Spherical ZnFe2O4 Nanoparticles on Nitrogen-Doped Graphene: A Synergistic Effect on Efficient Electrocatalytic Oxygen Evolution Reaction

The bottleneck of large-scale implementation for electrocatalytic water technology lies in the lack of cheap, efficient, and durable electrocatalysts to accelerate the slow oxygen evolution reaction (OER) kinetics. The spinel ZnFe2O4 electrocatalyst is low priced and facilely synthesized; however, an insufficient active site and poor conductivity limit its application on OER. Well-dispersed spherical ZnFe2O4 nanoparticles anchored on nitrogen-doped graphene (ZFO-NG) were aimed to be synthesized for enhancing OER catalytic activity and stability in this work. The ZFO-NG electrocatalyst exhibits a low overvoltage of only 240 mV at 10 mA cm–2 and a Tafel slope of 63.5 mV dec–1, which are superior to those of commercial IrO2 and other reported spinel OER electrocatalysts. ZFO-NG also had long-term stability of over 30 h. The splendid OER activity and stability are due to the strong Fe–N interaction between zinc ferrate and nitrogen-doped graphene. This work provides inspiration for synthesis of low-cost and efficient spinel catalysts for OER.