Ti3C2 Mxene/porous g-C3N4 interfacial Schottky junction for boosting spatial charge separation in photocatalytic H2O2 production

The development of efficient photocatalysts for the production of hydrogen peroxide (H2O2) is a promising strategy to realize solar-to-chemical energy conversion. Graphitic carbon nitride (g-C3N4) presents giant potential for photocatalytic H2O2 production, but the sluggish charge separation depresses its photocatalytic performance. Herein, an interfacial Schottky junction composed of Ti3C2 nanosheets and porous g-C3N4 nanosheets (TC/pCN) is constructed by a facile electrostatic self-assembly route to significantly boost the spatial charge separation to promote the activation of molecular oxygen for H2O2 production. As the optimal sample, TC/pCN-2 possesses the highest H2O2 production rate (2.20 mu mol L-1 min(-1)) under visible light irradiation (lambda > 420 nm), which is about 2.1 times than that of the porous g-C3N4. The results of superoxide radical detection and rotating disk electrode measurement suggest that the two-step single-electron reduction of oxygen is the predominant reaction step during this photocatalytic H2O2 production process. The enhanced photocatalytic performance is ascribed to the formation of Schottky junction and subsequent built-in electric field at their interface, which accelerate the spatial charge separation and restrain the charge recombination. This work provides an in-depth understanding of the mechanism of photocatalytic H2O2 production, and gives ideas for the design of highly active materials for photocatalytic H2O2 production.