Improved electrocatalytic oxygen evolution reaction properties using PVP modified direct growth Co-based metal oxides electrocatalysts on nickel foam

Polyvinyl pyrrolidone supported ZnCo2O4 and NiCo2O4 nanoparticles with 3D nanocactus and nanoflower-like morphology, respectively, directly grown on the surface of nickel foam through a one-step hydrothermal process followed by calcination treatment were used as improved electrocatalyst for oxygen evolution reaction. This study is continuation of our previous objective about the use of polyvinyl pyrrolidone as surface stabilizer and growth modifier during nanoparticles synthesis. The resulting products were analyzed by using X-ray diffraction (XRD), field emission scanning electron micrographs (FE-SEM) equipped with energy dispersive X-ray spectrometer (EDX), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). The calculated overpotential for ZnCo2O4 NPs is as low as 0.282 V while for NiCo2O4 NPs is 0.298 V. Additionally, ZnCo2O4 NPs had obtained a low Tafel slope of 79.90 mv dec (1) while 92.28 mV dec (1) Tafel slope for NiCo2O4 NPs. Lastly, the current density was almost retained during 24 h electrochemical running and obtained 97.74% and 96.18% efficiency, for ZnCo2O4 and NiCo2O4 NPs respectively. (c) 2018 Elsevier Ltd. All rights reserved.