Carbon sustained SnO2-Bi2O3 hollow nanofibers as Janus catalyst for high-efficiency CO2 electroreduction

Electrochemical reduction of CO2 (CRR) into valuable products like formate is an appealing way to alleviate the pressure of the excessive CO2 emission and achieve carbon neutrality. However, exploitation of electrocatalysts with commercial application potentials remains challenging. Herein, we fabricate a hierarchical Janus electrocatalyst with SnO2 and Bi2O3 assembled outside and inside the hollow carbon nanofiber skeleton, respectively. Due to the nanostructuring effect, the catalytic performance of Janus active sites was magnified, achieving a remarkable current density of −220 mA cm−2 for formate production and 91% faradic efficiency at −1.29 V vs. RHE in a flow cell. Besides, the selectivity for formate was maintained over 48 h operation with an outstanding half-cell energy efficiency of 51%. In-situ FT-IR further prove the Janus active sites are conducive to the HCOO* reaction pathway rather than the *COOH way. This study may pave another avenue to prepare nanostructured Janus electrocatalysts for highly efficient CO2 reduction.