Julio Bastos-Arrieta

Simple green routes for the customized preparation of sensitive carbon nanotubes/epoxy nanocomposite electrodes with functional metal nanoparticles

In this communication, we report novel, simple and effective methodologies for the incorporation of functional metal nanoparticles in carbon nanotubes/epoxy nanocomposite electrodes. The incorporation of nanoparticles was obtained by three different routes: (a) in situ functionalization of carbon nanotube surfaces, (b) incorporation and dispersion into a composite matrix and (c) composite surface modification by drop-attachment. These techniques offer a customized route for the preparation of sensitive amperometric sensors. Independent of the route of noble metal nanoparticle incorporation, the final result is a significant enhancement of the electroanalytical response.

CdS quantum dots as a scattering nanomaterial of carbon nanotubes in polymeric nanocomposite sensors for microelectrode array behavior

This work is focused on evaluating the direct electrochemical effect of semi-conducting nanocrystals when they are integrated in bulky nanocomposite sensors based on multiwalled carbon nanotubes (MWCNTs). For this aim, MWCNTs have successfully been functionalized with CdS quantum dots (CdS–QDs@MWCNTs) and then dispersed within an insulating polymeric matrix, as epoxy resin, for electroanalytical sensing purposes. After an accurate voltammetric and impedimetric characterization, some electrochemical parameters were surprisingly enhanced regarding the non-modified sensors, such as peak current height, electroactive area, and emphasizing the double-layer capacitance. These results can be explained since CdS–QDs confer to the nanocomposite sensor a microelectrode array behavior, dispersing the conductive microzones through the polymeric matrix, as revealed by morphological experiments. The feasibility of this approach was amperometrically evaluated for ascorbic acid and hydrogen peroxide, both used as reference analytes. Electroanalytical results demonstrated that this approach provides to the CdS–QDs-modified nanocomposite sensors the capability to determine low concentrations of analytes and improved sensitivities.

Morphological changes of gel-type functional polymers after intermatrix synthesis of polymer stabilized silver nanoparticles

This paper reports the results of intermatrix synthesis (IMS) of silver metal nanoparticles (Ag-MNPs) in Purolite C100E sulfonic ion exchange polymer of the gel-type structure. It has been shown that the surface morphology of the initial MNP-free polymer is absolutely smooth, but it dramatically changes after the kinetic loading of Ag on the polymer and then IMS of Ag-MNPs. These morphological changes can be explained by the interaction of Ag-NPs with the polymer chains, leading to a sort of additional cross-linking of the polymer. As a result, the modification of the gel-type matrix with Ag-MNPs leads to the increase of the matrix cross-linking, which results in the increase of its surface area and the appearance of nanoporosity in the polymer gel. Ag-MNPs are located near the polymer surface and do not form any visible agglomerations. All these features of the nanocomposites obtained are important for their practical applications in catalysis, sensor applications, and bactericide water treatment.

Ag Nanoparticles Drop-Casting Modification of Screen-Printed Electrodes for the Simultaneous Voltammetric Determination of Cu(II) and Pb(II)

A new silver nanoparticle modified screen-printed electrode was developed and applied to the simultaneous determination of Pb(II) and Cu(II). Two different types of silver nanoparticles with different shapes and sizes, Ag nanoseeds and Ag nanoprisms, were microscopically characterized and three different carbon substrates, graphite, graphene and carbon nanofibers, were tested. The best analytical performance was achieved for the combination of Ag nanoseeds with a carbon nanofiber modified screen-printed electrode. The resulting sensor allowed the simultaneous determination of Pb(II) and Cu(II) at trace levels and its applicability to natural samples was successfully tested with a groundwater certified reference material, presenting high reproducibility and trueness.

Bifunctional Polymer-Metal Nanocomposite Ion Exchange Materials

The unusual electrical, optical, magnetic, and chemical properties of metal colloids (better known in nowadays as metal nanoparticles, MNPs) have attracted increasing interest of scientists and technologists during the last decade. In fact, although Nanoscience and Nanotechnology are quite recent disciplines, there have already been a high number of publications that discuss these topics. [1-11] What is more, there are quite new high impact peer-reviewed journals especially devoted to these research fields and there is also a particular subject category “Nanoscience & Nanotechnology” in the Journal Citation Reports from Thomson Reuters.

Ecologically Friendly Polymer-Metal and Polymer-Metal Oxide Nanocomposites for Complex Water Treatment

In this regard,polymeric supports play a very important role for several reasons including, the ease of their preparation in the most appropriate physical forms (e.g., granulated, fi‐ brous, membranes, etc.), the possibility to produce the macroporous matrices with highly developed surface area and some others. However, the immobilization of NPs on the appro‐ priate polymeric support represents a separate task [2] and thus, the incorporation of poly‐

Intermatrix synthesis of Ag, AgAu and Au nanoparticles by the galvanic replacement strategy for bactericidal and electrocatalytically active nanocomposites

The intermatrix synthesis (IMS) technique has proven to be an environmentally friendly methodology for the preparation of functional metal nanoparticles (FMNPs) on different reactive matrices. The distribution of these FMNPs is an important feature to control depending on the final application of the nanocomposite: bactericide assays for water treatment, heterogeneous catalysis, electrocatalytic effects and others. IMS offers the feasibility to control the FMNP distribution, taking into account the adequacy of the ion exchange form of the reactive matrix and the chemical nature of the reducing agent used for the synthesis (the Donnan effect). Consequently, AgAu–FMNPs and Au–FMNPs containing nanocomposites have been prepared by coupling a galvanic replacement stage to IMS, with tested bactericide features attributed to the distribution of the nanoparticles on the material. In addition, Ag–FMNPs and Au–FMNPs contained on multiwalled carbon nanotubes have been synthesized and used as conducting nanofillers for the development of amperometric nanocomposite sensors based on epoxy resin. The incorporation of these FMNPs into the nanocomposite sensor has shown significant electrocatalytic effects, obtaining enhanced electrochemical and analytical parameters, such as higher signal-to-noise ratios as well as better detection limits, quantification limits and sensitivities for the oxidation of ascorbic acid in water, which was used as a model analyte.

Preparation and characterisation of Pd nanoparticles doped UO2 samples

To assess the safety of the deep geological disposal that would store the spent nuclear fuel (SNF), studies are centred on the SNF behaviour under repository conditions. UO2, which is the most common compound of SNF matrix, is highly sensitive to the redox potential and it could be oxidised to more soluble phases, enhancing the liberation of harmful radionuclides. Among fission products in the SNF, e-particles (nanoparticles) are believed to play an important role avoiding the oxidation. Consequently, scientists are testing efficient and low cost methodologies for the preparation of novel materials by incorporation of nanoparticles into bulk components. In this communication we present the methodology for preparation of non-irradiated UO2 doped with Pd Nanoparticles (Pd-NPs), as an analogue of e-particles present in the SNF. Pd-NPs doped UO2 samples were characterised by high resolution electron microscopy to identify the presence, the morphology and distribution of the nanoparticles.

Bi-Functional Polymer-Metal Nanocomposites: Modification of Ion-Exchange Materials with Silver Nanoparticles

This communication reports the results obtained by the modification of gel-type ion exchange materials with functional metal nanoparticles having biocide activity. The modification is carried out by using Intermatrix Synthesis technique coupled with Donnan Exclusion Effect which results in the most favorable distribution of silver nanoparticles near the surface of the nanocomposite material. The surface of the polymer-metal nanocomposite is characterized by the worm-like structure due to the interaction of metal nanoparticles with polymer chains. This interaction leads to the appearance of nanoporosity in the matrix which enhances its mass-transfer characteristics. Moreover, it has been shown that modification of gel-type ion exchangers with silver nanoparticles essentially does not change the ion exchange properties of the initial polymeric matrix. Graphical Abstract: Intermatrix synthesis (IMS) of Ag functional metal nanoparticles (FMNPs) leads to a significant Surface modification of gel-type polymers without changing ion exchange properties of the polymeric support. A) smooth surface confocal 3D image and SEM frame image of raw gel-type cationic resin before IMS B) rough surface confocal ·3D image and SEM frame image of gel-type cationic resin containing after IMS of Ag-FMNPs.