Physical, optical properties and antibacterial activity of silver nanoparticles: Nanoclusters to nanoparticles formation on glass substrate by in-situ annealing

Silver nanoparticles (AgNPs) formed on in-situ annealed microscopic glass substrates from silver nanoclusters (AgNCs) generated by DC magnetron sputtering with inert gas condensation (IGC) technique. The substrate's annealing temperature was below and above the glass transition temperature of 500 degrees C and 600 degrees C. The influence of annealing temperature on the surface morphology was studied using atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) were employed to investigate the surface composition, chemical states, and electronic states of the AgNPs on the glass substrates. On the in-situ annealed glass substrate at 500 degrees C, the produced AgNPs revealed accumulation and aggregation. For insitu annealed at 600 degrees C, a homogeneous distribution of AgNPs on the glass substrate was witnessed. The refractive index test revealed that AgNPs deposition at 600 degrees C achieved higher sensitivity with 27 nm/RIU (Refractive index unit). The antibacterial activity of AgNPs was also investigated using Escherichia coli and Bacillus cereus. In contrast, better antibacterial activity was obtained with in-situ annealing at 500 degrees C, where 4-fold reductions compared with the control sample. Pre-determined properties can be precisely executed to achieve the desired performance as the so-called application-oriented engineered surface in the UHV system is established. This research highlighted the differences between two different annealing temperatures' effect on the base substrate material, which subsequently impacts the structure of AgNPs and their applications. Furthermore, the outcome of this work could contribute to the multifunctional surface for detecting heavy metals, various organic pollutants, and disinfection of water and food-borne pathogenic diseases.