Facet-Regulating Local Coordination of Dual-Atom Cocatalyzed TiO2 for Photocatalytic Water Splitting

Bi- or multimetallic catalytic sites exhibit particularly high catalytic activities in contrast to regular single-atom catalysts. Until recently, it has remained a great challenge to precisely regulate the electronic coupling between neighboring atomically dispersed atoms. Herein, we experimentally demonstrated that the coordination environment of PtAu dual atoms could be facilely regulated by engineering the exposed facets of TiO2 supports. Due to the metal–support interactions originated from coordinatively unsaturated sites, atomic cocatalysts were anchored onto {001}-TiO2 through Pt–O and Au–O bonds, while {101}-TiO2 was preferential for Pt–O and Au nanoparticles. The dual-atom cocatalyzed PtAu/{001}-TiO2 presented a 1000-fold increase in the H2 evolution rate compared to blank {001}-TiO2, which was even 4 times higher than PtAu/{101}-TiO2. The enhancement mechanism relies on the synergy of PtAu dual-atom cocatalysts, which can mutually optimize the electronic states of both Pt and Au sites to decrease the Gibbs free energies of hydrogen adsorption. Particularly, the Pt atom is activated by the Au atom and the activity of catalysts is further enhanced through the dimer interaction. The strategy of neighboring interactive bimetallic sites provides emerging opportunities for the rational design of high-performance catalysts with atomically engineered electronic states.