An Oxygen Reduction Study of Graphene-Based Nanomaterials of Different Origin

The aim of this study is to compare the electrochemical behaviour of graphene-based materials of different origin, e.g., commercially available graphene nanosheets from two producers and reduced graphene oxide (rGO) towards the oxygen reduction reaction (ORR) using linear sweep voltammetry, rotating disc electrode and rotating ring-disc electrode methods. We also investigate the effect of catalyst ink preparation using two different solvents (2-propanol containing OH− ionomer or N,N-dimethylformamide) on the ORR. The graphene-based materials are characterised by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. Clearly, the catalytic effect depends on the origin of graphene material and, interestingly, the electrocatalytic activity of the catalyst material for ORR is lower when using the OH− ionomer in electrode modification. The graphene electrodes fabricated with commercial graphene show better ORR performance than rGO in alkaline solution