CO₂ activation on Cu-based Zr-decorated nanoparticles

Density functional theory (DFT) calculations have been applied to investigate the electronic and CO₂ adsorption properties of 55-atom Cu-based nanoparticles (NPs) decorated with Zr atoms (Cu_55-xZr_x, x = 0-12). Our results revealed that the Zr atoms preferably reside on the surface of the Cu NPs generating sites that chemisorb and activate CO₂ (linear to bent geometry and elongation of CO bonds). Importantly, we demonstrate that while the CO₂ formation of the activated state on the Cu NPs is endothermic, it becomes barrierless and exothermic on the Zr-decorated NPs. The CO₂ activation and chemisorption was attributed to charge transferred from the NPs to the CO₂ molecule. We identified the local-site d-band center and, interestingly, the ionization potential of the NP as descriptors correlating with the CO₂ chemisorption. As a result, we demonstrate that one can tune the ionization potential of the NPs and, in turn the CO₂ chemisorption energy, by varying the Zr content of the NPs. Additionally, we investigated the activity of CuZr NPs as catalysts for CO₂ dissociation to CO and determined that Cu₅₄Zr was a very efficient catalyst compared to Cu₅₅. Overall, this work highlights how surface decoration can change the electronic properties of the NPs and result in CO₂ activation, which are important steps for designing catalysts that capture and convert CO₂ to fuels and chemicals.