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.