High-performance flower-like and biocompatible nickel-coated Fe 3 O 4 @SiO 2 magnetic nanoparticles decorated on a graphene electrocatalyst for the oxygen evolution reaction.

The electrocatalytic oxygen evolution reaction (OER) plays a crucial role in renewable clean energy conversion technologies and has developed into an important direction in the field of advanced energy, becoming the focus of basic research and industrial development. Herein, we report the synthesis and application of flower-like nickel-coated Fe 3 O 4 @SiO 2 magnetic nanoparticles decorated on a graphene electrocatalyst for the OER that exhibit high efficiency and robust durability. The catalysts were optimized using a rotating ring-disk electrode to test their oxygen evolution properties in 1.0 M KOH solution. Importantly, owing to the high specific surface area and conductivity of C 3 N 4 and graphene, the as-synthesized Fe 3 O 4 @SiO 2 @NiO/graphene/C 3 N 4 exhibits a small Tafel slope of 40.46 mV dec -1 , low overpotential of 288 mV at 10 mA cm -2 , and robust OER durability within a prolonged test period of 100 h. The cytotoxicity of Fe 3 O 4 @SiO 2 , Fe 3 O 4 @SiO 2 @NiO, and Fe 3 O 4 @SiO 2 @NiO/graphene/C 3 N 4 was evaluated in HeLa and MC3T3-E1 cells, demonstrating that they are efficient and biocompatible catalysts for the OER. Owing to its excellent electrocatalytic efficiency and eco-friendliness, Fe 3 O 4 @SiO 2 @NiO/graphene/C 3 N 4 has considerable potential as a new multifunctional composite for large-scale applications in catalysis, biology, medicine, and high-efficiency hydrogen production.