Electrochemical oxidation of gaseous benzene on a Sb-SnO2/foam Ti nano-coating electrode in all-solid cell

Abstract

An all-solid cell with a solid polymer electrolyte was applied to electrochemical oxidation of low-concentration indoor gaseous aromatic pollution. Antimony-doped tin dioxide nanocoatings deposited on a titanium foam substrate (Ti/Sb-SnO2) with different Sb/Sn ratios (4.8–14.0 mol%) and loading weight of Sb-SnO2 (4.4–7.7 mg cm-2) were used as dimensionally stable anodes. Sn and Sb were homogeneously dispersed on the substrate, and a crack-free nanocoating was built when the loading of nanocoating was increased to 6.3 mg cm-2. The activity tests for oxidation of benzene showed that 40 ppm gaseous benzene was converted to CO2 with high selectivity (85%) at the low cell voltage of 2.0 V in this all-solid cell. The conversion of benzene was greatly increased from 30% to 100% upon increasing the Sb/Sn ratio of the nanocoating from 4.7 mol% to 14.0 mol%. With the increase of nanocoating loading (Sb/Sn = 14.0 mol%) from 6.3 to 7.7 mg cm-2, the conversion of 100 ppm benzene was increased from 70% to 100%. Cyclic voltammetry revealed that high Sb content in the oxide nanocoating increased the overpotential and current intensity of the oxygen evolution reaction. The large outer charge qo∗ related to the electroactive surface of the SS-7.7/Ti3 electrode was up to 305.3 mC cm−2, which were responsible for its excellent electrochemical performance in the benzene oxidation process. Our studies provide a potential method for removal of indoor VOCs at ambient temperature.