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

ABSTRACT Mo 2 TiC 2 MXene was exfoliated in situ using hydrofluoric acid solution and subsequently integrated with CdIn 2 S 4 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 CdIn 2 S 4 and surpasses the performance of most reported CdIn 2 S 4 ‐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 CdIn 2 S 4 and Mo 2 TiC 2 MXene. In this composite system, CdIn 2 S 4 primarily serves as the light‐absorbing component, whereas Mo 2 TiC 2 MXene functions as an efficient co‐catalyst. The formation of the Schottky junction drives the directional migration of photogenerated electrons from CdIn 2 S 4 to Mo 2 TiC 2 MXene. The resulting interfacial potential barrier significantly suppresses electron backflow, whereas the inherent high electrical conductivity of Mo 2 TiC 2 MXene and its abundant exposed active sites further accelerate the hydrogen evolution process. This study demonstrates the significant potential of Mo 2 TiC 2 MXene as a novel co‐catalyst for photocatalysis oriented toward renewable energy.