Electrochemical synthesis of urea at gas-diffusion electrodes Part II. Simultaneous reduction of carbon dioxide and nitrite ions at Cu, Ag and Au catalysts

摘要

Simultaneous reduction of CO_2 and nitrite ions was examined by using the gas-diffusion electrodes with Cu, Ag and Au catalysts. The formation of urea, CO, formic acid and ammonia was found in the simultaneous reduction. The maximum current efficiencies of urea formation at Cu, Ag and Au catalysts are 37%, 38% and 26% in the range of -0.75 to -3.0 V (SHE), respectively. Urea is supposed to be formed from both an ammonia precursor and CO precursor on the catalysts.