Orbital Orientation-based Theoretical Design of Single-Atom Catalysts for the Hydrogen Evolution Reaction

Hydrogen evolution reaction (HER) is regarded as one of the most effective routes to produce H2, but it usually suffers from the lack of the novel design concept of high-efficiency catalysts, especially in neutral condition. Herein, we report an orbital orientation-based theoretical principle for designing efficient single-atom HER catalysts. Through screening 14 catalysts consisting of the transition-metal single atoms doped into TiO2 (TM1@TiO2) nanosheets, we demonstrate that the d orbital orientation of TM1–Ti1 atomic pairs plays a key role in the regulation of catalytic activities. Among them, Pd1@TiO2 is screened out as an excellent HER catalyst in neutral media, where the Pd- d x 2 − y 2 orbital tends to be exposed due to the existence of Pd1–Ti1 atomic pair and thus promotes OH desorption and the overall hydrogen production. This work provides a new insight through tailoring high-performance orbital catalysts and sheds an orbital-level understanding of the HER mechanism.