Electrochemical synthesis of urea at gas-diffusion electrodes .1. Simultaneous reduction of carbon dioxide and nitrite ions at Zn catalysts

Simultaneous reduction of carbon dioxide and nitrite ions was carried out using the gas-diffusion electrodes having Zn catalysts. The formation of urea was found in the simultaneous reduction. The current efficiency of urea formation is approximately 50-55% at the potentials between -1.0 V and -2.4 V (SHE). Urea seems to be formed from both of ammonia precursor and CO precursor on the Zn catalysts, The most suitable condition of urea formation is as follows: (1)1 M nitrite ions, (2)CO2 pressure more than 1 atm, (3)10 degrees C.