Atomically dispersed indium and cerium sites for selectively electroreduction of CO₂ to formate

Currently, single-atom combo catalysts (SACCs) for carbon dioxide reduction reaction (CO₂RR) to the formation of HCOOH are still very limited, especially the lanthanide-based SACCs. In this work, the novel SACCs with atomically dispersed In and Ce active sites were successfully prepared on the nitrogen-doped carbon matrix (InCe/CN). Both aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) images and the extended X-ray absorption fine structure (EXAFS) spectra proved the well-isolated In and Ce atoms. The as-prepared InCe/CN shows a high Faradaic efficiency (FE) (77%) and current density of HCOOH formation (j_HCOOH) at −1.35 V vs. reversible hydrogen electrode (RHE), much higher than the single atom catalysts. Theoretical calculations have indicated that the introduced Ce single atom sites not only significantly promote electron transfer but also optimize the In-5p orbitals towards higher selectivity towards the HCOOH formation. This work innovatively extends the design of SACCs towards the main group and Ln metals for more applications.