KOH-activated CoO mesoporous nanoarrays for boosted supercapacitive performance

Highly active transition metal oxides mesoporous materials have tremendous potential applications in energy storage and catalysis due to their great physicochemical performance. However, the regulation of porous structures still faces many challenges, and the synthesis of mesoporous materials is usually costly and long-time consuming. Herein, using CoO as the example, a strategy based on KOH activation and substitution reaction has been proposed to prepare CoO nanoarrays mesoporous material and improve its electrochemical performance. The CoCO3Co(OH)2 nanoarrays on Ni foam are transformed into a Co(OH)2 nanoarrays with high crystallinity through the substitution reaction in KOH solution. Meanwhile, the activation effect of KOH provides abundant porous structures for etching the nanoarrays. During the annealing process, the high crystallinity of Co(OH)2 effectively alleviates pore collapse, thereby obtaining a CoO nanoarrays mesoporous material with excellent electrochemical performance (denoted as A-CoO@NF). As the positive electrode material for supercapacitors, A-CoO@NF shows a high specific capacity of 775.6 C g−1, far higher than that of CoO@NF (416.5 C g−1). The enhanced electrochemical performance is attributed to its unique mesoporous structures, which positively promote electrolyte permeation and ion diffusion, and the ultrafine nanocrystals and smaller lattice parameters provide numerous edge active sites and enhance the conductivity. The strategy proposed here is expected to become a template-free, low-cost, and efficient preparation route for synthesizing more types of highly active metal oxide mesoporous materials.