A simple and versatile approach has been developed to synthesize multi-walled carbon nanotubes/metal-doped ZnO nanohybrid materials (MWNT/M-doped ZnO) by means of the co-deposition method. The experimental results illuminate that MWNTs can be modified by metal-doped ZnO nanoparticles at 450 °C, such as Mn, Mg, and Co elements. Furthermore, the MWNT/Mg-doped ZnO hybrids have been proven to have a high photocatalytic ability for methyl orange (MO), in which the degraded rate for MO reaches 100 % in 60 min. The enhancement in photocatalytic activity is attributed to the excellent electriconal property of MWNTs and Mg-doping. The resultant MWNT/Mg-doped ZnO nanohybrids have potential applications in photocatalysis and environmental protection.

The local curvature of the space produced by the Sun causes not only the perihelion precession of Mercury's elliptical orbit, but also the variations of the whole orbit, in comparison with those predicted by the Newtonian theory of gravitation. Calculations show that the gravitational majoraxis contraction of the Mercury's elliptical orbit is 1.3 kilometers which can be confirmed by the present astronomical distance measurement technology. * Electronic address: quanhuiliu@gmail.com

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Multi-walled carbon nanotubes (MWNTs)/Cu-doped ZnO composite powders were prepared by co-precipitation method, and were characterized by X-ray diffraction, electron microscopy, fluorescence spectrum, and ultraviolet spectrum. Experimental results show that the MWNTs can be modified by Cu-doped ZnO nanoparticles with hexagonal wurtzite structure after annealed at 450 °C, and the nanoparticle size is about 15 nm. Two ultraviolet (UV) peaks and a green band centered at about 510 nm are observed in the fluorescence spectrum of MWNTs/Cu-doped ZnO composite powder annealed at 450 °C. Furthermore, MWNTs and Cu doping significantly improve the UV absorption ability of ZnO.

A simple and versatile approach decorated TiO 2 nanoparticles on the surface of multi-walled carbon nanotube (MWNTs) was reported. MWNTs can be continuously coated by the layer of anatase TiO 2 nanoparticles with the thickness of about 20 nm by the assistance of salicylamide. Moreover, anatase TiO 2 nanoparticles with the size of about 10 nm are uniformly deposited on MWNTs by using microwave radiation. The synthetic MWNTs/TiO 2 hybrids have been proven to be very high photocatalytic ability for methyl orange (MO) without any additional treatment.TiO 2 is the most commonly used photocatalyst because of its superior photocatalytic oxidation ability, high photocorrosion resistance and non-toxic and inexpensive characteristics. 1 However, it possesses low photocatalytic efficiency due to both the high rate of electronÀhole recombination in TiO 2 particles and small specific surface area. 2 In order to improve its properties, many efforts have been made in the controlled morphologies of TiO 2 , doped TiO 2 with metal ions, and used porous materials as the carrier of TiO 2 nanoparticles. 3À5 Carbon nanotubes (CNTs) are considered to be an ideal and excellent supported material for catalyst nanoparticles due to their unique internal structure, high surface area, extremely high mechanical strength, remarkable chemical stability and outstanding electronic conductivity. CNTs can not only act as photosensitizer for catalysts, but also hinder the recombination of electrons and holes. 6 Up to now, CNTs have widely been used to enhance the photocatalytic activity of TiO 2 nanoparticles and ZnO nanoparticles through the retardation of electronÀhole recombination. 7À13 Although the significant advancement has obtained in CNTs/TiO 2 hybrids at present, 14À16 CNTs often exist in the form of highly tangled ropes, and show poor solubility. Furthermore, it is very difficult to control the inhomogeneity and the quality of oxide nanoparticles coating on the surface of CNTs, which prevents their application. Research report has shown that it is very important for high photocatalytic acitivity to control fine, well-dispersed coatings on the surface of CNTs. 17 Some efficient approaches and technologies have been reported for controlling TiO 2 nanoparticles on CNTs. For instance, Liu et al. developed a facile liquid phase deposition method to prepare mesocrystals of anatase TiO 2 onto multi-walled carbon nanotubes (MWNTs) with controllable surface coverage, surface area, crystal orientation and TiO 2 /MWNTs ratio. 18 Yu et al. reported that the CNTs array used as templates can control the thickness of TiO 2 layer on the surface of CNTs and improve the photocatalytic activity. 19 In this paper, we developed a simple and efficient approach to control the deposition of TiO 2 nanoparticles on MWNTs. The TiO 2 nanoparticle layer and the fine TiO 2 nanoparticles are decorated on MWNTs, respectively. The preliminary investigation indicates that the prepared MWNTs/ TiO 2 hybrids are sufficiently active for photocatalytic degradation of organ...