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<p>CuAl<sub>2</sub>O<sub>4</sub> spinel photocatalyst was synthesized via a simple chemical route and investigated for visible-light-driven photodegradation of Rhodamine B (RhB). Unlike previous studies that mainly focus on photocatalytic activity alone, this work establishes a direct correlation between the intrinsic optical–dielectric properties of CuAl<sub>2</sub>O<sub>4</sub> and its photocatalytic performance. Structural and morphological analyses confirmed the formation of a single-phase cubic spinel with a porous agglomerated morphology. Optical characterization revealed a narrow band gap of approximately 1.39&#xa0;eV, while X-ray photoelectron spectroscopy valence band analysis enabled experimental construction of the electronic band structure. A comprehensive investigation of optical constants, dielectric constant, dielectric loss, relaxation time, and optical and electrical conductivity was carried out to elucidate charge carrier dynamics and polarization effects. Under visible-light irradiation, CuAl<sub>2</sub>O<sub>4</sub> achieved 51.8% degradation of Rhodamine B within 90&#xa0;min, following pseudo-first-order kinetics with an apparent rate constant of 9.59 × 10<sup>−3</sup>&#xa0;min<sup>−1</sup>, which is more than one order of magnitude higher than that of photolysis. Photoluminescence and electrochemical impedance spectroscopy analyses revealed suppressed charge carrier recombination and reduced charge-transfer resistance, consistent with the observed dielectric behavior. The photocatalyst exhibited good stability, retaining approximately 40% degradation efficiency after six cycles. This study demonstrates, for the first time, how optical and dielectric responses govern charge separation and photocatalytic efficiency in CuAl<sub>2</sub>O<sub>4</sub>, providing a structure–property–activity framework for designing spinel-based photocatalysts for visible-light-driven wastewater treatment.</p>

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Optical and dielectric insights into visible-light-driven Rhodamine B degradation over CuAl2O4 spinel

  • 期刊论文

  • 发表日期：

    2026年4月3日

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  • Khaled Derkaoui,
  • Ismail Bencherifa,
  • Amal Elfiad,
  • Khadidja Boukhouidem,
  • Mohamed Kechouane,
  • Yamina Mebdoua,
  • Toufik Hadjersi

摘要

CuAl2O4 spinel photocatalyst was synthesized via a simple chemical route and investigated for visible-light-driven photodegradation of Rhodamine B (RhB). Unlike previous studies that mainly focus on photocatalytic activity alone, this work establishes a direct correlation between the intrinsic optical–dielectric properties of CuAl2O4 and its photocatalytic performance. Structural and morphological analyses confirmed the formation of a single-phase cubic spinel with a porous agglomerated morphology. Optical characterization revealed a narrow band gap of approximately 1.39 eV, while X-ray photoelectron spectroscopy valence band analysis enabled experimental construction of the electronic band structure. A comprehensive investigation of optical constants, dielectric constant, dielectric loss, relaxation time, and optical and electrical conductivity was carried out to elucidate charge carrier dynamics and polarization effects. Under visible-light irradiation, CuAl2O4 achieved 51.8% degradation of Rhodamine B within 90 min, following pseudo-first-order kinetics with an apparent rate constant of 9.59 × 10−3 min−1, which is more than one order of magnitude higher than that of photolysis. Photoluminescence and electrochemical impedance spectroscopy analyses revealed suppressed charge carrier recombination and reduced charge-transfer resistance, consistent with the observed dielectric behavior. The photocatalyst exhibited good stability, retaining approximately 40% degradation efficiency after six cycles. This study demonstrates, for the first time, how optical and dielectric responses govern charge separation and photocatalytic efficiency in CuAl2O4, providing a structure–property–activity framework for designing spinel-based photocatalysts for visible-light-driven wastewater treatment.