تقدیم به آنان که اهل یافتنند نه اهل بافتن وآنان که معترفند حقیقتی یافته اند نه کل حقیقت را 1

IN THE NAME OF GOD 2

Nanostructured metal oxide & Its applications in analytical chemistry 3

Outline: i. definition nanostructured ii. The types of nanostructured iii. Metal oxide iv. Methods of preparation nanostructured metal oxide v. Application vi. Concluding Remarks and Future Work 4

definition nanostructured Nanostructured is definited as any material that be minimum one of its dimensions in scale nanometer. nanostructured attribute :  Increas respect surface to bulk  Particles size introduced to quantum trace of zone 5

The types of nanostructured 1.Zero dimension nanostructured:  Metal, semicoductors, ceramic of nanoparticles 2.One dimension nanostructured:  Nanowire:(1.metalic 2.organic 3.semiconductores),nanotube,nanorod 3.Two dimension nanostructured:  Films or fine layers 4.Three dimension nanostructured: 6

Spherical nano particles 7

One dimension nanostructured Zno2 nanorods Crbone nanotube 8

TEM of image CNT 9

Metal oxide  The metal elements are able to form a large diversity of oxide compound.  Metal oxide play a very important role in many areas of chemistry,physics,and materials science. 10

Methods of preparation nanostructured metal oxide:  Chemical methods  Physical-like methods in both of chemical and physical methods produce solid powders with a reasonable control of the primary particle size,ie,the size of a typical agglomerate of crystallites. 11

Advantages chemical methodes:  Chemical method offer potantial routes to obtain better materials in terms of chemical homogenity  Morphological control (i.e.,primary and secondary particle size) 12

Electrospining 13

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Physical methods:  Gas/vapor condensation  Thermochemical  Spray pyrolysis 16

Gas vapor condasation: In this method form a supersaturated vapor of metals in a first stage of condensation under(high pressure) innert gas with a subsequent stage of oxidation. 17

Advatage :  Their ease of performanc  High purity of the resulting solides Disadvantage:  High cost  Low yield 18

Termochemical /flam method: This method used to synthesize ceramic precursor powders. It is involve 2state: 1.c hemical salts/precursors vaporization 2.oxidized a combustion process using a fuel-oxidant mixtur which induces rapid thermal degradation and reaction with oxygen. 19

Advantag :  Due to low its cost used in industry Disadvantage:  Control of particle size and morphology is somewhat difficult. 20

Spray pyrolysis: 1. involves generation of aerosol by of a stating solution,sol or suspension of a precursor. 2. Further evaporation of the solvent 3. Drying 4. Thermlysis at high temprature to form microporous particles,which can sinter to form more or less dense materias depending on experimental coditions. 21

Advantage:  High purity Disadvantage:  It require the large amount of solvent 22

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STM images recorded before oxidizing nanoparticles on a Au(111)template Mo nanoparticles are present on a Au(111) substrate.due to the relatively high surface free energy of Mo with respect to Au,the Mo nanoparticles form three-dimentional aggreates and Mo/Au surface alloys. 25

STM images recorded after oxidizing nanoparticles on a Au(111)template Upon reaction with oxygen the Mo transforms into MoO3,which has a low surface free energy and spresds out covering the Au(111)subsrate.MoO3 nanoparticles formed by this approch have structure different from that seen in the most common phases of bulk MoO3. 26

Chemical methods:  Sol-gel  Micellar  Chemical/mechanochemical  CVD 27

Sol-gel: A standard method in synthesizing oxides. Hydrolysiss of reactive metal precursors(usually alkoxides in an alcohol solution,resulting in a gel). Thermally or hydrothermally treated to yield the nanostructured product. 28

Advantage:  The production of ultrafine powders having high chemical homogeneity. 29

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Sensitivitive comparison between sol gel and Electrspining: 31

Micellar: In this method micelles as microreactors in which the oxide or oxide precursor are obtained by reaction between solved cations and a precipitating agent. Disadvantage:  High cost production 32

Advantage:  To obtain ultrafine powders with signficant control of chemical homogeneity  Favorable Control particle size 33

Mechanochemical synthesis: Involves mechanical actvation of solid reactions by the milling of precursor powders(usually a salt and a metal oxide)to form the desired nanoscale compound,which can be typically obtained after heating and purification. 34

CVD 35

ApplicationS: Fabrication of  microelectronic circuits  Sensors  Piezoelectric devices  Fuel cells  semiconductores Coatings for the passivation of surfaces againts corrosion 36

Fuel cells 37

As catalyst: For example:  almost all used in industrial applications involve an oxide as active phase,promoter,or “support”.  For the control of environmental pollution 38

 The use of nanostructured metal oxide in chemical and petrochemical 39

Application nanostructured metal oxide in electrochemical & materils sepration:  Preparation electrochemical biosensores Based on DNA  The use of nanosructured as absorbent for extraction bio -environment pollutant compounds. 40

specific application:  Nanoscale metals and metal oxides can be used for the absorbance of metals (Nowack, 2008; Rickerby and Morrison, 2007).  Active agents like manganese oxide can be used to change the valance state of metal ions in water (e.g. arsenic oxide from 3+ to 5+ which can then be more easisly removed (Schorr, 2007)). 41

Specific application:  Reactions can often be enhanced through the addition of other nonomaterials such as copper (oxide) (Schorr, 2007). 42

43 specific application: Iron and other metal oxides (sometimes in combination with metals) can also adsorb heavy metals and radionucluides (Schourr, 2007).

Application metal Oxide-CNT:  A few studies investigate metal oxide-CNT composites for the removal of metals and anions (see also chapter on groundwater remediation).  Peng et al. (Peng et al., 2005a) synthesized among others carbon nanotubes-iron oxides magnetic composites as adsorbent for removal of Pb(II) and Cu(II) from water. 44

Tio2 nanoscale photocatalyst 45

Concluding Remarks and Future Work  the progress made in the development of methods and techniques for the preparation, and characterization of oxide nanostructures has been very impressive, but clearly much more research is necessary to produce the type of knowledge and understanding necessary for a rational design of these system 46

Concluding Remarks and Future Work  Size effects” have not been studied for many oxides in a systematic way.  the use of chemical-like methods for obtaining mixedoxides, the “fine-tuning” of the number of atoms in an oxide nanoparticle is still a challenge. 47

Concluding Remarks and Future Work  A real challenge is the characterization of oxide nanoparticles in-situ under the harsh Conditions employed in many industrial chemical processes.  Better and faster techniques for structural and electronic characterization have to be devised. 48

Marcos Ferna´ndez-Garcıawas born in Madrid, Spain. Jonathan Hansonwas born in Chicago, 49

Arturo Martı´nez Ariaswas born in Madrid in Jose´ A. Rodriguezwas born in Caracas, Venezuela. 50

Reference:  Nanostructured Oxides in Chemistry: Characterization and Properties M. Ferna´ndez-Garcı´a,*,† A. Martı´nez-Arias,† J. C. Hanson,‡ and J. A. Rodriguez*,‡ Instituto de Cata´lisis y Petroleoquı´mica, CSIC, C/ Marie Curie s/n, Campus Cantoblanco, Madrid, Spain, and Brookhaven National Laboratory, Chemistry Department, Building 555, Upton, New York

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(7) Handbook of Heterogeneous Catalysis; Ertl, G.; Knozinger, H.; Weitkamp, J., Ed.; Wiley-VHC: Weinheim, (8) Shelef, M.; Graham, G. W.; McCabe, R. W. In Catalysis by Ceria and Related Materials; Trovarelli, A., Ed.; Imperial College Press: London, 2002; Chapter 10. (9) Stirling, D. The Sulfur Problem: Cleaning Up Industrial Feedstocks; Royal Society of Chemistry: Cambridge, (10) Sherman, A. Chemical Vapor Deposition for Microelectronics: Principles, Technology and Applications; Noyes publications: Park Ridge, NJ,

(11) Gleiter, H. Nanostructured Mater. 1995, 6, 3. (12) Valden, M.; Lai, X.; Goodman, D. W. Science 1998, 281, (13) Rodriguez, J. A.; Liu, G.; Jirsak, T.; Hrbek, Chang, Z.; Dvorak, J.; Maiti, A. J. Am. Chem. Soc. 2002, 124, (14) Baumer, M.; Freund, H.-J. Prog. Surf. Sci. 1999, 61, 127. (15) Trudeau, M. L.; Ying, J. Y Nanostructured Mater. 1996, 7, 245. (16) Nanomaterials; Synthesis, Properties and Applications; Edelstein, A. S.; Cammarata, R. C., Eds.; Institute of Physics Publishing: London, (17) Khaleel, A.; Richards, R. M. in Nanoscale Materials in Chemistry; Kladunde, K. J., Ed.; Wiley: New York, 2001, Chapter 4. (18) Ayyub, P.; Palkar, V. R.; Chattopadhyay, S.; Multani, M. Phys. Rev. B. 1995, 51,

(19) Song, Z.; Cai, T.; Chang, Z.; Liu, G.; Rodriguez, J. A.; Hrbek, J. J. Am. Chem. Soc. 2003, 125, (20) Liu, P.; Rodriguez, J. A.; Muckerman, J. T.; Hrbek, J. Phys. Rev. B, 2003, 67,

Thanks for your attention 56