Electrokinetics of CO2 Reduction in Imidazole Medium Using RuO2.SnO2-Immobilized Glassy Carbon Electrode

The pursuit of electrochemical carbon dioxide reduction reaction (CO2RR) as a means of energy generation and mitigation of global warming is of considerable interest. In this study, a novel RuO2-incorporated SnO2-fabricated glassy carbon electrode (GCE) with a Nafion binder was used for the electrochemical reduction of CO2 in an aqueous alkaline imidazole medium. The electrode fabrication process involved the drop-casting method, where RuO2.SnO2 was incorporated onto the surface of the GCE. Electrochemical studies demonstrated that the GCE-RuO2.SnO2 electrode facilitated CO2 reduction at −0.58 V vs. the reversible hydrogen electrode (RHE) via a diffusion-controlled pathway with the transfer of two electrons. Importantly, the first electron transfer step was identified as the rate-determining step (RDS). A Tafel slope of 144 mV dec−1 confirmed the association of two-electron transfer kinetics with CO2RR. Moreover, the standard rate constant (ko) and formal potential (E°′) were evaluated as 2.89 × 10−5 cm s−1 and 0.0998 V vs. RHE, respectively. Kinetic investigations also reveal that the deprotonation and electron release steps took place simultaneously in the CO2RR. Based on the reported results, the GCE-RuO2.SnO2 electrode could be a promising candidate for CO2 reduction, applicable in renewable energy generation.