Modulation of Hot Electrons via Interface Engineering of Au@ZnIn2S4/MXene for Efficient Photoelectrochemical Seawater Splitting under Visible Light

Interface engineering in hybrid plasmonic metal/semiconductor heterostructures is an efficient approach to enhance the catalytic performance of photocatalysts and photoelectrochemical cells in harvesting and converting sunlight, especially in the range of visible light. Plasmon-induced hot electron injection plays a crucial role in the transfer of plasmonic energy from a plasmonic metal to semiconductor in a plasmonic metal/semiconductor system. Herein, the efficient injection and utilization of hot electrons are achieved by fabrication of a Au@ZnIn2S4/Ti3C2 (Au@ZIS/Ti3C2) system, in which the core–shell Au@ZIS nanoparticles with well-defined interfaces are anchored on the 2D Ti3C2 surface. The core–shell Au@ZIS nanostructure is first constructed by a cation exchange reaction method. The well-defined interface of the Au core and ZIS shell optimizes the electron transfer pathway and greatly promotes the extraction of hot electrons from Au to ZIS. Furthermore, the electrons concentrated on ZIS can be further transferred to Ti3C2 owing to its excellent electron mobility and conductivity, leading to highly efficient separation and transfer of electrons through a two-step transfer process. The activities of photoelectrochemical (PEC) seawater splitting demonstrate that the integration of Au and ZIS into an optimized core–shell structure and its further modification by Ti3C2 results in a drastic improvement in PEC activity. Therefore, Au@ZIS/Ti3C2 shows the highest photocurrent density and smallest charge transfer resistance among various samples, accompanied by 6.5 and 10.8 orders of enhancement in PEC H2 evolution compared to reference samples of ZIS/Ti3C2 and Au/Ti3C2. Elaborate design and construction of core–shell plasmonic metal@semiconductor nanostructure with a well-defined interface and 2D MXene support would provide a feasible and promising method to enhance the performance of PEC seawater splitting.