Electrochemical impedance spectroscopy for studying the SO2 electrocatalytic oxidation on Pt electrodes

The generation of green hydrogen for a more environmentally friendly and energetic environment is in the spotlight of electrocatalysis for a while. One emerging strategy is assisted water electrolysis, in which the oxidative reaction, the limiting one, can be substituted and the SO2 oxidation reaction (SO2OR) is an interesting candidate since it will consume a lethal atmospheric pollutant, at lower potentials. To better comprehend the electrochemical kinetics of this process, in the present work, we applied electrochemical impedance spectroscopy (EIS) as a tool to understand the electrolyte composition's influence on the activity. In this way, we have shown that, despite the three tested electrolytes, 0.5 mol L−1 H2SO4, HClO4, and 1:1 mixture of these two, presented the same DC response, EIS has shown that the adsorption kinetic is different for them all, presenting the different potential of zero charge values, double layer capacitance vs applied potential profiles and very different charge transfer resistance Tafel plots.