Production and Characterizations of Sol–Gel-Derived Li, Cu:NiO_x Particles: An Investigation on the Effects of Li and Cu Incorporation

Nickel oxide, a p-type semiconductor material with a large band gap (~ 3.6–4.0 eV), has gained interest from researchers due to its recent and widespread uses. In this work, pristine and doped (Li and Li, Cu) NiO_x particles were obtained by the sol–gel method with different fractions (Li: 0.05; Cu: 0.00, 0.05, 0.1, 0.15, 0.30). Phase structures, functional groups, elemental analyses, and optical properties were investigated by x-ray diffractometer (XRD), Fourier-transform infrared spectroscopy, x-ray photoelectron spectroscopy (XPS), and photoluminescence measurements, respectively. The XPS and XRD results indicated that Li⁺ and Cu²⁺ incorporation into NiO_x structure was successfully achieved and the crystallite size decreased owing to Li⁺ and Cu²⁺ addition. The particles were excited at 362 nm and exhibited a peak at 550 nm as a maximum emission peak with bi-exponential decay curves. With the Li⁺ and Cu²⁺ incorporation into the structure, both emission-based intensity and average decay time values decreased.