Electrocatalytic Reduction of Carbon Dioxide on Nanosized Fluorine Doped Tin Oxide in the Solution of Extremely Low Supporting Electrolyte Concentration: Low Reduction Potentials

Abstract

Fluorine doped tin oxide (FTO) has been prepared via the direct chemical reaction of tin oxide powders and hydrofluoric acid at room temperature. The image of FTO displays a sphere-like structure with an average diameter of 40–100 nm. The spectra of X-ray photoelectron spectroscopy (XPS) demonstrate that fluorine is doped into SnO2. A well-defined reduction peak at −0.50 V (vs SCE) is detected on the cyclic voltammogram (CV) of the nanosized FTO (n-FTO) electrode in CO2-saturated 3.6 × 10–4 μM H2SO4 solution of pH 5.5, which is strong evidence for the electrochemical reduction of CO2. This result indicates that the n-FTO electrode in such an extremely low supporting electrolyte concentration exhibits good electrocatalytic ability toward CO2 reduction under lower potentials. On the basis of reduction peak current as a function of scan rate, the reduction of CO2 is first performed via adsorption of CO2 on the n-FTO electrode surface, and then CO2 is reduced. The product solution obtained under a constant po...