Publications by authors named "Ioan Valentin Tudose"

The present communication reports on the effect of the sprayed solution volume variation (as a thickness variation element) on the detailed Raman spectroscopy for WO thin films with different thicknesses grown from precursor solutions with two different concentrations. Walls-like structured monoclinic WO thin films were obtained by the spray deposition method for further integration in gas sensors. A detailed analysis of the two series of samples shows that the increase in thickness strongly affects the films' morphology, while their crystalline structure is only slightly affected.

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Graphene nanoplatelets (GNPs) and multiwall carbon nanotubes (CNTs)-polypropylene (PP) composite materials for electromagnetic interference (EMI) shielding applications were fabricated as 1 mm thick panels and their properties were studied. Structural and morphologic characterization indicated that the obtained composite materials are not simple physical mixtures of these components but new materials with particular properties, the filler concentration and nature affecting the nanomaterials' structure and their conductivity. In the case of GNPs, their characteristics have a dramatic effect of their functionality, since they can lead to composites with lower conductivity and less effective EMI shielding.

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The present manuscript reports on optimized formulations of alcohol-based conductive paints for electromagnetic interference shielding (EMI), which can ensure compatibility and reduce the visibility of electronic equipment, as a continuation of our previous work in this field, which examined water-based formulations for other applications. Graphite, carbon black, graphene, FeO, Fe ore, and PEDOT:PSS in various ratios and combinations were employed in an alcohol base for developing homogeneous paint-like fluid mixtures that could be easily applied to surfaces with a paintbrush, leading to homogeneous, uniform, opaque layers, drying fast in the air at room temperature; these layers had a reasonably good electrical conductivity and, subsequently, an efficient EMI-shielding performance. Uniform, homogeneous and conductive layers with a thickness of over 1 mm without exfoliations and cracking were prepared with the developed paints, offering an attenuation of up to 50 dB of incoming GHz electromagnetic radiation.

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Current technology to prevent biofouling usually relies on the use of toxic, biocide-containing materials, which can become a serious threat to marine ecosystems, affecting both targeted and nontargeted organisms. Therefore, the development of broad-spectrum, less toxic antifouling materials is a challenge for researchers; such materials would be quite important in applications like aquaculture. In this respect, surface chemistry, physical properties, durability and attachment scheme can play a vital role in the performance of the materials.

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The development of materials offering electromagnetic interference (EMI) shielding is of significant consideration, since this can help in expanding the lifetime of devices, electromagnetic compatibility, as well as the protection of biological systems. Conductive paints used widely today in electromagnetic interference (EMI) shielding applications are often based on organic solvents that can create safety issues due to the subsequent environment problems. This paper concerned the development of eco-friendly conductive water-based paints for use in EMI-shielding applications.

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Nanostructured electrochromic VO thin films were prepared using spray pyrolysis technique growth at a temperature of 250 °C using air-carrier spray deposition, starting from ammonium metavanadate precursor in water, followed by annealing at 400 °C in O atmosphere for 2 h. The VO films were characterized by X-ray diffraction, scanning electron microscopy, and Raman spectroscopy, and their electrochromic behavior was studied using optical spectroscopy and cyclic voltammetry in both the as-deposited and postannealing case. The studies showed that the simple, cost -effective, suitable for large area deposition method used can lead to an interesting surface structuring with large active surface properties suitable for electrochromic applications.

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The incorporation of graphene nanoplatelets (GnPs) within a polymer matrix can play an important role in the physical properties and the functionality of the composite material. Composites consisting of low-density polyethylene (LDPE) and GnPs of different concentrations were developed by mixing GnPs with a molten form of the polymeric matrix. The effect of the GnPs content on the morphological, structural, and electrical properties of the composites were investigated.

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Structure, shape and surface morphology of the material are directly determined by the substrate and growth method used for material fabrication of nanostructured metal oxides. Those characteristics play a crucial role in the photocatalytic activity of the material. This paper presents a short review of some of the most recent relevant publications regarding pure and doped nanostructured metal oxides used for photocatalytic applications focusing on the structure, shape and surface morphology of the material effects on photocatalytic activity.

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