Electrocatalytic Activity of Co-4,4′dimethyl-2,2′-bipyridine Supported on Ketjenblack for Reduction of CO2 to CO Using PEM Reactor

Electrochemical reduction of CO 2 was carried out to synthesize CO by using a gas-electrolysis cell. Heat treatment of Co(dmbpy) 3 (dmbpy: 4,4′-dimethyl-2,2′-bipyridine) complex on Ketjenblack (KB) in a He stream at 673 K provided an effective electrocatalyst, as denoted Co-dmbpy/KB, for selective reduction of CO 2 to CO. Both Co loadings and dmbpy/Co ratios in the Co-dmbpy/KB precusors played important roles in determining their electrocatalytic activities. Under potentiostatic electrolysis at −0.70 V (standard hydrogen electrode (SHE)), Co-dmbpy/KB (Co loading 1 wt%, dmbpy/Co = 5) showed an excellent CO 2 reduction activity, a formation rate of CO 254 μmol h −1 cm −2 and a faradic efficiency of CO 78.0%. By localizing the electrocatalyst at the interface between cathode and Nafion, the electrocatalyst was efficiently utilized and a high turn-over number 1183 h −1 was achieved. Temperature-programmed desorption mass spectrometry for CO 2 (CO 2 TPD-MS) indicated that CO 2 adsorption capacity of the electrocatalyst was irreverent to their electroreduction activity for CO 2 . Graphical Abstract CoN x C y /ketjen-black electrocatalyst prepared by partial pyrolyzed precursor of Co(NO 3 ) 2 , 4,4'-dimethyl-2,2'-bipyridine (dmbpy, 5 eq.) and ketjen-black is effective for selective reduction of CO 2 to CO