The Electrochemical Oxidation of Sulphite on Gold Electrodes

Abstract

The electro‐oxidation of sulphite is studied in acid media on gold macroelectrodes and Au particle array modified boron doped diamond electrodes. The sulphite oxidation proceeds through a one‐electron transfer process followed by a chemical step of second order (EC2 mechanism), as evidenced by experimental voltammetry and digital simulation for both gold macroelectrodes and gold particle modified substrates. The diffusion coefficient of sulphite is calculated consistently for both cases at about 4×10−9 m2 s−1, with the reverse peak behaviour concentration dependent. The arrays are made by electrodeposition and show a morphological transition from a quasi‐spherical to a star shape as the growth time of the particles increases. Kinetic parameters inferred from the electro‐oxidation at the macroelectrode can be successfully applied to model the gold particle modified electrode data to confirm the EC2 mechanism, whilst recognising the overlapping diffusion layers of adjacent gold particles.

Concurrent Electrolysis under Pressured CO2 for Simultaneous CO2 Reduction and Hazardous SO2 Removal

“…These fundamentally make it promising to pair CO 2 RR with SOR at elevated CO 2 pressures for the flue gas treatment. In addition, the noble metals such as Au and Pt were mostly reported as electrocatalysts for SOR, 23,27,37,38 while the non-noble electrocatalysts with high performance at near-neutral pH are still scarce and, to the best of our knowledge, coupling of CO 2 RR and SOR at pressured CO 2 has not been reported.…”

A Sulfite/Air Fuel Cell with Alkali and Sulfuric Acid Byproducts: Bifunctional Electrocatalyst for Sulfite Oxidation and ORR Activity

“…The electrochemical oxidation of sulfite or dissolved SO 2 has been presented on a range of materials, such as platinum group materials, [15][16][17] gold, [18][19][20][21] graphite, [22][23][24][25] nitrogen-doped catalysts, 26,27 lead dioxide, 28 etc. As most of the graphite electrodes are inert, it is not suitable for sulfite/air fuel cell.…”

“…(b) Sulfite radicals can combine to form dithionate without electron transfer. The dithionate can then decompose into sulfite and sulfate via a disproportionation step at above 50 °C 19.…”