Refractive Index of Benchmark Polystyrene Nanoplastics by Optical Modeling of UV-Vis Spectra.

Optical recognition and identification of nanoplastics such as polystyrene nanobeads (PSbs), a widely used polymer and an actual source of environmental pollution, is a challenging task relying on knowledge of the PSbs' refractive index (RI) and its relation to the PSbs' morphology. This is, however, lacking for PSbs' sizes lower than 1 μm. Here, we bridge this gap by measuring UV-vis spectra of PSbs deposited on a sapphire substrate via spin coating and by connecting the experimental data to the RI, PSbs' morphology, and optical transitions through a new optical model based on the Mie theory.

Pt NPs Supported on CeO/C as Electrocatalysts for Oxygen Reduction Reaction: Novel Physicochemical Insights on the Synthesis and on the Improved Activity and Stability.

This study emphasizes the effect of CeO on the Pt nanoparticle (NP) dimension, stability, and activity versus the oxygen reduction reaction. It is demonstrated that the one-pot synthesis of Pt NPs along with CeO NPs over carbon support produces small Pt NPs (2 nm) with higher activity, than the sole Pt NPs, thanks to the cooperative interaction exerted by CeO. This is nicely demonstrated by using synchrotron wide-angle X-ray total scattering and advanced data analysis, monitoring the in situ nucleation and growth of Pt NPs in the presence of preformed CeO NPs or of a Ce precursor.

Light-Mediated Growth of Gold Nanoplates Carried Out in Total Darkness.

The plasmon-mediated growth of noble metal nanoplates through the reduction of metal precursors onto resonantly excited seeds lined with planar defects stands out as one of the triumphs of photochemistry and nanometal synthesis. Such growth modes are, however, not without their drawbacks and, with a lack of suitable alternatives, limitations remain on the use of light as a synthetic control. Herein, a two-reagent seed-mediated gold nanoplate synthesis is demonstrated as a photochemical pathway where the illumination of the growth solution, as opposed to the emerging nanoplates, is the key requirement for growth.

Optical discrimination of pathological red blood cells.

Fast diagnostic methods are crucial to reduce the burden on healthcare systems. Currently, detection of diabetes complications such as neuropathy requires time-consuming approaches to observe the correlated red blood cells (RBCs) morphological changes. To tackle this issue, an optical analysis of RBCs in air was conducted in the 250-2500 nm range.

Periodic arrays of structurally complex oxide nanoshells and their use as substrate-confined nanoreactors.

Sacrificial templates present an effective pathway for gaining high-level control over nanoscale reaction products. Atomic layer deposition (ALD) is ideally suited for such approaches due to its ability to replicate the surface topography of a template material through the deposition of an ultrathin conformal layer. Herein, metal nanostructures are demonstrated as sacrificial templates for the formation of architecturally complex and deterministically positioned oxide nanoshells, open-topped nanobowls, vertically standing half-shells, and nanorings.

Insights into the Photoelectrocatalytic Behavior of gCN-Based Anode Materials Supported on Ni Foams.

Graphitic carbon nitride (gCN) is a promising -type semiconductor widely investigated for photo-assisted water splitting, but less studied for the (photo)electrochemical degradation of aqueous organic pollutants. In these fields, attractive perspectives for advancements are offered by a proper engineering of the material properties, e.g.

Exploring multielement nanogranular coatings to forestall implant-related infections.

Introduction: As we approach the post-antibiotic era, the development of innovative antimicrobial strategies that carry out their activities through non-specific mechanisms could limit the onset and spread of drug resistance. In this context, the use of nanogranular coatings of multielement nanoparticles (NPs) conjugated to the surface of implantable biomaterials might represent a strategy to reduce the systemic drawbacks by locally confining the NPs effects against either prokaryotic or eukaryotic cells.

Methods: In the present study, two new multielement nanogranular coatings combining Ag and Cu with either Ti or Mg were synthesized by a gas phase physical method and tested against pathogens isolated from periprosthetic joint infections to address their potential antimicrobial value and toxicity in an experimental setting.

Synergistic Effect of Sn and Fe in Fe-N Site Formation and Activity in Fe-N-C Catalyst for ORR.

Iron-nitrogen-carbon (Fe-N-C) materials emerged as one of the best non-platinum group material (non-PGM) alternatives to Pt/C catalysts for the electrochemical reduction of O in fuel cells. Co-doping with a secondary metal center is a possible choice to further enhance the activity toward oxygen reduction reaction (ORR). Here, classical Fe-N-C materials were co-doped with Sn as a secondary metal center.

Mechanical Properties of Nanoporous Metallic Ultrathin Films: A Paradigmatic Case.

Nanoporous ultrathin films, constituted by a slab less than 100 nm thick and a certain void volume fraction provided by nanopores, are emerging as a new class of systems with a wide range of possible applications, including electrochemistry, energy storage, gas sensing and supercapacitors. The film porosity and morphology strongly affect nanoporous films mechanical properties, the knowledge of which is fundamental for designing films for specific applications. To unveil the relationships among the morphology, structure and mechanical response, a comprehensive and non-destructive investigation of a model system was sought.

A Bipolar CdS/Pd Photocatalytic Membrane for Selective Segregation of Reduction and Oxidation Processes.

A photocatalytically active bipolar membrane consisting of a CdS photocatalyst and Pd electrocatalyst has been constructed to carry out environmentally relevant oxidation and reduction processes. The ion exchange property of a bipolar membrane (BPM) has allowed us to load the CdS photocatalyst on one side and Pd electrocatalyst on the other side. By inserting the photocatalytic BPM-CdS/Pd membrane between the two compartments of an H-cell, we can separate the reduction and oxidation processes.

The Role of Substrate on Thermal Evolution of Ag/TiO Nanogranular Thin Films.

In multicomponent thin films, properties and functionalities related to post-deposition annealing treatments, such as thermal stability, optical absorption and surface morphology are typically rationalized, neglecting the role of the substrate. Here, we show the role of the substrate in determining the temperature dependent behaviour of a paradigmatic two-component nanogranular thin film (Ag/TiO) deposited by gas phase supersonic cluster beam deposition (SCBD) on silica and sapphire. Up to 600 °C, no TiO grain growth nor crystallization is observed, likely inhibited by the Zener pinning pressure exerted by the Ag nanoparticles on the TiO grain boundaries.

Photocatalytic Activity of Cellulose Acetate Nanoceria/Pt Hybrid Mats Driven by Visible Light Irradiation.

A photocatalytic system for the degradation of aqueous organic pollutants under visible light irradiation is obtained by an innovative approach based on ceria/platinum (Pt) hybrid nanoclusters on cellulose acetate fibrous membranes. The catalytic materials are fabricated by supersonic beam deposition of Pt nanoclusters directly on the surface of electrospun cellulose acetate fibrous mats, pre-loaded with a cerium salt precursor that is transformed into ceria nanoparticles directly in the solid mats by a simple thermal treatment. The presence of Pt enhances the oxygen vacancies on the surface of the formed ceria nanoparticles and reduces their band gap, resulting in a significant improvement of the photocatalytic performance of the composite mats under visible light irradiation.

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

Antimicrobial coatings are a promising strategy to counteract the spreading of multi-drug-resistant pathogens through cross-contamination of surfaces. Coatings with nanostructured characteristics can exploit the different antimicrobial mechanisms of nanomaterials provided the composition, the morphology and the mechanical properties of the film can be tuned by the specific synthesis methods. This review addresses the synthesis of antibacterial nanostructured coatings with a focus on physical synthesis methods.

Ag@TiO nanogranular films by gas phase synthesis as hybrid SERS platforms.

The synthesis of hybrid metallic-dielectric substrates as reliable SERS platforms relies on core-shell nanoparticles, obtained by wet chemistry, with an outer dielectric shell composed of SiO or TiO. Apart from the shell composition, the nanoparticle density and aggregation type strongly affect the surface-enhanced SERS. Going beyond a single layer by building random aggregates of hybrid NPs would result in a step forward in the production of reliable hybrid SERS platforms.

Tailored Ag-Cu-Mg multielemental nanoparticles for wide-spectrum antibacterial coating.

Bactericidal nanoparticle coatings are very promising for hindering the indirect transmission of pathogens through cross-contaminated surfaces. The challenge, limiting their employment in nosocomial environments, is the ability of tailoring the coating's physicochemical properties, namely, composition, cytotoxicity, bactericidal spectrum, adhesion to the substrate, and consequent nanoparticles release into the environment. We have engineered a new family of nanoparticle-based bactericidal coatings comprising Ag, Cu, and Mg and synthesized by a green gas-phase technique.

Photoacoustic Sensing of Trapped Fluids in Nanoporous Thin Films: Device Engineering and Sensing Scheme.

Accessing fluid infiltration in nanogranular coatings is an outstanding challenge, of relevance for applications ranging from nanomedicine to catalysis. A sensing platform, allowing quantifying the amount of fluid infiltrated in a nanogranular ultrathin coating, with thickness in the 10-40 nm range, is here proposed and theoretically investigated by multiscale modeling. The scheme relies on impulsive photoacoustic excitation of hypersonic mechanical breathing modes in engineered gas-phase-synthesized nanogranular metallic ultrathin films and time-resolved acousto-optical read-out of the breathing modes frequency shift upon liquid infiltration.

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

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.

Interaction of iron with a wagon wheel-like ultrathin TiOx film grown on Pt(111).

The structure and thermal evolution of Fe nanoparticles deposited on a wetting TiOx ultrathin film epitaxially grown on Pt(111) has been characterized by various surface science techniques. Combining the results obtained it is shown that, at room temperature, metallic Fe nucleates randomly and oxidizes at the interface. A thermal treatment causes Fe migration through the TiOx layer, forming a mixed oxide and a new hexagonal ultrathin film phase.

Highly bactericidal Ag nanoparticle films obtained by cluster beam deposition.

Unlabelled: The recent emergence of bacterial pathogens resistant to most or all available antibiotics is among the major global public health problems. As indirect transmission through contaminated surfaces is a main route of dissemination for most of such pathogens, the implementation of effective antimicrobial surfaces has been advocated as a promising approach for their containment, especially in the hospital settings. However, traditional wet synthesis methods of nanoparticle-based antimicrobial materials leave a number of key points open for metal surfaces: such as adhesion to the surface and nanoparticle coalescence.

Polyvinyl alcohol electrospun nanofibers containing Ag nanoparticles used as sensors for the detection of biogenic amines.

Polyvinyl alcohol (PVA) electrospun nanofibers containing Ag nanoparticles (NPs) have been deposited on glass substrates. The aim of the work was to test the feasibility of this approach for the detection of biogenic amines by using either the Ag localized surface plasmon resonance quenching caused by the adsorption of amines on Ag NPs or by detecting the amines by surface enhanced Raman spectroscopy (SERS) after adsorption, from the gas phase, on the metal NPs. Two different approaches have been adopted.

Tracking thermally-activated transformations in a nanostructured metal/oxide/metal system.

We present experimental and theoretical evidence of sequential redox processes and structural transformations occurring by increasing temperature in a metal/oxide/metal system obtained via deposition of Fe atoms onto a z'-TiO(1.25)/Pt(111) ultrathin film in UHV. The initial reduction of the z'-TiO(x) phase by Fe at room temperature is followed by Fe diffusion and partial penetration into the substrate at intermediate temperatures.

Stability and chemisorption properties of ultrathin TiO(x)/Pt(111) films and Au/TiO(x)/Pt(111) model catalysts in reactive atmospheres.

The stability of three ultrathin TiO(x)/Pt(111) films with different stoichiometry and defectivity and the corresponding Au/TiO(x)/Pt(111) model catalysts in CO or a CO-O(2) (1 : 1) gas mixture up to a pressure of 100 mbar has been investigated. According to previous studies, the ultrathin films proved to be effective substrates to deposit in UHV Au nanoparticles with specific morphologies and lateral sizes ranging between 1 and 6 nm. The films have been characterized before and after the exposure using X-ray photoemission spectroscopy (XPS), low-energy electron diffraction (LEED) and scanning tunnelling microscopy (STM).

Directed assembly of Au and Fe nanoparticles on a TiOx/Pt(111) ultrathin template: the role of oxygen affinity.

The essential role of O affinity in the directed assembly of size-selected Au and Fe nanoparticles (NPs) on a TiO(x)/Pt(111) ultrathin oxide phase, an effective template for size selected metal NP growth, is revealed through scanning tunneling microscopy and density-functional calculations. A weakly interacting element (Au) diffuses rapidly and gets trapped in the vacancy defects (picoholes) located inside parallel rows (troughs, spaced 1.44 nm apart) peculiar to the film structure, producing size-selected NPs arranged in regular linear arrays aligned along the troughs.

Au nanoparticles on a templating TiO(x)/Pt(111) ultrathin polar film: a photoemission and photoelectron diffraction study.

We present an in-depth investigation of Au nanoparticles self-assembled on a zigzag-like TiO(x)/Pt(111) ultrathin polar film, whose structure is known in great detail. The peculiar pattern of defects (picoholes) templates a linear array of size-selected (ca. 1 nm) Au nanoparticles without disruption of the titania layer, as observed by scanning tunneling microscopy.