In Situ Reconstruction of a Hierarchical Sn‐Cu/SnO x Core/Shell Catalyst for High‐Performance CO 2 Electroreduction

The electrochemical CO 2 reduction reaction (CO 2 RR) to give C 1 (formate and CO) products is one of the most techno‐economically achievable strategies for alleviating CO 2 emissions. Now, it is demonstrated that the SnO x shell in Sn 2.7 Cu catalyst with a hierarchical Sn‐Cu core can be reconstructed in situ under cathodic potentials of CO 2 RR. The resulting Sn 2.7 Cu catalyst achieves a high current density of 406.7±14.4 mA cm −2 with C 1 Faradaic efficiency of 98.0±0.9 % at −0.70 V vs. RHE, and remains stable at 243.1±19.2 mA cm −2 with a C 1 Faradaic efficiency of 99.0±0.5 % for 40 h at −0.55 V vs. RHE. DFT calculations indicate that the reconstructed Sn/SnO x interface facilitates formic acid production by optimizing binding of the reaction intermediate HCOO* while promotes Faradaic efficiency of C 1 products by suppressing the competitive hydrogen evolution reaction, resulting in high Faradaic efficiency, current density, and stability of CO 2 RR at low overpotentials.