Self-Standing 3D Core–Shell Nanohybrids Based on Amorphous Co–Fe–B_i Nanosheets Grafted on NiCo₂O₄ Nanowires for Efficient and Durable Water Oxidation

Here, a three-dimensional (3D) core–shell nanohybrid based on few-layer amorphous Co–Fe–B_i nanosheets directly grown on crystalline NiCo₂O₄ nanowires supported on the Ni foam (Co–Fe–B_i/NiCo₂O₄/NF) are facilely fabricated as highly efficient and durable electrocatalysts for water oxidation. This self-standing 3D core–shell nanohybrid design with unique materials chemistry and excellent interface engineering enhances the mass transport and stimulates the production of active sites during the oxygen evolution reaction. Serving as the anode catalysts, the resulting self-standing Co–Fe–B_i/NiCo₂O₄/NF nanohybrid electrocatalysts show a better electrocatalytic activity with an overpotential of 227 mV at 10 mA/cm², a Tafel slope of 45 mV dec^–1, excellent durability over 40 h, and the ability to deliver a current density of 200 mA/cm² at an overpotential of ∼410 mV in an alkaline medium. Thus, the excellent electrocatalytic performance of the Co–Fe–B_i/NiCo₂O₄/NF nanohybrid demonstrates the importance of design and development of core–shell nanohybrids for large-scale practical applications in a multitude of energy conversion devices.