.

Transition Metal Dichalcogenides [MX2] in Photocatalytic Water Splitting

The quest for a clean, renewable and sustainable energy future has been highly sought for by the scientific community over the last four decades. Photocatalytic water splitting is a very promising technology to proffer a solution to present day environmental pollution and energy crises by generating hydrogen fuel through a “green route” without environmental pollution. Transition metal dichalcogenides (TMDCs) have outstanding properties which make them show great potential as effective co-catalysts with photocatalytic materials such as TiO2, ZnO and CdS for photocatalytic water splitting. Integration of TMDCs with a photocatalyst such as TiO2 provides novel nanohybrid composite materials with outstanding characteristics. In this review, we present the current state of research in the application of TMDCs in photocatalytic water splitting. Three main aspects which consider their properties, advances in the synthesis routes of layered TMDCs and their composites as well as their photocatalytic performances in the water splitting reaction are discussed. Finally, we raise some challenges and perspectives in their future application as materials for water-splitting photocatalysts.

Construction of core-shell Fe3O4@GO-CoPc photo-Fenton catalyst for superior removal of tetracycline: The role of GO in promotion of H2O2 to •OH conversion

A novel core-shell structured Fe₃O₄@GO-CoPc magnetic catalyst, which is with magnetite (Fe₃O₄) as the core, graphene oxide (GO) as the interlayer and cobalt-phthalocyanine (CoPc) as the shell, was successfully prepared and used as a heterogeneous photo-Fenton catalyst for tetracycline (TC) degradation in this work. The core-shell structure of the catalyst was confirmed by XRD, FTIR, SEM and TEM. BET and magnetic hysteresis loops measurements indicated that Fe₃O₄@GO-CoPc catalyst owned large specific surface area and could be easily recovered under an external magnetic field. Meanwhile, the experimental results of TC degradation demonstrated that the photo-Fenton efficiency of Fe₃O₄@GO-CoPc was excellent. When the reaction time was 120 min, TC could be degraded almost completely in the photo-Fenton system with Fe₃O₄@GO-CoPc. The high photo-Fenton catalytic activity of Fe₃O₄@GO-CoPc could be resulted from the effective transfer of photo-generated electrons between CoPc and Fe₃O₄ by GO. Moreover, the main reaction species, •OH, O₂•-, ¹O₂ and h⁺, were verified by the analysis of active species in this system. Finally, the mechanism analyses and quantitative analysis results of active species indicated that the introduction of GO accelerated the cycle between Fe(II) and Fe(III) as well as improved the effective utilization of H₂O₂ (the efficiency of conversion of H₂O₂ to •OH).

Hierarchical NiCo2S4/ZnIn2S4 heterostructured prisms: High-efficient photocatalysts for hydrogen production under visible-light

Exploring low-cost co-catalyst to ameliorate the photocatalytic activity of semiconductors sets a clear direction for solving energy crisis and achieving efficient solar-chemical energy conversion. In this work, a unique hierarchical hollow heterojunction was constructed by in-situ growing ZnIn₂S₄ nanosheets on the porous NiCo₂S₄ hollow prisms through a low temperature solvothermal method, in which NiCo₂S₄ with semi-metal property acted as non-noble metal co-catalyst. NiCo₂S₄ co-catalyst was innovatively encapsulated in ZnIn₂S₄, which not only relieved the light shielding effect caused by the large loading amount of co-catalyst, but also supplied abundant active sites for H₂ evolution. The hierarchical hollow heterostructure of NiCo₂S₄/ZnIn₂S₄ provided a highly efficient channel for charge transfer. Combining these advantages, NiCo₂S₄/ZnIn₂S₄ composite demonstrated excellent photocatalytic activity. In the absence of sacrificial agent, the NiCo₂S₄/ZnIn₂S₄ photocatalyst achieved a remarkable improved H₂ yield of 0.77 mmol g^-1h^-1 under visible light irradiation (λ > 400 nm), which is 6.6 times greater than that of ZnIn₂S₄. Besides, NiCo₂S₄ even exhibited better performance on the H₂ evolution improvement of ZnIn₂S₄ than precious metal Pt. This work will offer novel insights into the reasonable design of non-noble metal photocatalysts with respectable activity for water splitting.

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.

Porous direct Z-scheme heterostructures of S-deficient CoS/CdS hexagonal nanoplates for robust photocatalytic H2 generation

Unique porous S-deficient CoS/CdS hexagonal nanoplates exhibited an outstanding photocatalytic capability for H2 production, due to excellent visible-light response, efficient Z-scheme charge separation, and abundant H2-evolving active sites.

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.

Interfacial chemical bond and internal electric field modulated Z-scheme Sv-ZnIn2S4/MoSe2 photocatalyst for efficient hydrogen evolution

Construction of Z-scheme heterostructure is of great significance for realizing efficient photocatalytic water splitting. However, the conscious modulation of Z-scheme charge transfer is still a great challenge. Herein, interfacial Mo-S bond and internal electric field modulated Z-scheme heterostructure composed by sulfur vacancies-rich ZnIn₂S₄ and MoSe₂ was rationally fabricated for efficient photocatalytic hydrogen evolution. Systematic investigations reveal that Mo-S bond and internal electric field induce the Z-scheme charge transfer mechanism as confirmed by the surface photovoltage spectra, DMPO spin-trapping electron paramagnetic resonance spectra and density functional theory calculations. Under the intense synergy among the Mo-S bond, internal electric field and S-vacancies, the optimized photocatalyst exhibits high hydrogen evolution rate of 63.21 mmol∙g^-1·h^-1 with an apparent quantum yield of 76.48% at 420 nm monochromatic light, which is about 18.8-fold of the pristine ZIS. This work affords a useful inspiration on consciously modulating Z-scheme charge transfer by atomic-level interface control and internal electric field to signally promote the photocatalytic performance.

Efficient hydrogen production at a rationally designed MoSe2@Co3O4 p-n heterojunction

During the past several years, transition metal compounds have shown high activity in the field of photocatalysis. Therefore, the MoSe₂@Co₃O₄ with excellent photocatalytic properties through simple hydrothermal and physical mixing methods was prepared. This composite material was composed of n-type semiconductor MoSe₂ and p-type semiconductor Co₃O₄. After optimizing the loading of Co₃O₄, the optimal hydrogen production can reached 7029.2 μmol g^-1h^-1, which was 2.34 times that of single MoSe₂. In addition, some characterization methods were used to explore the hydrogen production performance of the composite catalyst under EY sensitized conditions. Among them, the UV-vis diffuse reflectance spectra suggests that MoSe₂@Co₃O₄ exhibits stronger visible light absorption performance than the single material. Fluorescence performance and photoelectrochemical characterization experiments further prove that, the special structure formed by MoSe₂ and Co₃O₄ and the existence of p-n heterojunction effectively accelerate the separation and transfer of carriers meanwhile inhibit the recombination probability of electron-hole pairs. Combined with other characterizations such as XRD, XPS, SEM and BET, the possible hydrogen production mechanism was proposed.

Constructing a 2D/2D heterojunction of MoSe2/ZnIn2S4 nanosheets for enhanced photocatalytic hydrogen evolution

2D/2D MoSe₂/ZnIn₂S₄ heterojunctions exhibit high photocatalytic activity owing to MoSe₂ as a cocatalyst, which provides more active sites, reducing the overpotential and the activation energy for water reduction.

P-Doped CdS integrated with multiphasic MoSe2 nanosheets accomplish prominent photocatalytic activity for hydrogen evolution

The construction of P-doped CdS nanorods with multiphasic MoSe2 improves the separation and transfer efficiency of photogenerated carriers and apparently enhances the hydrogen production rate.

CdS nanoparticles grown in situ on oxygen deficiency-rich WO3−x nanosheets: direct Z-scheme heterojunction towards enhancing visible light-driven hydrogen evolution

This work introduces the synthesis of direct Z-scheme CdS/WO_3−x heterojunction photocatalysts and the application of photocatalytic hydrogen evolution.

Core-shell structured Fe3O4@GO@MIL-100(Fe) magnetic nanoparticles as heterogeneous photo-Fenton catalyst for 2,4-dichlorophenol degradation under visible light

A novel core-shell structured Fe₃O₄@GO@MIL-100(Fe) magnetic catalyst was successfully synthesized and used as heterogeneous photo-Fenton catalyst for 2,4-dichlorophenl (2,4-DCP) degradation. The catalyst was fully characterized by X-ray diffraction pattern (XRD), Raman spectroscopy, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunner-Emmet-Teller (BET) and magnetic hysteresis loops measurements. The effects of initial pH, H₂O₂ concentration, catalyst load and irradiation intensity on 2,4-DCP degradation were also investigated. The results showed that Fe₃O₄@GO@MIL-100(Fe) exhibited excellent photo-Fenton catalytic activity, achieving almost 100% of 2,4-DCP degradation within 40 min at reaction condition of 3 mmol/L H₂O₂, 50 mg/L 2,4-DCP, pH 5.5 and irradiation intensity of 500 W. The high catalytic activity of Fe₃O₄@GO@MIL-100(Fe) can be attributed to the efficient transfer of photo-generated electrons between MIL-100(Fe) and Fe₃O₄ by GO. The recycling experiments displayed that Fe₃O₄@GO@MIL-100(Fe) catalyst possessed good stability and could be easily recovered under an applied magnetic field. Finally, the possible mechanism of 2,4-DCP degradation in the photo-Fenton system catalyzed by Fe₃O₄@GO@MIL-100(Fe) was also proposed according to the analyses of reactive species, photoluminescence (PL) emission spectra and the photocurrent responses.

Molybdenum disulfide quantum dots directing zinc indium sulfide heterostructures for enhanced visible light hydrogen production

Photocatalytic hydrogen (H₂) production based on semiconductors is important to utilize solar light for clean energy and environment. Herein, we report a visible light responsive heterostructure, designed and constructed by molybdenum disulfide quantum dots (MoS₂-QDs) in-situ seeds-directing growth and self-assemble of zinc indium sulfide (ZnIn₂S₄) nanosheet to ensure their full contact through a simple one-step solvothermal method for highly improved visible light H₂ production. The MoS₂-QDs in-situ seeds-directing ZnIn₂S₄ heterostructure not only builds heterojunctions between MoS₂ and ZnIn₂S₄ to spatially separate the photogenerated electrons and holes, but also serves as the active sites trapping photogenerated electrons to facilitate H₂ evolution. As a result, MoS₂-QDs/ZnIn₂S₄ exhibits high photocatalytic activity for H₂ production, and the optimized 2 wt% MoS₂-QDs/ZnIn₂S₄ (2MoS₂-QDs/ZnIn₂S₄) heterostructure exhibits the highest H₂ evolution rate of 7152 umol·h^-1·g^-1 under visible light, ∼9 times of pure ZnIn₂S₄. Our strategy here could shed some lights on developing noble-metal free heterostructures for highly efficient photocatalytic H₂ production.

Sub-5 nm Ultra-Fine FeP Nanodots as Efficient Co-Catalysts Modified Porous g-C3N4 for Precious-Metal-Free Photocatalytic Hydrogen Evolution under Visible Light

Sub-5 nm ultra-fine iron phosphide (FeP) nano-dots-modified porous graphitic carbon nitride (g-C₃N₄) heterojunction nanostructures are successfully prepared through the gas-phase phosphorization of Fe₃O₄/g-C₃N₄ nanocomposites. The incorporation of zero-dimensional (0D) ultra-small FeP nanodots co-catalysts not only effectively facilitate charge separation but also serve as reaction active sites for hydrogen (H₂) evolution. Herein, the strongly coupled FeP/g-C₃N₄ hybrid systems are employed as precious-metal-free photocatalysts for H₂ production under visible-light irradiation. The optimized FeP/g-C₃N₄ sample displays a maximum H₂ evolution rate of 177.9 μmol h^-1 g^-1 with the apparent quantum yield of 1.57% at 420 nm. Furthermore, the mechanism of photocatalytic H₂ evolution using 0D/2D FeP/g-C₃N₄ heterojunction interfaces is systematically corroborated by steady-state photoluminescence (PL), time-resolved PL spectroscopy, and photoelectrochemical results. Additionally, an increased donor density in FeP/g-C₃N₄ is evidenced from the Mott-Schottky analysis in comparison with that of parent g-C₃N₄, signifying the enhancement of electrical conductivity and charge transport owing to the emerging role of FeP. The density functional theory calculations reveal that the FeP/g-C₃N₄ hybrids could act as a promising catalyst for the H₂ evolution reaction. Overall, this work not only paves a new path in the engineering of monodispersed FeP-decorated g-C₃N₄ 0D/2D robust nanoarchitectures but also elucidates potential insights for the utilization of noble-metal-free FeP nanodots as remarkable co-catalysts for superior photocatalytic H₂ evolution.

Hierarchical flower-like ZnIn2S4 anchored with well-dispersed Ni12P5 nanoparticles for high-quantum-yield photocatalytic H2 evolution under visible light

Ni₁₂P₅ nanoparticles were successfully anchored on hierarchical ZnIn₂S₄ through a facile solution phase route, and the Ni₁₂P₅/ZnIn₂S₄ composites manifested superior photocatalytic H₂ evolution under visible light.

Hydrogenated ZnIn2S4 microspheres: boosting photocatalytic hydrogen evolution by sulfur vacancy engineering and mechanism insight

The correlation between hydrogenation-induced surface sulfur vacancies and photocatalytic activity of hydrogenated ZnIn₂S₄ is tentatively proposed in this work.

In situ growth and activation of an amorphous MoSx catalyst on Co-containing metal–organic framework nanosheets for highly efficient dye-sensitized H2 evolution

In situ grown amorphous MoS_x on Co-containing MOF nanosheets could efficiently catalyze visible light H₂ evolution in an ErB-sensitized system.

Microwave synthesis of ZnIn2S4/WS2 composites for photocatalytic hydrogen production and hexavalent chromium reduction

A rapid microwave synthesis route for the fabrication of ZnIn₂S₄ powder and ZnIn₂S₄/WS₂ composites is presented.

Review on nanoscale Bi-based photocatalysts

Nanoscale Bi-based photocatalysts are promising candidates for visible-light-driven photocatalytic environmental remediation and energy conversion. However, the performance of bulk bismuthal semiconductors is unsatisfactory. Increasing efforts have been focused on enhancing the performance of this photocatalyst family. Many studies have reported on component adjustment, morphology control, heterojunction construction, and surface modification. Herein, recent topics in these fields, including doping, changing stoichiometry, solid solutions, ultrathin nanosheets, hierarchical and hollow architectures, conventional heterojunctions, direct Z-scheme junctions, and surface modification of conductive materials and semiconductors, are reviewed. The progress in the enhancement mechanism involving light absorption, band structure tailoring, and separation and utilization of excited carriers, is also introduced. The challenges and tendencies in the studies of nanoscale Bi-based photocatalysts are discussed and summarized.

Cr(VI) remediation from aqueous environment through modified-TiO2-mediated photocatalytic reduction

Cr(VI) exhibits cytotoxic, mutagenic and carcinogenic properties; hence, effluents containing Cr(VI) from various industrial processes pose threat to aquatic life and downstream users. Various treatment techniques, such as chemical reduction, ion exchange, bacterial degradation, adsorption and photocatalysis, have been exploited for remediation of Cr(VI) from wastewater. Among these, photocatalysis has recently gained considerable attention. The applications of photocatalysis, such as water splitting, CO2 reduction, pollutant degradation, organic transformation reactions, N2 fixation, etc., towards solving the energy crisis and environmental issues are briefly discussed in the Introduction of this review. The advantages of TiO2 as a photocatalyst and the importance of its modification for photocatalytic reduction of Cr(VI) has also been addressed. In this review, the photocatalytic activity of TiO2 after modification with carbon-based advanced materials, metal oxides, metal sulfides and noble metals towards reduction of Cr(VI) was evaluated and compared with that of bare TiO2. The photoactivity of dye-sensitized TiO2 for reduction of Cr(VI) was also discussed. The mechanism for enhanced photocatalytic activity was highlighted and attributed to the resultant properties, namely, effective separation of photoinduced charge carriers, extension of the light absorption range and intensity, increase of the surface active sites, and higher photostability. Advantages and limitations for photoreduction of Cr(VI) over modified TiO2 are depicted in the Conclusion. The various challenges that restrict the technology from practical applications in remediation of Cr(VI) from wastewater were addressed in the Conclusion section as well. The future perspectives of the field presented in this review are focused on the development of whole-solar-spectrum responsive, TiO2-coupled photocatalysts which provide efficient photocatalytic reduction of Cr(VI) along with their good recoverability and recyclability.

Facile synthesis of a ZnO-BiOI p-n nano-heterojunction with excellent visible-light photocatalytic activity

In this paper, an efficient method to produce a ZnO/BiOI nano-heterojunction is developed by a facile solution method followed by calcination. By tuning the ratio of Zn/Bi, the morphology varies from nanoplates, flowers to nanoparticles. The heterojunction formed between ZnO and BiOI decreases the recombination rate of photogenerated carriers and enhances the photocatalytic activity of ZnO/BiOI composites. The obtained ZnO/BiOI heterostructured nanocomposites exhibit a significant improvement in the photodegradation of rhodamine B under visible light (λ ≥ 420 nm) irradiation as compared to single-phase ZnO and BiOI. A sample with a Zn/Bi ratio of 3:1 showed the highest photocatalytic activity (≈99.3% after 100 min irradiation). The photodegradation tests indicated that the ZnO/BiOI heterostructured nanocomposites not only exhibit remarkably enhanced and sustainable photocatalytic activity, but also show good recyclability. The excellent photocatalytic activity could be attributed to the high separation efficiency of the photoinduced electron-hole pairs as well as the high specific area.

Mechanistic insights into plasmonic photocatalysts in utilizing visible light

The utilisation of sunlight as an abundant and renewable resource has motivated the development of sustainable photocatalysts that can collectively harvest visible light. However, the bottleneck in utilising the low energy photons has led to the discovery of plasmonic photocatalysts. The presence of noble metal on the plasmonic photocatalyst enables the harvesting of visible light through the unique characteristic features of the noble metal nanomaterials. Moreover, the formation of interfaces between noble metal particles and semiconductor materials further results in the formation of a Schottky junction. Thereby, the plasmonic characteristics have opened up a new direction in promoting an alternative path that can be of value to the society through sustainable development derived through energy available for all for diverse applications. We have comprehensively prepared this review to specifically focus on fundamental insights into plasmonic photocatalysts, various synthesis routes, together with their strengths and weaknesses, and the interaction of the plasmonic photocatalyst with pollutants as well as the role of active radical generation and identification. The review ends with a pinnacle insight into future perspectives regarding realistic applications of plasmonic photocatalysts.

A review on photocatalytic CO2 reduction using perovskite oxide nanomaterials

As the search for efficient catalysts for CO₂ photoreduction continues, nanostructured perovskite oxides have emerged as a class of high-performance photocatalytic materials. The perovskite oxide candidates for CO₂ photoreduction are primarily nanostructured forms of titanates, niobates, tantalates and cobaltates. These materials form the focus of this review article because they are much sought-after due to their nontoxic nature, adequate chemical stability, and tunable crystal structures, bandgaps and surface energies. As compared to conventional semiconductors and nanomaterial catalysts, nanostructured perovskite oxides also exhibit an extended optical-absorption edge, longer charge carrier lifetimes, and favorable band-alignment with respect to reduction potential of activated CO₂ and reduction products of the same. While CO₂ reduction product yields of several hundred μmol^-1 h^-1 are observed with many types of perovskite oxide nanomaterials in stand-alone forms, yield of such quantities are not common with semiconductor nanomaterials of other types. In this review, we present current state-of-the-art synthesis methods to form perovskite oxide nanomaterials, and procedures to engineer their bandgaps. This review also presents a comprehensive summary and discussion on crystal structures, defect distribution, morphologies and electronic properties of the perovskite oxides, and correlation of these properties to CO₂ photoreduction performance. This review offers researchers key insights for developing advanced perovskite oxides in order to further improve the yields of CO₂ reduction products.

Fe3C nanoparticles encapsulated in highly crystalline porous graphite: salt-template synthesis and enhanced electrocatalytic oxygen evolution activity and stability

Fe₃C nanoparticles encapsulated in highly crystalline porous graphite were prepared via an in situ salt template method and showed enhanced electrocatalytic OER activity and long-term stability.

CoAl-layered double hydroxide nanosheets as an active matrix to anchor an amorphous MoSx catalyst for efficient visible light hydrogen evolution

CoAl LDH nanosheet supported MoS_x efficiently catalyzes H₂ evolution from an erythrosin B–triethanolamine molecular system under visible light (≥420 nm).

Photocatalytic H2production by dirhodium(ii,ii) photosensitizers with red light

Photocatalytic H₂evolution uponλ_irr= 655 nm with dirhodium(ii,ii) photosensitizers demonstrates tunable oxidative and reductive quenching mechanisms.