Zr-modified TiO₂ nanocomposites with enhanced visible-light photocatalytic and photobiological performance

A green sol-gel method was utilized to produce a Zr-decorated TiO₂ nanocomposite exhibiting improved photocatalytic and biological activity under visible light irradiation. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) provided structural and morphological characterisation, confirming the coexistence of anatase and rutile phases, with acidic conditions (pH 2) promoting rutile production. Diffuse reflectance spectroscopy (DRS) demonstrated altered optical properties due to Zr inclusion and nanoscale phenomena. The photocatalytic efficacy was assessed via the degradation of Brilliant Green dye, revealing that the Zr-TiO₂ nanocomposite demonstrated much superior performance compared to pristine TiO₂, especially under solar illumination, due to enhanced visible-light absorption and charge separation. Operational parameters, such as solution pH, were tuned to improve degrading efficiency. In addition to photocatalysis, the nanocomposite exhibited significant antibacterial and antifungal properties, an elevated antioxidant capacity of 89.4%, and remarkable anti-inflammatory benefits. In vitro cytotoxicity investigations demonstrated selective anticancer efficacy against MCF-7, KB, and HepG2 cell lines, while displaying no harm towards normal NHDF B cells. These results underscore the promise of Zr-TiO₂ nanocomposites for combined environmental remediation and photobiological applications.