M. De Leo

Bio: M. De Leo is an academic researcher from Federal University of Rio Grande do Norte. The author has contributed to research in topics: Surface modification & Nanomaterials. The author has an hindex of 3, co-authored 4 publications receiving 122 citations.

Towards a Better Understanding of Gold Electroless Deposition in Track-Etched Templates

Abstract: The template method for preparing nanomaterials entails synthesis of tubular or fibrillar nanostructures within the pores of a microporous membrane. If the holes are completely filled, solid nanowires result, while a partial filling with a continuous coating gives rise to nanotubes. This paper focused on the study of the parameters controlling electroless gold deposition in track-etched polycarbonate membranes. The structure and morphology of the obtained nanomaterials are examined and compared by a variety of electron microscopies and atomic force microscopy and examined in relation to electrochemical and spectrophotometric results. As far as nanotubes are concerned, problems with obtaining such a nanostructure are observed, in particular when membranes with pore diameters equal to or smaller than 30 nm are used. In the case of nanowires, defects related to fabrication problems are evidenced when they are used to prepare nanoelectrode ensembles (NEEs), because defects dramatically influence their voltamm...

Polycarbonate-based ordered arrays of electrochemical nanoelectrodes obtained by e-beam lithography.

Abstract: Ordered arrays of nanoelectrodes for electrochemical use are prepared by electron beam lithography (EBL) using polycarbonate as a novel e-beam resist. The nanoelectrodes are fabricated by patterning arrays of holes in a thin film of polycarbonate spin-coated on a gold layer on Si/Si3N4 substrate. Experimental parameters for the successful use of polycarbonate as high resolution EBL resist are optimized. The holes can be filled partially or completely by electrochemical deposition of gold. This enables the preparation of arrays of nanoelectrodes with different recession degree and geometrical characteristics. The polycarbonate is kept on-site and used as the insulator that separates the nanoelectrodes. The obtained nanoelectrode arrays (NEAs) exhibit steady state current controlled by pure radial diffusion in cyclic voltammetry for scan rates up to approximately 50 mV s − 1. Electrochemical results showed satisfactory agreement between experimental voltammograms and suitable theoretical models. Finally, the peculiarities of NEAs versus ensembles of nanoelectrodes, obtained by membrane template synthesis, are critically evaluated.

Track-Etched Nanopore/Membrane: From Fundamental to Applications

Abstract: Biomimetic and bio-inspired membranes draw great attention and generate extensive efforts to solve environmental, health, and energy issues In this field, track-etched membranes present the advantage to be tuned from a single pore to a large-scale multipore membrane On one hand, from the large-scale membrane to a single nanopore, the research becomes more fundamental, meticulous, and quantitative to describe concrete processes inside confined spaces This allows understanding the role of the surface phenomena and nanoscale effects On the other hand, working from a single pore to a multipore membrane allows perfect control of the membrane properties This ensures a promising ability for upscale from the lab findings to applications In this review, a global insight on the track-etched nanopore/membrane is taken through presentation of fabrication and functionalization methods, transport properties, and the related applications By functionalization, track-etched nanopores can be used to understand ion transport under confined spaces with high aspect ratio, to analyze single molecules, to design stimuli-responsive membranes, and to generate energy from salinity gradient and light

Arrays of copper nanowire electrodes: Preparation, characterization and application as nitrate sensor

Abstract: Ensembles of copper nanowire electrodes (CuWNEEs) are prepared via electrodeposition in track-etched polycarbonate membranes. Three different preparation methods are compared showing that the better results in terms of sensor durability and reproducibility are achieved by pre-sputtering a thin gold film on the templating membrane and attaching it to a supporting electrode by exploiting the adhesion property and ionic conductivity of a thin Nafion interlayer. SEM-EDS analyses together with double layer charging currents measurements indicate that these arrays are formed by copper nanowires with 400 nm diameter, 10 μm length distributed with a spatial density of 1 × 10 8 nanowires/cm 2 . The voltammetric reduction of nitrate at CuWNEEs is characterized by a well-resolved cathodic peak at approximately −0.680 V vs Ag/AgCl, whose current scales linearly with the nitrate concentration in the 10–400 μM range. The limit of detection (LOD) achieved by simple linear sweep voltammetry is in the 1.7–3.0 μM range, depending on the CuWNEE preparation method, such LOD values being among the lowest reported up to now in the literature. The possibility to use CuWNEEs in chloride and nitrite containing water samples is demonstrated.