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Author: search.filters.author.Thongpool, VoranuchSubject: search.filters.subject.Green synthesis

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    Plant assisted synthesis of CuO/ZnO heterojunction nanocomposites using Mitragyna speciosa (Korth.) Havil leaf extract for photocatalytic activity under full spectrum LED light and antibacterial performance
    (2026-07-15)
    Phunpueok, Akapong
    ;
    Thongpool, Voranuch
    ;
    Jaiyen, Sarawut
    ;
    Bootchanont, Atipong
    ;
    Sukprasit, Nuchita
    CuO/ZnO heterojunction nanocomposites were synthesized through a green plant assisted method using Mitragyna speciosa leaf extract as a natural reducing and stabilizing agent. Structural and morphological analyses (XRD, FE-SEM, EDS, UV–vis, and BET) confirmed the formation of CuO/ZnO heterostructures with mesoporous characteristics. The 0.25CuO/0.75ZnO heterojunction nanocomposites exhibited the smallest ZnO crystallite size (∼8.06 nm) and the highest surface area (28.97 m<sup>2</sup>/g). Photocatalytic performance evaluated by methylene blue degradation under full-spectrum irradiation showed that the 0.25CuO/0.75ZnO heterojunction nanocomposites achieved 92.29% degradation within 90 min with a rate constant of 0.02491 min<sup>−1</sup>. In addition, the nanocomposites demonstrated strong antibacterial activity, achieving 99.9% reduction of E. coli and >99.9% inhibition of S. aureus . The enhanced performance is attributed to efficient charge separation at the CuO/ZnO heterojunction and the generation of reactive oxygen species.
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    Williamson-Hall analysis of lattice strain in green-synthesized ZnO nanoparticles using Mitragyna speciosa extract: microstructural insights and antibacterial application
    (2026-07-01)
    Thongpool, Voranuch
    ;
    Phunpueok, Akapong
    ;
    Jaiyen, Sarawut
    ;
    Limsuwan, Pichet
    Green synthesis is a sustainable method for producing ZnO NPs. However, detailed microstructural interpretation remains limited. In this study, ZnO NPs were synthesized using Mitragyna speciosa leaf extract and systematically analyzed with emphasis on lattice characteristics. Structural and morphological analysis using UV–vis, FTIR, FESEM-EDS, and XRD techniques confirmed the formation of highly crystalline ZnO with a hexagonal wurtzite structure. Williamson-Hall (W-H) analysis was applied using three deformation models: UDM, USDM, and UDEDM to separate crystallite size and lattice strain components of the crystal structure. The results revealed relatively large crystallite sizes (∼39–43 nm) with low microstrain (2.09–2.30 × 10⁻<sup>3</sup>) and low deformation energy density (3.1 × 10⁻<sup>4</sup> J m⁻<sup>3</sup>), suggesting comparatively low lattice strain characteristics. The optical band gap obtained from the Tauc plot analysis is approximately 3.03 eV, consistent with the properties of the ZnO semiconductor. Antibacterial activity was evaluated as a preliminary functional assessment, showing typical Gram-dependent behavior. This work highlights the applicability of W–H analysis for detailed microstructural evaluation in green-synthesized ZnO NPs.