Effect of method of preparation on the photocatalytic activity of NiAl2O4

Abstract

In the current investigation, Nickel aluminate (NA) nanoparticles were synthesized using two different methods namely sol–gel and co-precipitation in order to compare the photocatalytic activity of NA. In co-precipitation method, three different pH conditions were maintained (pH = 5; pH = 8; pH = 10.5) to synthesize nickel aluminate. Tetracycline (TC) and methylene blue (MB) were selected as model pollutants to study the effect of method on the photocatalytic activity of NA under ultraviolet light and visible light respectively. The synthesized nickel aluminate was characterised using PXRD, FT-IR, UV-DRS, SEM-EDAX and BET technique. Band gap engineering of the synthesized catalyst was analysed by following Tauc equation. NA synthesised by sol–gel method has lower band gap energy (3.00 eV) which is comparatively lower than its precipitation analogue (band gap energy of NA at pH 5 = 3.47 eV, pH 8 = 3.21 eV, pH 10.5 = 3.14 eV). The percentage degradation of tetracycline was 83.26% and 81.3% in 30 min under ultraviolet light using 25 mg of the catalyst synthesized through co-precipitation and sol–gel method respectively. The percentage degradation of MB under visible light was 47.1% in 60 min using 10 mg of the catalyst synthesized by co-precipitation method (pH = 10.5). Higher photocatalytic activity of NA synthesised by co-precipitation method at pH 10.5 could be due to the higher surface area (surface area = 157.23 m2/g) than NA prepared by sol–gel method (surface area = 35.36 m2/g).