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.

Key words: Photocatalytic hydrogen production, Ti₃C₂ MXene, Carbon layer, TiO₂, Ohmic junction