G. Nogami et al., INVESTIGATION OF FIXATION MECHANISM OF CARBON-DIOXIDE ON OXIDE SEMICONDUCTORS BY CURRENT TRANSIENTS, Journal of the Electrochemical Society, 140(4), 1993, pp. 1037-1041
The fixation mechanism of CO, on tin oxides which are likely to be deg
raded during the reduction processes was investigated by a current tra
nsient technique, which enables us to make a quick measurements for th
e electrode before being degraded. A current transient observed when a
step bias is applied was analyzed in terms of CO2 pressure, pH, and e
lectrode potential. The total charge passed during the transient was f
ound to depend on the square root of CO2 pressure and pH. Combining wi
th the XPS data, it was concluded that the hydrocarbonization mechanis
m of CO2 on SnO2 in acidic solutions is given by CO2 + H+ + 2e --> HCO
O(ad)-It is pointed out that the electroreduction mechanism deduced fr
om a long-term electrolysis which is performed under the steady-state
condition can be much different from that estimated from the transient
technique proposed here. A pulsed electroreduction technique will off
er a useful tool in synthesizing desired products from CO2.