Construction of WO3@Ni/Cr-LDHs Z-scheme heterojunction and photocatalytic degradation of norfloxacin

Abstract

In this study, WO₃@NiCr-LDHs Z-scheme heterojunctions have been synthesised for the photodegradation of NOR. A comprehensive investigation was conducted into the effects of the Ni/Cr ratio, catalyst dosage, norfloxacin concentration, temperature and pH of the aqueous environment on the degradation activity of the composites. Furthermore, the stability and reusability of the catalyst after the reaction were discussed. The structural composition and morphological features of the materials were characterised by XRD, SEM and TEM, and the photoelectric properties of the heterojunctions were investigated by photoluminescence spectroscopy and UV–vis diffuse reflectance spectroscopy. The experimental findings demonstrated that a quantity of 15 mg of WO₃@NiCr-LDHs in conjunction with 50 ml of a 10 mg/L norfloxacin solution in an aqueous environment at a temperature of 20°C and a pH of 7, resulted in 86.01 % of the material being degraded after 120 min of light irradiation. This value was found to be 2.75 and 1.23 times higher than that of WO₃ and LDHs, respectively. Kinetic and thermodynamic analyses indicated that the catalyst amount and temperature were the predominant factors influencing the photodegradation process. The efficient photodegradation is attributable to the built-in electric field produced by the Z-scheme heterojunction, which promotes the separation of photogenerated electron holes, allowing more electrons to be converted into free radicals to work with the holes in the degradation of NOR.