Environment pollution has caught great concern from many countries in the world, it has led to the drinking water source of people's lives and industrial water quality continue to decline, which leads to air pollution grow and results in the continuous destruction of the ecological environment,and poses a serious threat for human survival. In order to solve these problems, a variety of methods to control environmental pollution are carried out.

 

From the late 1970s, it is proposed the use of photocatalyst to decompose pesticides and malodorous substances and other organic matters in water and the atmosphere, as well as application examples like photocatalyst coated solid surfaces self-cleaning and so on. Currently, the photocatalyst is primarily titanium dioxide, which has been used to decompose pesticides and malodorous substances and other organic matter in water and the atmosphere, however the bandgap of titanium dioxide is 3.2eV, can only show activity in the ratio of 400nm shorter ultraviolet light and can only work indoors or where there is an ultraviolet lamp, hardly with visible light, which greatly limits the use of titanium dioxide photocatalyst.

 

Taking into account the practicality of the photocatalyst in the decomposition of harmful substances, sunlight as the light source is indispensable. Wavelength irradiated to the surface of the sun at about 500nm has the maximum intensity of visible light, energy of wavelength at 400nm-750nm in the visible region is about 43% of the total energy of sunlight, so in order to efficiently utilize the solar spectrum, finding the catalyst with light visible effect has aroused people's attention. Kinds of photocatalysts with visible effect reported are still limited currently, so it is necessary to research and develop new photocatalyst with highly efficient visible light effect. Tungsten bronze compounds are a series of important inorganic compounds, tungsten ions exist as mixed valence state of W^{6 +}, W^{5 +} and W^{4 +} in such compounds to make a balance in the overall charge. Rich crystal structure, the tunnel structure and this particular valence state lead to its excellent properties.

 

A kind of oxide containing lithium tungsten bronze structure as visible effect photocatalyst, the chemical formula of lithium tungsten bronze structure oxide is = Ba₅LiFe_0.5 (Nb_xTa_h) λ A. （0 <x <1） preparation steps of lithium tungsten bronze structure oxide are as follows: mix the 99.9% analytically pure chemicals of BaCO₃, Li₂CO₃, Fe₂O₃, Nb₂O₅ and Ta₂O₅ as formula Ba₅LiFe_0.5Nb_4.75Ta_{4. 75} O₃₀, put into the mill pot, add zirconia balls and ethanol, milling for 2-8 hours, mix grinding, remove and dry through 200-mesh sieve; the resulting powder material calcine at 1175-1275 ℃, and incubate for 6-8 hours, cool to room temperature, and then pulverized by ball mill so that the particle size gets smaller to 2 μm, then the lithium tungsten bronze structure oxide powder Ba₅LiFe_0.5Ta_9.5O₃₀ is obtained, 0 <x <10. This method is simple, with low cost, photocatalys obtained has excellent catalytic performance, with effects of decomposing harmful chemical substances, organic biomass and bactericidal under visible light irradiation.