Stabilizing Undercoordinated Zn Active Sites through Confinement in CeO2 Nanotubes for Efficient Electrochemical CO2 Reduction

Zn‐based catalysts hold great potential to replace the noble metal‐based ones for CO2 reduction reaction (CO2RR). Undercoordinated Zn (Znδ+) sites may serve as the active sites for enhanced CO production by optimizing the binding energy of *COOH intermediates. However, there is relatively less exploration into the dynamic evolution and stability of Znδ+ sites during CO2 reduction process. Herein, we present ZnO, Znδ+/ZnO and Zn as catalysts by varying the applied reduction potential. Theoretical studies reveal that Znδ+ sites could suppress HER and HCOOH production to induce CO generation. And Znδ+/ZnO presents the highest CO selectivity (FECO 70.9 % at −1.48 V vs. RHE) compared to Zn and ZnO. Furthermore, we propose a CeO2 nanotube with confinement effect and Ce3+/Ce4+ redox to stabilize Znδ+ species. The hollow core–shell structure of the Znδ+/ZnO/CeO2 catalyst enables to extremely expose electrochemically active area while maintaining the Znδ+ sites with long‐time stability. Certainly, the target catalyst affords a FECO of 76.9 % at −1.08 V vs. RHE and no significant decay of CO selectivity in excess of 18 h.