Modulating Pd eg orbital occupancy in Pd-Au metallic aerogels for efficient carbon dioxide reduction

The electronic structure of electrocatalysts plays a critical role in energy conversion, whereas for an efficient catalyst, it is challenging to modulate the orbitals. Herein, we present a new strategy to modulate the eg orbital occupancy of Pd by constructing composition-controllable Pd-Au metallic aerogels (MAs), optimizing the d-band center of Pd to achieve excellent performance for electrochemical carbon dioxide reduction reaction (CO2RR). Specifically, Pd1Au2 MAs achieve almost 100% Faraday efficiency (FE) of CO in the range of −0.40 to −0.80 V vs. reversible hydrogen electrode (RHE), as well as the long-term stability, being one of the best Pd-based materials for CO2RR. The X-ray photoelectron spectroscopy (XPS) results and density functional theory (DFT) calculations demonstrate that the introduction of Au modulates the Pd eg orbital occupancy, which significantly weakens *CO adsorption on Pd, reduces the CO2RR energy barrier and consequently improves the electrocatalytic activity and stability for long-term applications. Our work highlights a new strategy for designing efficient electrocatalysts for CO2RR and beyond.