Boosting Charge Separation in a CdIn 2 S 4 /Mo 2 TiC 2 MXene Schottky Heterojunction for Enhanced Photocatalytic Hydrogen Production

Mo2TiC2 MXene was exfoliated in situ using hydrofluoric acid solution and subsequently integrated with CdIn2S4 through physical stirring and grinding. The composite material demonstrated exceptional photocatalytic hydrogen evolution (PHE) activity without the loading of any noble metal co-catalysts, achieving a hydrogen production rate as high as 3.35 mmol·h−1 g−1. This represents a 55.83-fold enhancement compared to pristine CdIn2S4 and surpasses the performance of most reported CdIn2S4-based photocatalytic materials. Furthermore, the composite material maintained consistent hydrogen evolution performance throughout four consecutive cycling tests, demonstrating excellent cycling durability. Through systematic experimental analysis and theoretical simulations, it was confirmed that a Schottky heterojunction forms between CdIn2S4 and Mo2TiC2 MXene. In this composite system, CdIn2S4 primarily serves as the light-absorbing component, whereas Mo2TiC2 MXene functions as an efficient co-catalyst. The formation of the Schottky junction drives the directional migration of photogenerated electrons from CdIn2S4 to Mo2TiC2 MXene. The resulting interfacial potential barrier significantly suppresses electron backflow, whereas the inherent high electrical conductivity of Mo2TiC2 MXene and its abundant exposed active sites further accelerate the hydrogen evolution process. This study demonstrates the significant potential of Mo2TiC2 MXene as a novel co-catalyst for photocatalysis oriented toward renewable energy.