Highly Carbon-Doped TiO₂ Derived from MXene Boosting the Photocatalytic Hydrogen Evolution

The effective in situ carbon doping of titanium dioxide can greatly improve the lifetime of photogenerated carriers and widen the absorption range of light for photocatalytic reactions. Here, highly carbon-doped TiO2 (HC-TiO2) with a hierarchical structure and good crystallization was synthesized by using the exfoliated MXene supernatant at low temperature. The resultant HC-TiO2 was fully characterized, and its catalytic performance for photocatalytic hydrogen evolution was investigated. It was found that the high-content carbon doping induced a valence band tail state that promoted photogenerated carriers’ effective separation and reduced bandgap, which greatly improved the utilization of light for photocatalytic reactions. This band tail was attributed to the strong electron withdrawing carboxylate groups from in situ carbon doping. The photocatalytic hydrogen production rate of the hierarchical HC-TiO2 was 9.7 times that of the commercial P25 without cocatalyst under simulated sunlight. This work enriched the synthesis method of C-doped TiO2 and the application of MXene based materials.