Monotungsten carbide and titania nanocomposite with core-shell（WC@TiO2）structure was prepared by a new approach of spray drying and reduction-carbonization reaction,with titania nanopowder and ammonium metatungstate as precursors,methane as carbon source,and hydrogen as reduction gas.The sample was characterized by X-ray diffraction,scanning electron microscope,high resolution transmission electron microscope and X-ray energy dispersion spectroscopy.The results show that its crystal phase is composed of brookite,tungsten and monotungsten carbide.The morphology of the sample particle is irregular sphere-like,with a diameter smaller than 100 nm.Its chemical components are titanium,tungsten,carbon and oxygen.Monotungsten carbide nanoparticles lie on the surface of titania core and form an incomplete shell around titania core in the nanocomposite.The measurement with a microelectrode system of three electrodes shows that the sample is electrocatalytic active to nitrophenol in basic solution at room temperature.Its peak potential is at0.988 V（vs saturated calomel electrode （SCE））,which is more negative than the peak potential,0.817 V（vs SCE）,of mesoporous monotungsten carbide, and its peak current is 8.809μA,which is higher than the peak current,4.058μA,of mesoporous monotungsten carbide.The hydrogen generation potential of the sample is at1.199 V（vs SCE）,which is more negative than that of pure nanosized monotungsten carbide at1.100 V（vs SCE）.These results show that the presence of titania in the sample can lower the peak potential of nitrophenol electrocatalysis and its hydrogen generation potential,and increase its peak current of nitrophenol electrocatalysis in basic solution at room temperature.This indicates a synergistic effect of titania and monotungsten carbide in electrocatalysis.
Titanium dioxide (TiO2) nanoparticles of rutile phase were synthesized by hydrolysis of TiCl4 at 95 ℃ in aqueous solution. The samples as prepared and calcined at 500 ℃ were characterized by XRD, TG-DTA and TEM. The sample as prepared was of imperfect rutile structure, and its morphology was rod-like with a diameter of 10～20 nm, a length of 20～80 nm and an aspect ratio of 2～4. The structure of the sample calcined at 500 ℃ was a perfect rutile one, and its morphology was rod-like with a diameter of 15～25 nm, a length of 25～105 nm and an aspect ratio of 2～4. These results indicate that calcination temperature has a positive effect on the structure and the size of rutile nanocrystals, and has no effect on the aspect ratio of rutile nanocrystal. A model for the formation mechnism of rutile nanocrystal in aqueous solution under hydrolysis conditions has been proposed.
Nano-crystalline tungsten carbide thin films were deposited on Ni substrates by magnetron sputtering using WC as target material. The crystal structure and morphology of the thin films were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM） Electrochemical investigations showed that the electrode of the thin film exhibited higher electrocatalytic activity in the reaction of p-nitrophenol （PNP） reduction. FT-IR analysis indicated that p-aminophenol （PAP） was synthesized after two step reduction of PNP on nano-crystalline tungsten carbide thin film electrode.
High density tungsten carbide nanorod arrays have been prepared by magnetron sputtering （MS） using the aluminum lattice membrane （ALM） as template. Electrocatalytic properties of nitromethane electroreduction on the tungsten carbide nanorod arrays electrode were investigated by electrochemical method, and their electrocatalytic activity is approached to that of the Pt foil electrode.
