Theoretical insight into the relevance between the oxidation states of CeO2 supported Pt4+/2+/1+/0/2− and their HER performance

Abstract

The oxidation states (OSs) of Pt catalysts play a key role in the hydrogen evolution reaction (HER), which has become a focus in recent years. As for Pt/CeO₂ catalysts, we have systematically explored the effect of Pt^{4+/2+/1+/0/2−} OSs on the HER. H atoms could not adsorb on the Pt⁴⁺ and Pt_4c²⁺ sites, and they prefer to locate on the adjacent O atoms (labeled as Pt⁴⁺–O and Pt_4c²⁺–O). As for the other OSs, the adsorption ability of H atoms follows the order Pt⁰ > Pt_3c²⁺ > Pt¹⁺ > Pt²⁻. The electron-enriched Pt²⁻ is the most suitable oxidation state for the HER, no matter the reaction mechanism, which is the Volmer–Heyrovsky or Volmer–Tafel mechanism. The Pt OSs would greatly affect the electronic structures of Pt catalysts, which will further impact their overall catalytic properties. Our study could shed light on the research of Pt-based catalysts for the HER.