In-situ generation of Au–carbon–TiO2 Ohmic junction from Ti3C2 MXene for efficient photocatalytic H2 evolution

Abstract

Photogenerated charge separation is a challenging step in semiconductor-based photosynthesis. Though numerous efforts have been devoted to developing multi-component photocatalyst heterostructures for improving charge separation efficiency, the short distance between electrons and holes-aggregated regions still leads to undesirable charge recombination. Herein, a facile and commercial in-situ synthesis method was designed to directly prepare a three-component Au–carbon–TiO2 photocatalyst from Ti3C2 MXene, air, CO2, and HAuCl4, in which the carbon layer bridged Au and TiO2 nanoparticles for stable and efficient photocatalytic hydrogen production. Kelvin probe measurements and density functional theory (DFT) calculations demonstrated that a multi-interfacial charge transmission network was successfully constructed to achieve a directional and long-distance spatial charge separation/transfer channel between TiO2 and Au through carbon layer, desirably inhibiting the recombination of photogenerated charge carriers. The hydrogen production rate of the formed three-component Au/C–TiO2 (CTA) photocatalyst was demonstrated to be 27 times higher than that of Au–TiO2, which also surpassed many reported Ti3C2 MXene-derived carbon–TiO2 photocatalysts. This work sheds light on the ingenious use of 2D MXene to form a well-behaved TiO2-based photocatalytic system and helps to propose future design principles in accelerating charge transfer.