Theoretical investigation of CO2 hydrogenation to methanol catalyzed on Pd-Ga bimetallic catalysts: Insights into the effects of Ga in different coordination environments

Methanol is easy to store compared to other gaseous hydrogenation products. Moreover, it can be further converted to other advanced hydrocarbons, so the conversion of CO2 to methanol (CTM) is a promising reaction. PdGa bimetallic catalysts are candidate catalysts for CTM conversion, which can promote H spillover to the active site and react with adsorbed CO2 . However, the role of Ga atom in PdGa bimetallic catalysts and the underlying mechanism of CTM are still unclear at the molecular level. In this work, Ga atom with different coordination environments CN3, CN4 and CN5 were obtained on the Pd(1 1 1), and three reaction mechanisms of CTM on different catalysts are systematic investigated. Changes in the coordination environments of the Ga atom affected the adsorption configurations of HCOOH*, HCO*, and H2CO*, 2 CO*, among others. Three catalysts have similar superior pathways, and the order of CO2 reactivity is CN4 > CN3 > CN5. The PdGa bimetallic catalysts containing 4-coordinated Ga atom are proposed to be the ideal catalysts. We hope that the conclusions obtained can help understand the reasons for the outstanding reactivity and selectivity of CTM on PdGa bimetallic catalysts at the molecular level, and can provide some guidance for the design and development of highperformance bimetallic catalysts.