Electrochemical reduction of CO2 on an in KOH plus methanol at low temperature

The electrochemical reduction of CO2 in KOH + methanol electrolyte was investigated with a gold electrode at -25, -15, 0 and 15 degrees C. The main products from CO2 were carbon monoxide and formic acid. The current efficiency for CO formation was larger than that for formic acid formation. In general, the formation efficiency for CO increased as the temperature decreased, however in contrast, hydrogen formation decreased. The selectivity of CO2 reduction over H-2 evolution was ameliorated by decreasing temperature. From the Tafel plot study, a sufficiently high mass transfer of CO2 to the electrode was confirmed even in the low temperature region. Consequently, it was found that temperatures of less than 0 degrees C were effective for the suppression of hydrogen formation on the Au electrode in the KOH + methanol electrolyte. (C) 1998 Elsevier Science S.A.