Production of reduced graphene oxide via hydrothermal reduction in an aqueous sulphuric acid suspension and its electrochemical behaviour

Widespread availability of fuel cells is being delayed due to the scarcity and high expense of precious metal catalysts, which presently provide the most efficient oxygen reduction reaction (ORR). Research has shown efficient electrocatalysis towards ORR from carbon materials offers a possible alternative to precious metal catalysts. Increasing focus is being given to the provision of graphene by the reduction of graphene oxide (GO) as a facile method for possible up-scaled production. Presented is a novel method for the production of electrocatalytic graphene-like material, involving the hydrothermal reduction of GO suspended in 0.1 M sulphuric acid (denoted as rGO H2SO4). The rGO H2SO4 sample provides a more efficient electron transfer during ORR than GO reduction in hydrazine (denoted as rGO N2H4), a commonly employed, but toxic reducing agent. The overall current observed from the rGO H2SO4 preparation is similar to that provided by rGO N2H4 during diffusion-controlled linear sweep voltammetry analysis. Oxygen reduction catalysis of the rGO H2SO4 sample is seen to be promoted by the incorporation of sulphur, along with the high level of surface defects created after GO reduction. The diffusion-dependent conditions of cyclic voltammetry analysis confirms a pseudocapacitive response from the rGO preparations. The stability of this pseudocapacitance is significant for all reduced graphene oxide (rGO) samples discussed, opening the possible dual application of both electrical power generation and power storage capabilities.