A mixed-ligand MOF/g-C₃N₄ nanocomposite for enhanced sunlight-assisted methylene blue degradation and multifunctional bioactivity

The increasing discharge of organic pollutants and the growing demand for multifunctional materials with combined environmental and biomedical applications necessitate the development of efficient, sustainable, and versatile catalysts. In this study, a mixed-ligand metal organic framework (MIXMOF) was synthesised using benzene dicarboxylic acid and succinic acid and subsequently integrated with graphitic carbon nitride (g-C₃N₄) to form an heterostructured MIXMOF/g-C₃N₄ nanocomposite. The composite was systematically characterized using XRD, FTIR, SEM, TEM, BET, and UV-Vis absorption and reflectance techniques. Photocatalytic experiments revealed that the MIXMOF/g-C₃N₄ exhibited significantly enhanced sunlight driven methylene blue (MB) degradation efficiency (83.55%) compared to pristine g-C₃N₄ (33.24%) and MIXMOF (14.08%). Kinetic analysis confirmed a higher rate constant for the composite, indicating accelerated degradation kinetics. The improved performance is attributed to the formation of a Type-II heterojunction, which promotes effective charge separation and reactive oxygen species generation. In addition to its photocatalytic activity, the composite demonstrated moderate anti-inflammatory, antioxidant, anti-diabetic, and antibacterial properties, highlighting its multifunctional potential. The catalyst also exhibited good recyclability and mineralization efficiency, achieving 82.05% TOC removal. This work presents a rare mixed-ligand MOF/g-C₃N₄ heterostructure fabricated through a simple solvent-free grinding approach for simultaneous sunlight-assisted dye degradation and multifunctional bioactivity, extending the application of conventional MOF/g-C₃N₄ systems beyond photocatalysis. These findings highlight the potential of MIXMOF/g-C₃N₄ as novel efficient multifunctional material for environmental remediation and bio-related applications.