Hierarchical fabrication of hollow Co2P nanocages coated with ZnIn2S4 thin layer: Highly efficient noble-metal-free photocatalyst for hydrogen evolution

Interfacial tuning in FeP/ZnIn2S4 Ohm heterojunction: Enhanced photocatalytic hydrogen production via Zn-P charge bridging

Interfacial regulation is key to photocatalytic performance, yet modulating interfacial charge transfer in heterostructures remains challenging. Herein, a novel nanoflower-like FeP/ZnIn2S4 Ohm heterostructure is first designed, with Zn atoms in ZnIn2S4 (ZIS) acting as potential anchoring sites around P atoms, forming liganded Zn-P bonds. Combining 1D FeP nanowires and 2D ZIS nanosheets enhances the mobility of photogenerated electrons. The synergistic chain-type "electron pickup" mechanism of the Ohm heterojunction coupled with the Zn-P bond speeds up electron transport at the interface. The Ohm heterojunction initiates an internal electric field, creating a driving force to further transfer photogenerated electrons through the Zn-P rapid electron transport channel to FeP, which acts as a reservoir for active sites to release H2. The optimized FeP/ZIS demonstrates a remarkable H2 evolution rate at 4.36 mmol h-1 g-1, 3.6 times that of pristine ZIS. This work provides novel insights into optimizing photocarrier dynamics via interfacial microenvironment modulation.

Efficient spatial separation of charge carriers over Sv-ZnIn2S4/NH2-MIL-88B(Fe) S-scheme heterojunctions for enhanced photocatalytic H2 evolution and antibiotics removal performance

The exploration of highly efficient sunlight-assisted photocatalyst for photodegradation of organic contaminants or energy conversion is strongly encouraged. In this work, we designed a novel three-dimensional spindle-like Sv-ZIS@NMFe heterojunction made of amino functionalized NH2-MIL-88B(Fe) (NMFe) and ZnIn2S4 nanosheets with abundant sulfur vacancies (Sv-ZIS). The structural properties of NMFe materials, such as a clearly defined system of pores and cavities, were retained by the Sv-ZIS@NMFe composites. Additionally, the incorporation of sulfur vacancies, -NH2 functional groups, and well-matched energy level positions led to various synergistic effects that considerably enhanced internal electron transformation and migration, as well as improved adsorption performance. Consequently, under visible light irradiation, the optimized sample exhibited superior hydrogen production activity and tetracycline hydrochloride photodegradation performance. At last, density functional theory calculations was used to further elucidated the possible photoreactivity mechanism. This study demonstrates that the Sv-ZIS@NMFe heterojunction materials formed by ZnIn2S4 with suitable sulfur vacancies and amino functionalized Fe-MOFs have promising applications in photocatalysis.

Construction of shell-core Co2P/Cd0.9Zn0.1S photocatalyst by electrostatic attraction for enhancing H2 evolution

Solar energy-driven photocatalytic decomposition of water to produce H₂ is of great significance for promoting the development of clean energy. To improve the efficiency of H₂ production, a novel spherical Co₂P/Cd_0.9Zn_0.1S (Co₂P/CZS) composite with shell-core structure was successfully synthesized by electrostatic attraction. Under visible light irradiation, the optimal Co₂P/CZS achieves an excellent H₂ rate of 16.05 mmol h^-1 g^-1 in benzyl alcohol (PhCH₂OH) solution, with a quantum efficiency of 34.3% at 450 nm. The Co₂P thin layer coated on the CZS surface not only facilitates the photogenerated charge transfer from Co₂P to CZS under visible light illumination, but reduces the energy barrier of PhCH₂OH oxidation and H₂ evolution. The present results show that shell-core Co₂P/CZS composite may be one of promising catalyst to enhance the activity of H₂ evolution, which provides an important reference basis for new catalyst design and wide prospects for further application of metal sulfides.

Novel noble-metal-free Co2P/CdIn2S4 heterojunction photocatalysts for elevated photocatalytic H2 production: Light absorption, charge separation and active site

Constructing heterojunctions is an effective and controllable approach that can boost the activity of photocatalysts. Inspiringly, this study explored a simple method that can be used to construct novel noble-metal-free Co₂P/CdIn₂S₄ (CPCIS) heterojunction photocatalysts for photocatalytic hydrogen production. The heterojunction was formed by loading CdIn₂S₄ (CIS) nanoparticles on the surface of Co₂P (CP). The structure, morphology, and optical property of the as-prepared samples were characterized by a series of tests. The DRS results showed that, the light absorption range of CPCIS was extended to the full visible light range and its light absorption intensity obviously was enhanced at 500-800 nm. The PL and photoelectrochemical tests manifested that the formed heterojunction promoted the separation of charges. The LSV results indicated that CP reduced the H₂ evolution overpotential of the composites. Besides, CP could serve as active sites of H₂ evolution in heterojunction composites. Interestingly, the H₂-evolution rate for the optimum CPCIS (471.87 μmol h^-1 g^-1) was around 3.6 times than CIS-Pt. The elevated activity of CPCIS may mainly attribute to the following aspects: its enhanced light absorption, elevated charge separation and increased active site. More importantly, the photocatalytic activity of heterojunction composites didn't almost decrease after three cycles. This article delivers an idea that can be applied to form heterojunctions between CP and other sulfides for photocatalytic H₂ production, easily extending to other transition metal phosphides.

Construction of ZnIn2 S4 /CdS/PdS S-Scheme Heterostructure for Efficient Photocatalytic H2 Production

It is facing a tremendous challenge to develop the desirable hybrids for photocatalytic H₂ generation by integrating the advantages of a single semiconductor. Herein, an all-sulfide ZnIn₂ S₄ /CdS/PdS heterojunction is constructed for the first time, where CdS and PdS nanoparticles anchor in the spaces of ZnIn₂ S₄ micro-flowers due to the confinement effects. The morphology engineering can guarantee rapid charge transfer owing to the short carrier migration distances and the luxuriant reactive sites provided by ZnIn₂ S₄ . The S-scheme mechanism between ZnIn₂ S₄ and CdS assisted by PdS cocatalyst is testified by in situ irradiated X-ray photoelectron spectroscopy and electron paramagnetic resonance (EPR), where the electrons and holes move in reverse driven by work function difference and built-in electric field at the interfaces. The optimal ZnIn₂ S₄ /CdS/PdS performs a glaring photocatalytic activity of 191.9 µmol h^-1 (10 mg of catalyst), and the largest AQE (apparent quantum efficiency) can reach a high value of 26.26%. This work may afford progressive tactics to design multifunctional photocatalysts.

Decorating Zn0.5Cd0.5S with C,N Co-Doped CoP: An Efficient Dual-Functional Photocatalyst for H2 Evolution and 2,5-Diformylfuran Oxidation

Photocatalytic H₂ evolution and biomass-derived alcohol oxidation is a cooperative way for improving the utilization of photogenerated charge carriers. Herein, a highly efficient photocatalyst was fabricated by decorating Zn_0.5Cd_0.5S with a C,N codoped CoP polyhedron (referred to as CoP, derived from ZIF-67), and then it was used for H₂ evolution and 5-hydroxymethylfurfural (HMF) oxidation. For the optimized sample (20% CoP/Zn_0.5Cd_0.5S), the generated H₂ rate is significantly enhanced from that of the HMF aqueous solution with 2,5-diformylfuran (DFF) as a concomitant product, about 31.7 times higher than the pristine Zn_0.5Cd_0.5S under visible light irradiation. The separation of photoexcited electrons (e^-) and holes (h⁺) in the process was promoted, as both e^- and h⁺ were involved in the desired conversions. From the results of density functional theory (DFT) calculations and in situ XPS spectra, the utilization of e^- was further improved as a spontaneous transfer from Zn_0.5Cd_0.5S to CoP occurred due to the p-n heterojunction formed between Zn_0.5Cd_0.5S (n type) and CoP (p type). This work provides an efficient method to separate the photoinduced charge carriers and a new way for H₂ evolution accompanied by transformation of HMF to DFF.

Morphology engineering and photothermal effect derived from perylene diimide based derivative for boosting photocatalytic hydrogen evolution of ZnIn2S4

The construction of excellent photocatalysts for splitting water into hydrogen is highly desirable to realize carbon neutralization. In this work, an innovative and well-designed S-scheme photocatalyst composed of ultrathin ZnIn₂S₄ (ZIS) nanosheets uniformly anchored on the surface of organic semiconductor PDIIM is successfully fabricated. Within the heterojunction, perylene diimide with an imidazole group (PDIIM) is strategically applied as a structure template, which plays a crucial role in optimizing the morphology, increasing the active sites of sulfur vacancies, providing the additional photothermal effect, and promoting photogenerated charge separation of the catalyst. The photocatalytic H₂ generation rate of the ZIS/PDIIM heterojunction with an optimized mass ratio reaches up to 13.04 mmol/g/h, which is 2.64 times and 14.02 times higher than that of pristine ZIS and PDIIM, respectively. The outstanding photocatalytic activity is attributed to the synergistic effect of the above advantages. Importantly, the photothermal effect induced by PDIIM belonging to the perylene diimide-based derivative was discovered to accelerate photocatalytic H₂ generation for the first time. This work provides valuable insight into the utilization of perylene diimide-based derivatives in the construction of multi-effect enhancement photocatalysts and their application in photothermal-assisted photocatalytic hydrogen evolution.

Hexamethylenetetramine induced multidimensional defects in Co2P nanosheets for efficient alkaline hydrogen evolution

Crystal engineering is an important way to improve the catalytic performance of transition-metal phosphides. In this work, we propose a strategy for constructing multi-dimensional defects induced by hexamethylenetetramine, which effectively introduces grain boundaries, N doping and P vacancies into Co₂P nanosheets, and improves the activity and stability of the catalyst. Due to the synergistic effect of the multi-dimensional defects, the Co₂P nanosheets exhibit excellent HER catalytic performance, especially at a large current density of 100 mA cm^-2 with an overpotential of only 159 mV. Under 1 M KOH electrolyte and current density of 10 mA cm^-2, the long-term test for 36 h shows that the catalyst maintains a very high stability.

Spatial carrier separation in cobalt phosphate deposited ZnIn2S4 nanosheets for efficient photocatalytic hydrogen evolution

Developing photocatalyst with effective charge separation and fast surface reaction kinetics is crucial to high-efficiency photocatalytic H₂ evolution. Herein we spatially separate the reductive and oxidative reaction sites of ZnIn₂S₄ nanosheet and accelerate the hole transfer process by simply depositing cobalt phosphate (CoH_xPO_y, noted as Co-Pi), a non-precious co-catalyst, on its basal plane. Theoretical calculations combined with comprehensive characterizations reveal that Zn vacancies induced deep local energy levels serve as hole trap states to pin the photogenerated holes on (001) surface of ZnIn₂S₄. Upon Co-Pi deposition, Co atoms preferentially bond with S atoms nearby the Zn vacancies of ZnIn₂S₄. Taking advantage of the formation of Co-S bonds, Co-Pi acts as a hole receptor to extract the trapped holes effectively. As the photocatalytic activity of ZnIn₂S₄ is caused by active S atoms on its edge side, deposition of Co-Pi on planar side of nanosheets helps electron-hole migration to different facets. As a result of inert facet activation and spatial carrier separation, Co-Pi/ZnIn₂S₄ exhibits a superior photocatalytic H₂ evolution rate of 10.19 mmol g^-1h^-1 under visible light, which is superior to most of reported ZnIn₂S₄-based photocatalysts. This work will provide novel insights into the activation of inert basal planes of two-dimensional photocatalysts.

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.

g-C3N4 Sensitized by an Indoline Dye for Photocatalytic H2 Evolution

Protonated g-C3N4 (pCN) formed by treating bulk g-C3N4 with an aqueous HCl solution was modified with D149 dye, i.e., 5-[[4[4-(2,2-diphenylethenyl) phenyl]-1,2,3,3a,4,8b-hexahydrocyclopent[b]indol-7-yl] methylene]-2-(3-ethyl-4-oxo-2-thioxo-5-thiazolidinylidene)-4-oxo-thiazolidin-2-ylidenerhodanine, for photocatalytic water splitting (using Pt as a co-catalyst). The D149/pCN-Pt composite showed a much higher rate (2138.2 µmol·h−1·g−1) of H2 production than pCN-Pt (657.0 µmol·h−1·g−1). Through relevant characterization, the significantly high activity of D149/pCN-Pt was linked to improved absorption of visible light, accelerated electron transfer, and more efficient separation of charge carriers. The presence of both D149 and Pt was found to be important for these factors. A mechanism was proposed.