Single-Pass Electrooxidation of Glycerol on Bismuth-Modified Platinum Electrodes as an Anodic Process Coupled to the Continuous CO2 Electroreduction toward Formate

Abstract

CO2 electroreduction has emerged as a promising strategy for reducing emissions while simultaneously generating valuable products, particularly formic acid/formate. To further enhance the sustainability of this process, the traditional oxygen evolution reaction at the anode can be replaced by a more interesting reaction like glycerol oxidation to high value-added products, in a covalorization approach. In this study, the effect of the presence of a bismuth (Bi) atom supplier (Bi2O3 particles) in the anolyte solution during the glycerol electrooxidation process on platinum (Pt) electrodes coupled with the electroreduction of CO2 to formate is investigated for the first time, operating in a continuous mode with a single pass through the reactor. The results reveal that in the cathode, significant HCOO– production, with Faradaic efficiencies reaching 93%, and modest energy consumption of 208 kW h·kmol–1 were obtained in the continuous CO2 electroreduction to formate using Bi gas diffusion electrodes. On the other hand, in the anode, the presence of Bi2O3 particles leads to a significant alteration in the distribution of high-value-added oxidation products obtained. For instance, the anode demonstrates remarkable dihydroxyacetone (DHA) production of 283 μmol·m–2·s–1, surpassing the results obtained with the nonmodified Pt electrodes. The performance of this system offers a promising pathway for the simultaneous coproduction of high-value-added products from both CO2 and glycerol.