Preparation And Performance Study Of Black Titania Based Material

Environmental pollution is more and more serious with the development of society and energy consumption. Semiconductor photocatalyst is an efficient measure to solve this problem. As one kind of multifunctional semiconductor material, titania has non-toxic, cheap, corrosion resistant, effective use of ultraviolet to photocatalytic and other excellent properties. However, due to its large band gap（3.2e V for anatase） and fast electron-hole recombination rate, its photocatalytic performance is limited largely.The emergence of black titania greatly solve the two disadvantages of traditional titania, which make Ti O2 show well photocatalytic performance under visible light irradiation. In spite of these, due sole Ti O2 can be hardly meet the needs of practical application, developing black titania based composite materials has very important theory and application significance. Most methods of the preparation of black titanium dioxide is to reduce traditional titania by hydrogen gas. This article shows a simple preparation method of black titanium dioxide without hydrogenate and the success of preparation of the black titania based composite material. The specific content is as follows:1. Black titania was prepared using Tetrabutyl titanate as titanium source. Test results show that the black titanium dioxide has a strong visible-light absorption capability and low electron-hole recombination rate, and shows excellent photocatalytic performance under visible light irradiation. In addition, gas tightness during annealing has effect on the location of oxygen vacancies and photocatalytic activity.2. The colloid in the process of preparation of black titanium dioxide is used as titanium dioxide precursors. Graphene oxide/core-shell structured titania is obtained by calcining the mixture of graphene oxide and the colloid. Compared with sole black titanium dioxide, visible-light photocatalytic properties of the compound are improved greatly. In addition, the Graphene oxide/titania composites can be obtained when annealed in N2, but graphene oxide as carbon source is doped into titania when annealed in air.3. It is attempt to further improve the ability of light degradation by adding compound category. The carbon/silicon/ core-shell structured titanium dioxide compound is prepared sucessfully through calcine the mixture of carbon, silicon, black titanium dioxide precursor. Due to the overlap between Si and Ti O2, the core–shell structured titania can not be identified by HRTEM, whereas the results of EPR and XPS do indicate its formation. The presence of C and Si promote the transference of electrons and separation of e-/h+. The large number of oxygen vacancies in Ti O2 play a vital role in suppressing recombination of electrons derived from self excitation and transference. The synergistic effect of the Ti3+ and carbon and silicon is responsible for the excellent visible light photocatalytic activity.4. Carbon reduce bismuth oxide to prepare Bi₂O₃@Bi. It is attempt to use the plasma resonance phenomenon of bismuth to inhibit electron-hole recombination of titanium dioxide and bismuth oxide compound. Through appropriate carbon and bismuth oxide mixed with black titanium dioxide precursor and then calcine, the C/Bi₂O₃@Bi/Ti O2@Ti O2-x compounds was prepared successfully. Test results show that this compound has good visible-light photodegradation ability. Due to C oxidized easily in air, Bi₂O₃ is reduced to Bi₂O₃-x rather than Bi. In addition, based on the results of XRD, Raman spectroscopy and XPS of CBT（air）, C is doped into compounds and the Bi₂O₃-x is wrapped by Ti O2.5. The core-shelled titania is prepared by changing precursor before calcined, and the formation mechanism has been studied. Based on comparison among samples, it is found that the ration between urea and hydrochloric acid decides the extent of hydrolysis and the shell thickness of titania.