(343a) High-Efficiency Electrochemical Conversion of CO2 to Value Added Fuels Current Status, Challenges, and Future Directions

The electrochemical reduction of carbon dioxide (CO₂) into liquid fuels especially coupling with the intermittent renewable electricity offers a promising means of storing electricity in chemical form, which reduces the dependence on fossil fuels and mitigates the negative impact of anthropogenic CO₂ emissions on the planet. Although converting CO₂ to fuels is not in itself a new concept, the field has not substantially advanced in the last 30 years primarily because of the challenge of discovery of structural electrocatalysts and the development of membrane architectures for efficient collection of reactants and separation of products. In this presentation, I would summarize recent advances in electrocatalytic conversion of CO₂ and presents the challenges and future directions in producing value-added fuels.

Currently, copper, silver and tin are the most extensively scrutinized electrocatalysts, which can convert CO₂ to CO, CH₄, C₂H₄, alcohols and carbolic acid in aqueous electrolytes. A long-lasting challenge in the electrosynthesis of fuels from CO₂ is to achieve a durable electrochemical performance, an equally important characteristic of an electrode as the activity and selectivity, but it has not yet been clearly addressed in the open literature. Hypotheses for the origin of the deactivation of CO₂ reduction electrode included the formation of intermediates like oxide, hydroxide and carbon species, as well as the accumulation of a soluble CO₂ reduction product in the electrolyte causing a remarkable decrease in the selectivity. Hori et al. examined the deactivation of Cu electrode and postulated that the degradation of the cell performance was originated from the deposition of iron and zinc contaminants in the electrolyte on the active surface of the catalyst. The impurity alone, however, cannot explain the degradation since the ultrapure electrolyte coupled with pre-electrolysis was used, in which the degradation was still observed. I will discuss approaches to simultaneously achieve high efficiency and high stability of an electrocatalyst for the conversion to CO₂ to value-added fuels.