Elucidation of the Synergistic Effect of Dopants and Vacancies on Promoted Selectivity for CO2 Electroreduction to Formate

Abstract Sn‐based materials are identified as promising catalysts for the CO 2 electroreduction (CO2RR) to formate (HCOO − ). However, their insufficient selectivity and activity remain grand challenges. A new type of SnO 2 nanosheet with simultaneous N dopants and oxygen vacancies ( V O ‐rich N‐SnO 2 NS) for promoting CO 2 conversion to HCOO − is reported. Due to the likely synergistic effect of N dopant and V O , the V O ‐rich N‐SnO 2 NS exhibits high catalytic selectivity featured by an HCOO − Faradaic efficiency (FE) of 83% at − 0.9 V and an FE of > 90% for all C1 products (HCOO − and CO) at a wide potential range from −0.9 to − 1.2 V. Low coordination Sn–N moieties are the active sites with optimal electronic and geometric structures regulated by V O and N dopants. Theoretical calculations elucidate that the reaction free energy of HCOO* protonation is decreased on the V O ‐rich N‐SnO 2 NS, thus enhancing HCOO − selectivity. The weakened H* adsorption energy also inhibits the hydrogen evolution reaction, a dominant side reaction during the CO2RR. Furthermore, using the catalyst as the cathode, a spontaneous Galvanic Zn‐CO 2 cell and a solar‐powered electrolysis process successfully demonstrated the efficient HCOO − generation through CO 2 conversion and storage.