National Research Council of Canada. Energy, Mining and Environment
electrochemical reduction of CO₂; gas diffusion electrode; catalytic activity; onset potential; formic acid
Gas diffusion electrodes (GDEs) modified with N,Nʹ-Bis(salicylidene)-ethylenediamine-cobalt(II) (Cosalen) and conductive carbon black (BP) have been prepared. It is demonstrated that modified BP-Cosalen/GDE electrode is able to catalyze CO2 reduction in a more efficient and selective manner than that of bulk Cosalen/GDE in 0.5 M KHCO3 solution. In the presence of 60 wt% of BP, the as-prepared BP-Cosalen/GDE electrode exhibits the highest activity for catalyzing CO2 reduction reaction, wherever increase or decrease the amount of BP do not benefit to CO2 reduction. Compared to other BP-Cosalen/GDE electrodes, the BP-Cosalen/GDE60 shows the most positive onset potential, and the maximum current density reaches 21 mA cm−2. The improved catalytic activity is largely due to the excellent electrical conductivity and the developed pore structure of BP which provides more active phases for the electrochemical reduction of CO2. Further analysis of reduction product reveals that the product on BP-Cosalen/GDE60 electrode is formate in 0.5 M KHCO3 electrolyte. The highest faradaic efficiency reached 27 % along with the production rate of formate as much as 0.44 mM.
Journal of Solid State Electrochemistry19, no. 11: 3355–3363.