Predicted Structures of the Active Sites Responsible for the Improved Reduction of Carbon Dioxide by Gold Nanoparticles

Gold (Au) nanoparticles (NPs) are known experimentally to reduce carbon dioxide (CO₂) to carbon monoxide (CO), with far superior performance to Au foils. To obtain guidance in designing improved CO₂ catalysts, we want to understand the nature of the active sites on Au NPs. Here, we employed multiscale atomistic simulations to computationally synthesize and characterize a 10 nm thick Au NP on a carbon nanotube (CNT) support, and then we located active sites from quantum mechanics (QM) calculations on 269 randomly selected sites. The standard scaling relation is that the formation energy of∗COOH (δE_∗COOH) is proportional to the binding energy of∗CO (E^binding_∗CO); therefore, decreasing δE_∗COOH to boost the CO₂ reduction reaction (CO₂RR) causes an increase of E^binding_∗CO that retards CO₂RR. We show that the NPs have superior CO₂RR because there are many sites at the twin boundaries that significantly break this scaling relation.