Search results for "nanomaterial"

Proton Exchange Membrane Fuel Cells (PEMFCs): Advances and Challenges

2021

The study of the electrochemical catalyst conversion of renewable electricity and carbon oxides into chemical fuels attracts a great deal of attention by different researchers. The main role of this process is in mitigating the worldwide energy crisis through a closed technological carbon cycle, where chemical fuels, such as hydrogen, are stored and reconverted to electricity via electrochemical reaction processes in fuel cells. The scientific community focuses its efforts on the development of high-performance polymeric membranes together with nanomaterials with high catalytic activity and stability in order to reduce the platinum group metal applied as a cathode to build stacks of proton …

Rayleigh-instability-driven dewetting of thin Au and Ag films on indium-tin-oxide surface under nanosecond laser irradiations

2013

Investigations have been carried out on laser-beam-induced nanoparticle (NP) formation in thin (5 nm) Au and Ag films on indium-tin-oxide substrate. After the irradiation the films were observed to break-up into NPs through a dewetting mechanism. This mechanism was investigated as a Rayleigh-instability- driven process. In fact, for each used laser fluence, the resulting Au and Ag NPs' mean size and surface-to-surface mean distance were quantified and correlated between them in the framework of the Rayleigh-instability theory showing an excellent agreement. © The Institution of Engineering and Technology 2013.

Nanopartículas de oro: procesos fotoinducidos y estudios de transferencia de fase

2013

Las propiedades físicas y químicas de las nanopartículas de oro (AuNPs), tales como la interacción con la luz, solubilidad, catálisis, etc. dependen de varios factores:  El tamaño y la forma: la interacción de las AuNPs con la luz depende mucho de sus dimensiones físicas. Estos parámetros son cruciales para la aplicación de estos nanomateriales.  El ligando puede modificar las propiedades ópticas, las propiedades químicas, la estabilidad y la solubilidad de las AuNPs. Uno de los objetivos de esta tesis es optimizar la modificación controlada del tamaño/forma de AuNPs estabilizadas con tioles utilizando luz, ya sea en presencia o en ausencia de un fotosensibilizador. El otro objetivo, es e…

Physicochemical investigation of surfactant-coated gold nanoparticles synthesized in the confined space of dry reversed micelles

2006

Abstract Gold nanoparticle/surfactant composites have been synthesized by a novel reduction reaction in the confined space of dry sodium bis(2- ethylhexyl)sulfosuccinate (AOT) or lecithin reversed micelles dispersed in n-heptane and cyclohexane, respectively. The reaction was carried out by adding an opportune amount of anhydrous hydrazine/tetrahydrofuran solution to a suspension of HAuCl4-containing dry reversed micelles dispersed in organic solvent. UV–vis investigation ascertained the formation of stable metal gold nanoparticles and the analysis of FT-IR spectra highlighted the formation of an oriented surfactant monolayer at the nanoparticle surface. Simple evaporation under vacuum of t…

SMART NANOSPONGE-BASED SYSTEMS FOR ADVANCED APPLICATIONS

2023

Temperature-responsive hybrid nanomaterials based on modified halloysite nanotubes uploaded with silver nanoparticles

2022

New temperature-responsive hybrid nanomaterials based on modified halloysite nanotubes (HNTs) containing grafted polymer brushes with silver nanoparticles have been successfully fabricated. We used a three steps process including synthesis of the initiating coatings onto HNTs surface, fabrication of the POEGMA – poly(oligo(ethylene glycol)ethyl ether methacrylate) grafted brushes and synthesis of the silver nanoparticles (AgNPs). The synthesis and properties of hybrid nanomaterials were studied by FT-IR, TGA and DLS methods. It is shown that the introduction of AgNPs, formed from 0.005 M AgNO3 solution leads to a significant reduction of low critical solution temperature (LCST) of the polym…

Measuring optical anisotropy in poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) films with added graphene

2015

Abstract Graphene is a 2D nanomaterial having a great potential for applications in electronics and optoelectronics. Composites of graphene with conducting polymers have shown high performance in practical devices and their solution-processability enables low-cost and high-throughput mass manufacturing using printing techniques. Here we measure the effect of incorporation of graphene into poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) to the optical anisotropy, absorbance and conductivity of the film. Uniaxial anisotropy in PEDOT:PSS films has been thought to be caused by the spin-coating process used in fabrication. We have characterized spray- and spin-coated films …

Thiol-Stabilized Atomically Precise, Superatomic Silver Nanoparticles for Catalyzing Cycloisomerization of Alkynyl Amines

2018

Abstract Both the electronic and surface structures of metal nanomaterials play critical roles in determining their chemical properties. However, the non-molecular nature of conventional nanoparticles makes it extremely challenging to understand the molecular mechanism behind many of their unique electronic and surface properties. In this work, we report the synthesis, molecular and electronic structures of an atomically precise nanoparticle, [Ag206L72]q (L = thiolate, halide; q = charge). With a four-shell Ag7@Ag32@Ag77@Ag90 Ino-decahedral structure having a nearly perfect D5h symmetry, the metal core of the nanoparticle is co-stabilized by 68 thiolate and 4 halide ligands. Both electroche…

Engineered surface waves in hyperbolic metamaterials

2013

We analyzed surface-wave propagation that takes place at the boundary between a semi-infinite dielectric and a multilayered metamaterial, the latter with indefinite permittivity and cut normally to the layers. Known hyperbolization of the dispersion curve is discussed within distinct spectral regimes, including the role of the surrounding material. Hybridization of surface waves enable tighter confinement near the interface in comparison with pure-TM surface-plasmon polaritons. We demonstrate that the effective-medium approach deviates severely in practical implementations. By using the finite-element method, we predict the existence of long-range oblique surface waves. This research was fu…

A new forum for upconversion research: The UPCON conference

2019

International audience; The Conference and Spring School on Properties, Design and Applications of Upconversion Nanomaterials (UPCON) provides a new forum for all experts and newcomers in the field of upconversion research. On the occasion of the second UPCON 2018 in Valencia (Spain), we are pleased to present a collection of 12 reviews and research articles that reflect recent advances in upconversion materials, their unique luminescent properties and many applications spanning from nanoscale thermometry to biomedicine.