Thermally Treated Carbon Nanoparticles for Boosting Industrial CO ₂ Reduction to Formate on a SnO ₂ Electrocatalyst

Carbon black (CB) has been well-documented as an effective catalyst support for enhancing the performance and cost-effectiveness of catalysts in various electrochemical reactions. However, studies of these materials as catalyst supports for the CO2 reduction reaction are still limited. Therefore, in this study, we developed a simple approach involving the modification of supporting carbon black nanoparticles (∼29 nm) to improve the activity and stability of the SnO2 catalyst under industrially relevant conditions. Carbon black, as the supporting material, underwent calcination at moderate temperatures (350–550 °C) in the atmosphere, and the effects of the thermal treatment on the catalytic performance of the commercial SnO2 catalyst were examined. Electrochemical measurements revealed that SnO2 supported on CB thermally treated at 450 °C (SnO2/CB-450) exhibited superior activity and stability at industrially relevant current densities compared with other samples. While the SnO2-only and nontreated CB-supported samples showed rapid performance decay, the SnO2/CB-450 electrode maintained a Faradaic efficiency above 80% after 4 h and above 70% after 12 h of electrolysis in 2 M KOH at 200 mA cm–2. The impacts of the thermally treated CB on the electrocatalytic performance of SnO2 were assessed using various morphological and structural analyses, revealing a thermal treatment-induced surface modification of the CB nanomaterial support that effectively enhanced electrical conductivity and promoted the interaction and charge transfer between the catalyst and support, thereby improving overall catalyst performance and stability. Despite improvements, stability remains challenging, and the chemical and morphological changes of the electrode during the reaction were investigated over time to better understand the issue. This work introduces a straightforward and scalable strategy to enhance the activity and stability of the SnO2 catalyst by modifying the carbon black nanomaterial support, offering a practical and scalable implication for the electrochemical CO2 reduction reaction at high current densities.