Different Pathways of Oxygen Reduction Reaction Studied by Rotating Disk Electrode (RDE) Voltammetry

We propose here an experimental activity aimed at the advanced undergraduate level, introducing the basic principles of Rotating Disk Electrode (RDE) Voltammetry. The objectives are (i) to demonstrate basic concepts, (ii) to build up relevant experimental skills, and (iii) to apply RDE technique to the analysis of traces of electroactive species undergoing mass-transport controlled reduction reaction. In this laboratory exercise, students are able to assess quantitatively the impact of convection on the kinetics of oxygen and/or hydrogen peroxide reduction taking place on a platinum electrode. Applied in a relatively straight forward experimental layout, the RDE protocol enables herein the determination of both oxygen concentration and number of exchanged electrons of peroxide reduction in sodium sulfate solution. The acquired knowledge provides background on a key reduction protocol that is widely used in today’s fuel cell catalysis. The developed experimental skills could be extended to other quantitative studies performed in systems that feature mass-transport limited reaction kinetics.