cs7b03242_si_001.pdf (1.3 MB)
Selective Electrochemical Production of Formate from Carbon Dioxide with Bismuth-Based Catalysts in an Aqueous Electrolyte
journal contribution
posted on 2017-12-19, 00:00 authored by Chan Woo Lee, Jung Sug Hong, Ki Dong Yang, Kyoungsuk Jin, Jun Ho Lee, Hyo-Yong Ahn, Hongmin Seo, Nark-Eon Sung, Ki Tae NamFor the efficient
electroconversion of CO2 to formate,
CO and H2 evolution must be suppressed. Herein, carbon-supported
BiOx nanoparticles (BiOx/C) were investigated as a potential candidate for CO2 reduction. In bicarbonate solutions, the BiOx/C catalysts exhibited a high Faradaic efficiency of 93.4%
for formate from −1.37 to −1.70 V versus Ag/AgCl with
a negligible amount of CO and H2. Stable partial current
densities and high Faradaic efficiencies were also achieved in 0.5
M NaCl (12.5 mA cm–2 and 96.0%, respectively). The
possible reaction pathways and kinetic parameters of formate formation
were examined using systematic electrochemical methods, including
Tafel, pH dependence, and in situ X-ray absorption
near-edge structure analyses. From the results of these mechanistic
studies, we propose that dual mechanisms are functional on the BiOx/C catalysts. Specifically, a two-electron
and one-proton transfer reaction to adsorbed CO2 or a chemical
proton transfer reaction to CO2– anion
are the possible rate-determining steps (RDSs) at low potentials,
whereas a one-electron transfer reaction to CO2 is the
RDS at high potentials.