Nanofilms
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Recent papers in Nanofilms
The influence of processing parameters is investigated on the structural characteristics of single and mixed oxides produced by spray pyrolysis technique. The films were synthesized by spraying precursor solutions through a nozzle onto a... more
The influence of processing parameters is investigated on the structural characteristics of single and mixed oxides produced by spray pyrolysis technique. The films were synthesized by spraying precursor solutions through a nozzle onto a heated alumina substrate. The precursor consisted separately of aqueous solutions of tin chloride for SnO 2 and zinc chloride for ZnO for single oxide cases, and aqueous solutions of tin chloride and indium nitrate for SnO 2 + In 2 O 3 and zinc chloride and indium nitrate solutions for ZnO + In 2 O 3 for mixed oxide cases. The substrate temperature was varied accordingly for each single and mixed case. The films produced were characterized by X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy. The results indicate that a non-homogenous film is formed at low temperature for both single oxides considered. The temperature has significant effect on the composition of the synthesized films of both single oxides below 450˚C. The results for mixed oxides show that the best homogeneous films are obtained for 80 wt% ZnO + 20 wt% In 2 O 3 , and 80 wt% SnO 2 + 20 wt% In 2 O 3 .
Lightning strike protection (LSP) and electromagnetic interference (EMI) shielding topics have been extensively investigated, since composite material was first introduced to an aircraft a few decades ago. Generally, electrically and... more
Lightning strike protection (LSP) and electromagnetic interference (EMI) shielding topics have been extensively investigated, since composite material was first introduced to an aircraft a few decades ago. Generally, electrically and thermally conductive materials, such as metallic foils, metal mesh, ply-integrated interwoven wires, a continuous conductive path of low-resistance materials, and highly conductive nanoparticles and nanoflakes are used to dissipate the high-density current, shockwaves, electromagnetic forces/charges, and heat generated during lightning strikes. This study deals with the fabrication of pre-impregnated (prepreg) composite structures of carbon and glass fibers incorporated with submicron and nanoscale gold (Ag), silver (Au), aluminum (Al), and copper (Cu) films on top of composite surfaces during the curing process, and determining the effectiveness of LSP and EMI shielding. Initially, electrical conductivity experiments were conducted on composite test coupons and the electrical properties investigated under tensile loadings within the elastic regions of the composites. Test results indicated that the surface resistivity did not change much under the tensile loads. EMI shielding tests confirmed that noise was not audible on an AM radio because of the metallic submicron and nanoscale film surfaces on the composites. During lightning strike tests, a high current of 200-k amps was applied on the surface of the composite structures. The LSP test indicated that after the lightning strike, the resulting damage on both sides of the fiber composite was considerably low due to the metallic films co-cured on the fiber-reinforced composites. An increase in current with the metallic films certainly helped to reduce damage to the composites and avionics systems after lightning strike tests.
During the last decade and nowadays an enormous research effort has been deployed to the porous materials. Design, pores sizes, shapes, morphology and density are crucial features to increase the surface material, which helps to improve... more
During the last decade and nowadays an enormous research effort has been deployed to the porous materials. Design, pores
sizes, shapes, morphology and density are crucial features to increase the surface material, which helps to improve adsorption and absorption properties and helps the interaction of living cells with the porous material. To achieve this goal, the use
of coatings with gold and silver nanoparticles or nanofilms can increase the level of biocompatibility or biotoxicity, especially
due to their effect on cell adhesion and proliferation. The biocompatibility and other properties obtained for nanoparticles
application coatings are related to the particle size.
Gold and silver nanoparticles are size controlled when a colloid is form and later this particles are immobilized on a porous
silicone matrix, the pH, temperature, concentration, and proportion or ratio between the metal compound and the stabilizer
or reducing agent are factors to consider for a gold and silver particles control on the colloid formation, an lather on the
immobilization of these particles over a porous silicone matrix to obtain hybrid nanostructures that combine the best properties from porous polymers and metal particles based on the application.
sizes, shapes, morphology and density are crucial features to increase the surface material, which helps to improve adsorption and absorption properties and helps the interaction of living cells with the porous material. To achieve this goal, the use
of coatings with gold and silver nanoparticles or nanofilms can increase the level of biocompatibility or biotoxicity, especially
due to their effect on cell adhesion and proliferation. The biocompatibility and other properties obtained for nanoparticles
application coatings are related to the particle size.
Gold and silver nanoparticles are size controlled when a colloid is form and later this particles are immobilized on a porous
silicone matrix, the pH, temperature, concentration, and proportion or ratio between the metal compound and the stabilizer
or reducing agent are factors to consider for a gold and silver particles control on the colloid formation, an lather on the
immobilization of these particles over a porous silicone matrix to obtain hybrid nanostructures that combine the best properties from porous polymers and metal particles based on the application.
Editorial on the Research Topic Nanofilms and Nanostructures for Energy Applications Since the beginning of the nanotechnology era, many efforts have been made to fully understand and explore the potential of nanoscale science and... more
Editorial on the Research Topic Nanofilms and Nanostructures for Energy Applications Since the beginning of the nanotechnology era, many efforts have been made to fully understand and explore the potential of nanoscale science and technology. In the last decades, we witness how advances in this multidisciplinary field are increasingly present in our daily lives. Among its areas of application, the use of nanomaterials to improve the performance of energy conversion, harvesting, and storage devices is one of the hot topics. The outstanding properties of different types of nanomaterials provide a wide opportunity for researchers and designers to develop more efficient energy technologies. Currently, nanomaterials are explored in several energy devices, such as solar cells, fuel cells, supercapacitors, batteries, among others. In this context, a significant progress in the synthesis, characterization and processing of nanomaterials for energy applications is being achieved. This research topic collected five articles, three original research articles, one methods article and one review article, which cover recent findings and developments in nanofilms and nanostructures for energy applications. Relevant themes in nanotechnology for energy research field were explored in these publications, namely electrodeposited Ni-Cu foams as electrodes for supercapacitors, optical properties of plasmonic nanostructures, growth of titanium dioxide (TiO 2) thin films by atomic layer deposition (ALD), fabrication of high-efficiency hydrogenated amorphous-silicon (a-Si:H) solar cells and preparation of supported metal catalysts using non-thermal plasmas. Figure 1 illustrates these themes. The first original research article reports the results of the electrochemical characterization of electrodeposited porous nickel-copper metallic foams on stainless steel substrate by the dynamic hydrogen bubbling template technique aiming at its use as an electrode for supercapacitors. The effect of working parameters, such as the applied current density and deposition time, on the surface morphology and properties of the electrodeposited layers were also discussed. It was observed that the Ni-Cu foams have the potential to be used as an ideal electrode material for supercapacitors (Abdelfatah et al.). The second original research article presents a theoretical investigation on the optical properties of metallic nanostructures and how they support plasmon resonances that can be tuned in the desired range of the solar spectrum by changing their size, shape, and surrounding environment. This study focused on two different systems: isolated and coupled gold metal nanospheres. The results indicated that the simulation of extinction spectrum of these nanostructures can be further extended to coupled nanospheroids, coupled nanorods, and chains of nanoparticles, which can be used in several applications such as solar stills, solar collectors, and solar cells (Pathak). In the scope of thin film technology, the third original research article presents a detailed theoretical and experimental study on the impact of the precursor's pulse time on the growth per
DOWNLOAD FREE FOR 50 DAYS AT https://authors.elsevier.com/c/1bL5g3boDQ2CDq . Titanium dioxide is a compound of great interest, due to its functional properties; one of its most important uses is as a photocatalyst. TiO2 coatings can be... more
DOWNLOAD FREE FOR 50 DAYS AT https://authors.elsevier.com/c/1bL5g3boDQ2CDq . Titanium dioxide is a compound of great interest, due to its functional properties; one of its most important uses is as a photocatalyst. TiO2 coatings can be deposited using different techniques. Aerosol Assisted Chemical Vapour Deposition (AACVD) is particularly interesting, as high temperature or pressure are not necessary to generate the gaseous precursors. Furthermore, by carefully choosing the deposition conditions (i.e. deposition temperature, solvent), it is possible to obtain deposits with different morphology and, consequently, different functional properties. In this paper we present the synthesis of titanium dioxide coatings with AACVD using complexes between titanium isopropoxide (TIPP) and acetyl acetone (acac) as precursors. Deposition experiments were performed using different ratios of TIPP to acac, to assess the effect on the composition of the coatings, their morphology and photocatalytic activity. Results showed that the use of acac led to nanostructured titanium dioxide (nanoparticles of about 10−25 nm diameter). Raman analysis showed the presence of both anatase and rutile phases. XPS analysis indicated the presence of residual carbonaceous species in the coatings; despite this, they displayed photocatalytic properties similar or superior to AACVD films without carbon. Photocatalytic tests, performed measuring the Formal Quantum Efficiency (FQE) and the Formal Quantum Yield (FQY) in the degradation of resazurin, showed that a acac:TIPP ratio equal to 1 led to the material with the highest performance, as the FQE value was about three times higher than that for the coating prepared with TIPP alone. Overall the complexes between TIPP and acac are promising precursors for the AACVD technique, leading to nanostructured coatings with enhanced performance.
Surface modification, using biomaterials to mimic in vivo cell microenvironment, plays an important role in tissue engineering. Current work studies the growth and behaviour of primary bovine articular chondrocytes on layer-by-layer... more
Surface modification, using biomaterials to mimic in vivo cell microenvironment, plays an important role in tissue engineering. Current work studies the growth and behaviour of primary bovine articular chondrocytes on layer-by-layer self-assembled nanofilms of 11 different biomaterials, including polyelectrolytes and proteins [poly(styrene sulphonate) (PSS), fibronectin, poly-L-lysine (PLL), poly-D-lysine (PDL), laminin, bovine serum albumin (BSA), chondroitin sulphate (CS), poly(ethyleneimine) (PEI), poly(dimethyldiallylammonium chloride) (PDDA), collagen and poly(ethylene glycol) amine (PEG-NH2)]. Mono-, bi-, and tri-layer nanofilm architectures were deposited on 24-, 96-well plate polystyrene surfaces. Surface roughness of nanofilms was determined using atomic force microscopy. Chondrocytes cultured on nanofilms were analysed using microscopy, live-dead viability assay, and MTT proliferation assay. Statistical analyses of chondrocyte viability and metabolic activity results on mono-, bi-, and tri-layer nanofilm architectures indicate the significant influence of cell seeding density and number of nanofilm layers on the viability and metabolic activity of chondrocytes.
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