Maximizing the synergistic effect of PdAu catalysts on TiO2(1 0 1) for robust CO2 reduction: A DFT study

Abstract To provide insight into how to realize maximization of the synergistic effect of supported PdAu catalysts, we have performed first-principles calculations for CO2 reduction over PdAu/TiO2(1 0 1). The results indicate that introducing a secondary metal (Au) to supported Pd catalyst and controlling Au concentration can affect the binding energy of reactants and also alter the dominant reaction pathway. The energetically preferred path for CO2 reduction on Pd8-xAux/TiO2 changes from the formate pathway (referred to as the “CO2 HYD” pathway) (x = 0–3) to the reverse water-gas shift and CO hydrogenation (“RWGS + CO HYD”) pathway (x = 4–6). Notably, the CO2 reduction activity shows a volcano trend as a function of the binding energy of the initial reactant CO2* in the “CO2 HYD” pathway or the adsorption energy difference between CHO* and CO* in the “RWGS + CO HYD” pathway. In addition, there is a component-dependent relationship between the water-promotion-effect and the nanoalloy structure. This work proposes fundamental insights into the effect of nanoalloy composition and water promotion in maximizing the synergy of PdAu catalysts for CO2 reduction, providing facile descriptors for the activity of reaction pathways, and offering important guidance for rational design of supported nanoalloy catalysts.