Leaching-resistant SnO2/γ-Al2O3 nanocatalyst for stable electrochemical CO2 reduction into formate

Tin(IV) oxide (SnO2) is the catalyst most commonly used for electrochemical reduction of CO2 into formate. However, the electrocatalytic performance of SnO2 is not ensured due to its poor long-term stability. Here, we report our study on the electrochemical stability of SnO2 for 152 h and describe an approach to achieve stable SnO2 electrodes using a γ-alumina (γ-Al2O3) support. The γ-Al2O3 reduces the leaching of Sn from the supported-SnO2 during CO2 electrolysis due to the strong interaction of the support with the electrocatalyst. This maintains the particle size, morphology, and crystallinity of SnO2. Thereby, pulverization of SnO2 is prevented and stable selectivity towards CO2 reduction results. The prepared SnO2/γ-Al2O3 exhibits much more stable Faradaic efficiency (65.0% at 152 h) and partial current density (21.7 mA cm−2 at 152 h) for formate synthesis than does unsupported SnO2 electrocatalyst (14.2% Faradaic efficiency; 4.6 mA cm−2 of partial current density at 152 h).