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

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–TiO 2 photocatalyst from Ti 3 C 2 MXene , air, CO 2 , and HAuCl 4 , in which the carbon layer bridged Au and TiO 2 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 TiO 2 and Au through carbon layer, desirably inhibiting the recombination of photogenerated charge carriers. The hydrogen production rate of the formed three-component Au/C–TiO 2 (CTA) photocatalyst was demonstrated to be 27 times higher than that of Au–TiO 2 , which also surpassed many reported Ti 3 C 2 MXene-derived carbon–TiO 2 photocatalysts. This work sheds light on the ingenious use of 2D MXene to form a well-behaved TiO 2 -based photocatalytic system and helps to propose future design principles in accelerating charge transfer.