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<p>The LaAl<sub>1-x</sub>Fe<sub>x</sub>O<sub>3</sub> oxides (with x = 0, 0.05, 0.10 and 0.15) have successfully synthetized by the citrate-based Sol–Gel route. X-ray diffraction analysis confirms the preservation of the rhombohedral structure (as pristine-LaAlO<sub>3</sub>) with a linear increase of the lattice parameters according to the x value. The broadening of diffraction lines was indicated the nanometric nature of the synthetized oxides and the crystallites size was determined using the Scherrer equation. Additionally, the Diffuse Reflectance Spectroscopy revealed a modification of absorption properties for the iron-based compounds, suggesting their potential as effective photocatalysts under visible light. The photogenerated current was also exhibited an enhanced efficiency in the separation of electron–hole pairs for higher Fe<sup>3+</sup> ions substitution rates. The variation in current density follows a power-law relationship with light power density and a wavelength-dependent study demonstrated that compounds containing iron show significantly more effective absorption in the blue spectral region. Based on these findings, the photocatalytic properties were further investigated. For the unsubstituted LaAlO<sub>3</sub> (LA Sample), low photocatalytic activity, achieving only 10% of degradation within 30&#xa0;min under visible light irradiation was observed. For substituted oxides with x = 0.05 (LAF1), 0.10 (LAF2) and 0.15 (LAF3) a higher photocatalytic activity (65%, 72%, and 81% of degradation in 30&#xa0;min, respectively) and a pseudo-first order kinetic has been highlighted. Further, coupling photocatalysis with ultrasound to achieve sonophotocatalysis have shown a significant increase in carbofuran degradation rates after 30&#xa0;min compared to classical photocatalysis (i.e., 20%, 86%, 91%, and 99% of degradation for LA, LAF1, LAF2 and LAF3 samples, respectively). The kinetics studies showed 0.0064, 0.0322, 0.0418, and 0.0502&#xa0;min<sup>−1</sup> rate for LA, LAF1, LAF2 and LAF3 samples, respectively. A study carried out according to pollutant concentration and to the pH showed an optimal efficiency of 99% for LAF3 sample under the following conditions: 30&#xa0;min, 50&#xa0;ppm (carbofuran concentration) at pH = 6. Further, the mechanism was explored and tests in presence of scavengers were indicated that the holes (h<sup>+</sup>) and superoxide radicals (O<sub>2</sub><sup>•–</sup>) are the main reactive species for degradation of carbofuran.</p>

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Nanosized LaAl(1-x)FexO3 oxides: characterization, optical and sono-photocatalytic applications

  • 期刊论文

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  • 发表日期：

    2025年6月30日

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  • Hussien A. Abbas,
  • Suzan Saber,
  • Christian Mathieu,
  • Sébastien Saitzek,
  • Reda M. Abdelhameed,
  • Saber Ibrahim

摘要

The LaAl1-xFexO3 oxides (with x = 0, 0.05, 0.10 and 0.15) have successfully synthetized by the citrate-based Sol–Gel route. X-ray diffraction analysis confirms the preservation of the rhombohedral structure (as pristine-LaAlO3) with a linear increase of the lattice parameters according to the x value. The broadening of diffraction lines was indicated the nanometric nature of the synthetized oxides and the crystallites size was determined using the Scherrer equation. Additionally, the Diffuse Reflectance Spectroscopy revealed a modification of absorption properties for the iron-based compounds, suggesting their potential as effective photocatalysts under visible light. The photogenerated current was also exhibited an enhanced efficiency in the separation of electron–hole pairs for higher Fe3+ ions substitution rates. The variation in current density follows a power-law relationship with light power density and a wavelength-dependent study demonstrated that compounds containing iron show significantly more effective absorption in the blue spectral region. Based on these findings, the photocatalytic properties were further investigated. For the unsubstituted LaAlO3 (LA Sample), low photocatalytic activity, achieving only 10% of degradation within 30 min under visible light irradiation was observed. For substituted oxides with x = 0.05 (LAF1), 0.10 (LAF2) and 0.15 (LAF3) a higher photocatalytic activity (65%, 72%, and 81% of degradation in 30 min, respectively) and a pseudo-first order kinetic has been highlighted. Further, coupling photocatalysis with ultrasound to achieve sonophotocatalysis have shown a significant increase in carbofuran degradation rates after 30 min compared to classical photocatalysis (i.e., 20%, 86%, 91%, and 99% of degradation for LA, LAF1, LAF2 and LAF3 samples, respectively). The kinetics studies showed 0.0064, 0.0322, 0.0418, and 0.0502 min−1 rate for LA, LAF1, LAF2 and LAF3 samples, respectively. A study carried out according to pollutant concentration and to the pH showed an optimal efficiency of 99% for LAF3 sample under the following conditions: 30 min, 50 ppm (carbofuran concentration) at pH = 6. Further, the mechanism was explored and tests in presence of scavengers were indicated that the holes (h+) and superoxide radicals (O2•–) are the main reactive species for degradation of carbofuran.