Electrochemical CO 2 reduction with ionic liquids: review and evaluation

Abstract

Evaluation for electrochemical CO 2 reduction to C1 with Ionic liquids. The increasing CO 2 emission, as the chief culprit causing numerous environmental problems, could be addressed by the electrochemical CO 2 reduction (CO 2 R) to the added-value carbon-based chemicals. Ionic liquids (ILs) as electrolytes and co-catalysts have been widely studied to promote CO 2 R owing to their unique advantages. Among the potential products of CO 2 R, those only containing one carbon atom, named C1 products, including CO, CH 3 OH, CH 4 , and syngas, are easier to achieve than others. In this study, we first summarized the research status on CO 2 R to these C1 products, and then, the state-of-the-art experimental results were used to evaluate the economic potential and environmental impact. Considering the rapid development in CO 2 R, future scenarios with better CO 2 R performances were reasonably assumed to predict the future business for each product. Among the studied C1 products, the research focuses on CO, where satisfactory results have been achieved. The evaluation shows that producing CO via CO 2 R is the only profitable route at present. CH 3 OH and syngas of H 2 /CO (1 : 1) as the targeted products can become profitable in the foreseen future. In addition, the life cycle assessment (LCA) was used to evaluate the environmental impact, showing that CO 2 R to CH 4 is the most environmentally friendly pathway, followed by the syngas of H 2 /CO (2 : 1) and CO, and the further improvement of the CO 2 R performance can make all the studied C1 products more environmentally friendly. Overall, CO is the most promising product from both economic and environmental impact aspects.