Strong electronic coupling of Mo2TiC2 MXene/ZnCdS ohmic junction for boosting photocatalytic hydrogen evolution

Effective electron coupling is an effective method to enhance hydrogen evolution dynamics. Herein, a Mo2TiC2 MXene/ZnCdS ohmic junction was constructed for boosting photocatalytic hydrogen evolution. The terminal groups on the surface of Mo2TiC2 MXene provide abundant active sites and adsorption sites for the catalyst. The 2D/0D structure of Mo2TiC2/ZnCdS forms a tight interfacial contact, providing the shortest transport distance for electron transfer. At the same time, the 2D structure Mo2TiC2 MXene prevents the aggregation of ZnCdS, causing it to expose more active sites. The results of DFT calculation and XPS show that there is an obvious strong electron coupling interface between Mo2TiC2 MXene and ZnCdS, which increases the local electron density of Mo2TiC2 MXene and inhibits electron backflow. The increase of the d-band center reduced the filling of anti-bonding states and increase the bonding strength of H2, promote the separation efficiency of photogenerated electrons and enhance the ability of photocatalytic hydrogen evolution. Therefore, 25 %Mo2TiC2/ZnCdS showed the best photocatalytic hydrogen evolution activity (17.73 mmol g−1 h−1), which was 3.15 times that of ZnCdS (5.62 mmol g−1 h−1). And AQE can reach 16.22 % at 475 nm. This work provides some insights for constructing ohmic junction based on MXene material to adjust the local electronic structure of catalyst for photocatalytic hydrogen evolution.