Highly Selective Reduction of CO2 to Formate at Low Overpotentials Achieved by a Mesoporous Tin Oxide Electrocatalyst

A well-ordered mesoporous SnO2 prepared by a simple and inexpensive nanocasting method was used as catalysts for the electrochemical reduction of CO2 to formate. The as-prepared catalyst exhibited high activity toward CO2 reduction, which was capable of reducing CO2 to formate with 38% of Faradaic efficiency (FE) at an applied overpotential as low as 325 mV. The maximum FE for formate generation (75%) was achieved at an applied potential of −1.15 V (vs RHE), accompanied by a high current density of 10.8 mA cm–2. The enhanced catalytic activity obtained with the mesoporous SnO2 electrocatalyst is attributed to its high oxygen vacancy defects (promotes CO2 adsorption and lowers overpotential) and crystallinity that provides sufficient active sites for CO2RR as well as its distinctive structural configurations which reduces impedance to facilitate faster CO2RR reaction kinetics.