In Situ Reconstruction of a Hierarchical Sn-Cu/SnOx Core/Shell Catalyst for High-Performance CO2 Electroreduction.

The electrochemical CO2 reduction reaction (CO2 RR) to give C1 (formate and CO) products is one of the most techno-economically achievable strategies for alleviating CO2 emissions. Now, it is demonstrated that the SnOx shell in Sn2.7 Cu catalyst with a hierarchical Sn-Cu core can be reconstructed in situ under cathodic potentials of CO2 RR. The resulting Sn2.7 Cu catalyst achieves a high current density of 406.7±14.4 mA cm-2 with C1 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 C1 Faradaic efficiency of 99.0±0.5 % for 40 h at -0.55 V vs. RHE. DFT calculations indicate that the reconstructed Sn/SnOx interface facilitates formic acid production by optimizing binding of the reaction intermediate HCOO* while promotes Faradaic efficiency of C1 products by suppressing the competitive hydrogen evolution reaction, resulting in high Faradaic efficiency, current density, and stability of CO2 RR at low overpotentials.