Hydrous nickel oxides materials

Figure 32 Schematic electron density-of-states diagrams for electrochromic, EC, multilayer design. The materials include ln203 Sn (ITO), nickel oxide (presiunably hydrous), tungsten oxide (also presumably hydrous) prepared so that the EC and chemically protective (PR) properties are emphasized, and an electrol)de. The Fermi energy is denoted Ep, with Epi and Ep2 pertaining to the case of an applied potential, Ucoi fiUed states are denoted by shadings. (Ref 235. Reproduced by permission of Springer Verlag)...

In view of their major application in aqueous battery systems more work has been carried out on the structural aspects of the oxides of these two metals than any of the systems discussed earlier. Details of the structure and reactivity of the nickel oxide battery materials can be found in recent reviews by Briggs209 and Oliva et al.2 Both hydrous and anhydrous phases exist for both the Ni(II) hydroxide and Ni(III) oxyhydroxide systems. Most interesting are the comments of Le Bihan and Figlarz,210 and McEwen,211 with regard to turbostatic structures the latter are found in materials where the ordering of the oxide is quite limited, i.e., the systems consist of highly ordered nuclei linked in a disordered manner—the latter feature should certainly enhance mass transfer processes and may well be involved in many other hydrous oxide systems. 

Surface area, pore size, and pore volume are among the most fundamentally important properties in catalysis because the active sites are present or dispersed throughout the internal surface through which reactants and products are transported. The pores are usually formed by drying or calcining precipitates of hydrous oxides however, some materials possess porosity naturally, as in the case of carbons, natural zeolites, and others. Raney nickel catalysts... 

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