Interfacial Engineering of 2D–2D CdIn 2 S 4 /Ti 3 C 2 Heterojunctions for Enhanced Photocatalytic Hydrogen Generation

Abstract Utilization of solar energy through wireless water‐splitting technology offers a promising pathway toward a sustainable and environmentally conscious future. The rational design of 2D–2D heterojunctions leverages synergistic effects to optimize charge carrier dynamics, thereby boosting photocatalytic activity. In this study, well‐engineered heterojunction Ti 3 C 2 /CdIn 2 S 4 (TCIS) nanocomposites are synthesized via an in situ hydrothermal method and employed in photocatalytic hydrogen evolution (PHE). The hydrogen evolution rate of 9.799 mmol g −1 h −1 surpasses previously reported MXene‐based materials, and is 26 times higher than pristine CdIn 2 S 4 , with an AQE of 6.4% under 420 nm light irradiation. Optimizing the electronic structure of active metal sites enhances rapid electron transport and synergistic proton reduction. With insights from DFT and KPFM studies, an efficient charge transfer pathway, with electron accumulation on Ti 3 C 2 and depletion on CdIn 2 S 4 are revealed. This study highlights the critical role of interfacial engineering in MXenes for accelerating water dissociation and presents a promising strategy for the development of high‐performance materials for future energy applications.