Electrochemical Reduction of Carbon Dioxide Using Ag Catalysts Prepared by Electrodeposition in the Presence of Additives

초록

Ag catalysts were fabricated for the electrochemical reduction of CO2 by an electrodeposition method using various additives, such as polyvinylpyrrolidone, cetyltrimethylammonium bromide, benzotriazole, and polyethyleneimine. Ag catalysts with and without additives exhibited different physicochemical properties, including morphologies, crystallinities, and electrochemical activities to CO production. With the exception of Ag-polyvinylpyrrolidone catalysts, the Ag catalysts showed dendritic or porous structures with deposit sizes ranging from nanometer-to micrometer-scale. At a CO2 reduction potential of -1.5 V (V vs. saturated calomel electrode), dendritic Ag-benzotriazole catalysts achieved the highest CO faradaic efficiency (39.21%), while porous Ag-polyethyleneimine catalysts showed the highest CO production rate of (5.5 mu L/min) in CO2-saturated 0.5 M KHCO3 electrolyte. Among samples fabricated using the same additive, the trend in catalytic activities, represented by faradaic efficiency, was correlated with their Ag 220)/Ag(111) intensity ratios. As a result, Ag catalysts with high activities in CO2 reduction to CO or syngas were fabricated using electrodeposition in the presence of organic additives.

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