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 CO2 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 CO2 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 CO2 reduction activity, a formation rate of CO 254 mu mol 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 CO2 (CO2 TPD-MS) indicated that CO2 adsorption capacity of the electrocatalyst was irreverent to their electroreduction activity for CO2.