CO2 Electroreduction Coupled with the Electrooxidation of Alcohols and Sugars to Formate: Review and Evaluation.

Formate is a significant chemical raw material widely used in medicine, agriculture, dyes, and energy storage. The electroreduction of carbon dioxide (CO2) to formate has become a hot topic in the context of CO2 capture and utilization, which is relatively mature and industrially applicable. Currently, the oxygen evolution reaction (OER), which is the counter process at the anode of the electroreduction of CO2 to formate, is the cause of high energy demand. Alternatively, electrooxidation of alcohols and sugars (mono- and polyols) can be implemented as anode processes to decrease the energy requirements and enable the possibility of generating value-added products on both sides of the electrolysis cell. This article reviews the literature on CO2 electroreduction coupled with the electrooxidation of alcohols and sugars, with formate as a target product, and analyzes factors that influence their efficiency such as catalytic materials, electrolytes, and electrolyzer designs in the coupled configuration. Additionally, the current understanding of the economic and environmental feasibility of coupling these two reactions towards formate production and upscaling deployments will be analyzed. Finally, current challenges and possible future development directions towards implementation at scale are pointed out.