Fabrication of Bi/Sn bimetallic electrode for high-performance electrochemical reduction of carbon dioxide to formate

CO2 electrochemical reduction (CO2ER) can convert CO2 into value-added liquid fuel, which can not only mitigate the global warming problem caused by CO2, but also can be used for energy storage in the form of intermittent renewable energy. High-performance catalysts are required in order to efficiently conduct electrochemical carbon dioxide reduction under mild conditions. In this work, the bimetallic bismuth and tin were deposited on the copper mesh via a simple and speedy electrodeposition strategy and assessed as electrocatalysts for the conversion of CO2 to formate. The Bi5Sn60 electrode (bismuth deposition time of 5 min, tin deposition time of 60 min) exhibited an excellent catalytic activity with a remarkably high Faradaic efficiency of 94.8% and partial current density of 34.0 mA cm−2 at − 1.0 V vs RHE. More intriguingly, it exhibited a remarkable formate production rate of 634.3 μmol cm−2h−1 that outperformed most of the reported electrocatalysts. The pine needle-shaped dendritic structures could provide a considerable surface area and massive active sites. The fast electron transfer was of great benefit to the formation of CO2• − intermediate. The metal oxide/metal metastable interface was conducive to stabilizing the CO2• − intermediate and inhibiting the hydrogen evolution reaction (HER) process. Moreover, the optimized electronic structure strengthened the pathway related to the OCHO• intermediate, thereby boosted the conversion of CO2 to formate. The results demonstrated that the dendrite structured Bi/Sn bimetallic catalysts would be a promising candidate for high-efficiency CO2 reduction.