ELECTROCHEMICAL SYNTHESIS OF UREA AT GAS-DIFFUSION ELECTRODES - PART II - SIMULTANEOUS REDUCTION OF CARBON-DIOXIDE AND NITRITE IONS AT CU, AG AND AU CATALYSTS

Simultaneous reduction of CO2 and nitrite ions was examined by using t he gas-diffusion electrodes with Cu, Ag and Au catalysts. The formatio n of urea, CO, formic acid and ammonia was found in the simultaneous r eduction. 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 ammon ia precursor and CO precursor on the catalysts. (C) 1998 Elsevier Scie nce S.A.