Papers by Monserrat Bizarro
Materials Chemistry and Physics
Materials Today Communications
Environmental Science: Nano
The degradation pathway of temephos pesticide was elucidated using efficient photocatalytic ZnO n... more The degradation pathway of temephos pesticide was elucidated using efficient photocatalytic ZnO nanowire and flower-like films. The monitoring of the subproducts is crucial as they are even more toxic than the original pesticide.
Nanomaterials, 2021
Surface enhanced Raman spectroscopy (SERS) is considered a versatile and multifunctional techniqu... more Surface enhanced Raman spectroscopy (SERS) is considered a versatile and multifunctional technique with the ability to detect molecules of different species at very low molar concentration. In this work, hierarchical ZnO microspheres (ZnO MSs) and Ag/ZnO MSs were fabricated and decorated by hydrothermal and photodeposition methods, respectively. For Ag deposition, precursor molar concentration (1.9 and 9.8 mM) and UV irradiation time (5, 15, and 30 min) were evaluated by SEM, TEM, X-ray diffraction and Raman spectroscopy. X-ray diffraction showed a peak at 37.9° corresponding to the (111) plane of Ag, whose intensity increases as precursor concentration and UV irradiation time increases. SEM images confirmed the formation of ZnO MSs (from 2.5 to 4.5 µm) building by radially aligned two-dimensional ZnO nanosheets with thicknesses below 30 nm. The Raman spectra of Ag/ZnO MSs exhibited a vibration mode at 486 cm−1 which can be directly associated to Ag deposition on ZnO MSs surface. Th...
Growth of nano sized Bismuth oxy chloride (BiOCl) and Bismuth Oxide (Bi2O3) thin film on glass wa... more Growth of nano sized Bismuth oxy chloride (BiOCl) and Bismuth Oxide (Bi2O3) thin film on glass was achieved by Metal Organic Chemical Vapour Deposition (MOCVD) method. It was synthesized from solutions containing Bismuth chloride (BiCl3) in Acetone and Bi(NO3)3:5H2O in 1M HNO3.The BiCl3 solution was carried by nebulisation effect by Argon gas and Bi(NO3)3:5H2O by Oxygen in the reactor. The temperature degrades the chemical composition into nano thin films of desire particles on the glass surface. The expected reaction is mentioned below. NPs growth takes place on glass substrate at 600°C. Self assembly of BiOCl and Bi2O3 crystals were observed on the glass substrates. Obtained thin films were characterized by Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDS). Further, thin films of BiOCl and Bi2O3 were evaluated for photocatalytic study. BiOCl NPs thin film was tested against methyl orange dye and Bi2O3 thin film was tested against Acid ...
Journal of Photochemistry and Photobiology A: Chemistry, 2020
Temephos (Tem) is a widely used pesticide to control mosquito's proliferation in tropical countri... more Temephos (Tem) is a widely used pesticide to control mosquito's proliferation in tropical countries. This pesticide is put in stagnant water bodies where mosquitoes reproduce, killing larvae effectively. Recently, Tem has been identified as a DNA damaging agent; despite, people use it unmoderated in water reservoirs for personal consumption. Thus, Tem has become a hazard for human health and needs urgent attention. In order to reduce the risk of toxicity in those water sources we propose the use of nanostructured zinc oxide (ZnO) photocatalyst films to degrade this toxic compound. ZnO films with nanoflower morphology were prepared using a simple spray pyrolysis method. The band gap was 3.2 eV but a large number of natural defects present in the films allowed the absorption of visible light. The photocatalytic degradation ability of ZnO nanoflowers removed the toxic Tem under the illumination of a solar simulator. The UV-vis spectroscopy and High-Performance Liquid Chromatography analysis of Tem at regular intervals during photocatalysis confirmed the degradation of Tem, along with its transformation products or metabolites from water, reducing seven times the Tem half-life time in water. Total organic carbon measurements also indicated the mineralization of the compound.
Catalysis Science & Technology, 2019
The use of dyes to evaluate visible-light photocatalysts requires a proper determination of the c... more The use of dyes to evaluate visible-light photocatalysts requires a proper determination of the contribution from the competing processes: adsorption, sensitization, photobleaching and degradation.
Journal of Materials Science: Materials in Electronics, 2018
The photocatalytic reduction of 4-Nitrophenol was assisted with blue light irradiation using CdS ... more The photocatalytic reduction of 4-Nitrophenol was assisted with blue light irradiation using CdS semiconductor nanofiber. The kinetic study of the blue-photoreduction of 4-Nitrophenol to 4-Aminophenol was performed by using Na 2 SO 3 as "hole scavenger" in the presence of middle carboxylic acids (acetic, oxalic and citric acid). The effect of photocatalyst load, the carboxylic acid concentration and of the pH solution (acid, neutral and alkaline media) were investigated. The maximum 4-Nitrophenol photoreduction rate was reached in neutral media and it is related to the enhanced "hole scavenging" effect caused by the SO 3 2− or HSO 3 2− ions in the presence of carboxylic acid. Electrochemical characterization of CdS nanofiber was made in the presence of 4-NP and citric acid. The 4-NP photoreduction reaction follows a zero order reaction and a possible mechanism to explain the fast electron transfer process is discussed as a consequence of the carboxylic acid adsorbed on the CdS surface.
Journal of Nanomaterials, 2016
There is an increasing interest on the application of ZnO nanorods in photocatalysis and many gro... more There is an increasing interest on the application of ZnO nanorods in photocatalysis and many growth methods have been applied, in particular the spray pyrolysis technique which is attractive for large scale production. However it is interesting to know if the nanorod morphology is the best considering its photocatalytic activity, stability, and cost effectiveness compared to a nonoriented growth. In this work we present a systematic study of the effect of the precursor solution (type of salt, solvent, and concentration) on the morphology of sprayed ZnO films to obtain nanoflakes and nanorods without the use of surfactants or catalysts. The surface properties and structural characteristics of these types of films were investigated to elucidate which morphology is more favorable for photocatalytic applications. Wettability and photocatalytic experiments were carried out in the same conditions. After UV irradiation both morphologies became hydrophilic and achieved a dye discoloration ...
Catalysis Today, 2017
ZnO films with nanoflake and nanobar morphologies were obtained by spray pyrolysis by changing th... more ZnO films with nanoflake and nanobar morphologies were obtained by spray pyrolysis by changing the precursor salt and without any structure-directing agents. Nanoflakes were obtained from zinc acetate while nanobars with zinc chloride. Both films presented ZnO hexagonal wurtzite structure, a transmittance above 80% and band gap of 3.2 eV. The photocatalytic activity of the films was evaluated by the degradation of methyl orange and indigo carmine dyes in different concentrations. The film with nanoflake morphology showed the best performance in discoloration (96%) and it achieved a 51% in mineralization. The film with nanobars attained only a 67% in discoloration whereas it failed to mineralize the dye solution. The principal factors involved in the best performance of the nanoflake films were the less defective surface in the ZnO structure that diminished the electron-hole recombination, allowing the generation of hydroxyl radicals in a sufficient amount. The nanoflake film showed also a high stability after 10 degradation cycles, indicating a promising material for photocatalytic water treatment.
Ceramics International, 2016
A mixture of α/β-Bi 2 O 3 and α-Bi 2 O 3 powders were obtained by a simple solid state reaction-a... more A mixture of α/β-Bi 2 O 3 and α-Bi 2 O 3 powders were obtained by a simple solid state reaction-annealing route at 550°C. The structure, optical properties and surface area of the commercial α and β-Bi 2 O 3 and the synthesized α-phase and α/β-composite were well characterized by X-ray diffraction, diffuse reflectance spectra and N 2 physisorption. The annealed sample at 550°C showed 20% of β-phase, forming a heterojunction of α/β-Bi 2 O 3 whereas annealing at elevated temperature (650°C) lead to the α-phase. Optical properties showed that the presence of the β-phase is mainly responsible for narrowing the energy band gap. The photocatalytic activity of the commercial α and β-Bi 2 O 3 and the synthesized α-phase and α/β-composite were investigated in degradation of single dyes, Indigo Carmine (IC) and Rhodamine-B (RhB) under both UV and visible light-induced photocatalysis. For the best photocatalyst, the photodegradation in a two-dye mixture solution was systematically studied considering the type of dye, the adsorption capacity of the samples and the behavior of dye photodegradation. The photocatalytic performance of α/β-Bi 2 O 3 2 was comparatively much higher than the commercial α and β-Bi 2 O 3 , indicating that better performance of efficient charge separation and transfer across α/β-Bi 2 O 3 composite was obtained. Possible mechanism of the single dye and two-dye mixture degradation was given by using α/β-Bi 2 O 3 composite.
ChemistrySelect, 2016
Nanostructured composites based on plasmonic Ag metal nanoclusters with monoclinc-BiVO 4 nanopart... more Nanostructured composites based on plasmonic Ag metal nanoclusters with monoclinc-BiVO 4 nanoparticles were prepared by high energy ball milling technique. The agglomerated morphology with a spherical shape of 50-100 nm sized BiVO 4 particles associated with homogeneous distribution of 5-10 nm Ag clusters significantly enhanced the photocatalytic activity for the degradation of acid blue dyes. The Ag doping concentration with BiVO 4 was optimized at 3 at. % leading to almost 10 folds faster photocatalytic degradation rate as compared to pristine form. Thus, Ag doped BiVO 4 nanocomposites show efficient visible light driven photocatalytic activity due to charge distribution at the semiconducting-metal interfaces from band bending and the involvement of a radiation field enhanced by plasmon resonance effects at the surfaces of Ag-clusters.
Journal of Molecular Structure, 2016
TTF derivative of substituted pyrrole was obtained by means electrochemical synthesis, the result... more TTF derivative of substituted pyrrole was obtained by means electrochemical synthesis, the resultant colored mix was characterized by Mass spectrometry, NMR and EPR studies, its intrinsic electronic behavior was measured by a four point probe method, besides theoretical calculations were carried out on the possible structures of the resultant molecular adduct. All the results show that there is a net transfer of an electron between both organic moieties in solution giving place to a semiconductor species.
Catalysis Today, 2016
Bismuth oxide (Bi 2 O 3) thin films were deposited using a magnetron sputtering system under diff... more Bismuth oxide (Bi 2 O 3) thin films were deposited using a magnetron sputtering system under different conditions of power (radio frequency) and substrate temperature. The film structural characterization was done using X-ray diffraction, where it was demonstrated that films presenting different crystalline phases were obtained; cubic delta-Bi 2 O 3 and a mixture of ␣and -Bi 2 O 3 in different proportions. Three of these films were selected to compare their photocatalytic activity by measuring the percentage of photodiscoloration of 1 × 10 −6 M of methyl orange (MO, C 14 H 4 N 3 SO 3 Na) using UV light; moreover, the effect of the pH of the solution on the photodiscoloration was also investigated. The results indicated that the films were only active under acidic pH and that the cubic delta phase was the most efficient. The optical properties were also evaluated by ellipsometric spectroscopy and the results were compared to the optical transmittance spectroscopy. In order to gain understanding about the effect of the pH and the structure, the point of zero charge and the photoluminescence of the three samples were also obtained. Furthermore, the photocatalytic activity of the sample presenting the best results was evaluated using higher concentration of the MO dye, but also using indigo carmine dye and both UV and blue lights.
2015 12th International Conference on Electrical Engineering, Computing Science and Automatic Control (CCE), 2015
Physical Chemistry Chemical Physics, 2015
In the vapour–liquid–solid technique with Au as a catalyst (widely used to obtain ZnO nanowires),... more In the vapour–liquid–solid technique with Au as a catalyst (widely used to obtain ZnO nanowires), Au intruders can be incorporated accidentally. In this theoretical investigation we report that Au as an intruder in ZnO nanowires enhances their potential use for photonic and photovoltaic applications.
Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, Jan 24, 2015
Bismuth oxide thin films were obtained by the spray pyrolysis method using bismuth acetate as the... more Bismuth oxide thin films were obtained by the spray pyrolysis method using bismuth acetate as the precursor salt. The films were characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), UV-vis diffuse reflectance, X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). The XRD patterns indicated that the pure β phase is obtained at 450 °C and was also confirmed by FTIR. This phase presents a nanoplate morphology which is adequate for the photocatalytic reactions. Moreover, the band gap value was 2.6 eV indicating a good capacity of visible light absorption. The photocatalytic degradation of the Methyl Orange (MO) dye was pH dependent, an acid solution being easier to degrade. However, the Bi2O3 films were easily converted into BiOCl when they were in contact with a solution containing HCl. In order to preserve the β-Bi2O3 phase, the Acid Blue 113 dye with its natural pH of 8 was used to evaluate the stability of the photocatalytic activity ...
Materials Chemistry and Physics, 2010
Theoretical calculations were performed on 2,5-aromatic substituted pyrroles which have a nitrobe... more Theoretical calculations were performed on 2,5-aromatic substituted pyrroles which have a nitrobenzene or a cyano-benzene link to the nitrogen atom of the pyrrole fragment. The molecules manifested interesting semiconductor behavior that was confirmed when thin films were prepared and their corresponding electrical characterization was undertaken. The reason for this behavior is discussed, with reference to the electron-withdrawing feature of the substituents in the benzene chain.
Journal of Solid State Chemistry, 2013
Polymeric carbon nitride was synthesized by pyrolysis in nitrogen flux at different temperatures ... more Polymeric carbon nitride was synthesized by pyrolysis in nitrogen flux at different temperatures between 450 and 700 1C using melamine cyanurate as a reagent and sulfuric acid as a catalyst. The obtained carbon nitride consisted of curled nanosheets (650 1C), and globular particles (700 1C) with formula C 6 N 7 NHNH 2. The reaction yield of the catalyzed reaction was around the 15% for the sample treated at 700 1C, in a tapped crucible. The optical band gap of the polymer obtained at 700 1C is around 2.9 eV. The gap to the Fermi level is around 2 eV, considerably above the half of the band gap (due to electrons trapped in the gap), indicating that the polymer is probably a n-type semiconductor.
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Papers by Monserrat Bizarro