Ternary FeCoNi alloy nanoparticles embedded in N-doped carbon nanotubes for efficient oxygen evolution reaction electrocatalysis

The development of highly active and low-cost electrocatalysts toward oxygen evolution reaction (OER), especially the non-noble metal electrocatalysts with well-defined nanostructures, is of great significance for the practical application in metal–air batteries and overall water splitting. Herein, we report a simple pyrolysis method to construct the ternary FeCoNi alloy nanoparticles that encapsulated with bamboo-like N-doped carbon nanotubes (N-CNTs). By combining the advantages of FeCoNi alloy with N-CNTs, the as-fabricated FeCoNi@N-CNTs have large active surface area, ultrahigh content of graphitic carbon, and abundant active metal–C/N_x species to show better electrocatalytic performance for OER in alkaline media. The optimized Fe₁Co₁Ni₁@N-CNTs displays perfect electrocatalytic performance toward OER with an unexpectedly small onset potential of 1.43 V and an ultralow overpotential of 249 mV at 10 mA cm⁻², as well as remarkable long-time stability in alkaline media. More importantly, by coupling Fe₁Co₁Ni₁@N-CNTs as the anode electrode, our previous reported Fe₁Co₃Mo₃ P–O as cathode electrode, a potential of only 1.62 V is needed to drive the water electrolysis to reach to the current density of 10 mA cm⁻², comparable to the state-of-the-art IrO₂ ‖ Pt/C couple. This work provides new perspectives for constructing efficient and stable N-CNTs encapsulated non-precious metal electrocatalysts for OER.