Sustainable Hibiscus rosa-sinensis -templated MnO ₂ @TiO ₂ nanocomposites for the visible-light-driven photocatalytic degradation of hazardous organic dyes

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plant by a microwave-assisted method. Initially, we synthesized titanium dioxide nanoparticles for the photocatalytic degradation of methyl orange and methylene blue, which show degradation efficiencies of only 57.4849% and 70.55%, respectively. Their poor photocatalytic activity under visible light necessitated the incorporation of manganese dioxide to make manganese-implanted titania NCs. Surface modification with manganese dioxide highly increases the degradation efficiency for methyl orange and methylene blue, which is 85% and 95.51%, respectively, under visible light. A detailed characterization was performed using ultraviolet visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, dynamic light scattering, transmission electron microscopy, Brunauer-Emmett-Teller surface analysis, photoluminescence spectroscopy and electrochemical studies. The synthesized nanocomposite showed biological properties, similar to antibacterial and antioxidant properties, as a secondary application, due to the generation of ROS species, which also photocatalytically degraded the dyes effectively. The practical stability of the composite was confirmed by catalyst reusability over three successive cycles. This shows that the biosynthesized manganese dioxide with titanium dioxide is an excellent and versatile catalyst for wastewater treatment.