Nickel-Incorporated, Nitrogen-Doped Graphene Nanoribbons as Efficient Electrocatalysts for Oxygen Evolution Reaction

We report a scalable method for the preparation of nickel incorporated nitrogen-doped graphene nanoribbon (Ni/NGNRs) through a facile solvothermal process. Significantly, we show that the incorporation of nitrogen functionalities on graphene nanoribbon with tunable nickel content not only catalyzes efficiently the water oxidation reaction but enables to tweak the catalytic reactivity. Thus, Ni/NGNRs composite with higher nickel content exhibits an overpotential of 380 mV with a Tafel slope of 60 mV dec(-1) to sustain 10 mA cm(-2) under alkaline conditions. Furthermore, only a negligible current density drop is witnessed during the chronoamperometric studies suggesting the robust nature of the electrocatalyst. XPS analysis of the composite before and after polarization studies confirms the formation of nickel oxide on the exposed nickel nanoparticles during the electrochemical reaction but without any major adverse effect on the performance. We attribute the formation of nickel oxide on the exposed nickel nanoparticles as the major reason for the observed enhancement of electrocatalytic performance. (C) 2018 The Electrochemical Society.