Electrocatalytic reduction of low concentration CO(2)

Utilization of low concentration CO(2) 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 CO(2) by a Re(i)-complex catalyst that possesses CO(2)-capturing ability in the presence of triethanolamine. The reaction rate and faradaic efficiency of CO(2) reduction were almost the same when using Ar gas containing 10% CO(2) or when using pure CO(2) gas, and the selectivity of CO formation was very high (98% at 10% CO(2)). At a concentration of 1% CO(2), 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 CO(2) gas. The electrocatalysis was due to the efficient insertion of CO(2) into the Re(i)–O bond in fac-[Re(dmb)(CO)(3){OC(2)H(4)N(C(2)H(4)OH)(2)}] (dmb = 4,4′-dimethyl-2,2′-bipyridine).