OICC Press Iranian Journal of Catalysis 2345-4865 16 2 2026 06 23 Vanadium-Doped Zirconia as an Efficient Visible-Light Photocatalyst for Advanced Treatment of Dye-Loaded Wastewater 10.57647/ijc.2026.1602.15 EN Samra Tahir School of Chemistry, University of the Punjab, Lahore 54590, Pakistan https://orcid.org/0000-0002-6953-9974 Fatima Waheed School of Chemistry, University of the Punjab, Lahore 54590, Pakistan https://orcid.org/0009-0006-0998-1548 Momal Akram Department of Basic & Applied Chemistry, Faculty of Science & Technology, University of Central Punjab, Lahore 54000, Pakistan https://orcid.org/0000-0003-2795-2338 Muhammad Salman School of Chemistry, University of the Punjab, Lahore 54590, Pakistan Umar Farooq School of Chemistry, University of the Punjab, Lahore 54590, Pakistan Saad Saleem School of Chemistry, University of the Punjab, Lahore 54590, Pakistan Amna Ehsan School of Chemistry, University of the Punjab, Lahore 54590, Pakistan Journal Article 2026 06 23 The Vanadium oxide doped zirconia (V–ZrO₂) nanoparticles were synthesized via a wet-impregnation route and evaluated as visible-light photocatalysts for the degradation of malachite green (MG). Structural and surface analyses (XRD, FTIR, SEM–EDX, pHpzc) confirmed the formation of mixed-phase ZrO₂ with dispersed surface vanadium species that enhance light absorption and reduce band gap to ~2.2 eV. The photocatalytic performance was optimized by varying key operational parameters. The maximum degradation efficiency was obtained at pH 12, 0.3 g catalyst dose, 10 ppm initial dye concentration, 45 min irradiation, and 60 °C, achieving 95–97% MG removal. Kinetic analysis showed that the degradation followed the pseudo-second-order model (R² = 0.9645) more closely than the pseudo-first-order model (R² = 0.8521), supported by the Langmuir–Hinshelwood fit (R² = 0.99), indicating a surface-controlled, adsorption-dependent pathway. Temperature dependent kinetics yielded activation energies of 12.9 kJ·mol⁻¹ (PFO) and 30.6 kJ·mol⁻¹ (PSO), confirming efficient, low-energy degradation. Mechanistic evaluation revealed that the process is dominated by an indirect pathway involving reactive oxygen species (•OH and O₂•⁻). These results demonstrate that V–ZrO₂ is a promising visible-light photocatalyst for efficient treatment of dye-contaminated wastewater. Highlights 1.       Synthesis of vanadium oxide doped zirconia (V–ZrO₂) as an efficient photocatalyst. 2.       Vanadium doping of ZrO₂ successfully extends its photocatalytic activity into the visible light region by narrowing the bandgap. 3.       Structural modifications, crystallinity, and enhanced optical absorption due to vanadium integration were confirmed by pHpzc, XRD, FTIR, SEM-EDX, and UV-Vis analyses. 4.       High degradation efficiency of Malachite Green dye achieved under visible light 5.       Kinetic modeling indicates strong alignment with pseudo-second-order and Langmuir–Hinshelwood models, revealing surface-controlled reaction pathways. 6.       V-ZrO₂ proves to be effective and eco-friendly for treating dye-contaminated wastewater.