Inversely Tuning the CO₂ Electroreduction and Hydrogen Evolution Activity on Metal Oxide via Heteroatom Doping

Tuning the electronic states near the Fermi level can effectively facilitate the reaction kinetics. However, elucidating the role of a specific electronic state of metal oxide in simultaneously regulating the CO₂ electroreduction reaction (CO₂ RR) and competing hydrogen evolution reaction (HER) is still rare, making it difficult to accurately predict the practical CO₂ RR performance. Herein, replacing the Zn site by heteroatoms with different outer electrons (Mo and Cu) is found to tune both occupied and unoccupied orbitals near the Fermi level of ZnO. Moreover, the different electronic states significantly modulate both CO₂ RR and HER activity with a totally inverse trend, thus dramatically tuning the practical CO₂ RR performance. In parallel, the correlation between electronic states, reaction free energies and practical activity is demonstrated. This work provides a possibility for engineering efficient CO₂ RR eletrocatalysts through tunable composition and electronic structures.