Electrochemical Synthesis of Urea at Gas-diffusion Electrodes I. Simultaneous Reduction of Carbon Dioxide and Nitrite Ions at Zn Catalysts

Abstract

Simultaneous reduction of CO and nitrite ions was examined by using the gas-diffusion electrodes with Cu, Ag and Au catalysts. The 2 formation of urea, CO, formic acid and ammonia was found in the simultaneous reduction. The maximum current efficiencies of urea Ž. formation at Cu, Ag and Au catalysts are 37%, 38% and 26% in the range of y0.75 to y3.0 V SHE , respectively. Urea is supposed to be formed from both an ammonia precursor and CO precursor on the catalysts. q 1998 Elsevier Science S.A.