Facile synthesis of ZnCo2O4 mesoporous structures with enhanced electrocatalytic oxygen evolution reaction properties

Abstract

Recently, as one kind of ternary spinel metal oxide, ZnCo₂O₄ has attracted extensive attention in the energy storage and conversion field due to it being cost-effective, scalable, and environmentally friendly. Herein, porous ZnCo₂O₄ micro-spindles and truncated drums were synthesized by a solvent thermal route first and then with an annealing treatment with the precursors. The morphology and structure of ZnCo₂O₄ were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). It is worth noting that ZnCo₂O₄ porous micro-spindles show a high surface area of 65.85 m² g⁻¹ with an average pore diameter of ∼6.34 nm. The as-prepared ZnCo₂O₄ materials, especially micro-spindles, exhibited good electrocatalytic water-splitting performance with excellent activity and stability. The ZnCo₂O₄ micro-spindle catalyst exhibits an overpotential of 0.389 V at the benchmark of a current density of 10 mA cm⁻². The Tafel slope is 59.54 mV dec⁻¹ and the OER overpotential of the catalyst shows no obvious increase during 7200 s. The high activity, low Tafel slope, and good stability will pave the way for the use of ZnCo₂O₄ micro-spindles in practical applications.