Electrocatalytic reduction of low concentration CO2

• Published in: Chemical science (Cambridge) Vol. 10; no. 6; pp. 1597 - 1606
• Main Authors: Kumagai, Hiromu, Nishikawa, Tetsuya, Koizumi, Hiroki, Yatsu, Taiki, Go Sahara, Yamazaki, Yasuomi, Tamaki, Yusuke, Ishitani, Osamu
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2019
• Subjects: Carbon dioxide; Carbon sequestration; Chemical reduction; Curve fitting; Electrolysis; Exhaust gases; Gases; Infrared analysis; Infrared radiation; Infrared spectroscopy; Power consumption; Power plants; Selectivity; Thermal power plants; Triethanolamine
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c8sc04124e

Utilization of low concentration CO2 contained in the exhaust gases from various industries and thermal power stations without the need for energy-consuming concentration processes should be an important technology for solving global warming and the shortage of fossil resources. Here we report the direct electrocatalytic reduction of low concentration CO2 by a Re(i)-complex catalyst that possesses CO2-capturing ability in the presence of triethanolamine. The reaction rate and faradaic efficiency of CO2 reduction were almost the same when using Ar gas containing 10% CO2 or when using pure CO2 gas, and the selectivity of CO formation was very high (98% at 10% CO2). At a concentration of 1% CO2, the Re(i) complex still behaved as a good electrocatalyst; 94% selectivity of CO formation and 85% faradaic efficiency were achieved, and the rate of CO formation was 67% compared to that when using pure CO2 gas. The electrocatalysis was due to the efficient insertion of CO2 into the Re(i)–O bond in fac-[Re(dmb)(CO)3{OC2H4N(C2H4OH)2}] (dmb = 4,4′-dimethyl-2,2′-bipyridine).