Rationally Designed 2D CZIS/2D Ti3CNTx Heterojunctions for Photocatalytic Hydrogen Evolution Reaction

Highly efficient photocatalysts for solar energy conversion require effective charge carrier separation and rapid interfacial transport kinetics to maximize electron availability. Two-dimensional Ti3CNTx, a novel conductive material in the MXene family with exceptional electrical conductivity, has emerged as an ideal electron transfer mediator due to its large specific surface area and abundant active terminal groups. In this work, we strategically integrated the 2D multi-metal sulfide Cu-Zn-In-S (CZIS) with 2D Ti3CNTx nanosheets through physical mixture, constructing a heterostructured 2D/2D CZIS/Ti3CNTx composite photocatalyst for the hydrogen evolution reaction. The unique architecture significantly accelerates electron migration from CZIS to Ti3CNTx, while synergistically promoting the spatial separation and directional transfer of photogenerated electron–hole pairs (e−/h+). When the hydrogen evolution reaction is carried out under identical conditions, the hydrogen yield rate is 4.3 mmol g−1 h−1 with pristine CZIS but is improved dramatically to 14.3 mmol g−1 h−1 when the composite containing an adequate amount of 2D Ti3CNTx is used. This study offers new insight into the rational design and controllable synthesis of Ti3CNTx-based composite photocatalytic systems for efficient photocatalytic hydrogen production.