Abstract
Bi-based electrocatalysts have been widely investigated in the CO(2) reduction reaction (CO(2) RR) for the formation of formate. However, it remains a challenge to achieve high Faradaic efficiency (FE) and industrial current densities at low overpotentials for obtaining both high formate productivity and energy efficiency (EE). Herein, we report an Ag-Bi(2) O(3) hybrid nanofiber (Ag-Bi(2) O(3) ) for highly efficient electrochemical reduction of CO(2) to formate. Ag-Bi(2) O(3) exhibits a formate FE of >90% for current densities from -10 to -250 mA ⋅ cm(-2) and attains a yield rate of 11.7 mmol ⋅ s(-1) ⋅ m(-2) at -250 mA ⋅ cm(-2) . Moreover, Ag-Bi(2) O(3) increased the EE (52.7%) by nearly 10% compared to a Bi(2) O(3) only counterpart. Structural characterization and in-situ Raman results suggest that the presence of Ag induced the conversion of Bi(2) O(3) from a monoclinic phase (α-Bi(2) O(3) ) to a metastable tetragonal phase (β-Bi(2) O(3) ) and accelerated the formation of active metallic Bi at low overpotentials (at > -0.3 V), which together contributes to the highly efficient formate formation.