Defect-rich carbon-coated nickel–cobalt alloy nanoparticles enhanced the OER catalytic activity through surface reconstruction

Abstract

The development of cheap but high activity and strong stability OER electrocatalysts is of great significance to improve electrochemical energy storage and conversion efficiency. A kind of nickel–cobalt alloy nanoparticle coated with a defect-rich carbon layer derived from citric acid was developed as an advanced alkaline OER electrocatalyst by simply annealing the citrate-coordinated nickel–cobalt complex. The formation of the alloy has promoted internal electron transfer, and the catalyst features unique structural advantages. The metal center was confined to the citrate-derived defect-rich carbon layer structure, which reduced the agglomeration of nanoparticles, increased the electrical conductivity, and exposed more active sites. The as-synthesized Ni_0.8Co_0.2(CA) showed a remarkable catalytic activity (an overpotential of 200 mV at 10 mA cm⁻² and a Tafel slope of 87 mV dec⁻¹), which also had good long-term stability. This study will contribute to deeper understanding of ligand selection and the design of high-performance alloy catalysts.