Electronic Structure Modulation of Unconventional Phase Metal Nanomaterials for Highly Selective Carbon Dioxide Electroreduction

The electrochemical carbon dioxide (CO₂) reduction reaction (CO₂RR) has been considered as a promising approach to convert atmospheric CO₂ to value-added chemicals to promote carbon neutrality. However, developing electrocatalysts with superior activity and high selectivity toward individual products remains a great challenge. Herein we report the electronic structure modulation of unconventional phase metal nanomaterials to achieve highly efficient CO₂ electroreduction. It has been found that growing cerium oxide (CeO_x) nanostructures on 4H/face-centered cubic (fcc) gold (Au) nanorods can significantly enhance their catalytic activity and selectivity toward the electrochemical conversion of CO₂ to carbon monoxide. X-ray analysis indicates the electronic structure change of 4H/fcc Au nanorods after CeO_x overgrowth. In-situ attenuated total reflection infrared spectroscopy measurements reveal that the HCO₃^- concentration near the surface of Au-CeO_x heteronanostructures is much higher than that of Au nanorods, facilitating the CO₂ reduction process. Density functional theory calculations suggest the activation effect of CeO_x on the 4H/fcc Au nanorod surface for the electrocatalytic CO₂RR. The synergy between 4H/fcc Au and CeO_x promotes the formation of carboxyl (*COOH) species and thus boosts the electrocatalytic CO₂RR performance. This work highlights the importance of rational electronic structure regulation of unusual phase nanomaterials toward the electrocatalytic conversion of small molecules.