The influence of surface modification on the optical and capacitive properties of NiO nanoparticles synthesized via surfactant-assisted coprecipitation

Abstract

Material design and surface properties are considered as the main challenges towards the fabrication of a well-functionalized and stable device. In this work, surface-functionalized mesoporous NiO nanoparticles are synthesized via a facile one-pot precipitation method using sodium dodecyl sulfate and urea at 80 °C. The surface modification takes place via the addition of different bases such as NH4OH, NaOH, or K2HPO4 and the mechanism of NiO formation is highlighted. XRD verifies the formation of NiO as a major phase. IR proves the surface modification of NiO by sulfur, carbon, and nitrogen. Interestingly, ultrathin Ni(OH)2/NiO nanosheets of graphene-like shape are formed for the samples prepared by NH4OH demonstrating an enhancement in the specific capacitance, making it an attractive material for supercapacitors. On the other hand, mixed-shaped nanoparticles of ammine enriched surface are formed for the samples treated with NaOH demonstrating unusual ferromagnetic behavior and causing a narrowing in the band gap for NiO. XPS confirms the existence of sodium and potassium on the NiO surface, which improve the CO2 selective adsorption. Thus, surface functionalization is found to play a significant role in tuning the electronic, optical, and magnetic properties of NiO providing new future perspectives towards different applications.