Use of Rotating Ring-Disk Electrodes to Investigate Graphene Nanoribbon Loadings for the Oxygen Reduction Reaction in Alkaline Medium

The oxygen reduction reaction (ORR) is typically slow. Its kinetics, however, are influenced not only by the structure, nature, and doping of electrocatalysts, but also by the loadings of these materials, where all of these factors influence ORR selectivity to produce H2O and/or H2O2. The loadings employed for graphene nanoribbon (GNR)-modified glassy carbon (GC) electrodes and GC disk modified with commercial Pt (20 wt.%) on carbon (PtC) at 150 gcm(-2) (also resulting in electrode roughness) produced turbulence in the electrolyte flow, significantly changing the geometry of the rotating ring-disk electrode (RRDE) and collection efficiency (N), as well as causing N to change with the rotation rate of the electrode. This effect toward the ORR was investigated with two analytical methods derived by Wu etal. and Zhou etal. A current deconvolution method for a better-resolved Tafel analysis separating HO2- formation and reduction reactions resulted in more insightful understanding of the ORR responses provided by the RRDE for different GNR and PtC loadings.