Synthesis of SiO2 (core)/Au (shell) nanoparticles via the electro-wire explosion plasma method combined with pulsed laser ablation

A simple technique for synthesizing SiO2–Au core–shell nanoparticles (NPs) has been examined in the present work. An Au wire was electro-exploded in SiO2 colloidal NP solution for preparing the NPs, and after that, the core–shell structure was better covered by pulsed laser ablation. Plasma electron temperature as well as electron density were measured using optical emission spectroscopy. The slope of the Boltzmann plot created utilizing the intensities of many spectral lines as a function of their corresponding excitation energy has been utilized in order to calculate electron temperature was determined as 6.86 eV. The electron number density is determined from the Stark broadening of well-isolated Ar-I (696.54 nm) spectral line after de-convolution of the Voigt profile. Scanning electron microscopy (SEM), x-ray diffraction (XRD), and energy-dispersive x-ray spectroscopy (EDX) have been used to analyze the NPs’ structural characteristics. Au NPs gradually covered SiO2, according to XRD measurements, and this has been dependent on the laser pulse power density as well as Au exploding-wire current. Analysis of the SEM images revealed a narrow size range and spherical particle shape, along with a noticeable shift in the average particle size brought on by changes in laser pulse power density, and the average particle size of the SiO2–Au core–shell nanoparticles decreased from 89.32 nm (at a laser pulse energy of 100 mJ) down to approximately 20 nm (at 500 mJ). The elemental weight percentage (wt. %) from the EDX spectrum of gold (Au) on the silica cores increased quantitatively from 11.17 wt. % (at 100 mJ) to 20.68 wt. % (at 500 mJ), confirming the progressive coverage of the Au shell, and verified that SiO2–Au microspheres had formed successfully.