ZIF/MOF-Derived ZnO Nanostructures for Photocatalytic Applications

Abstract

Organic dyes and other persistent pollutants pose a serious threat to water quality, highlighting the need for efficient and sustainable treatment technologies. Semiconductor photocatalysis is a promising approach for pollutant degradation, and zinc oxide (ZnO) has attracted considerable attention because of its wide band gap, high electron mobility, and low cost. However, particle agglomeration and rapid electron–hole recombination can limit its photocatalytic performance. In this study, ZIF-8 was employed as a sacrificial template to synthesise nanostructured ZnO through controlled calcination at 500 °C. The influence of methanol volume during ZIF-8 synthesis and subsequent thermal treatment on the structural and optical properties of the derived ZnO was investigated. X-ray diffraction confirmed the formation of hexagonal wurtzite ZnO, while crystallographic parameters, crystallite size, dislocation density, and Zn–O bond length were evaluated using established structural analysis methods. UV–Vis spectroscopy and Tauc analysis revealed a direct optical band gap of approximately 3.2 eV. The surface morphology and particle characteristics were further examined using field-emission scanning electron microscopy. The photocatalytic activity of the ZIF-8-derived ZnO nanostructures was evaluated through the degradation of a model organic dye under light irradiation. This work aims to establish a clear synthesis–structure–performance relationship for MOF-derived ZnO and to support the development of cost-effective, high-surface-area photocatalysts for sustainable water treatment applications.

Keywords: Zinc Oxide (ZnO); ZIF-8; Metal-Organic Framework