Daniel Zanetti de Florio

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• PhD
• Professor at Federal University of ABC

Methane (CH 4 ), the major constituent of natural gas and biogas, is an abundant source to obtain value-added hydrocarbons. The oxidative coupling of methane (OCM) is a direct catalytic route to convert CH 4 towards C 2 hydrocarbons, ethane (C 2 H 6 ) and ethylene (C 2 H 4 ). Using a solid oxide fuel cell (SOFC) is a strategy to overcome some chall...

Methane (CH4), the major constituent of natural gas and biogas, is an abundant source to obtain value-added hydrocarbons. The oxidative coupling of methane (OCM) is a direct catalytic route to convert CH4 towards C2 hydrocarbons, ethane (C2H6) and ethylene (C2H4). Using a solid oxide fuel cell (SOFC) is a strategy to overcome some challenges of fix...

The design of nanomaterials by tailoring the size, shape, and surface chemistry has a significant impact on their properties. The fine-tuning of structural defects of ceria rod-like and cube-like-shaped nanoparticles was performed via La3+ doping in molar ratios of 0–70 mol %. Morphology control was achieved by varying the hydrothermal synthesis te...

The search for alternative non‑carbon-emitting uses of the huge reserves of natural gas has renewed the interest on direct conversion of methane to value added chemicals. Oxidative coupling of methane (OCM) is a key potential route to convert methane directly to ethylene and innumerous works have focused on the study and development of catalysis fo...

The conversion of methane into chemicals is of interest to achieve a decarbonized future. Fuel cells are electrochemical devices commonly used to obtain electrical energy but can be utilized either for chemicals’ production or both energy and chemicals cogeneration. In this work, the partial oxidation of methane in fuel cells for electricity genera...

The conversion of methane into chemicals is of interest to achieve a decarbonized future. Fuel cells are electrochemical devices commonly used to obtain electrical energy, but can be utilized either for chemicals production or both energy and chemicals cogeneration. In this work, the partial oxidation of methane in fuel cells for electricity genera...

We couple the spark plasma sintering (SPS) technique with the ball mill process to fabricate a new electro-chemo-mechanical functional carbon-metal oxide hybrid material. Graphene oxide (GO) or carbon nanotubes (CNT)...

Cosintering (La0.84Sr0.16MnO3 thin‐film cathode/ZrO2: 8 mol% Y2O3 thin‐film solid electrolyte/55 vol.% ZrO2:8 mol% Y2O3 + 45 vol.% NiO anode, ϕ = 12 × 1.5 mm thick pellet) was achieved by applying an electric field for 5 min at 1200°C. Impedance spectroscopy measurements of the anode‐supported three‐layer cell show an improvement of the electrical...

Resistive switching (RS) devices are promising forms of non-volatile memory. However, one of the biggest challenges for RS memory applications is the device-to-device (D2D) variability, which is related to the intrinsic stochastic formation and configuration of oxygen vacancy (VO) conductive filaments. In order to reduce the D2D variability, contro...

Bismuth titanate is a lead-free piezoelectric ceramic with outstanding properties that strictly depend on the composition and microstructure. However, bismuth-based materials are difficult to synthesize due to bismuth volatilisation that causes secondary phases and stoichiometry deviations. In this work, we propose a low-temperature chemical route,...

Resistive switching devices are promising emerging non-volatile memories. However, one of the biggest challenges for resistive switching (RS) memory applications is the device-to-device (D2D) variability which is related to the intrinsic stochastic formation and configuration of oxygen vacancy (VO) conductive filaments. In order to reduce D2D varia...

A comprehensive study on the correlations of structural, magnetic, and electronic properties of a new disordered Nd 2 CoFeO 6 double perovskite has been conducted. The lack of strong divergence of the magnetic susceptibility suggests competition between magnetic interactions at the magnetic phase transition T N = 246 K, which is confirmed by the ab...

Layer-by-layer thin films with up to 11 layers of N,N´-bis(2-phosphonoethyl)-3,4,9,10-perylenediimide (PPDI) were deposited on indium tin oxide (ITO) substrates by the zirconium phosphonate method. Film growth was studied by UV-visible absorption spectroscopy, x-ray photoelectron spectroscopy (XPS), x-ray reflectivity (XRR) and atomic force microsc...

The effects of Fe substitution on Mn site of Mn2Sn compound was investigated by means of scanning electron microscopy with X-ray energy dispersive spectrometer, X-ray diffraction, magnetization and magnetocaloric measurements. The produced Mn2-yFeySn series (0.50≤ y ≤1.75) presented two phases, a major non-stoichiometric Mn2-xSn and a minor Mn3Sn,...

A fast and accurate experimental method is demonstrated to assess the fraction of exsolved metallic nanoparticles using magnetic measurements. As a benchmark, nanometric metallic nickel exsolved from (La1−xSrx)(Cr1−yNiy)O3−δ is used for its high relevance as a solid oxide fuel cell component. The method is based on the difference in the magnetic re...

Green compacts of Li7La3Zr1.9Ta0.1O12 ceramic powders, synthesized by solid state reaction, were sintered by applying electric fields at 590 oC and 670 oC during 5 min. Thickness shrinkage, electric voltage and current were monitored simultaneously. The electrical resistivity of the sintered pellets was evaluated by the impedance spectroscopy techn...

Compositions of (ZrO2)0.92(Y2O3)0.08 (zirconia: 8 mol % yttria—8YSZ) and (CeO2)0.8(Sm2O3)0.2 (ceria: 20 mol % samaria—SDC20) ceramic powders were prepared by attrition milling to form an equimolar powder mixture, followed by uniaxial and isostatic pressing. The pellets were quenched to room temperature from 1200 °C, 1300 °C, 1400 °C and 1500 °C to...

Gadolinium-, yttrium- and samarium-doped barium cerate compounds were sintered either conventionally at 1500 °C or applying an electric field at 1200 °C. The combined results of dilatometry and impedance spectroscopy measurements in electric field-assisted sintered specimens show substantial improvement of the electrical conductivity. Improved grai...

Herein we report for the first time the synthesis of ceramic–organic three-dimensional (3D) layered gadolinium-doped cerium oxide (Ce1−XGdXO2−δ, CGO) and its exfoliation into two-dimensional (2D) nanosheets. We adopt a water-based synthetic route via a homogenous precipitation approach at low temperatures (10–80 °C). The reaction conditions are tun...

Dense zirconia (8% molar yttria-stabilized ZrO2)-titanium nitride (TiN) composites are fabricated to obtain mixed ionic-electronic conducting ceramic systems with high degree of electronic and thermal conductivity. The composites are consolidated by spark plasma sintering (SPS), starting from pure powders of the pristine phases mixed in different r...

Gadolinium, yttrium and samarium-doped barium cerate (BCGd, BCY and BCSm, respectively) polycrystalline green pellets were submitted to electric field-assisted pressureless sintering experiments isothermally in the temperature range 800-1200 o C under 100-200 V cm ⁻¹ electric fields, limiting to 1-5 A the electric current pulse amplitude. The sinte...

Gadolinium-doped cerium oxide (GDC) is an attractive ceramic material for solid oxide fuel cells (SOFCs) both as the electrolyte or in composite electrodes. The Ni/GDC cermet can be tuned as a catalytic layer, added to the conventional Ni/yttria-stabilized zirconia (YSZ), for the internal steam reforming of different fuels. Such an anode allows the...

Nafion exhibits one of the highest proton conductivity at room temperature and it is the standard electrolyte of proton exchange membrane fuel cells (PEMFC). However, the temperature dependence of ionic conductivity of Nation is highly dependent on the measuring conditions and it is still a matter of debate. In the present study, detailed dielectri...

Electrodes for electrolyte-supported solid oxide fuel cells (SOFC's) were fabricated by spin coating. Strontium-doped lanthanum manganite (LSM) cathode and nickel yttria-stabilized zirconia cermet anodes were synthesized and processed for enhanced deposition conditions. The influence of electrode microstructural parameters was investigated by a sys...

Nafion-mesoporous silica composites were investigated aiming at improved performance of direct ethanol fuel cells (DEFC) operating at high temperature. Mesoporous silica (MPS) was synthesized by a sol–gel technique and added as the inorganic filler into Nafion membranes by casting process. The performance of DEFC using both Nafion and Nafion-MPS co...

Fast elemental diffusion at the Gd-doped ceria/Y-stabilized zirconia interface occurs under reducing conditions at low oxygen activity (pO2 < 10⁻¹² atm) and high temperature (1400 °C). This effect leads to formation of thick ceria-zirconia solid solution reaction layers in the micro-range vs. thin layers of few tens of nanometers under oxidative co...

The valence and size of cations influence mass diffusion and oxygen defects in ceria. Here we show that reduction of Ce4+ to Ce3+, at high temperatures and low oxygen activity, activates fast diffusion mechanisms which depend on the aliovalent cation concentration. As a result, polycrystalline solid solutions with enhanced electrochemical propertie...

In this work gadolinium doped barium zirconate (gadolinium oxide = 0, 5, 10, 15 and 20% mol) was prepared by Pechini method from nitrate precursors. The powders were studied by simultaneous thermal analysis, X-ray diffraction, and scanning electron microscopy. These powders were then uniaxially pressed in cylindrical discs. The pellets were sintere...

High proton conductivity perovskites can be utilized in many important applications. In this work gadolinium doped barium zirconate ([gadolinium oxide] = 0, 5, 10, 15 and 20% mol) was prepared by Pechini method from nitrates precursors. The powders were studied by simultaneous thermal analysis, X-ray diffraction, and scanning electron microscopy. T...

For the sintered materials, the mechanical properties are strongly dependent on the density of the final product. A substantial reduction of the porosity can be achieved using additives in the powder mixture which promote the formation of a liquid phase during sintering. Boron is a potential liquid phase promoter in ferrous alloys, when sintering i...

The polarization resistance of La0.3Ba0.7CoO3-delta (LBC7) as cathode material was studied by impedance spectroscopy measurements in the temperature range of 450 <= T <= 750 degrees C, in air, on samples prepared by the solid state reaction (SSR) method and a wet chemical (WC) route, using symmetrical cells with single-layer and graded composition...

Self-assembled monolayers (SAMs) of N,N′-bis(2-phosphonoethyl)-3,4,9,10-perylenediimide (PPDI), a perylene dye substituted with phosphonic acid groups, were deposited on indium tin oxide (ITO) substrates. Dye deposition was confirmed by UV–visible absorption spectroscopy and by electrochemical methods. Electrochemical characterization of the SAM wa...

Nafion beta-relaxation was studied by detailed dielectric spectroscopy measurements carried out in a wide range of both temperature and relative humidity. Cast and extruded Nafion were compared in the H+, Na+, and Cs+ forms to evaluate contributions arising from membrane morphology and ionic interactions. The experimental data indicated that beta-r...

Nafion β-relaxation was studied by detailed dielectric spectroscopy measurements carried out over a wide range of both temperature and relative humidity. Both cast and extruded Nafion were compared in the H⁺, Na⁺, and Cs⁺ forms to evaluate contributions arising from membrane morphology and ionic interactions. The combined data indicated that β-rela...

The present study shows the development of anode-supported solid oxide fuel cells (SOFC) using conventional yttria stabilized zirconia (YSZ) materials and wet chemistry techniques for both the synthesis and deposition of components. Electrodes have been synthesized at IPEN by using wet chemistry techniques, which result in controlled phase composit...

An electrolyte supported solid oxide fuel cell (SOFC) using standard electrodes, doped-lanthanum manganite cathode and Ni-cermet anode, was operated with direct (anhydrous) ethanol for more than 100 h, delivering essentially the same power output as running on hydrogen. A ceria-based layer provides the catalytic activity for the gradual internal re...

We present the synthesis and characterization of ZrO 2 :x mol% In 2 O 3 ceramics with x = 8, 10 and 12. Sintering has been achieved with spark plasma sintering which allows for higher densification (~ 97% of theoretical density). The powders were characterized by thermal analyses, scanning electron microscopy, and x-ray diffraction. The electrical...

In this work, mesoporous silica with medium surface area was prepared. The synthesized mesoporous silica was characterized by BET, SEM and TEM demonstrating the formation of an organized pore structure of the silica. Nafion-SiO2 composite membrane with 5% of the filler was characterized by thermogravimetry and ac impedance spectroscopy. The composi...

The solid oxide fuel cell (SOFC) has attracted a great deal of attention due to its high efficiency and variety of usable fuels like hydrocarbon or alcohols. In this work, aiming at the use of carbon-containing fuels in SOFC, ZnO was added to the SOFC anode ceramic-metal composite yttria-stabilized zirconia/nickel (YSZ/Ni) in a wide range of relati...

The sintering behavior of gadolinia-doped ceria powders was studied by the master sintering curve (MSC). Dilatometric analyses of powders produced by a soft chemical method were performed to provide the experimental data set for the construction of the MSC. The assumed model provided good fittings of the MSC and the activation energy for the sinter...

In the present study, the sintering of (ZrO2:8 mol%Y2O3)1−m–(MgO)m, YSZ–mMg composites, with m in the 0–30 mol% range, has been investigated by impedance spectroscopy (IS), dilatometry, and X-ray diffraction. Impedance diagrams were collected at 400 °C after heating the green compacts up to a selected sintering temperature, which was increased step...

The synthesis and electrical characterization of La 1-x Sr x Mn 0.5 Cr 0.5 O 3 compounds are reported. These compounds, with perovskite structure, have been pointed out as a promising alternative for the nickel-based cermet anode of solid oxide fuel cells. Polycrystalline samples, with x = 0.3, 0.4, and 0.5, were prepared by the citrate technique....

The fabrication of yttria stabilized-zirconia/single-wall carbon nanotube (YSZ/SWCNT) composites is reported. Electrical conductivity measurements from 25 to 800 °C revealed that the composites exhibit mixed ionic-electronic conduction. At room temperature, the conductivity increases by 11 orders of magnitude with the addition of SWCNT to the YSZ....

This manuscript shows an overview of the solid oxide fuel cell (SOFC) technology based on industrial developments. The information presented has been collected mostly at conferences that the authors attended. It is observed that several companies have been pursuing the development of the SOFC technology. Significant advances in stability and power...

This manuscript shows an overview of the solid oxide fuel cell (SOFC) technology based on industrial developments. The information presented has been collected mostly at conferences that the authors attended. It is observed that several companies have been pursuing the development of the SOFC technology. Significant advances in stability and power...

A laboratory setup was designed and put into operation for the development of solid oxide fuel cells (SOFCs). The whole project consisted of the preparation of the component materials - anode, cathode, and electrolyte - and the buildup of a fuel leaking-free sample chamber with platinum leads and current collectors for measuring the electrochemical...

Nano-sized Ce1-xGdxO2-0.5x (0 < x < 0.3) powders, with a narrow particle size distribution in the 5-10 nm range, were synthesized via a soft chemical route. The obtained materials showed to be highly sinteractive and their grain growth to be strongly controlled by gadolinium dopant content. Selected fast firing and conventional sintering processes...

Unitary planar solid oxide fuel cells with gadolinium-doped barium cerate protonic conductor solid electrolyte, slurry- coated thin film La0.6Ca0.4Fe0.8Co0.2O2.74 anode, and thin film Pt cathode have been put into operation in the temperature range 500ºC-900ºC using different fuel-oxidant combinations: H2-air, (30%H2,70%N2)-air, (10%CH4,90%Ar)-air,...

The synthesis and electrical characterization of La1- xSrxMn0.5Cr0.5O3 compounds are reported. Such a perovskite has been pointed out as a promising alternative for the nickel- based cermet anode. Polycrystalline samples, with x = 0.3, 0.4, and 0.5, have been prepared by the citrate technique. The crystalline phase and the chemical compatibility wi...

Compostos da família La1-xSrxCr0,5Mn0,5O3 são apontados como potenciais anodos cerâmicos de células a combustível de óxidos sólidos. A utilização de anodos cerâmicos tem como objetivo eliminar os problemas de depósito de carbono na superfície do níquel e a baixa resistência a ciclos de redução/oxidação observados no compósito cerâmica-metal à base...

La1-xSrxCr0.5Mn0.5O3 perovskites have been pointed out as potential ceramic anode materials for solid oxide fuel cell. The use of a ceramic anode is desirable in order to overcome both the coke formation on the Ni surface and the redox cycling instability of the stabilized-zirconia/Ni cermets, which is the most used anode in solid oxide fuel cells....

Multi-walled carbon nanotubes (MWNT) were produced by chemical vapor deposition using yttria-stabilized zirconia/nickel (YSZ/Ni) catalysts. The catalysts were obtained by a liquid mixture technique that resulted in fine dispersed nanoparticles of NiO supported in the YSZ matrix. High quality MWNT having smooth walls, few defects, and low amounts of...

A laboratory setup was designed and put into operation for the development of solid oxide fuel cells (SOFCs). The whole project consisted of the preparation of the component materials: anode, cathode and electrolyte, and the buildup of a hydrogen leaking-free sample chamber with platinum leads and current collectors for measuring the electrochemica...

The preparation of the (YSZ/NiO) composites by a modified liquid mixture technique is reported. Nanometric NiO particles dispersed over the yttria-stabilized zirconia (YSZ) were prepared, resulting in dense sintered specimens with no solid solution formation between the oxides. Such a feature allowed for the electrical characterization of the com...

We report the preparation and characterization of yttria-stabilized zirconia/nickel oxide composites (YSZ/NiO). This composite is the precursor material of the cermet YSZ/Ni, which is used as solid oxide fuel cell anode material. The performance of the anode is strongly dependent on the microstructural properties of the cermet. Therefore, the contr...

Reactive pure and manganese-doped (5% and 10 at.%) ceria nanosized powders were prepared by the polymeric precursor technique. Physical properties of powder materials were studied by X-ray diffraction, nitrogen adsorption, and diffuse reflectance infrared Fourier transform spectroscopy. Characterization of powder compacts after fast firing at 1200...

Perovskite-type powders were prepared using a complex polymeric precursor method. Thermal analysis was carried out on the perovskite precursor to investigate the oxide-phase formation. The structural phase of the powders was determined by X-ray diffraction. These results showed that the decomposition of the precursors occurs in a two-step reactio...

A detailed study of the microstructural and electrical properties of the yttria-stabilized zirconia/nickel oxide (YSZ/NiO) composite was performed. This material is the precursor to the solid oxide fuel cell anode cermet YSZ/Ni. A liquid mixture technique was developed to produce the YSZ/NiO composite to fabricate high-performance SOFC anodes. This...

A partir da definição de células a combustível, é feita uma introdução sucinta dos tipos de células e dos materiais cerâmicos que são empregados em projeto e fabricação destes dispositivos geradores de energia elétrica. Tomando por base a ampla literatura científica disponível em publicações periódicas internacionais indexadas e arbitradas, bem com...

Specimens of yttria fully stabilized zirconia with different amounts of boron oxide have been studied by X-ray diffraction at room temperature and at higher temperatures up to 1250 °C. A boron oxide-assisted cubic-to-monoclinic phase transformation was determined in the temperature range 800–1250 °C. In situ high temperature X-ray diffraction exper...

Sintering of ZrO2:Y2O3 ceramic compacts have been studied by impedance spectroscopy measurements at 400°C in the 5 Hz–13 MHz frequency range. Cold-pressed samples processed by a co-precipitation route were heat treated at 1350°C for different periods of time. The intragranular resistivity remains constant while the intergranular resistivity decreas...

Dissertação (Mestrado).