Microwave-assisted one-pot synthesis of CrMnFeCoNi multimetallic nanoparticle-loaded UiO-66 for visible-light photocatalytic degradation of methylene blue

Abstract

The increasing contamination of water resources with synthetic dyes, particularly methylene blue (MB), from textile industries necessitates the development of efficient and environmentally friendly remediation technologies. Herein, the first-time synthesis of multimetallic nanoparticles with an equimolar ratio of Fe, Co, Cr, Mn, and Ni, anchored on UiO-66 metal–organic framework (MM@UiO-66), is presented using microwave-assisted one-pot synthesis. The nanocomposite was well characterized using powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), thereby confirming retention of the UiO-66 framework and incorporation of multimetallic species in near-equimolar proportions. Photocatalytic performance was evaluated via visible-light-driven degradation of MB under optimal conditions. The MM@UiO-66 composite showed excellent photocatal e, achieving 95.1% MB degradation under low-power LED light illumination. Parametric systematic research under optimized conditions revealed the optimal performance at 20 mg catalyst loading, pH 7.5, and 10 mg L⁻¹ initial MB concentration. Kinetic analysis showed that MB was degraded rapidly, following a pseudo-first-order reaction model. Owing to its stable framework, MM@UiO-66 maintained strong catalytic performance and could be reused efficiently through six successive cycles without significant loss of activity. Scavenger experiments confirmed hydroxyl radicals (˙OH) and photogenerated holes (h⁺) as predominant oxidative species. The synergistic combination of UiO-66's chemical tunability and high surface area and the multi-element active sites of the multimetallic nanoparticles led to enhanced photocatalysis compared to conventional systems, indicating excellent potential for sustainable treatment of wastewater.