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<p>Engineering the structural and optical properties of functional metal oxides is often essential for enhancing their performance in practical applications. This study presents a comprehensive investigation into the comparative and synergistic effect of aliovalent doping (Zn,Cd) on the structural, defects, optical and electronic properties of CeO<sub>2</sub> nanostructures. Undoped CeO<sub>2</sub>, Zn-doped, Cd-doped and Zn-Cd co-doped CeO<sub>2</sub> nanostructures have been successfully synthesized via facile chemical co-precipitation method. A rigorous multiple characterization techniques including XRD, TEM, Raman, UV–Vis and PL spectroscopy combined with DFT modeling was employed to elucidate the dopant induced modifications. Structural analysis confirms that cubic fluorite geometry of CeO<sub>2</sub> remains stable even after doping and co-doping. While the significant lattice contraction in Zn-doping and lattice expansion in Cd doping relative to the undoped CeO<sub>2</sub> has been observed. Microstructural imaging depicts the formation of monodispersed spherical particles with sizes in the range 5 to 7&#xa0;nm distributed uniformly in all the samples. Spectroscopic evaluation via Raman and PL techniques demonstrates that Zn,Cd co-doping has synergistically promoted the oxygen vacancies in the host matrix as evidenced by the highest defect band intensity and emission peaks. Optical studies uncover two distinct opposing band gap engineering regimes; Zn-doping and Zn,Cd co-doping in CeO<sub>2</sub> resulted in the widening of band gap attributed to the Burstein-Moss effect while the Cd-doping in CeO<sub>2</sub> facilitates the narrowing of band gap by introduction of mid-gap states. DFT results corroborate this electronic modification and shifting by showing the donor states near the conduction band for Zn and in gap states for Cd. Furthermore, the thermodynamic calculations reveal that the Zn,Cd co-doped nanoparticles achieve the optimally aligned superior band edges potentials (Ecb = −1.00&#xa0;eV, Evb =  + 3.25&#xa0;eV vs NHE) which could offer a powerful thermodynamic deriving force, making them promising candidates for the redox reactions. This study provides an initial insight into the impact of (Zn,Cd) co-doping on the structural and optical properties of CeO<sub>2</sub> nanoparticles, offering valuable information for designing metal oxide semiconductors for targeted applications.</p>

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Synergistic enhancement of oxygen vacancies and band-gap engineering in (Zn,Cd) co-doped CeO2 nanostructures: a comparative experimental and theoretical study

  • 期刊论文

  • 发表日期：

    2026年5月26日

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  • Abdul Mateen,
  • Sohail Azmat,
  • Ejaz Muhammad,
  • Hussain Ahmad,
  • Zahid Farooq,
  • Tariq Jan

摘要

Engineering the structural and optical properties of functional metal oxides is often essential for enhancing their performance in practical applications. This study presents a comprehensive investigation into the comparative and synergistic effect of aliovalent doping (Zn,Cd) on the structural, defects, optical and electronic properties of CeO2 nanostructures. Undoped CeO2, Zn-doped, Cd-doped and Zn-Cd co-doped CeO2 nanostructures have been successfully synthesized via facile chemical co-precipitation method. A rigorous multiple characterization techniques including XRD, TEM, Raman, UV–Vis and PL spectroscopy combined with DFT modeling was employed to elucidate the dopant induced modifications. Structural analysis confirms that cubic fluorite geometry of CeO2 remains stable even after doping and co-doping. While the significant lattice contraction in Zn-doping and lattice expansion in Cd doping relative to the undoped CeO2 has been observed. Microstructural imaging depicts the formation of monodispersed spherical particles with sizes in the range 5 to 7 nm distributed uniformly in all the samples. Spectroscopic evaluation via Raman and PL techniques demonstrates that Zn,Cd co-doping has synergistically promoted the oxygen vacancies in the host matrix as evidenced by the highest defect band intensity and emission peaks. Optical studies uncover two distinct opposing band gap engineering regimes; Zn-doping and Zn,Cd co-doping in CeO2 resulted in the widening of band gap attributed to the Burstein-Moss effect while the Cd-doping in CeO2 facilitates the narrowing of band gap by introduction of mid-gap states. DFT results corroborate this electronic modification and shifting by showing the donor states near the conduction band for Zn and in gap states for Cd. Furthermore, the thermodynamic calculations reveal that the Zn,Cd co-doped nanoparticles achieve the optimally aligned superior band edges potentials (Ecb = −1.00 eV, Evb =  + 3.25 eV vs NHE) which could offer a powerful thermodynamic deriving force, making them promising candidates for the redox reactions. This study provides an initial insight into the impact of (Zn,Cd) co-doping on the structural and optical properties of CeO2 nanoparticles, offering valuable information for designing metal oxide semiconductors for targeted applications.