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 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 CO₂ (CO₂ TPD-MS) indicated that CO₂ adsorption capacity of the electrocatalyst was irreverent to their electroreduction activity for CO₂.CoN_xC_y/ketjen-black electrocatalyst prepared by partial pyrolyzed precursor of Co(NO₃)₂, 4,4'-dimethyl-2,2'-bipyridine (dmbpy, 5 eq.) and ketjen-black is effective for selective reduction of CO₂ to CO<graphic></graphic> [ABSTRACT FROM AUTHOR]