H-assisted CO2 dissociation on PdnPt(4−n)/In2O3 catalysts: a density functional theory study

Abstract

CO₂ hydrogenation into valuable chemical compounds can effectively address the issues of greenhouse gas emissions and energy scarcity. The activation and dissociation processes of CO₂ are crucial for its reduction reactions, but the effects of *H adatoms on the C–O cleavage are still confusing. This study investigates the H-assisted CO₂ dissociation pathways on the Pd_nPt_(4−n)/In₂O₃ (n = 0–4) catalysts via DFT calculation. Initially, the adsorption properties of *H₂, *COOH, and *HCOO species are calculated. Then, two H-assisted CO₂ dissociation channels, i.e., *CO₂ + *H → *COOH → *CO + *OH and *CO₂ + *H → *HCOO → *CHO + *O, are studied. Results show that Pt and Pd promote the CO₂ hydrogenation and C–O bond cleavage reactions, respectively. In comparison to CO₂ direct dissociation, the COOH-mediated and HCOO-mediated channels facilitate and impede the C–O bond cleavage, respectively. Overall, the Pd₃Pt/In₂O₃ constituent is suggested for the H-assisted CO₂ dissociation reaction. The electronic effects of the Pd_nPt_(4−n) bimetals adjust the stabilities of the intermediates and barriers of the elementary steps, and the interactions between Pd_nPt_(4−n) and In₂O₃ provide extra sites for the adsorbates and reaction steps. This study reveals the effects of *H on the C–O bond dissociation processes and provides useful insight into designing PdPt/In₂O₃ catalysts for CO₂ hydrogenation reactions.