Dispersión De Nanoparticulas Siw12 En Nanotubos De Carbono Multipared
Páginas: 16 (3875 palabras)
Publicado: 30 de agosto de 2011
Journal of Nano Research Vol. 14 (2011) pp 11-18 Online available since 2011/Apr/14 at www.scientific.net © (2011) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/JNanoR.14.11
Dispersion of SiW12 Nanoparticles on Highly Oxidized Multiwalled Carbon Nanotubes and their Electrocatalytic Behavior Ana Karina Cuentas-Gallegos1, a, Abraham Zamudio-Flores1, b and MontseCasas-Cabanas2,c
1
Centro de Investigación en Energía-Universidad Nacional Autónoma de México, Privada Xochicalco S/N Col. Centro, AP 34, CP 62580 Temixco, Morelos, México
2
Laboratoire CRISMAT/ENSICAEN, 6 Bd du Maréchal Juin 14050, Caen, France
a
akcg@cie.unam.mx, babraham.zf@hotmail.com, cmontserrat.casas-cabanas@ensicaen.fr
Submitted: September 1, 2010; revised: November 12, 2010;accepted: November 22, 2010 Key words: Polyoxometalates, Nanocomposites. Keggin, SiW12, Carbon Nanotubes, Hybrid Materials,
Abstract. Nanocomposite hybrid materials (NHM) based on the immobilization and dispersion of SiW12 polyanion (H4SiW12O40) on a highly oxidized multiwalled carbon nanobue matrix (NTS) are presented. The synthesis procedure followed is designed in order to increase the SiW12particles concentration on the NHM. XRD, FTIR, N2 adsorption isotherms, EDS, SEM, TEM, and cyclic voltammetry confirmed the presence of SiW12 nanoparticles, whose microstructure and dispersion characteristics were correlated with their BET surface area and their electrochemical behavior. Based on these studies, SiW12 nanoparticles are successfully nanodispersed in the highly oxidized carbon nanotubematrix (NTS), obtaining the highest SiW12 concentration and best electrochemical behavior for sample MH3. The electrocatalytic properties are evaluated for this optimized hybrid (MH3) in the electroreduction of bromated ion with good results. Introduction Polyoxometalates (POMs) are molecular oxides that can be applied taking advantage of their redox properties, photochemical responses, ionic charge,and conductivity. Mainly 80-85% of all the reported work are in the catalyst area, and the rest 15-20% in many other applications (capacitors, anticorrosive coatings, electrochromic, photochromic, wood pulp bleaching, etc) [1]. Among their applications in the catalysis field, the electrocatalytic properties have been studied more recently on the electroreduction of different analytes (nitrate,bromated, iodate, hydrogen peroxide) due to their potential use in the development of amperometric sensors. [2-17] POMs in their acidic form are known as Heteropolyacids (HPAs) consisting of large polyanions with Keggin structure (primary structure), cations, water crystallization, and other molecules. This 3D arrangement is known as the secondary structure, while the ternary structure determinesthe particle size, surface area, pore size, etc, and is very determinant on their final properties as solid HPAs [18]. HPAs have low surface areas (1-15m2/gr) revealing their high solubility in water. Nevertheless, the surface area can be increased and the pores can be manipulated by substituting the protons by other cations as Cs, NH4, etc. Dispersing HPAs on solid supports with high surface areasis another way of increasing their surface area and tune their porosity, which is very important in their potentiality in solid-state applications. In general, HPAs strongly interact with supports at low loading levels. Among the supports that have been used as a matrix for HPAs are a great diversity of carbons, such as: active carbons [19-20], carbon cloth and fibers [14,21], gels [22], glassycarbon [8-23], paste [24-25], nanofibers [26] and more recently nanotubes [6,9-10,13,27-33], etc. This type of supports compared to others can firmly immobilized HPAs and show high stability against their leakage into solvent, due to a covalent bonding between functional groups of the carbon matrices and the HPAs [10,19,21-22,29-30,32,34-37]. It has been reported in this type of materials that the...
Dispersion of SiW12 Nanoparticles on Highly Oxidized Multiwalled Carbon Nanotubes and their Electrocatalytic Behavior Ana Karina Cuentas-Gallegos1, a, Abraham Zamudio-Flores1, b and MontseCasas-Cabanas2,c
1
Centro de Investigación en Energía-Universidad Nacional Autónoma de México, Privada Xochicalco S/N Col. Centro, AP 34, CP 62580 Temixco, Morelos, México
2
Laboratoire CRISMAT/ENSICAEN, 6 Bd du Maréchal Juin 14050, Caen, France
a
akcg@cie.unam.mx, babraham.zf@hotmail.com, cmontserrat.casas-cabanas@ensicaen.fr
Submitted: September 1, 2010; revised: November 12, 2010;accepted: November 22, 2010 Key words: Polyoxometalates, Nanocomposites. Keggin, SiW12, Carbon Nanotubes, Hybrid Materials,
Abstract. Nanocomposite hybrid materials (NHM) based on the immobilization and dispersion of SiW12 polyanion (H4SiW12O40) on a highly oxidized multiwalled carbon nanobue matrix (NTS) are presented. The synthesis procedure followed is designed in order to increase the SiW12particles concentration on the NHM. XRD, FTIR, N2 adsorption isotherms, EDS, SEM, TEM, and cyclic voltammetry confirmed the presence of SiW12 nanoparticles, whose microstructure and dispersion characteristics were correlated with their BET surface area and their electrochemical behavior. Based on these studies, SiW12 nanoparticles are successfully nanodispersed in the highly oxidized carbon nanotubematrix (NTS), obtaining the highest SiW12 concentration and best electrochemical behavior for sample MH3. The electrocatalytic properties are evaluated for this optimized hybrid (MH3) in the electroreduction of bromated ion with good results. Introduction Polyoxometalates (POMs) are molecular oxides that can be applied taking advantage of their redox properties, photochemical responses, ionic charge,and conductivity. Mainly 80-85% of all the reported work are in the catalyst area, and the rest 15-20% in many other applications (capacitors, anticorrosive coatings, electrochromic, photochromic, wood pulp bleaching, etc) [1]. Among their applications in the catalysis field, the electrocatalytic properties have been studied more recently on the electroreduction of different analytes (nitrate,bromated, iodate, hydrogen peroxide) due to their potential use in the development of amperometric sensors. [2-17] POMs in their acidic form are known as Heteropolyacids (HPAs) consisting of large polyanions with Keggin structure (primary structure), cations, water crystallization, and other molecules. This 3D arrangement is known as the secondary structure, while the ternary structure determinesthe particle size, surface area, pore size, etc, and is very determinant on their final properties as solid HPAs [18]. HPAs have low surface areas (1-15m2/gr) revealing their high solubility in water. Nevertheless, the surface area can be increased and the pores can be manipulated by substituting the protons by other cations as Cs, NH4, etc. Dispersing HPAs on solid supports with high surface areasis another way of increasing their surface area and tune their porosity, which is very important in their potentiality in solid-state applications. In general, HPAs strongly interact with supports at low loading levels. Among the supports that have been used as a matrix for HPAs are a great diversity of carbons, such as: active carbons [19-20], carbon cloth and fibers [14,21], gels [22], glassycarbon [8-23], paste [24-25], nanofibers [26] and more recently nanotubes [6,9-10,13,27-33], etc. This type of supports compared to others can firmly immobilized HPAs and show high stability against their leakage into solvent, due to a covalent bonding between functional groups of the carbon matrices and the HPAs [10,19,21-22,29-30,32,34-37]. It has been reported in this type of materials that the...
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