Water-gas-shift reaction over Au single-atom catalysts with reversible oxide supports: A density functional theory study

Abstract

The low-temperature water-gas-shift (LT-WGS) reaction has shown remarkable activity for Au single-atom supported on reducible oxide catalysts. The water dissociation step of the WGS reaction is calculated using density functional theory (DFT) over four single Au atom (Au1)-pristine reversible oxides support systems Au1/MaOb-Ov (Au1/TiO2-x, Au1/ZrO2-x, Au1/CeO2-x and Au1/Co3O4-x) system and four Au1-supports with O vacancy (Ov) systems Au1/MaOb (Au1/TiO2, Au1/ZrO2, Au1/CeO2 and Au1/Co3O4). According to its greatest H2O adsorption energy, lowest water dissociation barrier, and slightest structural distortion, Au1/CeO2-x is chosen as the most beneficial catalyst for the WGS process. Afterwards, for Au1/CeO2-x, three reaction pathways (redox path, formate path and carboxyl path) are calculated. The predominant reaction pathway is the carboxyl pathway, and hydrogen production is the rate-determining step (RDS). For the purpose of designing single metal-support catalysts for the LT-WGS reaction, this paper gives information on the strong metal-support interaction (SMSI).