Examination and prevention of ring collection failure during gas-evolving reactions on a rotating ring-disk electrode

Use of a rotating ring-disk electrode during gas-evolving reactions has been shown liable to errors under higher current densities, since product collection on the ring is vulnerable to the formation of gas bubbles at the disk-ring interspace. In this study, we explored methods of reducing such bubble-related errors and improving the reliability of the collection factor under high-intensity gas evolution. We attempted the mounting of a thin wire close to the surface, to dislodge bubbles that formed specifically on the interface between the disk and the disk-ring spacer. This approach was tested for the detection of chlorine during parallel chlorine and oxygen evolution, and resulted in a notable alteration of the collection efficiency; its value became lower than theoretical expectations and also quite stable, even under higher current densities. We also coated the RRDE tip in a hydrophilic polymer, to reduce the tendency of bubble formation; this was tested for the collection of hydrogen and oxygen gas, and led to a mild increase in overall performance. The coating allowed for approximately 50% higher hydrogen evolution current density without ring failure, and for oxygen collection led to an overall improvement in behaviour. © 2019 The Authors