Non-precious metal single-atom loading and further strain engineering on SrTiO₃ (100) surface for optimizing hydrogen evolution reaction

Single-atom loading of the non-precious transition metals (M = Ti, V, Mn, and Fe) on the (100) surface of SrTiO₃ (STO) was theoretically investigated to evaluate the hydrogen evolution reaction (HER) with Gibbs free energy for hydrogen adsorption (∆G_H^*). V₁-STO stood out owing to the ∆G_H^* of − 0.08 eV, which was competitive to the metallic Pt with the value of − 0.09 eV. The d band center rationalized well the primary screening of single-atom non-precious transition metals on STO. Furthermore, strain engineering was applied to refine the HER performance of V₁-STO. The tensile strain increased the ∆G_H^*, while the compressed strain decreased the ∆G_H^*. A new descriptor of the d orbital splitting (ε_d−gap) was proposed to explain the optimization of the HER performance arising from the surface strains. This work conceives a combinational strategy to evaluate the HER performance, and may give guidance for the sequential design of HER catalysts.