Preparation of the flower-like MoS2/SnS2 heterojunction as an efficient electrocatalyst for hydrogen evolution reaction

Noble metal-free CZTS electrocatalysis: synergetic characteristics and emerging applications towards water splitting reactions

This review provides a comprehensive overview of the production and modification of CZTS nanoparticles (NPs) and their application in electrocatalysis for water splitting. Various aspects, including surface modification, heterostructure design with carbon nanostructured materials, and tunable electrocatalytic studies, are discussed. A key focus is the synthesis of small CZTS nanoparticles with tunable reactivity, emphasizing the sonochemical method's role in their formation. Despite CZTS's affordability, it often exhibits poor hydrogen evolution reaction (HER) behavior. Carbon materials like graphene, carbon nanotubes, and C60 are highlighted for their ability to enhance electrocatalytic activity due to their unique properties. The review also discusses the amine functionalization of graphene oxide/CZTS composites, which enhances overall water splitting performance. Doping with non-noble metals such as Fe, Co., and Ni is presented as an effective strategy to improve catalytic activity. Additionally, the synthesis of heterostructures consisting of CZTS nanoparticles attached to MoS2-reduced graphene oxide (rGO) hybrids is explored, showing enhanced HER activity compared to pure CZTS and MoS2. The growing demand for energy and the need for efficient renewable energy sources, particularly hydrogen generation, are driving research in this field. The review aims to demonstrate the potential of CZTS-based electrocatalysts for high-performance and cost-effective hydrogen generation with low environmental impact. Vacuum-based and non-vacuum-based methods for fabricating CZTS are discussed, with a focus on simplicity and efficiency. Future developments in CZTS-based electrocatalysts include enhancing activity and stability, improving charge transfer mechanisms, ensuring cost-effectiveness and scalability, increasing durability, integrating with renewable energy sources, and gaining deeper insight into reaction processes. Overall, CZTS-based electrocatalysts show great promise for sustainable hydrogen generation, with ongoing research focused on improving performance and advancing their practical applications.

Ion-Electron Transduction Layer of the SnS2-MoS2 Heterojunction to Elevate Superior Interface Stability for All-Solid Sodium-Ion Selective Electrode

The high selectivity and fast ion response of all-solid sodium ion selective electrodes were widely applied in human sweat analysis. However, the potential drift due to insufficient interfacial capacitance leads to the deterioration of its stability and ultimately affects the potential accuracy of ion analysis. Designing a novel ion-electron transduction layer between the electrode and the ion selective membrane is an effective method to stabilize the interfacial potential. Herein, the SnS2-MoS2 heterojunction material was constructed by doping Sn in MoS2 nanosheets and used as the ion electron transduction layers of an all-solid sodium ion selective electrode for the first time, achieving the stable and efficient detection of Na+ ions. The proposed electrode exhibited a Nernst slope of 57.86 mV/dec for the detection of Na+ ions with a detection limit of 10-5.7 M in the activity range of 10-6-10-1 M. Via the electronic interaction at the heterojunction interfaces between SnS2 and MoS2 materials, the micro-nanostructure of the SnS2-MoS2 heterojunction was changed and SnS2-MoS2 as the ion-electron transduction layer acquired excellent capacitance (699 μF) and hydrophobicity (132°), resulting in a long-term potential stability of 1.37 μV/h. It was further proved that the large capacitance and high hydrophobicity of the ion-electron transduction layer are primary reasons for the excellent stability of the all-solid sodium ion selective electrode toward Na+ ions.

Hydrothermal Synthesis of MoS2/SnS2 Photocatalysts with Heterogeneous Structures Enhances Photocatalytic Activity

The use of solar photocatalysts to degrade organic pollutants is not only the most promising and efficient strategy to solve pollution problems today but also helps to alleviate the energy crisis. In this work, MoS₂/SnS₂ heterogeneous structure catalysts were prepared by a facile hydrothermal method, and the microstructures and morphologies of these catalysts were investigated using XRD, SEM, TEM, BET, XPS and EIS. Eventually, the optimal synthesis conditions of the catalysts were obtained as 180 °C for 14 h, with the molar ratio of molybdenum to tin atoms being 2:1 and the acidity and alkalinity of the solution adjusted by hydrochloric acid. TEM images of the composite catalysts synthesized under these conditions clearly show that the lamellar SnS₂ grows on the surface of MoS₂ at a smaller size; high-resolution TEM images show lattice stripe distances of 0.68 nm and 0.30 nm for the (002) plane of MoS₂ and the (100) plane of SnS₂, respectively. Thus, in terms of microstructure, it is confirmed that the MoS₂ and SnS₂ in the composite catalyst form a tight heterogeneous structure. The degradation efficiency of the best composite catalyst for methylene blue (MB) was 83.0%, which was 8.3 times higher than that of pure MoS₂ and 16.6 times higher than that of pure SnS₂. After four cycles, the degradation efficiency of the catalyst was 74.7%, indicating a relatively stable catalytic performance. The increase in activity could be attributed to the improved visible light absorption, the increase in active sites introduced at the exposed edges of MoS₂ nanoparticles and the construction of heterojunctions opening up photogenerated carrier transfer pathways and effective charge separation and transfer. This unique heterostructure photocatalyst not only has excellent photocatalytic performance but also has good cycling stability, which provides a simple, convenient and low-cost method for the photocatalytic degradation of organic pollutants.

Two-Dimensional ZnS/SnS2 Heterojunction as a Direct Z-Scheme Photocatalyst for Overall Water Splitting: A DFT Study

Direct Z-scheme photocatalysts have attracted extensive attention due to their strong redox ability and efficient separation of photogenerated electron-hole pairs. In this study, we constructed two types of ZnS/SnS₂ heterojunctions with different stacking models of ZnS and SnS₂ layers, and investigated their structures, stabilities, and electronic and optical properties. Both types of heterojunctions are stable and are direct Z-scheme photocatalysts with band gaps of 1.87 eV and 1.79 eV, respectively. Furthermore, their oxidation and reduction potentials straddle the redox potentials of water, which makes them suitable as photocatalysts for water splitting. The built-in electric field at the heterojunction interface improves the separation of photogenerated electron-hole pairs, thus enhancing their photocatalytic efficiency. In addition, ZnS/SnS₂ heterojunctions have higher carrier mobilities and light absorption intensities than ZnS and SnS₂ monolayers. Therefore, the ZnS/SnS₂ heterojunction has a broad application prospect as a direct Z-scheme visible-light-driven photocatalyst for overall water splitting.

Super-stable SnO2/MoS2 enhanced the electrocatalytic hydrogen evolution in acidic environments

We designed a superstable SnO2/MoS2 coupled nanosheet array on carbon cloth, which exhibited interface engineering of SnO2/MoS2 with fast electron transfer and proton adsorption boosting electrocatalytic hydrogen evolution in acidic environments.

Improved hydrogen evolution with SnS2 quantum dot-incorporated black Si photocathode

Black silicon (bSi), possessing appealing light-trapping properties and large specific surface area, ranks high among many other photocathode materials. However, the insufficient dynamics towards HER seriously bother black Si. Herein, a novel photoelectrode with ultrasmall size tin sulfide quantum dot (SnS₂ QD) incorporated black silicon was employed. Nanosized SnS₂ possesses numerous active sites for electrochemical reactions. Impressively, benefiting from SnS₂ QDs, the downward band bending of the Si Fermi level at the interface of electrolyte becomes higher, which remarkably suppresses the recombination of photo-generated carriers, thereby facilitating the participation of photo-generated electrons in PEC-HER. As a result, the thus-designed SnS₂/bSi reveals an exceptional PEC-HER activity with a positive onset potential of 0.235 V vs. reversible hydrogen electrode (RHE), a high photocurrent of 1.23 mA cm^-2 at 0 V vs. RHE, and long-term stability. Besides, the saturated photocurrent of ∼41 mA cm^-2 is achieved at about -0.51 V vs. RHE.

Coupling SnS2 and rGO aerogel to CuS for enhanced light-assisted OER electrocatalysis

In order to harvest more light wavelengths to improve the light-assisted electrochemical water splitting capacity, we developed a novel heterostructure of three-dimensional (3D) flower-like CuS architecture with accompanying SnS2 nanoparticles and reduced graphene oxide (rGO) aerogel for outstanding light-assisted electrocatalytic OER performance and good stability. The excellent catalytic kinetics, effective capturing of visible light, and rapid charge transfer of the CuS/SnS2/rGO (CSr) heterostructure were demonstrated. The overpotential (264 mV@10 mA cm-2) under light-assisted conditions is 20% lower than that under light-chopped conditions. SnS2 can harvest more light wavelengths and this boosts its intrinsic activity. However, with the increase of the SnS2 content, the OER activity decreases. The combination of the CS heterostructure and the rGO conductive aerogel achieves rapid charge transfer. Furthermore, the possible mechanism of the light-assisted electrocatalytic OER was also proposed. Overall, this work provides new insights into the simple and scalable fabrication of a highly efficient, low-cost, and stable non-noble-metal-based electrocatalyst.

Ultra-Thin SnS2-Pt Nanocatalyst for Efficient Hydrogen Evolution Reaction

Transition-metal dichalcogenides (TMDs) materials have attracted much attention for hydrogen evolution reaction (HER) as a new catalyst, but they still have challenges in poor stability and high reaction over-potential. In this study, ultra-thin SnS₂ nanocatalysts were synthesized by simple hydrothermal method, and low load of Pt was added to form stable SnS₂-Pt-3 (the content of platinum is 0.5 wt %). The synergistic effect between ultra-thin SnS₂ rich in active sites and individual dispersed Pt nanoclusters can significantly reduce the reaction barrier and further accelerate HER reaction kinetics. Hence, SnS₂-Pt-3 exhibits a low overpotential of 210 mV at the current density of 10 mA cm⁻². It is worth noting that SnS₂-Pt-3 has a small Tafel slope (126 mV dec⁻¹) in 0.5 M H₂SO₄, as well as stability. This work provides a new option for the application of TMDs materials in efficient hydrogen evolution reaction. Moreover, this method can be easily extended to other catalysts with desired two-dimensional materials.