The Mott–Schottky heterojunction MoC@NG@ZIS with enhanced kinetic response for promoting photocatalytic hydrogen production

Abstract

The Mott–Schottky heterojunction MoC@NG@ZIS exhibits an excellent photocatalytic hydrogen evolution performance of 32.96 mmol g ⁻¹ h ⁻¹ with great stability. The enhanced charge and reaction kinetics explain the remarkable photocatalytic activity.

Abstract

Mott–Schottky heterojunctions have been widely used to enhance photocatalytic activity by improving the separation and transfer of photogenerated charges. However, an in-depth exploration of design concepts and photocatalytic mechanisms of Mott–Schottky heterojunctions is still lacking. In this work, we have constructed the two-dimensional (2D) ultrathin Mott–Schottky heterojunction MoC@NG@ZIS by combining the photon capturer ZnIn ₂S ₄ (ZIS) with electrocatalyst MoC@NG (nitrogen-doped graphene loaded with MoC quantum dots). The addition of MoC@NG not only boosts the reaction kinetics but also provides abundant and high-activity reactive sites for hydrogen production. Meanwhile, the 2D ultrathin structure and plentiful interfaces of Mott–Schottky heterojunction MoC@NG@ZIS facilitate mass transfer and provide numerous channels for charge transport. Spectroscopic and electrochemical analyses reveal that MoC@NG@ZIS has extended light absorption and enhanced photoelectric response. Furthermore, due to the presence of a Schottky barrier, efficient charge separation is realized through the unidirectional pathway of charge transfer. Therefore, the optimized photocatalyst MoC@NG-15@ZIS exhibits a great hydrogen evolution performance of 32.96 mmol g ⁻¹ h ⁻¹ with excellent photochemical stability, which is higher than those of most reported ZIS-based photocatalysts. This study provides constructive insights into the design of efficient Mott–Schottky heterojunctions and reveals the mechanism of performance enhancement.