Z-Scheme Modulated Charge Transfer on InVO4 @ZnIn2 S4 for Durable Overall Water Splitting

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.

Advances in the heterostructures for enhanced hydrogen production efficiency: a comprehensive review

The growing global energy demand and heightened environmental consciousness have contributed to the increasing interest in green energy sources, including hydrogen production. However, the efficacy of this technology is contingent upon the efficient separation of charges, high absorption of sunlight, rapid charge transfer rate, abundant active sites and resistance to photodegradation. The utilization of photocatalytic heterostructures coupling two materials has proved to be effective in tackling the aforementioned challenges and delivering exceptional performance in the production of hydrogen. The present article provides a comprehensive overview of operational principles of photocatalysis and the combination of photocatalytic and piezo-catalytic applications with heterostructures, including the transfer behavior and mechanisms of photoexcited non-equilibrium carriers between the materials. Furthermore, the effects of recent advances and state-of-the-art designs of heterostructures on hydrogen production are discussed, offering practical approaches to form heterostructures for efficient hydrogen production.

Incorporating ReS2 Nanosheet into ZnIn2S4 Nanoflower as Synergistic Z-Scheme Photocatalyst for Highly Effective and Stable Visible-Light-Driven Photocatalytic Hydrogen Evolution and Degradation

Inspired by natural photosynthesis, the visible-light-driven Z-scheme system is very effective and promising for boosting photocatalytic hydrogen production and pollutant degradation. Here, a synergistic Z-scheme photocatalyst is constructed by coupling ReS2 nanosheet and ZnIn2S4 nanoflower and the experimental evidence for this direct Z-scheme heterostructure is provided by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance. Consequently, such a unique nanostructure makes this Z-scheme heterostructure exhibit 23.7 times higher photocatalytic hydrogen production than that of ZnIn2S4 nanoflower. Moreover, the ZnIn2S4/ReS2 photocatalyst is also very stable for photocatalytic hydrogen evolution, almost without activity decay even storing for two weeks. Besides, this Z-scheme heterostructure also exhibits superior photocatalytic degradation rates of methylene blue (1.7 × 10-2 min-1) and mitoxantrone (4.2 × 10-3 min-1) than that of ZnIn2S4 photocatalyst. The ultraviolet-visible absorption spectra, transient photocurrent spectra, open-circuit potential measurement, and electrochemical impedance spectroscopy reveal that the superior photocatalytic performance of ZnIn2S4/ReS2 heterostructure is mostly attributed to its broad and strong visible-light absorption, effective separation of charge carrier, and improved redox ability. This work provides a promising nanostructure design of a visible-light-driven Z-scheme heterostructure to simultaneously promote photocatalytic reduction and oxidation activity.

InVO4-Decorated Ti3C2 MXene for Efficient Photocatalytic Hydrogen Evolution

The generation of hydrogen through photocatalysis is a fascinating technology for addressing environmental concerns and the energy crisis. Nevertheless, the quest for cost-effective, stable, and efficient photocatalysts in the realm of energy conversion remains a significant challenge. Herein, we designed novel InVO4/Ti3C2 MXene (IVTC) heterostructures by employing acid etching to produce Ti3C2 MXene with an accordion-like morphology, using the hydrothermal technique for the production of orthorhombic InVO4 nanoparticles (NPs), and integrating them through a self-assembly approach. Both field-emission scanning electron microscopy and HRTEM analyses revealed a consistent distribution of InVO4 NPs with an average size of 43.4 nm on both surfaces and between the sheets of Ti3C2 MXene. The intimate interface between the Ti3C2 MXene nanosheet and InVO4 suppressed carrier recombination and promoted charge transfer, thereby boosting photocatalytic H2 production. Under visible light exposure, the rate of hydrogen evolution is enhanced in IVTC heterostructures containing an optimized 10% loading of InVO4, exhibiting over a 3-fold increase compared to pristine InVO4 NPs, maintaining efficiency across four cycles. This research presents a promising method for designing and creating high-efficiency heterostructures possessing excellent visible-light-driven photocatalytic activity for H2 evolution.

Plasmonic coupling-boosted photothermal composite photocatalyst for achieving near-infrared photocatalytic hydrogen production

The development of photocatalysts that effectively utilize low-energy photons for efficient photocatalysis still faces a number of challenges. Herein, an efficient NIR-driven system based on WO3-x/ZnIn2S4 (WO3-x/ZIS) prepared by a simple low-temperature water-bath method, and the optimal WO3-x/ZIS-3 composites can reach a hydrogen-production efficiency of 14.05 μmol g-1h-1 under NIR light irradiation. The localized surface plasmon (LSPR) resonance effect in WO3-x quantum dots (QDs) not only broadens the ZIS photo-response range, but also the photothermal effect of WO3-x can increase the local reaction temperature of WO3-x/ZIS composite system, thus enhancing the photothermal-assisted photocatalytic activity. In addition, density functional theory (DFT) calculations show that the difference in work function between WO3-x and ZIS can lead to the formation of interfacial electric field (IEF), which not only promotes the separation and migration efficiency of photogenerated carriers, but also facilitates the photocatalytic water splitting for hydrogen production. This study provides possible directions for the construction of NIR-driven photothermal-assisted photocatalytic hydrogen production system.

Metallic 1T phase molybdenum disulfide cocatalyst with abundant edge and substrate active sites for enhanced photocatalytic hydrogen production activity of zinc indium sulfide nanoflowers

The formation of composites by loading co-catalysts on semiconductor photocatalysts to improve hydrogen (H2) evolution performance is a feasible strategy. Metallic 1T phase molybdenum disulfide (MoS2) as cocatalysts were decorated on zinc indium sulfide (ZnIn2S4) nanoflowers by a grinding method to construct 1T-MoS2@ZnIn2S4 composites. The H2 production rate of 1T-MoS2@ZnIn2S4 composites with optimum 7 wt% 1T-MoS2 loading achieves 15.6 mmol g-1 h-1, 5.5 times higher than ZnIn2S4 nanoflowers. The apparent quantum efficiency (AQY) increases from 3.1 % (ZnIn2S4 nanoflowers) to 13.0 % (1T-MoS2@ZnIn2S4 composites) under the wavelength light irradiation at λ = 370 nm. The loading of metallic 1T-MoS2 with abundant edge and substrate active sites on ZnIn2S4 can enhance visible light absorption, promote the transfer of electrons, and inhibit carrier recombination, thereby improving photocatalytic performance. This work offers inspiration for the design of composite photocatalysts with efficient photocatalytic capabilities.

Principle of CoS2/ZnIn2S4 heterostructure effect and its mechanism of action in a visible light-catalyzed antibacterial process

The development of visible-light-driven catalytic antimicrobial technology is a significant challenge. In this study, heterojunctions were constructed for the appropriate modification of semiconductor-based photocatalysts. A simple hydrothermal method was used for material reconstruction, and smaller CoS2 nanoparticles were deposited and in situ grown on two-dimensional nanoflower-like ZnIn2S4 carriers to form CoS2/ZnIn2S4 (CS/ZIS) Schottky heterojunctions. Systematic study via characterization techniques and density functional theory calculations indicated that the excellent photocatalytic activity of CS/ZIS stemmed from the solid interfacial coupling between the two solid-phase materials. These materials acted as co-catalysts to increase the number of active reaction sites, enhance charge transfer, drive unidirectional electron movement, and improve charge separation efficiency, which effectively facilitated the production of reactive oxygen species (ROS). The optimized CS/ZIS heterojunction exhibited excellent performance for the efficient photocatalytic degradation of organic matter and inactivation of Escherichia coli (E. coli) compared with the ZnIn2S4 photocatalyst. Moreover, the antibacterial mechanism of the heterojunction photocatalyst and the extent of damage to the cell membrane and internal cytoplasm were explored by performing various assays. It was demonstrated that superoxide radicals are the predominant active species and multiple ROS act together to cause oxidative stress damage and cell inactivation.

Facile Synthesis of P-Doped ZnIn2S4 with Enhanced Visible-Light-Driven Photocatalytic Hydrogen Production

ZnIn₂S₄ (ZIS) is widely used in the field of photocatalytic hydrogen production due to its unique photoelectric properties. Nonetheless, the photocatalytic performance of ZIS usually faces problems of poor conductivity and rapid recombination of charge carriers. Heteroatom doping is often regarded as one of the effective strategies for improving the catalytic activity of photocatalysts. Herein, phosphorus (P)-doped ZIS was prepared by hydrothermal method, whose photocatalytic hydrogen production performance and energy band structure were fully studied. The band gap of P-doped ZIS is about 2.51 eV, which is slightly smaller than that of pure ZIS. Moreover, due to the upward shift of its energy band, the reduction ability of P-doped ZIS is enhanced, and P-doped ZIS also exhibits stronger catalytic activity than pure ZIS. The optimized P-doped ZIS exhibits a hydrogen production rate of 1566.6 μmol g^-1 h^-1, which is 3.8 times that of the pristine ZIS (411.1 μmol g^-1 h^-1). This work provides a broad platform for the design and synthesis of phosphorus-doped sulfide-based photocatalysts for hydrogen evolution.