S-scheme photocatalysts have demonstrated great potential in solar fuel production. To study the electron transfer pathways in S-scheme heterojunctions, in situ irradiated X-ray photoelectron spectroscopy (ISIXPS) is an effective and widely used technology. However, the mechanism of ISIXPS in identifying the electron transfer pathways in S-scheme heterojunction has not yet been elucidated. In this Perspective, the development process and the formation mechanism of S-scheme photocatalysts are first introduced. Afterward, the principles of XPS and ISIXPS measurements are thoroughly explained, and the applications of XPS and ISIXPS in confirming the interfacial electron transfer in S-scheme heterojunctions are discussed. Finally, suggestions for future research on the utilization of ISIXPS in S-scheme heterojunctions are proposed. This Perspective will provide deep insight into the electron transfer mechanism in S-scheme photocatalysts through ISIXPS.

In Situ Irradiated X-ray Photoelectron Spectroscopy Investigation on Electron Transfer Mechanism in S-Scheme Photocatalyst.

ZnIn2S4-based photocatalysts for photocatalytic hydrogen evolution via water splitting

An ultra-thin piezoelectric nanogenerator with breathable, superhydrophobic, and antibacterial properties for human motion monitoring

Solvent-assisted self-assembly to fabricate a ternary flexible free-standing polyaniline@MXene-CNTs electrode for high-performance supercapacitors

Photocatalytic hydrogen production using semiconductor photocatalysts provides a promising strategy for solving the energy crisis. Metal sulfide photocatalysts have received extensive attention due to its visible‐light response, adjustable band structures, and relatively mild preparation conditions. In this review, the emerging strategies to improve photocatalytic performance and stability of metal sulfides are summarized, including engineering of heterojunction, defect engineering, loading single‐atom cocatalyst, photothermal effect, loading dual cocatalysts, and coating stable shell. Special attention is paid to the influence mechanism of latest strategies on the photocatalytic process, with a focus on charge transfer, separation, and participation in surface chemical reaction behavior. Finally, with the goal of promoting the rapid progress of metal sulfides for solar hydrogen production, the key challenges of the latest research frontiers and the prospects on future development of metal sulfides are discussed.

Metal Sulfides for Photocatalytic Hydrogen Production: Current Development and Future Challenges

Efficient solar‐to‐hydrogen (STH) conversion through water splitting relies on the development of low‐cost photocatalysts with high photoactivity and stability. ZnxCd1−xS, an emerging metal sulfide (MS) solid solution for STH, possesses several unique advantages, such as a tunable bandgap, abundant elemental constituents, and high stability. Although ZnxCd1−xS‐based photocatalysts are investigated for hydrogen evolution, their photoactivity still has to be enhanced for commercial applications. Herein, the design concept, crystal and band structure properties, and original photoactivity of ZnxCd1−xS are briefly introduced, and ZnxCd1−xS solutions with different morphologies and structures, modifications, synthesis methods, and vacancy engineering are then discussed. Subsequently, the combination of ZnxCd1−xS and cocatalysts and several representative ZnxCd1−xS‐based heterojunction photocatalysts for hydrogen evolution are reviewed and discussed in detail. Finally, the unsolved issues in the application of ZnxCd1−xS photocatalysts and their potential solutions for developing advanced ZnxCd1−xS‐based photocatalysts are discussed.

Recent Advances in the Hydrogen Evolution Reaction of ZnxCd1−xS‐Based Photocatalysts

A weldable MXene film assisted by water

Reliable coaxial wet spinning strategy to fabricate flexible MnO2-based fiber supercapacitors

High-efficiency photocatalytic hydrogen evolution (PHE) relies on the development of inexpensive, stable, and efficient photocatalysts. Cadmium sulfide (CdS), as a typical binary metal sulfide, has attracted considerable research attention due to its negative conduction band position, narrow band gap for visible-light response, and strong driving force for PHE. However, the construction of CdS-based photocatalysts and the PHE rate still require improvement for practical applications. In this review, recent advances in CdS-based photocatalysts for PHE via water splitting are systematically summarized. First, the semiconductor properties of CdS, including the crystal and band structures, are briefly introduced. Afterward, the fundamental mechanisms of PHE using semiconductor photocatalysts via water splitting are discussed. Subsequently, the photoactivity of bare CdS with different morphologies and structures, CdS with cocatalyst loading, and CdS-based heterojunction photocatalysts are reviewed and discussed in detail. Finally, the challenges and prospects for exploring advanced CdS-based photocatalysts are provided. 

Recent Advances in Cadmium Sulfide-Based Photocatalysts for Photocatalytic Hydrogen Evolution

Stimulus-responsive MXene films demonstrate extensive application scenarios, such as artificial muscles and biomedical devices. However, the shape deformation of such materials entails continuous stimulation, thus limiting their implementation in specific fields when temporary shapes have to be maintained without external stimuli. This work fabricates a kind of shape-programmable MXene-based supermolecular nanocomposite film by integrating MXene and polyvinyl alcohol. In this film, MXene provides extra intermolecular hydrogen bond interaction between polyvinyl alcohol and acts as cross-linking points in the nanocomposite, thus endowing this film with a good shape-fixing property. Furthermore, with the osmotic plasticization of water on the polyvinyl alcohol chains, the as-prepared nanocomposite film demonstrates excellent water-responsive shape-memory performance. This material cannot only overcome the inability of traditional stimulus-responsive MXene films to maintain temporary structures without continuous stimulation, but also expands potential applications in some fields including controlled release and intelligent bio-robots. 

Yuqi Yang

Papers

Recent Advances in the Hydrogen Evolution Reaction of ZnxCd1−xS‐Based Photocatalysts

A weldable MXene film assisted by water

Reliable coaxial wet spinning strategy to fabricate flexible MnO2-based fiber supercapacitors

Recent Advances in Cadmium Sulfide-Based Photocatalysts for Photocatalytic Hydrogen Evolution

A shape programmable MXene-based supermolecular nanocomposite film