In the hydrothermal synthesis of TiO2, [Ti(OH)h(H2O)6−h]4−h (h is the hydrolysis ratio) monomers are generated by the dissolution of the precursor containing titanium ions and then, the monomers form TiO2 polymorphs via a condensation reaction.

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In this paper, the Langmuir-Hinshelwood (L-H) model has been used to investigate the kinetics of photodegradation of gaseous benzene by nitrogen-doped TiO 2 (N-TiO 2 ) at 25 • C under visible light irradiation. Experimental results show that the photoreaction coefficient k pm increased from 3.992 × 10 −6 mol·kg −1 ·s −1 to 11.55 × 10 −6 mol·kg −1 ·s −1 along with increasing illumination intensity. However, the adsorption equilibrium constant K L decreased from 1139 to 597 m 3 ·mol −1 when the illumination intensity increased from 36.7 × 10 4 lx to 75.1 × 10 4 lx, whereas it was 2761 m 3 ·mol −1 in the absence of light. This is contrary to the fact that K L should be a constant if the temperature was fixed. This phenomenon can be attributed to the breaking of the adsorption-desorption equilibrium by photocatalytically decomposition. To compensate for the disequilibrium of the adsorption-desorption process, photoreaction coefficient k pm was introduced to the expression of K L and the compensation form was denoted as K m . K L is an indicator of the adsorption capacity of TiO 2 while K m is only an indicator of the coverage ratio of TiO 2 surface. The modified L-H model has been experimentally verified so it is expected to be used to predict the kinetics of the photocatalytic degradation of gaseous benzene.

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The electronic structures and transport properties of prototype carbon nanotube (CNT) (10,10) and boron-nitride nanotube (BNNT) (10,10) nanocables, including (VBz) n @CNT and (VBz) n @BNNT (where Bz = C 6 H 6 ), are investigated using the density functional theory (DFT) and the non-equilibrium Green's function (NEGF) methods. It is found that (VBz) n @CNT shows a metallic character while (VBz) n @BNNT exhibits a half-metallic feature. Both (VBz) n @CNT and (VBz) n @BNNT nanocables show spin-polarized transport properties, namely, spin-down state gives rise to a higher conductivity than the spin-up state. For (VBz) n @CNT, the CNT sheath contributes the metallic transport channel in both spin-up and spin-down states, while the (VBz) n core is an effective transport path only in the spin-down state. For (VBz) n @BNNT, the BNNT sheath is an insulator in both spin-up and spin-down states. Hence, the transport properties of the (VBz) n @BNNT nanocable are attributed to the spin-down state of the (VBz) n core. The computed spin filter efficiency of (VBz) n @CNT is less than 50% within the bias of À1.0 to 1.0 V. In contrast, the spin filter efficiency of (VBz) n @BNNT can be greater than 90%, suggesting that the (VBz) n @BNNT nanocable is a very good candidate for a spin filter. Moreover, encapsulating (VBz) n nanowires into either CNTs or BNNTs can introduce magnetism and the computed Curie or Neél temperatures of both (VBz) n @CNT and (VBz) n @BNNT are higher than 2000 K. These novel electronic and transport properties of (VBz) n @CNT and (VBz) n @BNNT nanocables render them as potential nanoparts for nanoelectronic applications.

Electronic and transport properties of novel ferrocene based carbon nanotube (CNT) and boron-nitride nanotube (BNNT) nanopeapods, including Fe(Cp) 2 @CNT, Fe 2 (Cp) 3 @CNT, Fe(Cp) 2 @BNNT, and Fe 2 (Cp) 3 @BNNT (where Cp refers as cyclopentadiene), are investigated using the density functional theory and non-equilibrium Green's function methods. Computed electronic structures of the Fe(Cp) 2 @CNT and Fe 2 (Cp) 3 @CNT nanopeapods suggest that their electric conductivity is primarily contributed by the CNT p channel while the electron hopping from the core Fe(Cp) 2 or Fe 2 (Cp) 3 to the sheath CNT may have some contribution to the transport properties. Encapsulating Fe(Cp) 2 into BNNT is more favorable for the electron conduction, owing to the splitting of the BNNT bandgap by the Fe(Cp) 2 state. In contrast, introducing Fe 2 (Cp) 3 into the BNNT is not beneficial to the conduction due to intramolecular electron transfer within the core Fe 2 (Cp) 3 which can cause a trap effect. Because the transport channels can be changed by the applied bias voltage, the transport properties cannot be solely predicted from the electronic structures of infinite systems alone. For computing transport properties, we use two-probe device model systems with a finite-sized nanopeapod sandwiched between two CNT electrodes. Again, we find that encapsulating either Fe(Cp) 2 or Fe 2 (Cp) 3 into CNTs has little effect on the conductivity owing to the strong metallic character of the CNT sheath. Encapsulating Fe(Cp) 2 into BNNTs can notably enhance electron conducting due to electron hopping from the core Fe(Cp) 2 to the sheath BNNT. Encapsulating Fe 2 (Cp) 3 into BNNTs, however, has little effect on the electron conductivity of BNNT nanopeapods due to the trap effect of the longer guest molecules. Hence, the length of guest molecules can effectively tune electronic and transport properties of the BNNT nanopeapods.

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