2D/2D heterojunction of Ti3C2/g-C3N4 nanosheets for enhanced photocatalytic hydrogen evolution

Abstract

Photocatalytic hydrogen evolution from water has received enormous attention due to its ability to address a number of global environmental and energy-related issues. Here, we synthesize 2D/2D Ti₃C₂/g-C₃N₄ composites by electrostatic self-assembly technique and demonstrate their use as photocatalysts for hydrogen evolution under visible light irradiation. The optimized Ti₃C₂/g-C₃N₄ composite exhibited a 10 times higher photocatalytic hydrogen evolution performance (72.3 μmol h⁻¹ g_cat⁻¹) than that of pristine g-C₃N₄ (7.1 μmol h⁻¹ g_cat⁻¹). Such enhanced photocatalytic performance was due to the formation of 2D/2D heterojunctions in the Ti₃C₂/g-C₃N₄ composites. The intimate contact between the monolayer Ti₃C₂ and g-C₃N₄ nanosheets promotes the separation of photogenerated charge carriers at the Ti₃C₂/g-C₃N₄ interface. Furthermore, the ultrahigh conductivity of Ti₃C₂ and the Schottky junction formed between g-C₃N₄/MXene interfaces facilitate the photoinduced electron transfer and suppress the recombination with photogenerated holes. This work demonstrates that the 2D/2D Ti₃C₂/g-C₃N₄ composites are promising photocatalysts thanks to the ultrathin MXenes as efficient co-catalysts for photocatalytic hydrogen production.