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 ZnFe 2 O 4 electrocatalyst is low priced and facilely synthesized; however, an insufficient active site and poor conductivity limit its application on OER. Well-dispersed spherical ZnFe 2 O 4 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 IrO 2 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.