Growth kinetics of novel nickel oxide (NiO) nano fibers on glass substrates by SILAR process: A solution to remove AZO dye

Abstract

This article presents the growth of uniformly distributed nickel oxide (NiO) nanofibers on a glass substrate by the Successive Ionic Layer Adsorption and Reaction (SILAR) process and explores its photocatalytic features towards an AZO dye. The nanofiber grown by the SILAR process is subjected to annealing at 400°C to decompose the hydroxide group into oxide. X-ray diffraction pattern divulges the Face-Centered Cubic (FCC) structure of NiO, and its average crystallite size (46–61 nm). The fibrous morphology with the width varying from 37.83 to 42.05 nm is confirmed through FESEM micrographs. The existence of nickel and oxide, with atomic percentages in the ratio 40:60 is confirmed by EDX analysis. From the UV–visible spectrum, the band gap energy Eg is determined using a Tauc plot and the values are varied between 3.38 eV and and 3.41 eV. Photocatalytic degradation efficiency for the Congo red dye is found to be 93% for reusable NiO nanofibers under the illumination of UV light. The photodegradation pathway of Congo red dye is presented based on gas chromatography-mass spectrometry (GC-MS) analysis. The prospective applications of the current work in wastewater treatment make it significant.