Nanoparticle metal oxide

Synthesis of polymer/nanoparticles composite materials is very important for the advanced material science. Materials of this type combine unique properties of nanoparticles with properties of polymers, and even reveal new properties not specific for their components. Moreover, a polymer also plays a role of stabilizer for extremely active nanoparticles. Metal oxides are an interesting class of inorganic nanoparticles due to optical, magnetic and electronic features [1-3],... 

Ivanov, R, Stankova, M., Llobet, E., Vilanova, X., Brezmes, J., Gracia, I., Cane, C., Calderer, J. and Correig, X. (2005), Nanoparticle metal-oxide films for micro-hotplate-based gas sensor systems ,/ Sens. 5(5), 798-809. 

Different types of species have been successfully encapsulated inside MOFs through use of any of the three methods desalbed above. These species include metal nanoparticles, metal oxides, quantum dots, polyoxometalates, polymers, graphene, carbon nanotubes, biomolecules, and so on. A brief overview of the systems prepared so far is given below. 

Metallic nanoparticles Metallic oxide nanoparticles Biomolecules... 

C. Clavero, Plasmon-induced hot-electron generation at nanoparticle/metal-oxide interfaces for photovoltaic and photocatalytic devices on Au. Nat. Photonics 8, 95-103 (2014)... 

Table 11.2 and assume A=100, which is rather conservative value, to compute J via Eq. (11.32) and O via Eq. (11.22). The results show t p 0.91 which implies that the O2 backspillover mechanism is fully operative under oxidation reaction conditions on nanoparticle metal crystallites supported on ionic or mixed ionic-electronic supports, such as YSZ, Ti02 and Ce02. This is quite reasonable in view of the fact that, as already mentioned an adsorbed O atom can migrate 1 pm per s on Pt at 400°C. So unless the oxidation reaction turnover frequency is higher than 103 s 1, which is practically never the case, the O8 backspillover double layer is present on the supported nanocrystalline catalyst particles. 

There is currently considerable interest in processing polymeric composite materials filled with nanosized rigid particles. This class of material called "nanocomposites" describes two-phase materials where one of the phases has at least one dimension lower than 100 nm [13]. Because the building blocks of nanocomposites are of nanoscale, they have an enormous interface area. Due to this there are a lot of interfaces between two intermixed phases compared to usual microcomposites. In addition to this, the mean distance between the particles is also smaller due to their small size which favors filler-filler interactions [14]. Nanomaterials not only include metallic, bimetallic and metal oxide but also polymeric nanoparticles as well as advanced materials like carbon nanotubes and dendrimers. However considering environmetal hazards, research has been focused on various means which form the basis of green nanotechnology. 

Metal oxides of variable oxidation state as supports or support modifiers [202] are well known in gold catalysis. In the previous section we have already indicated some metal-support interactions influencing the electronic state of gold nanoparticles as well as the metallic or ionic state of gold. Of the numerous literatures we have to mention Haruta and Date [169], Bond [195], as well as Goodman works [186,203]. Further results can be found on the iron oxide system in recent literatures [162,204]. 

Dendrimer-protected colloids are capable of adsorbing carbon monoxide while suspended in solution, but upon removal from solution and support on a high surface area metal oxide, CO adsorption was nil presumably due to the collapse of the dendrimer [25]. It is proposed that a similar phenomena occurs on PVP-protected Pt colloids because removal of solvent molecules from the void space in between polymer chains most likely causes them to collapse on each other. Titration of the exposed surface area of colloid solution PVP-protected platinum nanoparticles demonstrated 50% of the total metal surface area was available for reaction, and this exposed area was present as... 

Scheme 2. General scheme showing the entrapment process of unprotected noble metal nanoclusters within the matrix of metal oxide nanoparticles. (Reprinted from Ref [18], 2004, with permission from Elsevier.)...

Among various methods to synthesize nanometer-sized particles [1-3], the liquid-phase reduction method as the novel synthesis method of metallic nanoparticles is one of the easiest procedures, since nanoparticles can be directly obtained from various precursor compounds soluble in a solvent [4], It has been reported that the synthesis of Ni nanoparticles with a diameter from 5 to lOnm and an amorphous-like structure by using this method and the promotion effect of Zn addition to Ni nanoparticles on the catalytic activity for 1-octene hydrogenation [4]. However, unsupported particles were found rather unstable because of its high surface activity to cause tremendous aggregation [5]. In order to solve this problem, their selective deposition onto support particles, such as metal oxides, has been investigated, and also their catalytic activities have been studied. 

M. Haruta, Catalysis of gold nanoparticles desposited on metal oxides, Cattech, 2002, 6, 102. 

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