ZnIn 2 S 4 hybrid with MoS 2 : A non-noble metal photocatalyst with efficient photocatalytic activity for hydrogen evolution

A compendium of all-in-one solar-driven water splitting using ZnIn2S4-based photocatalysts: guiding the path from the past to the limitless future

Photocatalytic water splitting represents a leading approach to harness the abundant solar energy, producing hydrogen as a clean and sustainable energy carrier. Zinc indium sulfide (ZIS) emerges as one of the most captivating candidates attributed to its unique physicochemical and photophysical properties, attracting much interest and holding significant promise in this domain. To develop a highly efficient ZIS-based photocatalytic system for green energy production, it is paramount to comprehensively understand the strengths and limitations of ZIS, particularly within the framework of solar-driven water splitting. This review elucidates the three sequential steps that govern the overall efficiency of ZIS with a sharp focus on the mechanisms and inherent drawbacks associated with each phase, including commonly overlooked aspects such as the jeopardising photocorrosion issue, the neglected oxidative counter surface reaction kinetics in overall water splitting, the sluggish photocarrier dynamics and the undesired side redox reactions. Multifarious material design strategies are discussed to specifically mitigate the formidable limitations and bottleneck issues. This review concludes with the current state of ZIS-based photocatalytic water splitting systems, followed by personal perspectives aimed at elevating the field to practical consideration for future endeavours towards sustainable hydrogen production through solar-driven water splitting.

MoS2-Based Nanocomposites for Photocatalytic Hydrogen Evolution and Carbon Dioxide Reduction

Photocatalysis is a facile and sustainable approach for energy conversion and environmental remediation by generating solar fuels from water splitting. Due to their two-dimensional (2D) layered structure and excellent physicochemical properties, molybdenum disulfide (MoS₂) has been effectively utilized in photocatalytic H₂ evolution reaction (HER) and CO₂ reduction. The photocatalytic efficiency of MoS₂ greatly depends on the active edge sites present in their layered structure. Modifications like reducing the layer numbers, creating defective structures, and adopting different morphologies produce more unsaturated S atoms as active edge sites. Hence, MoS₂ acts as a cocatalyst in nanocomposites/heterojunctions to facilitate the photogenerated electron transfer. This review highlights the role of MoS₂ as a cocatalyst for nanocomposites in H₂ evolution reaction and CO₂ reduction. The H₂ evolution activity has been described comprehensively as binary (with metal oxide, carbonaceous materials, metal sulfides, and metal-organic frameworks) and ternary composites of MoS₂. Photocatalytic CO₂ reduction is a more complex and challenging process that demands an efficient light-responsive semiconductor catalyst to tackle the thermodynamic and kinetic factors. Photocatalytic reduction of CO₂ using MoS₂ is an emerging topic and would be a cost-effective substitute for noble catalysts. Herein, we also exclusively envisioned the possibility of layered MoS₂ and its composites in this area. This review is expected to furnish an understanding of the diverse roles of MoS₂ in solar fuel generation, thus endorsing an interest in utilizing this unique layered structure to create nanostructures for future energy applications.

The three-dimensionally ordered microporous CaTiO3 coupling Zn0.3Cd0.7S quantum dots for simultaneously enhanced photocatalytic H2 production and glucose conversion

Glucose conversion assisted photocatalytic water splitting technology to simultaneously produce H₂ and high value-added chemicals is a promising method for alleviating the energy shortage and environmental crisis. In this work, we constructing type II heterojunction by in-situ coupling Zn_0.3Cd_0.7S quantum dots (ZCS QDs) on three-dimensionally ordered microporous CaTiO₃ (3DOM CTO) for photocatalytic H₂ production and glucose conversion. The DFT calculations demonstrate that substitution of Zn on the Cd site improves the separation and transmission of photogenerated carriers. Therefore, 3DOM CTO-ZCS composite exhibits best H₂ production performance (2.81 mmol g^-1h^-1) and highest apparent quantum efficiency (AQY) (5.56 %) at 365 nm, which are about 47 and 18 times that of CTO nanoparticles (NPs). The improved catalytic performance ascribed to not only good mass diffusion and exchange, highly efficient light harvesting of 3DOM structure, but also the efficient charges separation of type Ⅱ heterojunction. The investigation on photocatalytic mechanism indicates that the glucose is mainly converted to gluconic acid and lactic acid, and the control reaction step is gluconic acid to lactic acid. The selectivity for gluconic acid on 3DOM CTO-ZCS is 85.65 %. Our work here proposes a green sustainable method to achieve highly efficient H₂ production and selective conversion of glucose to gluconic acid.

Construction of Hollow Co3O4@ZnIn2S4 p-n Heterojunctions for Highly Efficient Photocatalytic Hydrogen Production

Photocatalysts derived from semiconductor heterojunctions for water splitting have bright prospects in solar energy conversion. Here, a Co₃O₄@ZIS p-n heterojunction was successfully created by developing two-dimensional ZnIn₂S₄ on ZIF-67-derived hollow Co₃O₄ nanocages, realizing efficient spatial separation of the electron-hole pair. Moreover, the black hollow structure of Co₃O₄ considerably increases the range of light absorption and the light utilization efficiency of the heterojunction avoids the agglomeration of ZnIn₂S₄ nanosheets and further improves the hydrogen generation rate of the material. The obtained Co₃O₄(20) @ZIS showed excellent photocatalytic H₂ activity of 5.38 mmol g^-1·h^-1 under simulated solar light, which was seven times more than that of pure ZnIn₂S₄. Therefore, these kinds of constructions of hollow p-n heterojunctions have a positive prospect in solar energy conversion fields.

Photoelectrochemical Immunosensor Based on a 1D Fe2O3/3D Cd-ZnIn2.2Sy Heterostructure as a Sensing Platform for Ultrasensitive Detection of Neuron-Specific Enolase

Lung cancer is a high-mortality cancer related to the concentration of neuron-specific enolase (NSE). In this work, a sandwich-type photoelectrochemical (PEC) immunosensor was constructed for ultrasensitive detection of NSE, which is based on iron trioxide/indium zinc cadmium sulfide (Fe₂O₃/Cd-ZnIn_2.2S_y) as a sensing platform and Ag-modified polyaniline (Ag@PANI) as a signal amplification label. The 1D Fe₂O₃ porous nanorods with a large specific surface area were synthesized by calcination of Fe-MIL-88A and etching of NaOH. To improve the photocurrent response, the 3D architecture Cd-ZnIn_2.2S_y was combined with the 1D Fe₂O₃ porous nanorods to form a 1D Fe₂O₃/3D Cd-ZnIn_2.2S_y heterostructure. Specifically, the Fe₂O₃/Cd-ZnIn_2.2S_y heterostructure with a good energy level matching (the two can form a stepped energy level matching, which accelerates the transfer rate of electrons) can improve the separation efficiency of electron-hole pairs (e^-/h⁺) under visible light irradiation, which enhances the photocurrent response. Ag@PANI has a strong electron transport capability and can be used as a secondary antibody marker for the signal amplification of the immunosensor. The sensor exhibits a good linear detection range of 100 fg/mL to 100 ng/mL with a low detection limit of 33.5 fg/mL. Moreover, the constructed sandwich-type PEC immunosensor shows good performance and possesses excellent specificity, selectivity, and stability over a period of 4 weeks for NSE detection. With these excellent properties, the immunosensor can be extended to analyze and diagnose other disease biomarkers.

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.

Enhanced visible-light-driven photocatalytic H2 production and Cr(vi) reduction of a ZnIn2S4/MoS2 heterojunction synthesized by the biomolecule-assisted microwave heating method

Photocatalytic applications of flower-like ZnIn₂S₄/MoS₂ composite, synthesized by biomolecule-assisted microwave heating method, in H₂ evolution and Cr(vi) reduction reactions.

Path of electron transfer created in S-doped NH2-UiO-66 bridged ZnIn2S4/MoS2 nanosheet heterostructure for boosting photocatalytic hydrogen evolution

This work introduces the synthesis of ZnIn₂S₄/NH₂-UiO-66/MoS₂ sheet heterostructure photocatalysts and their application to photocatalytic hydrogen evolution.

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.

Photocatalytic Hydrogen Production: Role of Sacrificial Reagents on the Activity of Oxide, Carbon, and Sulfide Catalysts

Photocatalytic water splitting is a sustainable technology for the production of clean fuel in terms of hydrogen (H2). In the present study, hydrogen (H2) production efficiency of three promising photocatalysts (titania (TiO2-P25), graphitic carbon nitride (g-C3N4), and cadmium sulfide (CdS)) was evaluated in detail using various sacrificial agents. The effect of most commonly used sacrificial agents in the recent years, such as methanol, ethanol, isopropanol, ethylene glycol, glycerol, lactic acid, glucose, sodium sulfide, sodium sulfite, sodium sulfide/sodium sulfite mixture, and triethanolamine, were evaluated on TiO2-P25, g-C3N4, and CdS. H2 production experiments were carried out under simulated solar light irradiation in an immersion type photo-reactor. All the experiments were performed without any noble metal co-catalyst. Moreover, photolysis experiments were executed to study the H2 generation in the absence of a catalyst. The results were discussed specifically in terms of chemical reactions, pH of the reaction medium, hydroxyl groups, alpha hydrogen, and carbon chain length of sacrificial agents. The results revealed that glucose and glycerol are the most suitable sacrificial agents for an oxide photocatalyst. Triethanolamine is the ideal sacrificial agent for carbon and sulfide photocatalyst. A remarkable amount of H2 was produced from the photolysis of sodium sulfide and sodium sulfide/sodium sulfite mixture without any photocatalyst. The findings of this study would be highly beneficial for the selection of sacrificial agents for a particular photocatalyst.

Construction of noble-metal-free TiO2 nanobelt/ZnIn2S4 nanosheet heterojunction nanocomposite for highly efficient photocatalytic hydrogen evolution

A binary nanocomposite composed of two-dimensional (2D) ultrathin ZnIn₂S₄ nanosheets and one-dimension (1D) TiO₂ nanobelts was prepared and applied as a noble-metal-free photocatalyst for hydrogen evolution under solar-light irradiation. The TiO₂ nanobelt/ZnIn₂S₄ nanosheet heterojunction nanocomposites show higher light absorption capacity, larger surface area and higher separation of charge carriers in comparison to pristine TiO₂ and ZnIn₂S₄. As a result, the hydrogen production over the TiO₂/ZnIn₂S₄ nanocomposite with 15 wt% TiO₂ can reach up to 348.21 μmol · g^-1 · h^-1, even without noble metals, which is about 26 and 2.3 times higher than the pristine TiO₂ and ZnIn₂S₄, respectively. Meanwhile, a possible photocatalytic mechanism of TiO₂/ZnIn₂S₄ heterojunction nanocomposites was proposed and corroborated by photoluminescence (PL) spectroscopy and photoelectrochemical (PEC) results. This work paves a way for developing low-cost and high-efficiency noble-metal-free photocatalytic systems for solar-to-hydrogen 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.

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.

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

A highly efficient visible-light-driven photocatalyst is urgently necessary for photocatalytic hydrogen generation through water splitting. Herein, ZnIn₂ S₄ hierarchical architectures assembled as ultrathin nanosheets were synthesized by a facile one-pot polyol approach. Subsequently, the two-dimensional-network-like MoSe₂ was successfully hybridized with ZnIn₂ S₄ by taking advantage of their analogous intrinsic layered morphologies. The noble-metal-free ZnIn₂ S₄ /MoSe₂ heterostructures show enhanced photocatalytic H₂ evolution compared to pure ZnIn₂ S₄ . It is noteworthy that the optimum nanocomposite of ZnIn₂ S₄ /2 % MoSe₂ photocatalyst displays a high H₂ generation rate of 2228 μmol g^-1  h^-1 and an apparent quantum yield (AQY) of 21.39 % at 420 nm. This study presents an unprecedented ZnIn₂ S₄ /MoSe₂ metal-sulfide-metal-selenide hybrid system for H₂ evolution. Importantly, the present efficient hybridization strategy reveals the potential of hierarchical nanoarchitectures for a multitude of energy storage and solar energy conversion applications.

In situ construction of a heterojunction over the surface of a sandwich structure semiconductor for highly efficient photocatalytic H2 evolution under visible light irradiation

Developing a heterostructure on the surface of a "sandwich" structure semiconductor is essential for full utilization of its heterojunction function and hence for designing efficient solar energy conversion systems. Here, we show that 2D-2D MoS₂/MnSb₂S₄ heterostructure composites are designed for the first time and successfully synthesized by a simple in situ calcination pathway. Under visible light irradiation, the ca. 3.3 wt% MoS₂/MnSb₂S₄ samples exhibited the highest activity for H₂ evolution, which was 7.7 times higher than that of the pristine MnSb₂S₄ monolayer. The outstanding photocatalytic performance was attributed to the MoS₂ nanosheets intimately growing on the surface [SbS]⁺ layers of monolayer MnSb₂S₄ nanosheets with the [SbS]⁺-[MnS₂]^2--[SbS]⁺ sandwich substructure to form the 2D-2D MoS₂/MnSb₂S₄ heterojunction structure. More importantly, we prove that this specific heterojunction structure can lead to more weakening of the constraint of the valence electrons in the composited photocatalysts, which can promote the transfer of photogenerated electrons from MnSb₂S₄ to MoS₂. The present study provides a new design strategy for the construction of a heterostructure to improve the photocatalytic H₂ production activity highly efficiently.