Two‐Step Synthesis of Cobalt Iron Alloy Nanoparticles Embedded in Nitrogen‐Doped Carbon Nanosheets/Carbon Nanotubes for the Oxygen Evolution Reaction

Abstract

There is a vital need to explore highly efficient and stable non-precious-metal catalysts for the oxygen evolution reaction (OER) to reduce the overpotential and further improve the energy-conversion efficiency. Herein, we report a unique and cost-effective lyophilization and thermal treatment two-step procedure to synthesize a high-performance hybrid consisting of CoFe alloy nanoparticles embedded in N-doped carbon nanosheets interspersed with carbon nanotubes (CoFe-N-CN/CNTs) hybrid. The lyophilization step during the catalyst preparation leads to a uniform dispersion of carbon-like precursors and avoids the agglomeration of metal particles. In addition, the inserted CNTs and doped N in this hybrid provide a good electrical conductivity, an abundance of chemically active sites, good mass transport capability, and effective gas adsorption/release channels. All these lead to a high specific surface area of 240.67 m² g^-1 , favorable stability, and remarkable OER activities with an overpotential of only 285 mV at a current density of 10 mA cm^-2 and a Tafel slope of 51.09 mV dec^-1 in 1.0 m KOH electrolyte, which is even superior to commercial IrO₂ catalysts. The CoFe-N-CN/CNTs hybrid thus exhibits great potential as a highly efficient and earth-abundant anode OER electrocatalyst.