Synergistic experimental and theoretical investigation of ZnO derived from ZIF-8 photocatalysts for methylene blue degradation under visible light

Abstract

Metal organic frameworks (MOFs) have emerged as a promising structure to improve the physicochemical performance of semiconductors by constructing MOF-based structures. In this study, ZnO photocatalysts were successfully synthesized from zeolitic imidazolate framework-8 (ZIF-8) utilizing an elementary notion aqueous approach, which requires mixing at room temperature. By adjusting the heating temperature and total amount of organic ligands in the MOF structure, the optical and structural properties of the resultant ZnO were successfully controlled. The resulting ZnO derived from ZIF-8 was applied as water pollutant removal by degrading methylene blue (MB) under visible light irradiation, and the ZnO-650 sample outperformed the other samples, removing approximately 91% of MB within 30 min. The enhanced activity was primarily due to the sample’s improved crystallinity and increased specific surface area preserved from the ZIF-8 precursor, as well as the decreased photoluminescence intensity, which reduced electron–hole recombination. Furthermore, density functional theory was used to simulate the ZnO-derived ZIF-8 structures and calculate the samples’ energy bandgap and work function, which explain the charge migration process sufficiently to better understand the photocatalytic pathway of ZnO derived from ZIF-8, allowing us to propose a potential MB degradation mechanism. Overall, this study will offer an effective procedure for creating and establishing efficient semiconductor photocatalysts that utilize the advantage of MOFs’ superb properties.