Francisco Xavier Nobre

Instituto Federal do Amazonas | IFAM · Disciplinas básicas

Biosensors harness biological materials as receptors linked to transducers, enabling the capture and transformation of primary biorecognition signals into measurable outputs. This study presents a novel carboxylation method for synthesizing carboxylated graphene (CG) under acidic conditions, enhancing biosensing capabilities. The characterization o...

Extensive research in the last few decades has conclusively demonstrated the significant influence of experimental conditions, surfactants, and synthesis methods on semiconductors’ properties in technological applications. Therefore, in this study, the synthesis of molybdenum oxide (MoO3) was reported by the addition of 2.5 (MoO3_2.5), 5 (MoO3_5),...

This study presents a simple, low-cost, and efficient route to obtain zinc oxide by adopting the thermal decomposition method of zinc acetate at 300 (Gr@ZnO_300), 400 (Gr@ZnO_400), 500 (Gr@ZnO_500), and 600 ◦C (Gr@ZnO_600) for 1 h. The diffraction patterns collected for the samples indicated the majority formation of the hexagonal phase (P63mc) for...

The combination of materials to improve properties of interest has become one of the strategies widely used for numerous applications, including new catalysts, over the last few decades. In this study, silver molybdate (β-Ag2MoO4) microcrystals were efficiently obtained by the hydrothermal method, obtaining composites with different amounts of grap...

The primary goal of this study is to elucidate the structural and electrical characteristics, alongside potential applications , of ceramic-polymeric composites. These composites are achieved by incorporating lithium-lanthanum titanates (Li 3x La 2/3−x TiO 3-LLTO) into a polyvinyl alcohol polymeric matrix (PVA). The synthesis of lithium-lanthanum t...

This study aimed to modify poly(ε‐caprolactone) (PCL) membranes with sodium heparin (SH) and essential fatty acids (EFA) for later application in wound healing. The electrospinning technique was used to prepare the membranes containing the maximum concentration of SH and EFA, which were then sterilized with ozone. Microbiological tests confirmed ef...

The design of particle size and morphology are a promising approach to investigating the properties exhibited by different types of materials. In the present study, the silver phosphate microcrystals (Ag3PO4) were first time synthesized using the hydrothermal and solvothermal method by combination of the solvents water/isopropyl alcohol (SP-IA), wa...

Biosensors comprise devices that use a material of biological nature as receptors connected to transducers, these devices are capable of capturing biorecognition signals, called a primary signal, and converting it to a measurable signal. In this study, we report the synthesis of carboxylated graphene (CG) through a carboxylation method in acid medi...

This study aims to explore the structural and electrical properties of thermoplastic membranes made of polyvinyl alcohol (PVA) with Lithium Perchlorate (LiClO 4), which were prepared using the solvent evaporation method. The PVA crystalinity were calculated by using the Rietveld method on X-ray diffraction(XDR), thus, it was possible to notice modi...

The article presents a new route of synthesis of tin tungstate (β-SnWO 4) by high-energy ball milling (HEBM), starting from the precursors metallic tin (Sn) and tungsten trioxide (WO 3). After 4 h of grinding, the pure phase was obtained for the beta (β-SnWO 4) of cubic structure and space group P2 1 3, with a high crystallinity was confirmed by X-...

A new hybrid material was created by blending sodium titanate ceramics (Na2Ti3O7/Na2Ti6O13) with a polyvinyl alcohol (PVA) matrix, resulting in enhanced semiconductive characteristics. The synthesis process involved intense ultrasonic treatment and subsequent heat treatment at 900 °C. Utilizing a solvent casting method, Na2Ti3O7/Na2Ti6O13/PVA compo...

Yellow passion fruit peel and cupuaçu seeds are common wastes. Usually, they have few or no applications and are discarded, causing environmental pollution. To use them in a new way and reduce ecological pollution, we obtained the ash of yellow passion fruit peels by calcination. We characterized it using Fourier‐transform infrared spectroscopy wit...

In this study, we report the easy and low-cost synthesis of calcium niobate (CaNb2O6) with the isomorphic structure of the Rynersonite mineral for CaTa2O6. The samples were prepared by the ball milling method at room temperature at a synthesis time of 0.5, 1, 2, 3, and 4h. The structural analysis by XRD, Rietveld refinement, and vibrational Raman s...

In this work, the effect of lithium hydroxide (LiOH) amalgamation on the properties of polyvinyl alcohol thermoplastic membranes, obtained by the solvent casting method, is presented. FTIR and Raman spectroscopy show the effect of \({\mathrm{Li}}^{+}\) on vibrations of C=O, C–O and O–H functional groups. Moreover, DRX analysis confirmed the semi-cr...

In the focus of environmental problems and climate change, research for alternative materials becomes essential. In this sense, research on geopolymers is very relevant, due to its sustainability characteristics linked to mechanical and physical properties. Metakaolin is a geopolymer precursor and obtained from kaolin, whose characteristics, which...

In summary, we report a fast, easy, and low-cost green synthesis approach to obtain calcium tungstate nanoparticles (CaWO4NPs_GS) using eggshells as a source of calcium by the sonochemistry method at room temperature. These nanomaterials were structurally characterized by X-ray diffraction (XRD) and Rietveld refinement analysis, where a pure phase...

Herein, we report, for the first time, the reduction reaction kinetics of ciprofloxacin organic molecules based on structural and micromorphological conditions of an electrocatalytic system of Bi0.5Na0.5Ba(TiO3)2 (BNT-BT) thin films. XRD analysis showed the coexistence of rhombohedral and tetragonal structures for the BNT-BT thin films annealed at...

In this paper, we report the obtention of synthetic Atacamite-like β-Cu2(OH)3Cl microcrystals using the sonochemistry route at room temperature. The synthesized material was structurally characterized, confirming the formation of single phase β-Cu2(OH)3Cl with a synthesis time of 30 min. The characteristic vibrational active modes of an orthorhombi...

We probed the structural modifications and electronic behavior of composites obtained from the admixture of a biphasic titanate ceramic system (Na 2 Ti 3 O 7 /Na 2 Ti 6 O 13) with a poly(o-methoxyaniline, POMA) matrix. The composites were obtained by the addition of Na 2 Ti 3 O 7 /Na 2 Ti 6 O 13 to a POMA matrix in mass concentrations from 0 to 35%...

This paper reports easy and fast synthesis of PbMoO4 nanocrystals by microwave-assisted hydrothermal (MH) method at different synthesis times (1, 10, 30 and 60 min) at 100 °C. X-ray diffraction, Rietveld refinement and Raman spectroscopy confirm all characteristics of diffraction peaks and active vibrational modes of the pure scheelite structure (t...

In this work, the variation in the structural and electrical properties of lithium-doped sodium titanate, obtained from an ultrafast (15 min) microwave-assisted synthesis has been reported. X-ray diffraction and Rietveld analysis have been done to identify the present phases, their composition, and lattice parameters. Na 2 Ti 3 O 7 was identified a...

In this study, the production of a mortar was proposed in which plastic waste replaced sand by 0%, 50%, and 100% in order to create a sustainable alternative for construction. The performance of the mortars was tested with two types of activators, one with NaOH, as a simple activator, and the other with NaOH and Na2SiO3, as a compound activator. Th...

The temperature dependence of the electrical properties of composites formed by bipha-sic sodium titanate and poly(o-methoxyaniline) (Na2Ti3O7/Na2Ti6O13/POMA) with different concentrations of POMA (0%, 1%, 10%, 15%, 35% and 50%) in the ceramic matrix was determined from measurements of complex impedance. The structural details were studied by means...

TiO2 time-dependent electrodeposited thin films were synthesized using an electropho-retic apparatus. The XRD analysis revealed that the films could exhibit a crystalline structure composed of ~81% anatase and ~6% rutile after 10 s of deposition, with crystallite size of 15 nm. AFM 3D maps showed that the surfaces obtained between 2 and 10 s of dep...

Silver tungstate microcrystals and their performance over several clinical multidrug resistant microorganisms, Colloids and Surfaces A: Abstract In this paper, we report the screening antimicrobial properties against several pathogenic microorganisms of silver tungstate microcrystals synthesized by the hydrothermal method at 120 °C for 12 h. These...

Improper disposal of batteries can cause several environmental problems. Thus, this work aimed to apply the electrolytic paste (SB) of spent AA batteries as a catalyst. The SB was heat-treated (400 and 800 °C) and characterized by FTIR, XRF, XRD, TGA, SEM-EDX, titratable acidity, and soluble alkalinity. Although the thermal treatment changed the co...

Improper disposal of batteries can cause several environmental problems. Thus, this work aimed to apply the electrolytic paste (SB) of spent AA batteries as a catalyst. The SB was heat-treated (400 and 800 °C) and characterized by FTIR, XRF, XRD, TGA, SEM-EDX, titratable acidity, and soluble alkalinity. Although the thermal treatment changed the co...

Mixed phases of sodium titanate ceramics are obtained using both conventional and laser sintering methods. It was observed a clear dependence on the structural, microstructural and electrical resistivity with the employed sintering method. The temperature dependence of the resistivity in the ceramics shows an increase of three orders of magnitude i...

This work reports on obtaining iron phosphate-supported from activated carbon derived from the açaí fruit (Euterpe oleracea Mart.) waste, with H3PO4 and Fe(NO3)2 as precursors. The samples were well-prepared by thermal decomposition at 400 °C (CP-400) and 500 °C (CP-500) with biomass, phosphoric acid, and iron nitrate ratio of 1:1:1 (wt/wt/wt). We...

This study processed and characterized the biphasic ceramics Na2Ti3O7/Na2Ti6O13 that were obtained from semi-crystalline nanoparticles synthesized using sonochemical methods. Structural characterization techniques, such as X-ray diffraction and Raman spectroscopy, were used to identify the crystalline phases present. The Rietveld refinement reveale...

Biodiesel is a renewable fuel with various advantages, such as the reduced emissions of toxic gases (CO2, SO2, CO, and HC) when compared to fossil diesel. It can be produced by esterification or transesterification reactions. In this chapter, the application of nanomaterials as a catalyst in these reactions is investigated through a critical review...

In this paper, we introduced an advanced discussion of the 3D morphology of TiO2 coatings deposited on ITO substrate by electrodeposition, under different deposition times. Atomic force microscopy was applied for obtain topographic images of the samples. The images were processed using the MountainsMap 8.0 commercial software according to ISO 2517...

This study report the ciprofloxacin photodegradation TiO2/SnO2 nanocomposites as heterogeneous photocatalyst. Ciprofloxacin has been chosen because it is a drug used on a large scale and it is also responsible for the contamination of several aquatic matrices. Titanates nanotubes were synthesized by hydrothermal method and then ion exchange modifie...

The use of thin films for the development of high-performance solar panels has been widely studied. In this study, ITO substrate (glass coated with Indium Tin Oxide) was coated with TiO2 nanoparticles by electrodeposition processes. AFM technique was used to study the morphology, thickness, and surface roughness. Five films were produced for differ...

In this paper, CaWO4 nanoparticles were prepared by the hydrothermal method using the temperature of 100 (CaWO4-100), 120 (CaWO4-120), 140 (CaWO4-140), and 160 °C (CaWO4-160) for 1 h. These nanoparticles have a tetragonal structure (I41/a) exhibiting a high crystallinity degree and average crystallite size from 24.61(0.12) nm to 40.13(0.18) nm. The...

Copper molybdate nanoplates were synthesized by a sonochemical process at room temperature, which we report as a simple and cost-effective route. Structural analysis of the material by the Rietveld method of X-ray diffraction (XRD) data revealed lindgrenite Cu3(MoO4)2(OH)2 in a single-phase structure. All the vibrational modes characteristic of the...

A biphasic ceramic (Na2Ti3O7/Na2Ti6O13) and a new class of composites (Na2Ti3O7/Na2Ti6O13/POMA) are reported. The POMA content influence on the structural and electrical properties is investigated. Sonochemical method and conventional chemical polymerization are used by synthesized sodium titanates and POMA, respectively. Rietveld refinement showed...

In this work, lindgrenite [Cu3(MoO4)2(OH)2] microstructures were obtained by the coprecipitation and ultrasound-assisted coprecipitation methods at different irradiation times, 10, 20, and 30 min. According to Raman's active modes and infrared spectroscopies, the X-ray diffraction patterns confirmed the synthesized samples' monoclinic structure. Th...

h-MoO3 rod-like microcrystals were successfully prepared using the hydrothermal microwave method and evaluated as an adsorbent for MB dye’s adsorption from an aqueous medium. The metastable phase with hexagonal structure (h-MoO3) was well confirmed by X-ray diffraction (XRD) and Raman spectroscopy. FE-SEM images of these microcrystals confirm the r...

Biodiesel is a renewable fuel with various advantages, such as the reduced emissions of toxic gases (CO2, SO2, CO, and HC) when compared to fossil diesel. It can be produced by esterification or transesterification reactions. In this chapter, the application of nanomaterials as a catalyst in these reactions is investigated through a critical review...

In this present work, we report the photocatalytic activity of microcrystals of silver molybdate (β-Ag 2 MoO 4) synthesized at 120 • C for 2 h by hydrothermal method. These microcrystals have been structurally characterized by X-ray diffraction (XRD), Rietveld refinement and micro-Raman (MR). The optical properties and the structure of the band gap...

One of the ways to produce biodiesel is through fatty acid esterification via heterogeneous catalysis. The water treatment plants in Manaus-Amazonas/Brazil produce about 20 tons of sludge per day. In order to establish an application to this abundant waste as a new heterogeneous catalyst, acid and heat treatments were performed and characterized by...

In this work, we report the obtention of the LDH@Bi2WO6 heterostructure using an easy and low-cost method. The LDH was synthesized through the co-precipitation method with the metallic ratio of Mg2+/Al3+ = 2.0, while the bismuth tungstate nanoplates were prepared using the hydrothermal method. The LDH@Bi2WO6 heterostructure was obtained mixing LDH...

In recent years, interest in dealing with the growing environmental problem arising from the pollution of wastewater from industrial factories has increased. In order to minimize this environmental impact, the aqueous adsorption technique has been an alternative widely explored today. Therefore, this study aimed to investigate the adsorptive capaci...

Sodium titanate Na2TinO2n+1 (2 ≤ n ≤ 9) is a well-known semiconductor that exhibits interesting electrical properties allowing numerous applications, such as: electrodes for solid-state batteries. In this work, we reported a novel, fast and simple route to produce sodium titanate (Na2Ti3O7 - NT) structures at low temperature and short time, by usin...

Homogeneous catalysts used for biodiesel synthesis have several limitations, including non-recoverability/reusability, saponification, emulsification, equipment corrosion, and environmental pollution. To overcome these limitations, we synthesized a novel catalyst via calcination of pineapple leaves waste. This catalyst was characterized by X-ray po...

In this work, we report the room-temperature synthesis of pure 7 calcium tungstate (CaWO 4) and copper-doped calcium tungstate solid solution 8 (Ca 0.99 Cu 0.01 WO 4) by using a sonochemistry method. These materials were 9 structurally characterized by X-ray diffraction (XRD) and Raman spectroscopy. 10 The obtained XRD patterns were submitted to a...

In the past years, semiconductive sodium titanate material has been widely studied due to its diverse applications and advantageous physico - chemical properties. In this direction, the present work reports the effect of sonication time on the structural and electrical properties of sodium titanate (Na2Ti6O13) ceramics. In addition, Mott-Schottky m...

Titanium dioxide nanoparticles (nTiO2) were used in heterogeneous photocatalysis for remediation of herbicide Tordon 2,4-D. These nTiO2 was synthesized by the sol-gel method followed by thermal treatment at 450 °C for 2 h. The structural characterization by X-ray diffraction and Rietveld refinement confirm that the mixture of phases is 21.28 % of a...

In this paper, we report the first study about the synthesis of CaMoO4 nanocrystals using the sonochemistry method at room temperature, characterization, and cytotoxic and genotoxic assay by Somatic Mutation and Recombination Test (SMART) using the Drosophila melanogaster fed with the calcium molybdates nanoparticles. The structural characterizatio...

In this study we report the synthesis of silver tungstate microcrystals (α-Ag2WO4) by sonochemistry method (SC) at 65 °C and sonochemistry followed by conventional hydrothermal (SC + HC) for 1, 6 and 12 h, at 140 °C. The structural characterization by XRD confirms the alpha phase of the orthorhombic structure and the space group Pn2n, for all synth...

Solid state electrolytes based on ionic conductive ceramics, such as: the sodium titanate family, are promissory for secondary batteries. Thus, in this work, we reported for the first time, the synthesis of the Na2Ti6O13 nanocrystals phase by using sonochemical method. X-ray diffraction and scanning electron microscopic techniques were employed to...

12 Solid state electrolytes based on ionic conductive ceramics, such as: the sodium 13 titanate family, are promissory for secondary batteries. Thus, in this work, we reported 14 for the first time, the synthesis of the Na 2 Ti 6 O 13 nanocrystals phase by using 15 sonochemical method. X-ray diffraction and scanning electron microscopic techniques...

Protonated titanate nanotubes (HTiNts) were synthesized using the hydrothermal method, followed by proton exchange with acid. Gold nanoparticles decorated titanate nanotubes (AuHTiNts) were obtained by the reduction of AuCl4- under vigorous stirring with an aqueous solution of HTiNts containing 1 wt% of ascorbic acid. To investigate the surface str...

Solid state electrolytes based on ionic conductive ceramics, such as: the sodium titanate family, are promissory for secondary batteries. Thus, in this work, we reported for the first time, the synthesis of the Na2Ti6O13 nanocrystals phase by using sonochemical method. X-ray diffraction and scanning electron microscopic techniques were employed to...

In this paper, we report the initial research to obtain hybrids (PU@Hap-1%, PU@Hap-2% and PU@Hap-3% compound by hydroxyapatite (Hap) synthesized by coprecipitation (CP) method, with monoglycerides (MG) of castor oil ( Ricinus communis ) polymerized with hexamethylene diisocyanate (HDI). Hap, was characterized by X-ray diffraction (XRD), Rietveld re...

In this paper, we report the synthesis of titanium dioxide nanoparticles (nTiO2) by the sol-gel method followed thermal treatment at 100, 300, 500 and 700 °C. The structural characterization by XRD and Rietveld refinement method confirmed the mixture of phases in the synthesized nanoparticles. Raman spectroscopy corroborated the presence of phase m...

We present a study about the thermal dependence of saturation magnetization in ZnO nanoparticles doped with Co and Cr, obtained by the sol gel method. The X-ray diffraction (DRX), confirmed a single crystalline phase corresponding to the wurtzite structure of ZnO with hexagonal structure. The lattice parameter, a exhibits values from 3.2456 Å to 3....

In this paper, we report about hydrothermal synthesis, structural characterization and photocatalytic properties of beta-silver molybdate (β-Ag2MoO4) microcrystals obtained at different temperatures (100, 120, 140 and 160 °C) for 2 h. These crystals were characterized structurally using X-ray diffraction (XRD), X-ray fluorescence, Rietveld refineme...

In the present study, typical ZnO microcrystals exhibiting the wurtzite hexagonal crystal structure were produced successfully, characterized by a high degree of crystallinity, via hydrothermal processing at 120, 150 and 180 °C, assisted by N-cetyl-N,N,N-trimethylammonium (CTAB). The samples were characterised by XRD, Raman and infrared, FE-SEM, UV...

RESUMO No presente trabalho, falaremos como foi realizada a síntese e caracterização da mistura de fases composta por WO 3 e Na 2 W 4 O 13 , dopadas com prata. Na obtenção das amostras X1; X2 e X3, utilizou-se do método de ultrassonificação, seguido da calcinação a 500 °C por 2 h. Mediante análise elementar percentual por FRX e caracterização estru...