Publications by authors named "Carla Bittencourt"

This paper presents the fabrication of sensors based on tungsten trioxide nanowires decorated with osmium oxide nanoparticles using the aerosol-assisted chemical vapor deposition (AACVD) technique. This methodology allows the obtention of different osmium oxide decoration loadings on the tungsten oxide nanowires. The morphological and chemical characteristics; and the structural properties of the sensing layers of the sensors were studied using different techniques such as FESEM, HR-TEM, and ToF-SIMS.

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La-decorated BiOCO (BCO-La) microspheres are synthesized using a facile wet chemical strategy for sensing low-concentration nonanal (CHO) at room temperature. These BCO-La gas sensors are applied to evaluate agricultural product quality, specifically for cooked rice. The sensitivity of the BCO-6La sensor significantly surpassed that of the pure BCO sensor, achieving a response value of 174.

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Article Synopsis
  • - Nanostructured transition metal dichalcogenides, like tungsten disulfide (WS), have potential for use in sensors due to their unique structure and high surface area, but producing them in large quantities on various surfaces has been a challenge.
  • - This study successfully synthesized WS sheets in quantities of hundreds of milligrams using a chemical vapor deposition method, allowing for easy application onto different substrates through printing techniques.
  • - The WS sensors demonstrated excellent ammonia detection capabilities, achieving full response at 5 ppm and maintaining stability in humid conditions, while also showing high selectivity against other gases, with theoretical simulations supporting the experimental results.
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Ambient pressure X-ray photoelectron spectroscopy (APXPS) is combined with simultaneous electrical measurements and supported by density functional theory calculations to investigate the sensing mechanism of tungsten disulfide (WS)-based gas sensors in an dynamic experiment. This approach allows for the direct correlation between changes in the surface potential and the resistivity of the WS sensing active layer under realistic operating conditions. Focusing on the toxic gases NO and NH, we concurrently demonstrate the distinct chemical interactions between oxidizing or reducing agents and the WS active layer and their effect on the sensor response.

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This study investigates the simultaneous decoration of vertically aligned molybdenum disulfide nanostructure (VA-MoS) with Ag nanoparticles (NPs) and nitrogen functionalization. Nitrogen functionalization was achieved through physical vapor deposition (PVD) DC-magnetron sputtering using nitrogen as a reactive gas, aiming to induce p-type behavior in MoS. The utilization of reactive sputtering resulted in the growth of three-dimensional silver structures on the surface of MoS, promoting the formation of silver nanoparticles.

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Quantifying microplastics (MPs) in marine environments is challenging due to the complexities of differentiation from other materials. This study aims to distinguish petro-sourced plastic microfilaments from organic ones in environmental samples using scanning electron microscope coupled with energy dispersive X-ray (SEM-EDX) analysis. Therefore, 38 particles resembling MPs (PRMPs) from sediments and organisms in Madagascar were analyzed.

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The impact of different synthesis parameters, such as thickness, postsynthesis annealing temperature, and oxygen gas flow rate, upon the electronic structure is discussed in detail in the present experimental investigation. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) spectroscopy techniques are used to evaluate the surface electronic properties along with the presence and stability of the CdO surface oxide in CdZnO ( = 0.4) composite thin films.

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CeO-TiO is an important mixed oxide due to its catalytic properties, particularly in heterogeneous photocatalysis. This study presents a straightforward method to obtain 1D TiO nanostructures decorated with CeO nanoparticles at the surface. As the precursor, we used HTiO nanoribbons prepared from sodium titanate nanoribbons by ion exchange.

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Nanostructured tungsten disulfide (WS) is one of the most promising candidates for being used as active nanomaterial in chemiresistive gas sensors, as it responds to hydrogen gas at room temperature. This study analyzes the hydrogen sensing mechanism of a nanostructured WS layer using near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) and density functional theory (DFT). The W 4f and S 2p NAP-XPS spectra suggest that hydrogen makes physisorption on the WS active surface at room temperature and chemisorption on tungsten atoms at temperatures above 150 °C.

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A novel reusable, high-compressible cotton regenerated cellulose/chitosan composite aerogel (RC/CSCA) was prepared using N-methylmorpholine-N-oxide (NMMO) as the green cellulose solvent, and glutaraldehyde (GA) as the crosslinking agent. The regenerated cellulose obtained from cotton pulp could chemically crosslink with chitosan and GA, to form a stable 3D porous structure. The GA played an essential role in preventing shrinkage and preserving the deformation recovery ability of RC/CSCA.

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Green chromium and red iron oxides are technically important pigments due to their high color intensity, good dispersibility in paints, and superior hiding power. We report on the synthesis of colored pigments of mixed oxides with a corundum-type structure. The pigments are obtained via the addition of coloring ions to boehmite from recycled metallic aluminium.

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Co-abietate and Cu-abietate complexes were obtained by a low-cost and eco-friendly route. The synthesis process used resin and an aqueous solution of CuSO/CoSO at a mild temperature (80 °C) without organic solvents. The obtained complexes are functional pigments for commercial architectural paints with antipathogenic activity.

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Developing strategies for the green synthesis of novel materials, such as pigments for protection from solar radiation, is a fundamental research subject in material science to mitigate the heat island effect. Within this perspective, the current study reports on the synthesis of blue pigments of ZnAlO:M (M = Co and Co/Nd) using recycled metallic aluminum (discarded can seal) with reflective properties of Near-infrared radiation. The pigments were characterized by XRD, SEM, XPS, UV-Vis, NIR diffuse reflectance spectroscopy, and CIE-1976 L*a*b* color measurements.

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Nanostructured noble metal thin films are highly studied for their interesting plasmonic properties. The latter can be effectively used for the detection of small and highly diluted molecules by the surface-enhanced Raman scattering (SERS) effect. Regardless of impressive detection limits achieved, synthesis complexity and the high cost of gold restrict its use in devices.

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The present study described three synthesis routes using different natural polysaccharides as low-cost non-toxic fuels and complexing agents for obtaining MgO. Cassava starch, leaves (mainly acemannan) gel, and citric pectin powder were mixed with magnesium nitrate salt and calcined at 750 °C for 2 h. The samples were named according to the polysaccharide: cassava starch (MgO-St), citrus pectin (MgO-CP), and (MgO-Av).

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The synthesis of structured MgO is reported using feedstock starch (route I), citrus pectin (route II), and (route III) leaf, which are suitable for use as green fuels due to their abundance, low cost, and non-toxicity. The oxides formed showed high porosity and were evaluated as antimicrobial agents. The samples were characterized by energy-dispersive X-ray fluorescence (EDXRF), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM).

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The COVID-19 pandemic has increased the need for developing disinfectant surfaces as well as reducing the spread of infections on contaminated surfaces and the contamination risk from the fomite route. The present work reports on the antiviral activity of coatings containing ZnO particles obtained by two simple synthesis routes using Aloe vera (ZnO-aloe) or cassava starch (ZnO-starch) as reaction fuel. After detailed characterization using XRD and NEXAFS, the obtained ZnO particles were dispersed in a proportion of 10% with two different waterborne acrylic coatings (binder and commercial white paint) and brushed on the surface of polycarbonates (PC).

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The search for less expensive and viable products is always one of the challenges for research development. Commonly, the synthesis of coordination compounds involves expensive ligands, through expensive and low-yield routes, in addition to generating toxic and unusable residues. In this work, the organic ligand used is derived from the resin of a reforestation tree, Pinus elliottii var.

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Rough structures have gained increasing attention since they are essential for surfaces with special wettability, which can be used for various applications. It is still a challenge to find a low-cost and simple way to fabricate rough surfaces despite extensive efforts. Herein, we report a facile strategy to fabricate self-roughened surfaces based on polarity-induced phase separation.

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We report on the synthesis of boehmite aluminum oxide hydroxide particles with lamellar structure (γ-AlO(OH)) obtained from the recycling of metallic can seals, with the addition of silver nanoparticles (Ag-NPs) reduced by extract. X-ray diffractometry (XRD) confirmed the γ-phase, and scanning electron microscopy (SEM) showed the presence of Ag-NPs on the boehmite particle surface, confirming the efficiency of the synthesis to obtain the composite material. The samples were used to treat lake water, according to the Standard Methods for the Examination of Water and Wastewater.

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In this study, two green synthesis routes were used for the synthesis of Ag/ZnO nanoparticles, using cassava starch as a simple and low-cost effective fuel and Aloe vera as a reducing and stabilizing agent. The Ag/ZnO nanoparticles were characterized and used for bacterial disinfection of lake water contaminated with (). Characterization indicated the formation of a face-centered cubic structure of metallic silver nanoparticles with no insertion of Ag into the ZnO hexagonal wurtzite structure.

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Laminated metal dichalcogenides are candidates for different potential applications ranging from catalysis to nanoelectronics. However, efforts are still needed to optimize synthesis methods aiming to control the number of layers, morphology, and crystallinity, parameters that govern the properties of the synthesized materials. Another important parameter is the thickness and the length of the samples with the possibility of large-scale growth of target homogeneous materials.

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This data article is associated with the work "Ecofriendly synthesis of Zn-abietate complex derived from resin and its application as an antibacterial pigment against and ". The characterization data of the Zn-abietate complex obtained from resin and their reactional intermediary (Na-abietate) are reported. The Na-abietate was prepared with purified Pinus resin and sodium hydroxide (≥ 99%) in a stoichiometric ratio of 1:1.

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TiO nanoparticles doped with different amounts of Nd (0.5, 1, and 3 wt.%) were synthetized by the sol-gel method, and evaluated as potential temperature nanoprobes using the fluorescence intensity ratio between thermal-sensitive radiative transitions of the Nd.

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The outstanding versatility of graphene for surface functionalization has been exploited by its decoration with synthesized polypyrrole (PPy) nanoparticles (NPs). A green, facile, and easily scalable for mass production nanocomposite development was proposed, and the resulting PPy@Graphene was implemented in chemoresistive gas sensors able to detect trace levels of ammonia (NH) under room-temperature conditions. Gas exposure for 5 min revealed that the presence of nanoparticles decorating graphene entail greater sensitivity (13-fold) in comparison to the bare graphene performance.

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