Óxido de grafito dopado con diaminomaleonitrilo: efecto en sus propiedades estructurales y eléctricas

Óxido de grafito (OG) y OG dopado con Diaminomaleonitrilo (OGDAMN) fueron nsintetizados por un método de Hummers y se evaluaron sus propiedades eléctricas por voltamperometría cíclica (VC). Los compuestos grafíticos fueron caracterizados por espectroscopia de Infrarrojo (FTIR), Raman, Espectroscopia fotoelectrónica de rayos (XPS) y Microscopia Electrónica de Alta Resolución (HREM). El OGDAMN mostró una mayor histéresis que la de OG en las curvas de VC, así como una mayor capacitancia específica de 138.8 F.g-1, dos veces más para OGDAMN que para OG. Este comportamiento en parte se debió a un cambio en las distancias intercapa relacionado a la formación de grupos imidazol entre los grupos funcionales del OG y DAMN. Las distancias interplanares de OGDAMN obtenida por HREM fueron en promedio de 7.39Å.Graphite oxide (GO) and GO doped with Diaminomaleonitrile (GODAMN) were synthesized by a Hummer's method and their electrical properties were evaluated by cyclic voltammetry (CV). Graphitic compounds were characterized by Infrared Spectroscopy (FTIR), Raman, X-ray photoelectron spectroscopy (XPS) and High Resolution Electron Microscopy (HREM). GODAMN showed a greater hysteresis than GO in the CV curves, as well as a greater specific capacity of 138.8 F.g-1, twice more for GODAMN than for OG. This behaviour was partly due to a change in the interlayer distances associated with an imidazole formation between the functional groups of OG and DAMN. The interplanar distances of OGDAMN obtained by HREM were on average 7.39Å

Síntesis y caracterización de óxido de grafito dopado con carbonato de plata y su aplicación como fotocatalizador en la degradación del azul de metileno

Óxido grafito (OG) y OG dopado con Ag₂CO₃ (OG-Ag) fueron sintetizados por un método de Hummers modificado y evaluados en la fotodegradación de azul de metileno (AM). El OG y OG-Ag obtuvieron 50 y 80% de conversión en 30 min de reacción, respectivamente. Donde ambas reacciones se ajustaron a cinéticas de pseudo-primer orden respecto a 100 ppm de AM. Los materiales grafiticos fueron caracterizados por medio de espectroscopia FTIR, Raman, fotoelectrónica de rayos X (XPS) y Microscopia electrónica de barrido (SEM) con Espectroscopia de energía dispersiva de rayos X (EDS o EDX). Dichas micrografías mostraron comportamiento nemático debido a la formación de cúmulos superficiales de plata en la red de grafito asociados a una mala dispersión y un alto contenido de plata (c.a. 39.4% peso) obtenido por EDS.Graphite oxide (GO) and GO doped with Ag₂CO₃ (GO-Ag) were synthesized by a modified Hummers' method and evaluated in the methylene blue (MB) photodegradation. OG and OG-Ag obtained 50 and 80% conversion in 30 min of reaction, respectively. Where both reactions were adjusted to pseudo-first order kinetics with respect to 100 ppm of MB. The graphitic materials were characterized by FTIR, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) with Energy-dispersive X-ray spectroscopy (EDS or EDX). These micrographs showed nematic behaviour due to the formation of superficial clusters of silver in the graphite network associated with a poor dispersion and a high silver content (c.a. 39.4% weight) obtained by EDS

Indium Doped Zinc Oxide Thin Films Deposited by Ultrasonic Chemical Spray Technique, Starting from Zinc Acetylacetonate and Indium Chloride

The physical characteristics of ultrasonically sprayed indium-doped zinc oxide (ZnO:In) thin films, with electrical resistivity as low as 3.42 × 10−3 Ω·cm and high optical transmittance, in the visible range, of 50%–70% is presented. Zinc acetylacetonate and indium chloride were used as the organometallic zinc precursor and the doping source, respectively, achieving ZnO:In thin films with growth rate in the order of 100 nm/min. The effects of both indium concentration and the substrate temperature on the structural, morphological, optical, and electrical characteristics were measured. All the films were polycrystalline, fitting well with hexagonal wurtzite type ZnO. A switching in preferential growth, from (002) to (101) planes for indium doped samples were observed. The surface morphology of the films showed a change from hexagonal slices to triangle shaped grains as the indium concentration increases. Potential applications as transparent conductive electrodes based on the resulting low electrical resistance and high optical transparency of the studied samples are considered

Synthesis, characterization and photocatalytic activity of 1D TiO2 nanostructures

Nanowire/nanorod TiO2 structures of approximately 8 nm in diameter and around 1,000 nm long were synthesized by alkaline hydrothermal treatment of two different TiO2 nanopowders. The first precursor was TiO2 obtained by the sol-gel process (SG-TiO2); the second was the well-known commercial TiO2 P-25 (P25-TiO2). Anatase-like 1D TiO2 nanostructures were obtained in both cases. The one-dimensional (1D) nanostructures synthesized from SG-TiO2 powders turned into rod-like nanostructures after annealing at 400 °C for 2 h. Conversely, the nanostructures synthesized from P25-TiO2 preserved the tubular structure after annealing, displaying a higher Brunauer–Emmett–Teller surface area than the first system (279 and 97 m2/g, respectively). Despite the higher surface area shown by the 1D nanostructures, in both cases the photocatalytic activity was lower than for the P25-TiO2 powder. However, the rod-like nanostructures obtained from SG-TiO2 displayed slightly higher efficiency than the sol-gel prepared powders. The lower photocatalytic activity of the nanostructures with respect to P-25 can be associated with the lower crystallinity of 1D TiO2 in both materials.Fil: Cabrera, Julieta. Universidad Nacional de Ingeniería; PerúFil: Alarcón Cavero, Hugo Arturo. Universidad Nacional de Ingeniería; Perú. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: López, Alcides. Universidad Nacional de Ingeniería; Perú. Instituto Peruano de Energía Nuclear; PerúFil: Candal, Roberto Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Acosta, Dwight. Universidad Nacional Autónoma de México; MéxicoFil: Rodríguez, Juan. Universidad Nacional de Ingeniería; Per

1D TiO2 Nanostructures Prepared from Seeds Presenting Tailored TiO2 Crystalline Phases and Their Photocatalytic Activity for Escherichia coli in Water

TiO2 nanotubes were synthesized by alkaline hydrothermal treatment of TiO2 nanoparticles with a controlled proportion of anatase and rutile. Tailoring of TiO2 phases was achieved by adjusting the pH and type of acid used in the hydrolysis of titanium isopropoxide (first step in the sol-gel synthesis). The anatase proportion in the precursor nanoparticles was in the 3–100% range. Tube-like nanostructures were obtained with an anatase percentage of 18 or higher while flake-like shapes were obtained when rutile was dominant in the seed. After annealing at 400°C for 2 h, a fraction of nanotubes was conserved in all the samples but, depending on the anatase/rutile ratio in the starting material, spherical and rod-shaped structures were also observed. The photocatalytic activity of 1D nanostructures was evaluated by measuring the deactivation of E. coli in stirred water in the dark and under UV-A/B irradiation. Results show that in addition to the bactericidal activity of TiO2 under UV-A illumination, under dark conditions, the decrease in bacteria viability is ascribed to mechanical stress due to stirring

TiO2 films on CoFe2O4 nanoparticles for the photocatalytic oxidation of rhodamine B: Influence of the alcoholic solutions

In the present work, photocatalytic oxidation of Rhodamine B solutions were performed using a composite material prepared by titanium dioxide films deposited onto cobalt ferrite nanoparticles. Cobalt ferrite nanoparticles were prepared by coprecipitation of Co(II) and Fe(II) ions in basic medium, followed by a controlled oxidation process carried out by nitrate ions in basic medium in inert atmosphere at 95°C. The effect of 2 alcohols (ethanol and 2-propanol) as solvents in the deposition of TiO2 films was studied as a function of CoFe2O4/TiO2 mass ratios. Cobalt ferrite nanoparticles exhibited (36 ± 20) nm diameter with spheroidal shapes as confirmed by SEM studies. TiO2 films deposited onto CoFe2O4 were thicker using ethanol as solvent according to SEM and TEM studies. Cobalt ferrite nanoparticles exhibit a weak oxidation behaviour since around 40% of Rhodamine is eliminated after 90 min of exposition. The 4 composite materials studied oxidize 100% of Rhodamine B after 60 min of reaction and kinetics results fitted a second order degradation reaction equation. As Rhodamine B solution pH was 5.83, faster reactions occur when composite materials develop low surface charge (PZC closer to 5.83) due to small surface charge repulsion. Materials prepared with CoFe2O4/TiO2 ratios between 4 to 6 present higher kinetic constants which is confirmed by a faster Rhodamine B degradatio

Chromium and Ruthenium-Doped Zinc Oxide Thin Films for Propane Sensing Applications

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