Effect of Elastic Strains on Adsorption Energies of C, H and O on Transition Metal Oxides

Platinum (Pt)-based noble metal catalysts (PGMs) are the most widely used commercial catalysts, but they have the problems of high cost, low reserves, and susceptibility to small-molecule toxicity.Transition metal oxides (TMOs) are regarded as potential substitutes for PGMs because of their stability in oxidizing environments and excellent catalytic performance.In this study, comprehensive investigation into the influence of elastic strains on the adsorption energies of carbon (C), hydrogen (H) and oxygen (O) on TMOs was conducted.Based on density functional theory (DFT) calculations, these effects in both tetragonal structures (PtO 2 , PdO 2 ) and hexagonal structures (ZnO, CdO), along with their respective transition metals were systematically explored.It was identified that the optimal adsorption sites on metal oxides pinpointed the top of oxygen or the top of metal atom, while face-centered cubic (FCC) and hexagonal close-packed (HCP) holes were preferred for the transition metals.Furthermore, under the influence of elastic strains, the results demonstrated significant disparities in the adsorption energies of H and O between oxides and transition metals.Despite these differences, the effect of elastic strains on the adsorption energies of C, H and O on TMOs mirrored those on transition metals: adsorption energies increased under compressive strains, indicating weaker adsorption, and decreased under tension strains, indicating stronger adsorption.This behavior was rationalized based on the d-band model for adsorption atop a metallic atom or the p-band model for adsorption atop an oxygen atom.Consequently, elastic strains present a promising avenue for tailoring the catalytic properties of TMOs.