Crystallinity regulation of ZIF-67 via defective MgO layer made by high voltage-assisted oxidation approach for optimal 4-nitrophenol reduction

Abstract

Due to their unique structural characteristics, metal-organic frameworks (MOFs) have emerged as favorable contenders for photocatalytic applications. In this study, the crystallization of ZIF-67, a subclass of MOFs, on Mg and MgO substrates via dip coating was explored, and the resulting materials were employed as a photocatalyst for the 4-nitrophenol reduction. Due to the defective surface resulting from plasma activity during the high-voltage-assisted oxidation of AZ31 Mg alloy, MgO significantly impacts the crystallization of ZIF-67. This influence promotes the formation of a stable foundation and strong bonds, contributing to the emergence of a regular and symmetrical structure. This differs from the asymmetrical and irregular structure observed in ZIF-67@Mg when ZIF-67 is grown directly on the Mg substrate. Hence, the ZIF-67@MgO catalyst demonstrated remarkable enhancements in the reduction of 4-nitrophenol to 4-aminophenol, achieving an efficiency of approximately 97.12 % within 12 min under visible light. Importantly, the catalyst exhibited no stability decay even after ten consecutive cycles, surpassing the performance of previously reported catalysts. This research sheds light on the superior capabilities of ZIF-67@MgO in the context of visible-light-driven reduction of 4-NP. The results suggest potential for future progress in creating effective and eco-friendly photocatalytic materials for addressing environmental challenges.