Silver anchored Cu–Na and Co–Na atrane MOFs as photocatalysts for the visible-light-driven degradation and decolourization of a hydroxyanthraquinone dye

Abstract

This study includes the synthesis of atrane-based Cu–Na and Co–Na MOFs and the inclusion of silver nanoparticles (AgNPs) into their skeletons for fabricating Ag/Cu–Na MOF and Ag/Co–Na MOF nanocomposites. The fabrication of each product has been confirmed by using various techniques like FTIR, TGA, BET, PXRD, FESEM, HRTEM, DLS, EDAX, and XPS analyses. The Tauc plots, EIS, photoluminescence studies, and HOMO–LUMO band gap analysis of Ag/Cu–Na MOF and Ag/Co–Na MOF nanocomposites revealed improvement in their optical properties over the parental MOFs in terms of reduced band gaps, improved charge separation, and increased photocatalytic activity. The photocatalytic activities of Ag/Cu–Na and Ag/Co–Na MOFs were evaluated by investigating the photodegradation and decolourization of a representative anthraquinone dye (i.e. 2-hydroxyanthraquinone or 2-HAQ) at room temperature under visible light without using external oxidants (at pH 6). The nanocomposites have significantly achieved 79% degradation and 2.64% (min⁻¹) decolourization of 2-HAQ within 30 min. The degradation process is driven by the reactive oxygen species (ROS) in the form of free radicals (˙OH and ˙O₂⁻) due to reduced band gaps, confirmed by EPR analysis. The involvement of reactive sites, mechanism of degradation and formation of degradation products have been supported by LC–MS analysis, DFT calculations and Fukui charges. Additionally, the composites demonstrate excellent structural stability and consistent catalytic activity over four cycles, highlighting their potential as sustainable and environment-friendly photocatalysts.