Optimized Cu/Zr Co-doped TiO2 nanocomposites as high performance photocatalyst for visible light induced methylene blue degradation

This study reports the synthesis and visible light-driven photocatalytic performance of Cu:Zr co-doped TiO 2 (CZTO) nanocomposites for the degradation of methylene blue (MB), a model organic pollutant. The nanocomposites synthesis was carried out through a hydrothermal process with varying Zr doping concentrations (0.5 %, 1 %, and 1.5 %) and characterized using XRD, Raman spectroscopy, SEM, UV-Vis spectroscopy, and photoluminescence (PL) analysis. Structural and optical characterizations confirmed successful integration of Cu and Zr elements into the TiO 2 structure, resulting in enhanced visible light absorption and improved charge separation. Among the synthesized samples, the 1 % CZTO nanocomposite showed superior photocatalytic activity, achieving 92 % degradation of MB within 120 min under visible light irradiation, and displayed a superior apparent rate constant (k = 0.0208 min −1 ). This rate constant is over 4.6 times higher than pristine TiO 2 (0.0045 min −1 ) and about 2.7 times greater than Cu-TiO 2 (0.0076 min −1 ), demonstrating the synergistic benefit of dual Cu/Zr doping. The material maintained 85 % efficiency after five cycles, demonstrating excellent reusability. The cooperative interaction between Cu and Zr dopants enhanced light absorption, reduced recombination rates, and improved surface morphology. This work highlights the novelty of Cu/Zr co-doping, where Zr stabilizes the TiO 2 lattice and Cu enhances charge trapping, together yielding superior visible-light photocatalysis compared to single-doped TiO 2 systems. • Cu/Zr co-doping significantly enhanced TiO 2 photocatalytic activity. • 1 % CZTO nanocomposite showed the best performance. • Characterizations confirmed bettervisible light absorption. • Effective strategy for wastewater treatment using doped TiO 2 .