N-doped graphene anchored ultrasmall Ir nanoparticles as bifunctional electrocatalyst for overall water splitting

Seeking for extremely active and durable bifunctional electrocatalysts towards the overall water splitting possesses a strategic significance on the development of sustainable and clean energy for the replacement of fossil fuels. Ir-based nanomaterials are deemed as one of the most high-efficiency oxygen evolution reaction electrocatalysts while the hydrogen evolution reaction performance is unfavorable. In this work, we report a one-pot hydrothermal synthesis of N-doped graphene anchored Ir nanoparticles (Ir/N-rGO) with ultrasmall particle size (similar to 2.0 nm). Apart from the predictably superior OER performance, the resultant Ir/N-rGO also displays excellent hydrogen evolution reaction (HER) performance, requiring merely 76 and 260 mV overpotentials to achieve the current density of 10 mA cm(-2) towards HER and OER, respectively. When applied as the bifunctional electrodes for overall water splitting, Ir/N-rGO needs a lower overpotential (1.74 V) to achieve a current density of 50 mA cm(-2) in alkaline solution, exceeding that of Pt/C and RuO2 couple (1.85 V). Thus, the as-fabricated Ir/N-rGO has a commendable prospect in the practical application of alkaline water electrocatalysis. (c) 2021 Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.