Ru Single-Atom Decorated Black TiO2 Nanosheets for Efficient Solar-Driven Hydrogen Production

Solar-driven hydrogen production is an ideal way to fundamentally solve energy and environmental issues to some extent. TiO2 as a class of promising photocatalysts has attracted intensive attention. However, low light utilization and serious recombination of photo-induced charge carriers lead to a low efficiency. Herein, black TiO2 (B–TiO2) nanosheets have been first synthesized by H2/Ar plasma treatment, onto which Ru single atoms are anchored by dipping RuCl3 solution. X-ray absorption fine spectra reveal that the Ru–O coordination number is ∼5 from the scattering between the Ru center and O atoms of B–TiO2, demonstrating the strong interplay between Ru atoms with TiO2. Density functional theory (DFT) simulations and photoelectrochemical tests clarify that the introduction of Ru single-atoms produces impurity levels, which serves as charge-trapping sites, and facilitates the photo-generated electron separation and transportation. Furthermore, the Gibbs free-energy of the adsorbed H* over RuSAs/B–TiO2 is much closer to zero compared to that of pristine TiO2, thus considerably boosting the photocatalytic performance. The hydrogen evolution over RuSAs/B–TiO2 reaches 17.81 mmol/g/h with an apparent quantum efficiency (AQE) of 21.3% at 365 nm. It is expected that this facile strategy can be employed to fabricate other efficient photocatalysts for new energy production and environmental remediation.