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<p>High-surface-area Mg–Al layered double hydroxide (LDH) nanosheets were synthesized via a one-step ultrasound-assisted method and thermally converted at 700 °C into magnesium aluminate (MgAl₂O₄). Structural, morphological, and optical properties were characterized using XRD, SEM, BET, UV–Vis, and FTIR. XRD confirmed phase purity, with LDH showing a rhombohedral structure and MgAl₂O₄ forming a cubic spinel phase. SEM revealed nanosheet morphology was largely retained post-calcination, though BET showed a surface area drop from 349.3 m<sup>2</sup>/g to 235.9 m<sup>2</sup>/g due to partial agglomeration. Electrochemical studies indicated capacitive redox behavior in LDH, while MgAl₂O₄ exhibited a diffusion-controlled oxidation mechanism linked to enhanced electron mobility and defect sites. Catalytic reduction experiments using NaBH₄ and 20 mg/L methyl orange (MO) solution showed MgAl₂O₄ outperformed LDH, achieving complete MO reduction, within 5 min with an apparent pseudo-first-order rate constant of 0.215 min⁻<sup>1</sup>, compared to 0.0112 min⁻<sup>1</sup> for LDH. This nearly 20-fold enhancement is attributed to MgAl₂O₄’s efficient electron transport and spinel structure, highlighting its dual potential in environmental remediation and electrochemical applications.</p>

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Ultrasound-assisted synthesis of Mg–Al LDH and spinel MgAl₂O₄ nanocrystals: structural, optical, electrochemical, and catalytic properties

  • 期刊论文

  • 发表日期：

    2026年4月13日

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  • Tarek Alammar

摘要

High-surface-area Mg–Al layered double hydroxide (LDH) nanosheets were synthesized via a one-step ultrasound-assisted method and thermally converted at 700 °C into magnesium aluminate (MgAl₂O₄). Structural, morphological, and optical properties were characterized using XRD, SEM, BET, UV–Vis, and FTIR. XRD confirmed phase purity, with LDH showing a rhombohedral structure and MgAl₂O₄ forming a cubic spinel phase. SEM revealed nanosheet morphology was largely retained post-calcination, though BET showed a surface area drop from 349.3 m2/g to 235.9 m2/g due to partial agglomeration. Electrochemical studies indicated capacitive redox behavior in LDH, while MgAl₂O₄ exhibited a diffusion-controlled oxidation mechanism linked to enhanced electron mobility and defect sites. Catalytic reduction experiments using NaBH₄ and 20 mg/L methyl orange (MO) solution showed MgAl₂O₄ outperformed LDH, achieving complete MO reduction, within 5 min with an apparent pseudo-first-order rate constant of 0.215 min⁻1, compared to 0.0112 min⁻1 for LDH. This nearly 20-fold enhancement is attributed to MgAl₂O₄’s efficient electron transport and spinel structure, highlighting its dual potential in environmental remediation and electrochemical applications.