Evidencing Interfacial Charge Transfer in 2D CdS/2D MXene Schottky Heterojunctions toward High-Efficiency Photocatalytic Hydrogen Production

Photocatalytic water splitting by heterojunction nanostructures is considered as one of the most favorable pathways for direct solar-to-hydrogen conversion. High-efficiency solar hydrogen production demands an effective separation of charge carriers and their rapid transport to the interface, whereas the charge-transfer pathway in heterojunction photocatalysts is largely elusive. Herein, 2D CdS/2D MXene Schottky heterojunctions are synthesized via a sequence of electrostatic self-assembly process and solvothermal method. The composite photocatalysts exhibit highly efficient and robust hydrogen-evolving performance, far superior than the pristine CdS nanosheets. Furthermore, density functional theory (DFT) calculations are adopted to unveil the charge-transport pathway. It is revealed that an intimate Schottky contact is constructed between CdS and MXene, which further steers the formation of charge flow and expedites the charge migration from CdS to MXene, thus suppressing the recombination of photogenerated charge carriers and boosting the photocatalytic activity for hydrogen evolution.