Doping methods, networks

The most productive group in the networks field is the group of Tomoji Kawai from Osaka that pubhshed an extended series of experiments on different networks and with various doping methods [69, 70, and references therein]. In one of their early experiments they measured the conductivity of a single bundle [67]. This was done in a similar way to the de Pablo experiment [58] (see Fig. 7), placing the bundle between a metal-covered AFM tip on one side of the molecule and under a metal electrode that covered the rest of the bundle (see Fig. 9). The conductivity of a poly(dG)-poly(dC) bundle was measured as a function of length (50-250 nm) and was compared with that of a poly(dA)-poly(dT) bundle. The results showed a very clear... 

The standard method of adjusting the conductivity of a semiconductor and choosing the nature (electrons or holes) of the dominant, majority, carriers is by controlled doping. Dopants are incorporated into the solid s covalent bond network. This allows the construction of p-n junctions in which the concentration profiles of the dopants, and therefore the spatial dependence of the energy-level positions, remain stable despite the existence of high internal electric fields, p-n junctions have been the basic element of many electronic components [230]. 

Improvement in the photocatalytic activity of these materials has been achieved in recent years by different methods including sensitization of the catalyst using dye molecules and doping the catalyst with norrmetals such as nitrogen, carbon, fluoride and iodide, and transition metals (Au, Pt, Ag, and Pd). Hahnemann and Ismail [110] have recently reviewed the recent developments in the syntheses of mesoporous TiOj as active photocatalysts by the surfactant assembly as well as the preparation and characterization of doped mesoporous Ti02 networks with transition metals ions, noble metals, and nonmetal species. Mesoporous titania nanoparticles will play an important role in the environmental protection and the search for renewable and clean technologies. 

---