Electroreduction of CO2 to formate on modified graphene-supported Sn nanoparticles

Abstract

In this study, tin (Sn) nanoparticles are demonstrated to effectively catalyze the reduction of CO₂ to formate in an alkaline medium. Catalytically active Sn-based nanoparticles, supported on carbon black (Sn/C) and highly conductive graphene nanosheets (Sn/GN), present a promising approach to mitigating atmospheric CO₂ emissions when integrated with capture technologies. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were employed to evaluate the prepared catalysts in CO₂-saturated 0.5 M KHCO₃ using a three-electrode rotating disk electrode (RDE) configuration. The results revealed a significantly lower charge-transfer resistance for graphene-supported tin compared to carbon black-supported tin. The CO₂ reduction to formate was further demonstrated in a full electrochemical cell setup resembling the architecture of a low-temperature polymer electrolyte fuel cell (PEFC) operating in an alkaline medium with an anion exchange membrane (AEM). Performance tests were conducted with both triple-serpentine and parallel flow field architectures, showing flow rate-dependent behavior. Additionally, an ex-situ RDE technique was utilized to detect and quantify formate production during CO₂ reduction in the full-cell configuration. This work highlights the importance of catalyst support materials and flow field design in optimizing CO₂ electroreduction systems.