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<p>The development of visible-light-active photocatalysts for simultaneous removal of dye and pharmaceutical contaminants remains a significant challenge in wastewater remediation. In this study, Zn-doped ZrO<sub>2</sub> (ZZr) and Mo–Zn co-doped ZrO<sub>2</sub> (MZZr) nanophotocatalysts were successfully synthesized via a precipitation–calcination and incipient wetness impregnation approach. Comprehensive physicochemical characterization using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX), inductively coupled plasma optical emission spectroscopy (ICP-OES), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), and differential scanning calorimetry (DSC) confirmed successful dopant incorporation, lattice distortion, reduced crystallite size, enhanced surface hydroxylation, and band gap narrowing from 3.78&#xa0;eV (ZrO<sub>2</sub>) to 2.58&#xa0;eV (ZZr) and 2.16&#xa0;eV (MZZr). Photocatalytic performance was evaluated against Congo Red (CR) and Ciprofloxacin (CIP) under visible-light irradiation. The MZZr catalyst exhibited superior degradation efficiencies compared with ZZr, achieving approximately 98–99% removal of CR and 97–99% removal of CIP at an initial pollutant concentration of 5&#xa0;mg&#xa0;L<sup>−1</sup>, while sustaining 79–80% (CR) and 73–75% (CIP) degradation at an elevated concentration of 30&#xa0;mg&#xa0;L<sup>−1</sup>. The enhanced performance is attributed to improved charge separation, increased defect density, and enhanced reactive oxygen species (ROS) generation inferred from the structural and optical changes induced by Mo–Zn co-incorporation. Kinetic behavior followed Langmuir–Hinshelwood-type mechanisms, with optimal degradation observed at near-neutral to alkaline pH and moderate catalyst dosage. The synergistic interaction between Zn and Mo dopants effectively engineered the structural and electronic properties of ZrO<sub>2</sub>, making MZZr a promising visible-light-responsive photocatalyst for complex wastewater treatment applications involving dyes and antibiotics.</p>

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Synergistic effect of Zn and Mo co-doping in ZrO2 for efficient photodegradation of Congo Red and Ciprofloxacin under visible irradiation

  • 期刊论文

  • 发表日期：

    2026年6月16日

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  • Samra Tahir,
  • Momal Akram,
  • Muhammad Salman,
  • Balal Ahmad,
  • Umar Farooq,
  • Farzam Ali

摘要

The development of visible-light-active photocatalysts for simultaneous removal of dye and pharmaceutical contaminants remains a significant challenge in wastewater remediation. In this study, Zn-doped ZrO2 (ZZr) and Mo–Zn co-doped ZrO2 (MZZr) nanophotocatalysts were successfully synthesized via a precipitation–calcination and incipient wetness impregnation approach. Comprehensive physicochemical characterization using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX), inductively coupled plasma optical emission spectroscopy (ICP-OES), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), and differential scanning calorimetry (DSC) confirmed successful dopant incorporation, lattice distortion, reduced crystallite size, enhanced surface hydroxylation, and band gap narrowing from 3.78 eV (ZrO2) to 2.58 eV (ZZr) and 2.16 eV (MZZr). Photocatalytic performance was evaluated against Congo Red (CR) and Ciprofloxacin (CIP) under visible-light irradiation. The MZZr catalyst exhibited superior degradation efficiencies compared with ZZr, achieving approximately 98–99% removal of CR and 97–99% removal of CIP at an initial pollutant concentration of 5 mg L−1, while sustaining 79–80% (CR) and 73–75% (CIP) degradation at an elevated concentration of 30 mg L−1. The enhanced performance is attributed to improved charge separation, increased defect density, and enhanced reactive oxygen species (ROS) generation inferred from the structural and optical changes induced by Mo–Zn co-incorporation. Kinetic behavior followed Langmuir–Hinshelwood-type mechanisms, with optimal degradation observed at near-neutral to alkaline pH and moderate catalyst dosage. The synergistic interaction between Zn and Mo dopants effectively engineered the structural and electronic properties of ZrO2, making MZZr a promising visible-light-responsive photocatalyst for complex wastewater treatment applications involving dyes and antibiotics.