Investigation of defect centres in porous structure of nickel oxide synthesized by ecofriendly route for photocatalytic application

Porous nickel oxide nanoparticles were synthesized by solution combustion synthesis method using different concentrations (0.1, 0.2, 0.3 and 0.4 mol) of glycine as fuel and reducing agent. X-ray diffraction (XRD) pattern of the samples showed FCC structure with pure phase for all samples. By tuning the molar ratio of glycine to nickel nitrate, the porosity enhanced which was evidenced by scanning electron microscope (SEM). Transmission electron spectroscopy (TEM) exhibited spherical morphology with 30–40 nm particle size. Specific surface area was done using methylene blue dye method. The optical studies were studied systematically. The optical bandgap decreased on increasing the concentration of glycine. The room temperature Photoluminescence showed band edge emission at 359 nm and defect centres from 400 to 500 nm. The violet luminescent NiO can be used in optoelectronic devices. Porous 0.4 NiO with high defect centres was taken as photocatalyst for Methylene blue degradation under visible light.