Porous 3D columnar-sphere of NiO nanomaterials synthesized for supercapacitors via hydrothermal route: impact of thiourea concentration

Abstract

The charge storage application has witnessed a dramatic increase in terms of the short charge–discharge time of supercapacitors, specifically in highly active electrode materials. For charge storage supercapacitor applications, highly porous materials are preferable. In this research article, thiourea acts as a leaving agent in the preparation of the porous 3D spherical architecture of NiO nanomaterials. The influence of the molar concentration of thiourea on structural, morphological, and electrochemical charge storage applications has been studied. X-ray diffraction reveals a cubic structure with Fmm space group for the NiO nanomaterials. The scanning electron microscopy (SEM) images show the porous 3D columnar spherical structure, and FTIR has been used for the optical analysis of the NiO materials. The 1D–3D columnar-spherical structure of the NiO flakes exhibits a high electrochemical charge storage pseudocapacitive nature. The optimized 0.40 M thiourea–NiO (Th–NiO) nanomaterial is highly hydrophilic, exhibiting a maximum specific capacity of 171.1 mA h g⁻¹ at 5 mV s⁻¹ by CV and 148.5 mA h g⁻¹ at 0.2 mA cm⁻² by GCD. The highest power, energy densities are 0.96 kW kg⁻¹ and 6.66 W h kg⁻¹ with the highest charge–discharge cycle rating of 92% up to 5000 cycles of the asymmetric NiO//rGO hybrid supercapacitor device.