Photocatalytic removal of congo red dye using ZIF-8@BiVO4: impact of catalyst design and operational parameters

Abstract

Metal–organic frameworks (MOFs) are an exciting class of porous crystallized materials that have gained significant attention for applications in sustainable energy and environmental remediation. In this study, we explore the photocatalytic degradation of Congo Red (CR) dye using a novel composite material composed of ZIF-8 and BiVO₄ (BVO). The synergistic integration of ZIF-8 and BVO enhances charge transfer at the interface, effectively reducing the recombination of electrons and holes, thus boosting photocatalytic efficiency. Comprehensive characterization of the composites was performed using Powder X-ray diffraction (PXRD), Field emission scanning electron microscopy (FESEM), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS), Thermogravimetric Analysis (TGA), and Fourier Transform Infrared spectroscopy (FT-IR). BET analysis revealed a high surface area of 1107.2 m²/g for ZIF-8 and 807.53 m²/g for the Z/BVO composite, contributing to enhanced photocatalytic activity. Notably, Z/BVO-25 demonstrated superior CR dye degradation efficiency, achieving 94.37% degradation under sunlight within 90 min, compared to 80.74% for ZIF-8 and 60.4% for BVO alone. The composite also exhibited excellent stability and reusability, retaining 86.3% of its initial efficiency after four cycles. Furthermore, this novel ZIF-8@BVO composite showed exceptional adsorption capability for the rapid removal of CR from aqueous solutions. In addition to demonstrating outstanding photocatalytic performance, we have discussed the underlying dye degradation mechanism, limitations, and future challenges associated with this composite material. This work presents a strategic approach to enhance photocatalytic performance by integrating MOFs with semiconductor materials, offering a promising solution for environmental remediation.