Photonic crystals in biology

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P Poster Session, Tuesday, June 15 Theme A1 - B702 Structural, surface and catalytic properties of individual and binary Ni and Ce oxides system N. M. Deraz 1 PChemistry Department , College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia 1 Abstract-NiO, R CeOR2 and R NiO/CeOR2 catalysts were prepared obtained by ceramic and wet impregnation routes followed by calcination at 400 °C, respectively. The crystalline phases produced by calcination the mentioned temperature were characterized by XRD measurement. The microstructure, surface and catalytic properties of the calcined products of various solids were determined by transmission electron microscope, nitrogen adsorption at °C and isopropanol dehydrogenation at different temperatures. The results reveled that the crystallite sizes, specific surface areas and catalytic activity of individual o xides were smaller than those of binary system. The binary oxides calcined at 400 1T°1TC constituted of well crystalline Ni and Ce oxides. A portion of NiO dissolved in R CeOR2 lattice in the binary oxides system by heating at 400 °C and the other portion remained as a separate phase. The dissolution process resulted in the formation of Ni-Ce-O compound with subsequent decrease in the degree of crystallinity of NiO and CeOR2 Rphases. The activation energy of the catalytic reaction was determined for various investigated solids and was found to be dependent on the nature of the as-prepared system. Metal oxides as catalytic materials were used in many important commercial catalytic reactions [1-5]. There are various parameters, such as suitable support and doping with certain foreign cations, must be considered in order to improve the catalytic activity and selectivity of these oxides employed in some different industrial reactions [1-3]. The supporting on a suitable carrier results in an increase in the dispersion of catalytically active constituents and increases their thermal stability via hindering their grain growth [1, 5]. The catalytic activity of most of transition metal oxides can be greatly improved by their loading on a suitable support such as alumina, silica, magnesia and ceria [1-5]. Nickel has emerged as a possible alternative catalyst due to its low cost but tends to deactivate by coke formation. The use of suitable support and/or dopant such as R CeOR2 as support in the preparation of traditional Ni based catalysts can contribute to enhance the catalytic activity and reduce the coke formation [6]. The important role of ceria played in catalytic reactions, is suggested to be the generation and participation of surface oxygen species and anionic vacancies [7, 8]. Various studies have shown that the redox properties of metal oxide can be significantly enhanced if additional elements are introduced into its lattice depending upon forming a solid solution [7, 8– 10]. Previous studies on Pt and Cu supported on R CeOR2 catalysts have shown that strong metal-ceria interactions, by formation of solid solution in the mixed o xides catalyst [7, 11, 12]. The strong metal-to-support interaction appeared as one of the reasons of the observed high catalytic activity and stability during the hydrocarbons’ partial oxidation and oxidative steam reforming. The catalytic conversion of isopropanol has been probed in the past by many workers over various solids like clays [13], perovskites [14] aluminophosphates [15-17] spinel ferrite [18] and ceria [19]. On acidic catalytic surfaces the reaction proceeds via dehydration to alkenes while on metallic or basic surfaces via dehydrogenation to ketone and/or aldehyde. The ceria based catalysts have been extensively scrutinized in redox applications [19]. Such applications stem from the wellknown ability of cerium oxides to store oxygen when in oxidative atmosphere and release it when in reductive one. In the present work, a comparative study on the structural, morphological, surface and catalytic properties of the individual and binary Ni and Ce oxides has been determined. Since the metal- support interaction often plays a key role in determining the details of the previous properties; one objective of this investigation is to establish the relationship between the surface and catalytic characteristics and the metal-support interaction by applying the Ni/Ce mixed oxide o catalysts calcined at 400 P PC to R NR2 adsorption and catalytic conversion of isopropanol. *Corresponding author: 2Tn.deraz@yahoo.com2T [1] N. M. Deraz, M.M. Selim and M. Ramadan, Mater. Chem. Phys. 113 (2009) 269. [2] N. M. Deraz, Colloid. Sur. A 207 (2002) 197. [3] N.M. Deraz, Colloid. Sur. A 218 (2003) 213. [4] N. M. Deraz, Chin. J. Catal. 29(8)(2008)687. [5] N. M. Deraz, Appl. Sur. Sci. 255 (2009) 3884. [6] L. Wenying, F. Jie, X. Kechang, React. Kinet. Catal. Lett. 64(1998)381. [7] N. Laosiripojana, S. Assabunsrungrat, J. Power Sources 158(2006) 1348. [8] A. Trovarelli, C. de Leitenburg, G. Dolcetti, Chemtech. 27(1997) 32. [9] H. S. Potdar, H.-S. Roh, K.–W. Jun, Ji M, Z.-W. Liu, C atal. Lett. 84(2002)95 [10] Yisup N, Cao Y, Feng W-L, Dai Ws-L, Fan K–N (2005) Catal Lett 99:207 [11] Pino L, Vita A, Cordaro M, Recupero V, Hegde MS (2003) Appl Catal A 243:135 [12] L. Pin A 306(2006) 68. [13] A.K. Ladavos, P.N. Trikalitis, P.J. Pomonis, J. Mol. Catal. A: Chem. 106 (1996) 241. [14] P.N. Trikalitis, P.J. Pomonis, Appl. Catal. A 131(1995)309. [15] D.E. Petrakis, P.J. Pomonis, A.T. Sdoukos, J. Chem. Soc. Faraday Trans. 85 (1989)3173. [16] D.E. Petrakis, P.J. Pomonis, A.T. Sdoukos, J. Chem. Soc. Faraday Trans. 87 (1991) 1439. [17] K.M. Kolonia, D.E. Petrakis, A. K. Ladavos, PCCP 5 (2002) 217. [18] N.M. Deraz, M.K. El-Aiashy, Suzan A. Ali, Adsorp. Sci. Technol. 27(8)(2009), In Press. [19] N.M. Deraz, A. Alarifi, Adsorp. Sci. Technol. 27(4)(2009)413. 6th Nanoscience and Nanotechnology Conference, zmir, 2010 244
Poster Session, Tuesday, June 15 Theme A1 - B702 Characterization of NiS and SrS nanoparticles synthesized by solid-gas reaction of sulfidizing gas mixture Halil Guler 1 and Figen Kurtulus 1 * Balikesir University, Faculty of Science, Chemistry Department, , Balikesir 10145, Turkey 1 Abstract- In this study, the sulfidizations of NiO, SrNO 3 and SrCO 3 were investigated by using solid-gas reactions under sulfidizing gas mixture, which contains the gas mixture of carbonyl sulfide (COS), carbon disulfide (CS 2 ) and sulfur (S 2 ). The powder crystalline forms of nickel sulfide (NiS) and strontium sulfide (SrS) were prepared purely by solid-gas reaction technique. The product crystalline phases were characterized by the X-Ray Diffraction (XRD) technique. XRD data of the NiS and SrS were in good agreement with the Joint Committee for Powder Diffraction Systems (JCPDS) card numbers, 2-1280 and 8-489 in series. The crystalline grain sizes of samples were estimated by using Debye Scherrer formula. The grain sizes of the products are in the range of nano sizes. In light of this study, it could be proposed that the compounds, NiS and SrS could be prepared purely through sulfidizing gas mixture by solid-gas reactions under cooling of a nitrogen atmosphere. Metal chalcogenide nanocrystals such as NiS, ZnS, SrS, CdS and PbS have attracted great interest in recent years owing to their unique properties in physics and chemistry that significantly differ from those of their bulk counterparts. These types of material usually show novel 0,9 optical, electronic and magnetic properties due to their D peculiar quantum-size effect and large specific surface B cos B areas. Therefore, these metal sulfides have important applications in the field of opto-electronic technology and fabrication of photo catalysis materials [1,2]. Nickel sulfide nanoparticles have been used as IR detectors, solar storage devices, photoconductive materials and hydrodesulfurization catalysis [3,4]. The electromagnetic property of the nickel sulfide (NiS) is also interesting since it transforms fro m a paramagnetic metal to an antiferromagnetic semiconductor upon cooling under the transition temperature Tt ~379 0 C [5]. Finally, the SrS was used to obtain an efficient blue phosphor light for the full color thin film electro lu minescent (TFEL) display products for many years [6]. On the experimental practice, the NiS and SrS were prepared separately through solid gas reaction of sulfidizing gas mixture of COS, CS 2 , and S 2 with the initial reactants of NiO and SrNO 3 (and also SrCO 3 ). The XRD patterns of the products NiS and SrS are given in Figure 1. As shown, the experimental XRD data of the NiS and SrS were in good agreement with the ICDD card numbers 2-1280 (crystal system was unidentified) and 8- 489 (cubic structure, a = 6.020Å, space group = Fm3m and Z = 4), respectively. We obtained the same XRD patterns for the SrS with the sulfidization of the raw materials, SrNO 3 and SrCO 3 . It could be concluded that both initial reactants could be used as an initial reactant for the synthesis of SrS. The crystalline grain sizes of the synthesized products of the metal sulfides, NiS and SrS, were calculated by using Debye Scherrer formula [7]. The Scherrer equation is written as follows: (1) Where in the equation (1), is the wavelength of the X-ray radiation and B is the full width at half maximum of peak of the XRD pattern. The grain sizes (D) of the NiS and SrS were calculated as 25.871 and 98.690 nm, respectively. The results show that the crystalline grain sizes of the NiS and SrS have in the range of nano extension. In light of this study, it could be proposed that the compounds, NiS and SrS could be prepared in nano extention and purely through sulfidizing gas mixture by solid-gas reaction under cooling of a nitrogen atmosphere. *Corresponding author : fdemiral@balikesir.edu.tr [1] I. Honma, S. Hirakawa, K.Yamada, J.M. Bae. Solid State Ionics, 118, 29 (1999). [2] M.L. Curri, R. Comparelli, P.D. Cozzoli, G. Mascolo, A. Agostiano. Mater. Sci. Eng., C, Biomim. Mater., Sens. Syst., 23, 285 (2003). [3] W.J.J.Welters, G. Vorbeck, H.W. Zandbergen, J.W. Dehaan, V.H.J. Vansaten, R.A. Vansaten. J. Catal. 150, 155(1994). [4] S.D. Sartale, C.D. Lokhande. Mater. Chem. Phys., 72, 101 (2001). [5] D.W. Bishop, P.S. Thomas, A.S. Ray. Mater. Res. Bull., 33, 1303 (1998). [6] Sey-Shing. Sun Displays, 19, 145 (1999). [7] B.D. Cullity, Elements of X- ray diffraction, 2nd Edition, AddisonWesley, Reading, MA (1978). 100 311 222 110 331 420 400 200 220 102 a) b) 111 101 103 201 200 004 202 2 theta(degree) Figure 1. XRD patterns of a)NiS and b)SrS. 6th Nanoscience and Nanotechnology Conference, zmir, 2010 245
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