TiO2–@C/MoO2 Schottky junction: Rational design and efficient charge separation for promoted photocatalytic performance

Limited solar light harvesting, sluggish charge transfer kinetics, and inferior affinity for adsorbed hydrogen species (H*) severely restrict the photocatalytic hydrogen generation activity of TiO2 photocatalysts. Herein, we present a novel TiO2–x@C/MoO2 Schottky junction prepared via a simple one-step in situ phase-transition-regulation strategy. Crucially, the abundant oxygen vacancies in TiO2–x@C/MoO2 narrow the bandgap and introduce defects to improve the photoresponse. The strongly bonded carbon layer not only serves as a fast charge-transport channel to improve the interlayer charge transfer efficiency but also protects oxygen vacancies from oxidation. Moreover, the Schottky barrier effectively impairs the recombination of electrons and holes and promotes the utilization of photogenerated electrons. Furthermore, the MoO2 cocatalyst optimizes the Gibbs free energy for H2 evolution. As a result of the favorable synergy, the resulting TiO2–x@C/MoO2 presents a significantly enhanced photocatalytic H2 production rate of 506 μmol g−1 h−1 compared to those of TiO2–x and TiO2–x@C (125.5- and 15.8-times larger, respectively). Moreover, outstanding stability over 27 h was achieved because of the protection provided by the surface carbon layer. This ingenious design and facile synthetic strategy offer exciting avenues for the design of strongly coupled Schottky junction photocatalysts for efficient solar-to-chemical conversions.