Mass Transport Influence in the SO2 Oxidation Reaction on Au Electrodes

The use of fossil fuels as energy source is unsustainable in the long term and net-zero carbon processes need to be implemented to maintain environmental balance. One could make use of assisted water electrolysis to produce clean hydrogen and avoid high overpotentials observed for the oxygen evolution reaction by switching to the SO2 oxidation reaction (SO2OR). This process exhibits a complex mechanism on Au electrodes, which is strongly affected by convection, exhibiting an anti-Levich behavior, in which the limiting current linearly decreases with the square root of the rotation rate. Likewise, the bi-stability region observed in the j/E profiles narrows in a sigmoidal profile with the rotation rate, leading to a non-linear phenomenon with two controlling parameters, mass transport and potential applied. These events were understood to be related to the changing in the reaction mechanism by controlling the electrode rotation, much related to the decrease in the current aforementioned.