Exploring the Optical and Morphological Properties of Ag and Ag/TiO2 Nanocomposites Grown by Supersonic Cluster Beam Deposition

Abstract

Nanocomposite systems and nanoparticle (NP) films are crucial for many applications and research fields. The structure-properties correlation raises complex questions due to the collective structure of these systems, often granular and porous, a crucial factor impacting their effectiveness and performance. In this framework, we investigate the optical and morphological properties of Ag nanoparticles (NPs) films and of Ag NPs/TiO2 porous matrix films, one-step grown by supersonic cluster beam deposition. Morphology and structure of the Ag NPs film and of the Ag/TiO2 (Ag/Ti 50-50) nanocomposite are related to the optical properties of the film employing spectroscopic ellipsometry (SE). We employ a simple Bruggeman effective medium approximation model, corrected by finite size effects of the nano-objects in the film structure to gather information on the structure and morphology of the nanocomposites, in particular porosity and average NPs size for the Ag/TiO2 NP film. Our results suggest that SE is a simple, quick and effective method to measure porosity of nanoscale films and systems, where standard methods for measuring pore sizes might not be applicable.

Antimicrobial Nanostructured Coatings: A Gas Phase Deposition and Magnetron Sputtering Perspective

“…This NPs structure [137,138] is remarkably different from the simple Ag decoration of TiO 2 nanostructures obtained by sol-gel [57], solvothermal [58], hydrothermal [59], and hydrolyzed solution [139] methods. Moreover, the work clearly indicates that the compositional changes in the pristine rod (i.e., pure Ag, AgTi8020, AgTi5050) correspond to an analogous variation in the synthesized bi-NPs stoichiometry [71,125], proving that SCBD is a powerful tool for tailoring the NPs' chemical composition by simply adjusting the Ag/Ti relative concentration in the initial rod. Finally, the nanostructured Ag-Ti coating shows good adhesion to the substrate and exhibits an exceptional bactericidal effect against major GN nosocomial pathogens, remarkably similar to a pure Ag NPs coating [70], but with an 85% lower Ag mass content.…”

“…A feasible alternative to tackle the different issues discussed above is to employ a different physical method, namely Supersonic Cluster Beam Deposition (SCBD) [6,70,71,[124][125][126][127]. The peculiar characteristics of this method are related to the working principle described in detail elsewhere [19,90,126,127] and schematized in Figure 2b.…”

“…The flexibility of the methods to directly synthesize and deposit coatings with multi-elemental NPs has been demonstrated in the work of Benetti et al, showing the possibility to synthesize bi-element NPs of Ag and Ti with variable elemental concentrations [71,125]. Two different rods for the SCBD setup have been used; the first (AgTi8020) has nominal weight contents of 80% Ag and 20% Ti, and the second (AgTi5050) has nominal weight contents of 50% Ag and 50% Ti [71,125]. The synthesized NPs, characterized by high-resolution scanning transmission electron microscope (HR-STEM), can be observed in Figure 8.…”

“…This route was pursued again using SCBD, since this technique has been employed to grow NPs films of different materials (Ti [3,90], C [135], Pd [136]) but has also been used to dope TiO 2 NPs with Cr and N at atomic concentrations of 3% to 7 % [6][7][8]71,124], suggesting that the method could in principle be able to deposit NPs and granular films with tunable element concentrations. The flexibility of the methods to directly synthesize and deposit coatings with multi-elemental NPs has been demonstrated in the work of Benetti et al, showing the possibility to synthesize bi-element NPs of Ag and Ti with variable elemental concentrations [71,125]. Two different rods for the SCBD setup have been used; the first (AgTi8020) has nominal weight contents of 80% Ag and 20% Ti, and the second (AgTi5050) has nominal weight contents of 50% Ag and 50% Ti [71,125].…”

A New Synthetic Strategy of Ag‐TiO2 Nanocomposites Based on Ligand‐to‐Metal Charge Transfer under Visible Light Irradiation: Characterizations and Photocatalytic Activity

“…Several approaches have been reported for the synthesis of noble metal‐loaded TiO 2 . Ag‐TiO 2 catalysts have mainly been synthesized by two types of methods, one of which is non‐wet synthesis, including usage of gas‐phase deposition technique, supersonic cluster beam deposition, magnetron sputtering techniques, electrospinning, atomic layer deposition, femtosecond laser irradiation . High temperature and pressure conditions and complex equipment are great problems associated with non‐wet synthetic methods.…”