Facile Synthesis of N, S-Doped Graphene from Sulfur Trioxide Pyridine Precursor for the Oxygen Reduction Reaction

In the work presented here, nitrogen and sulfur co doped on porous graphene was synthesized using pyrolysis at 900°C for 2h and the hydrothermal technique at 180°C for 24h as metal-free electrocatalysts for oxygen reduction reaction (ORR) under alkaline conditions. All the materials have been characterized by Scanning Electron Microscopy (SEM) and X-ray photo-electron spectroscopy (XPS). Moreover for electrochemical evaluation of samples, Rotating Disk electrode (RDE) and Cyclic Voltammetry techniques (CV) were employed. The results showed that co-doping of S and N into porous graphene significantly enhance the ORR performance. Moreover, it is revealed that the catalyst prepared by the pyrolysis method shows outstanding catalytic activity for the ORR for which the number of electron in the pyrolysis method was calculated to be 4.1; whereas it became 2.6 in the hydrothermal approach. So regarding the obtained results, it can be stated that the samples prepared through the pyrolysis method exhibits excellent resistance towards methanol crossover effects, indicating their promising potential as ORR electrocatalysts for alkaline fuel cells.