Exploration of grown cobalt-doped zinc oxide nanoparticles and photodegradation of industrial dye

Cobalt-doped and undoped zinc oxide (ZnO) nanoparticles (NPs) with different dopant concentrations were synthesized via the sol-gel method. The structural, morphological, and optical properties of the synthesized NPs were investigated using various techniques. The NPs exhibit a wurtzite structure with an average crystallite size of 20-34 nm. Change in photoluminescence (PL) spectra from dual to single band with dopants suggested decreasing surface state contribution. The PL lifetime of the 430 nm band is too short (< 10 ps), where it is multi-exponential and significantly large for the 550 nm band with a major contribution of 0.3-1.0 ns and a minor contribution of 7-9 ns and 119-126 ns. The photocatalytic performance of NPs was examined by decomposing a Congo red dye under dark, white (LED) light and UV irradiation. Among all the doped NPs, 20% Co(2+ )doped ZnO shows superior photocatalytic activity for dye degradation with a faster reaction rate constant.