Electrochemical Reduction of CO₂ at Sb and Bi Electrodes in KHCO₃ Solution

Electrochemical reduction of CO2in KHCO3solutions was studied using differently preparedSbandBielectr(xlesWithSbplatedelectrodesH2wasproducedmainlywitha small amount ofHCOOH Sb was not efective for CO2reductionOn the other hand withBielectrodesHCOOH wasproducedinhighcurrenteciencies with a trace amount ofCOThe current emciency and the rate for HCOOH formation were largely improved by the use of Bi plated electrodesand depen(lent on the kind of electrode substrates on which Bi was platedThe utility ofa Bi plate(l glassy carbon electro(le gave HCOOH in near100currenteciencyinthepotentialregionof_14to_17VvsSCEatthe production rate of ca1Adm-2The crent emciency seems to be dependent on the purity of the electrode surface and the particle size of Bi plated rather than the roughness factor ofthe electrode surface 11NTRODUCTlON The amount of CO2in the air has been recently increasingresulting in the consi(lerable een house efect1)Electrochemical re(luction of CO2will be one of the most efective methods for the conversion of CO2to useful materialsIt has been studied by many investigators using a varietyofmetallic and semi-conductor electrodes in a(1ueous and non-aqueous solutions2-13) showing that the elecrochemical reduction products are varied by the kind of metallic electrodes use(1These results are summarized systematically on the periodic table310)That is most of the light transition metals and light metals inB and WB groups are not effective for CO2reductionHeavy metls in H BB and V B groups produce HCOOH eectivelyAg and Au in the IB group are effective for CO productionCu in the IB group gives CH4and C2H4with small amounts of C2H50H and n