Role of Specific N-Containing Active Sites in Interconnected Graphene Quantum Dots for the Enhanced Electrocatalytic Activity towards Oxygen Evolution Reaction

Electrochemical water oxidation is a dynamic and basal approach for several energy conversion technologies such as solar fuels and metal–air batteries. Herein, we report a novel ‘nitrogen’ (N) enriched interconnected graphene quantum dots (C-GQDs) as efficient oxygen evolution electrocatalyst, a potential candidate to replace the noble metal OER electrocatalysts. Interestingly, C-GQDs deliver a current density of 10 mAcm-2 at 350 mV, a small Tafel slope of 55 mV/dec and outstanding durability which is much superior to the state-of-the-art precious RuO2. More precisely, the unexpected behaviour of graphene quantum dots towards oxygen evolution reaction (OER) is attributed to the interconnection through N-rich framework (25 %) among the discrete particles. Predominantly, in the pyridine N-oxide, N acts as nucleophilic site and pyridinic N develops p- type doping, responsible for enhanced the OER electrocatalytic activity. The co-existence of both pyridinic N and pyridine N-oxide N induces charge redistribution through π-π delocalization to reduce the *OOH thermodynamic energy barrier. We hope that our study will encourage to develop more efficient electrocatalysts with more effective doping or surface functionalized structure by understanding the dopant nature.