CO2 activation and dissociation on In2O3(110) supported PdnPt(4−n) (n = 0–4) catalysts: a density functional theory study

Abstract

Converting CO₂ into valuable chemicals via catalytic reactions can mitigate both the greenhouse effect and energy shortage problems, thus designing efficient catalysts have attracted considerable attention over the past decades. In this work, a density functional theory (DFT) calculation was carried out to investigate the CO₂ activation and dissociation processes on various Pd_nPt_(4−n)/In₂O₃ (n = 0–4) catalysts. The Pd_nPt_(4−n)/In₂O₃ models were initially built, and the interface sites of Pd_nPt_(4−n)/In₂O₃ for CO₂ adsorption were confirmed among cluster sites and substrate sites. The CO₂ adsorption geometries, charger transfer, and projected density of states (PDOS) were analyzed to study the CO₂–Pd_nPt_(4−n)/In₂O₃ interactions. From the adsorbed *CO₂, the transition states (TSs) for CO₂ dissociation to form *CO and *O were gained to reveal the characteristics of the activated CO₂^δ−. Overall, according to the adsorption energy E_ads results, the bimetallic PdPt₃/In₂O₃ and Pd₃Pt/In₂O₃ catalysts showed the strongest and weakest CO₂ adsorption stabilities, respectively, while the Pd element addition decreases the barriers for CO₂ dissociation with the priority order of Pd₄ > Pd₃Pt > Pd₂Pt₂ > PdPt₃ > Pt₄. The Brønsted–Evans–Polanyi (BEP) relation between activation barriers (E_b) and reaction energies E was obtained for the CO₂ dissociation mechanism on Pd_nPt_(4−n)/In₂O₃ catalysts with the equation of E = 0.20E_b + 0.40. Finally, the optimal Pd₂Pt₂/In₂O₃ catalyst for CO₂ activation and dissociation was proposed. This study provides useful information for CO₂ activation and conversation procedures on bimetal-oxide catalysts, and helps to take the optimal design of PdPt/In₂O₃ catalysts for the CO₂ reaction.