Modulating Activity through Defect Engineering of Tin Oxides for Electrochemical CO₂ Reduction

The large-scale application of electrochemical reduction of CO₂, as a viable strategy to mitigate the effects of anthropogenic climate change, is hindered by the lack of active and cost-effective electrocatalysts that can be generated in bulk. To this end, SnO₂ nanoparticles that are prepared using the industrially adopted flame spray pyrolysis (FSP) technique as active catalysts are reported for the conversion of CO₂ to formate (HCOO⁻), exhibiting a FE_HCOO⁻ of 85% with a current density of −23.7 mA cm⁻² at an applied potential of −1.1 V versus reversible hydrogen electrode. Through tuning of the flame synthesis conditions, the amount of oxygen hole center (OHC; Sn≡O●) is synthetically manipulated, which plays a vital role in CO₂ activation and thereby governing the high activity displayed by the FSP-SnO₂ catalysts for formate production. The controlled generation of defects through a simple, scalable fabrication technique presents an ideal approach for rationally designing active CO₂ reduction reactions catalysts.