Preparation Of Tungsten Carbide And Titania Nanocompasite And Its Electrocatalytic Activity

Tungsten carbide (WC) has platinum-like behavior, but its catalytic activity is much lower than the catalytic capability of Pt. Researchers pay more attention to it for the catalytic activity can be significantly improved when tungsten carbide and titania nanocomposite was fabricated, coupled with its low price and excellent resistance to catalyst poisoning capability, etc. A tungsten carbide and titania nanocomposite was fabricated by ball mill and immersion approaches with reduction-carbonization technology. X-ray diffraction (XRD)、scanning electron microscopy (SEM) and transmission electron microscope (TEM) methods were used to characterize the morphology of the samples, the electrocatalytic activity of samples were measured by the powder microelectrode in this paper. The main results were as follows:In the p-nitrophenol’s electroreduction process, the samples prepared by ball mill approach had catalytic activity for p-nitrophenol in acidic、 neutral and basic solutions, its catalytic activity had a significant improvement when compared to the pure TiO2 and WC. The experiment results have shown that the catalytic activity of samples are related to its crstaly phase combination, and the best catalytic activity sample was WC(1-x/TiO2+Ti6O11. The catalytic activity was also affected by the solutions, the results showed that the samples with the best catalytic activity was obtained in acidic solutions and the worst catalytic activity in basic solutions because of the p-nitrophenol’s hydrogenation reaction. The high concentration of hydrogen ions in the acidic solutions improved the electroreaction of p-nitrophenol.In the methanol’s electrooxidation process, the samples prepared by ball mill and immersion approaches had catalytic activity for methanol in acidic neutral and basic solutions, its catalytic activity had a significant improvement when compared to the pure TiO2 and WC. The catalytic activity of samples was affected by three aspects:(1) crystal phase combination, the best catalytic activity sample was W2C+WC/Ti02; (2) solution, the best catalytic activity sample was obtained in basic solutions and the worst catalytic activity in acidic solutions. The high concentration of hydroxyl ions in bisic solution can be easily reacted into hydroxyl radicals with TiO2, which was good for the electrooxidation of methanol; (3) W and Ti mole ratio, the best catalytic activity sample was obtained when the mole ratio was W:Ti (1:3). The experiment results showed that the samples prepared by ball mill approach had a better catalytic activity when the reduction-carbonization time was shorter than 5 h, the samples prepared by immersion approach had a better catalytic activity when the reduction-carbonization time was longer than 5 h.Experiment results showed that the samples prepared by this two methods had better catalytic activity compared to the pure TiO2 and WC, which proved that a synergistic effect was exist between the TiO2 and WC. Ctalytic activity of samples that prepared under different methods was largely affected by the reduction-carbonization time. Optimization parameters obtained by examining the impact of various factors on performance are:over 5 h reduction-carbonization time when the samples prepared by ball mill approach; less than 5 h reduction-carbonization time and tungsten titanium mole ratio control in below 1:3 when the samples prepared by immersion approach.