CO2 Electrolysis Paired with Glycerol Oxidation on Transition-Metal Single-Atom Catalysts

Abstract

Pairing the carbon dioxide reduction process with the electrocatalytic oxidation of glycerol (GOR), instead of the typically applied oxygen evolution reaction, can substantially decrease the cell voltage while forming high-value products at both electrodes. In this contribution, glycerol oxidation was driven as the anode process of a CO2 electrolyzer cell employing different metal (Fe, Ni, and FeNi)-containing nitrogen-doped carbon single-atom catalysts. Under optimal conditions, GOR was sustained at industrially relevant reaction rates (above 100 mA cm–2 current density) with above 90% Faradaic efficiency toward formate formation. At identical total metal loading, the bimetallic FeNi-NC reached around 35–40% higher GOR activity and stability (more than 5 h) under industrially relevant conditions compared to its monometallic counterparts. We demonstrated that a considerable decrease in the metal loading can be achieved by employing single-atom catalysts instead of nanoparticulate catalysts to drive the GOR without sacrificing activity, selectivity, and long-term stability. Our results could serve as a stable foundation in designing future GOR catalysts that could be readily applied as anodes in CO2 electrolyzer cells.