Lanthanide single-atom catalysts for efficient CO-to-CO electroreduction.

Single-atom catalysts (SACs) have received increasing attention due to their 100% atomic utilization efficiency. The electrochemical CO reduction reaction (CORR) to CO using SAC offers a promising approach for CO utilization, but achieving facile CO adsorption and CO desorption remains challenging for traditional SACs. Instead of singling out specific atoms, we propose a strategy utilizing atoms from the entire lanthanide (Ln) group to facilitate the CORR. Density functional theory calculations, operando spectroscopy, and X-ray absorption spectroscopy elucidate the bridging adsorption mechanism for a representative erbium (Er) single-atom catalyst. As a result, we realize a series of Ln SACs spanning 14 elements that exhibit CO Faradaic efficiencies exceeding 90%. The Er catalyst achieves a high turnover frequency of ~130,000 h at 500 mA cm. Moreover, 34.7% full-cell energy efficiency and 70.4% single-pass CO conversion efficiency are obtained at 200 mA cm with acidic electrolyte. This catalytic platform leverages the collective potential of the lanthanide group, introducing new possibilities for efficient CO-to-CO conversion and beyond through the exploration of unique bonding motifs in single-atom catalysts.