The influence of calcination temperature on the optical, magnetic and capacitive properties of NiO nanocrystals prepared with gas–liquid diffusion method

Abstract

• The morphology of NiO samples evolve with increasing calcination temperature. • The hydrophilicity of nickel oxide decreases with the increase of calcination temperature. • The magnetic susceptibility of NiO samples decreases with decreasing defects and oxygen vacancies. Three NiO nanocrystals have been obtained by calcinating nickel-based precursor synthesized with a gas–liquid diffusion method. The characterization methods such as XRD, SEM, TEM and BET were used to analyze the structure and morphology of NiO samples. XRD data analysis indicated the crystallites size of three NiO samples increased with increasing calcination temperatures. SEM and TEM characterization can also demonstrate an increase in the size of the nano-microspheres. The optical properties were investigated by Ultraviolet–visible (UV–vis) analysis. Surface wettability test was realized by measuring the contact angle. The magnetic measurement was conducted with vibrating sample magnetometer. The electrochemical testing technologies such as CV and GCD were used to evaluate electrochemical behavior of three NiO samples in 2 mol L −1 KOH. The test results showed that surface area, hydrophilicity, magnetic susceptibility and specific capacitance all decreased with the increase in calcination temperatures. The optical properties study indicated that there were both red shift and decreasing intensity for absorption peaks of the NiO samples with the increase in calcination temperature.