Doping with heteroatoms

In an attempt to further optimize the fuel cell performance of OMC, the materials can also be functionalized and oxygen-containing groups introduced into the surface [80] (see also Section 7.3.2), as well as doped with heteroatoms, such as... 

CNTs and graphene can also be doped with heteroatoms as a substitute for carbon in the hexagonal lattice, known as substitutional doping. The most common heteroatoms are boron, a p-type dopant in carbon, and nitrogen, a n-type dopant in carbon. " Dopants significantly effect the electronic properties like the DOS near Ep and the band structure. Nitrogen-doped CNTs (N-CNTs) exhibit strong electron donor states on the conduction band near Likewise, boron-doped... 

Commercial LiMn204 products are mostly produced by solid-state reactions, similar to the process for the production of LiCo02. Most of the products are doped with heteroatoms. As mentioned in Section 4.4.6, to achieve good electrochemical performance, LiMn204 should preferably be coated. Some coatings are carried out by an in situ process, as shown in Figure 4.19, which can be processed continuously. 

Significant barriers, such as voltage fade and slow Li+ diffusion, need to be overcome by methods such as doping with heteroatoms and surface coating with oxides, fluorides, and other materials. 

Scheme 3.14 Procedure proposed to obtaiii doped G from the pyrolysis (b) of alginate modified with heteroatoms (a).

Besides nitrogen, carbons can be doped with other heteroatoms such as boron, sulfur, and phosphorous. Among these heteroatoms, boron has been the most widely investigated. Boron-doped diamond has been explored as an electrocatalyst... 

As well as efforts directed towards elucidating the physical and chemical properties of magic clusters, studies have also been conducted to produce metal clusters with specific features. Heteroatom doping studies have revealed that doping Au25(SR)i8 with a single palladium [25] or platinum [26] atom (Fig. 3.4) can lead to an increase in the overall stability of the clusters. Doping with these elements not only increased the stability of the clusters but also altered the chemical... 

The key property required of the inorganic species is ability to build up (polymerize) around the template molecules into a stable framework. As is already evident in this article, the most commonly used inorganic species are silicate ions, which yield a silica framework. The silica can be doped with a wide variety of other elements (heteroatoms), which are able to occupy positions within the framework. For example, addition of an aluminium source to the synthesis gel provides aluminosilicate ions and ultimately an aluminosilicate mesoporous molecular sieve. Other nonsilica metal oxides can also be used to construct stable mesoporous materials. These include alumina, zirconia, and titania. Metal oxide mesophases, of varying stability, have also been obtained from metals such as antimony (Sb), iron (Fe), zinc (Zn), lead (Pb), tungsten (W), molybdenum (M), niobium (Nb), tantalum (Ta), and manganese (Mn). The thermal stability, after template removal, and structural ordering of these mesostructured metal oxides, is far lower, however, than that of mesoporous silica. Other compositions that are possible include mesostructured metal sulfides (though these are unstable to template removal) and mesoporous metals (e.g., platinum, Pt). 

Fig. 6.26 Integral enthalpy of displacement per unit surface area A p H (taken with the opposite sign) measured in the liquid-flow ctdorimetry experiment for adsorption of f-butanol from a 2g L solution in n-heptane at 298 K onto ordered mesoporous sdica of the SBA-15 type tmd three mesoporous silica-based materitds doped with various heteroatoms [92]...

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