How Do Structurally Distinct Au/α‐Fe2O3 Interfaces Determine Surface OH/H2O reactivity, Intermediate Evolution, and Product Formation in Low‐temperature Water‐gas Shift Reaction?

Abstract

AbstractThree structurally distinct interfaces, i. e. Au/α‐Fe2O3‐THB‐Air, Au/α‐Fe2O3‐HS‐Air, and Au/α‐Fe2O3‐QC‐Air, with the major substrate facet being {113}, {001}, and {012} respectively, were controllably prepared. The low temperature water gas shift (WGS) reaction (100–260 °C) was applied to these unique systems to reveal how these structurally distinct interfaces can impact on the reaction behavior. With the detailed performance evaluation plus the characterizations of CO‐TPSR, XPS, and in situ‐FTIR in particular, the correlations between the evolution of different intermediates and the distinct catalytic behaviors have been established. The substrate facet structure and the Au entity largely determine the form and reactivity of surface OH/H2O species which in turn determine the formation of different intermediates and eventually the product formation. The Au/α‐Fe2O3‐THB‐Air is enriched with oxygen vacant sites, favorable for dissociative adsorption of H2O, carboxyl intermediate formation and H2 production. The Au/α‐Fe2O3‐HS‐Air is enriched with surface lattice oxygen, favorable for molecular adsorption of H2O, formate intermediate formation, and CO2 production. The Au/α‐Fe2O3‐QC‐Air interface is enriched with surface Fe sites, favorable for dissociative adsorption of H2O and evolution of stable carboxyl intermediate as well as isolated OH species at low reaction temperatures. The findings are informative to control the interfacial structure for the WGS and other reactions.