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<p>In this study, core–shell nanoparticles (NPs) were synthesized using laser ablation in liquid, and were characterized utilizing various techniques. The Au@WO<sub>3</sub> core–shell NPs were synthesized at varying Au concentrations (0.42 μg/mL, 0.84 μg/mL, 1.31 μg/mL, 1.75 μg/mL, and 2.01 μg/mL) using a 1064-nm Nd:YAG laser. The results of ultraviolet–visible (UV–Vis) spectroscopy showed absorption peaks in the wavelength range of 300–600&#xa0;nm. Nanoparticles of WO<sub>3</sub> and gold with surface plasmon resonance were determined to be responsible for the absorption peaks that were detected. It was also noted that the absorption rate of the Au@WO<sub>3</sub> core–shell NPs increased as the concentration of Au increased. However, increasing the Au concentration led to a slight decrease in the bandgap energy from 3.12&#xa0;eV to 2.94&#xa0;eV. Five prominent peaks centered at wavelengths of 366&#xa0;nm, 368&#xa0;nm, 370&#xa0;nm, 371&#xa0;nm, and 373&#xa0;nm were revealed by photoluminescence (PL) spectroscopy, with an increase in the intensity of the prepared NPs due to increasing core size (Au). X-ray diffraction (XRD) study confirmed the existence of Au and WO<sub>3</sub> NPs. The Raman spectra of Au@WO<sub>3</sub> NPs revealed vibrational modes at 714&#xa0;cm<sup>−3</sup> and 958&#xa0;cm<sup>−3</sup>, associated with W=O and O–W–O stretching bonds, respectively. These modes were identified because they were attached to the stretching bonds, and matched the characteristics of WO that forms in a monoclinic structure. Energy-dispersive x-ray (EDX) spectroscopy revealed that the structure’s gold signal weight percentage increased from 21.11% to 39.55% as a result of the higher Au content, and the morphology determined by field-emission scanning electron microscopy aligned with this increase in core size (Au), showing that the NP size increased from 68.13&#xa0;nm to 123.11&#xa0;nm. Transmission electron microscopy experiments ultimately yielded a high-resolution image for the core–shell structure of the synthesized Au@WO<sub>3</sub> NPs. As the concentration of Au increased, the core size expanded, resulting in larger cores and NPs. This study examines the impacts of varying Au concentration on the characterization of Au@WO<sub>3</sub> core–shell NPs. The electrical properties demonstrated an enhancement in electrical conductivity; at a gold concentration of 1.75 μg/mL, the average activation energy values were reduced by 0.48524&#xa0;eV and 0.43573&#xa0;eV simultaneously.</p>

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Laser-Ablated Au@WO3 Core–Shell Nanoparticles: Unveiling Morphological, Optical, and Electrical Transformations through Gold Concentration Tuning

  • 期刊论文

  • 发表日期：

    2025年8月28日

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  • Evan T. Salim,
  • Rana O. Mahdi,
  • Doaa Mahmoud,
  • Subash C. B. Gopinath,
  • Motahher A. Qaeed

摘要

In this study, core–shell nanoparticles (NPs) were synthesized using laser ablation in liquid, and were characterized utilizing various techniques. The Au@WO3 core–shell NPs were synthesized at varying Au concentrations (0.42 μg/mL, 0.84 μg/mL, 1.31 μg/mL, 1.75 μg/mL, and 2.01 μg/mL) using a 1064-nm Nd:YAG laser. The results of ultraviolet–visible (UV–Vis) spectroscopy showed absorption peaks in the wavelength range of 300–600 nm. Nanoparticles of WO3 and gold with surface plasmon resonance were determined to be responsible for the absorption peaks that were detected. It was also noted that the absorption rate of the Au@WO3 core–shell NPs increased as the concentration of Au increased. However, increasing the Au concentration led to a slight decrease in the bandgap energy from 3.12 eV to 2.94 eV. Five prominent peaks centered at wavelengths of 366 nm, 368 nm, 370 nm, 371 nm, and 373 nm were revealed by photoluminescence (PL) spectroscopy, with an increase in the intensity of the prepared NPs due to increasing core size (Au). X-ray diffraction (XRD) study confirmed the existence of Au and WO3 NPs. The Raman spectra of Au@WO3 NPs revealed vibrational modes at 714 cm−3 and 958 cm−3, associated with W=O and O–W–O stretching bonds, respectively. These modes were identified because they were attached to the stretching bonds, and matched the characteristics of WO that forms in a monoclinic structure. Energy-dispersive x-ray (EDX) spectroscopy revealed that the structure’s gold signal weight percentage increased from 21.11% to 39.55% as a result of the higher Au content, and the morphology determined by field-emission scanning electron microscopy aligned with this increase in core size (Au), showing that the NP size increased from 68.13 nm to 123.11 nm. Transmission electron microscopy experiments ultimately yielded a high-resolution image for the core–shell structure of the synthesized Au@WO3 NPs. As the concentration of Au increased, the core size expanded, resulting in larger cores and NPs. This study examines the impacts of varying Au concentration on the characterization of Au@WO3 core–shell NPs. The electrical properties demonstrated an enhancement in electrical conductivity; at a gold concentration of 1.75 μg/mL, the average activation energy values were reduced by 0.48524 eV and 0.43573 eV simultaneously.