Long-term stable and selective conversion of carbon dioxide to formate using dental amalgam electrode

• Published in: Journal of CO2 utilization 2021-03, Vol.45, p.101435, Article 101435
• Main Authors: Park, Mijung, Shin, Woonsup
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Dental amalgam, Formate; Electrochemistry; Long-term electrolysis; Selective conversion
• ISSN: 2212-9820; 2212-9839
• DOI: 10.1016/j.jcou.2021.101435

•A newly developed dental amalgam electrode system enabled selective CO2-to-formate conversion for more than a month.•It showed a faradaic efficiency of 80–100 % for the formate production at a wide potential range of -1.5 to -2.3 V vs. Ag/AgCl.•The selectivity of the carbon conversion was 100 % in the range of -1.6 to -2.3 V vs. Ag/AgCl.•The high concentration formate production up to 2.4 M (18 wt%) was obtained. The process of electrochemical conversion of CO2 to a valuable chemical requires the use of an electrode material with high selectivity and stability. In this study, we successfully fabricated a dental amalgam composition on a copper foam electrode and demonstrated the selective conversion of CO2 to formate. The faradaic efficiency was 80–100 % at current densities ranging from 50 to 250 mA∙cm−2. The residual electricity was used solely to produce H2, and all the carbon atoms in CO2 were converted to formate. It enabled the easy separation of the highly water-soluble formate from the gaseous hydrogen. The produced formate concentration was up to 2.4 M (18 wt%), and the electrolyzer based on the dental amalgam electrode was effectively operated both continuously and intermittently for over a month. The results demonstrated the feasibility of the economic and large-scale CO2-to-formate conversion process.