Visible light-responded photocatalyst
Li
2
Bi
3
Nb
7
O
23
And preparation method thereof
Technical field
The present invention relates to a kind of visible light-responded photocatalyst Li2Bi3Nb7O23And preparation method thereof, belong to inorganic field of photocatalytic material.
Background technology
Along with socioeconomic development, people increasingly pay close attention to for the energy and ecological environment, solve energy shortage and problem of environmental pollution be realize sustainable development, improve people's living standard and safeguard national security in the urgent need to.
From phase late 1970s, there has been proposed and utilize in photocatalyst decomposition water and the Organic substance such as pesticide in air and odorant, and scribble the application example such as self-cleaning of the surface of solids of photocatalyst.The principle of light-catalyzed reaction be photocatalyst after absorbing higher than the photon of its band-gap energy, generate hole and electronics, these holes and electronics carry out oxidation reaction and reduction reaction respectively, reach to decompose harmful chemical, organic-biological matter and the purpose of sterilization.Photocatalyst has many kinds, and the most most representative is titanium dioxide (TiO2), utilize titanium dioxide that the Organic substances such as the pesticide in water and in air and odorant are decomposed, but the band gap of titanium dioxide is 3.2eV, under the ultraviolet irradiation shorter than 400nm, only just can show activity, can only be at indoor or the local work having uviol lamp, being little to utilize visible ray, this greatly limits the use of titanium dioxide optical catalyst.
In view of photocatalyst practicality in decomposing harmful substances, it is indispensable for utilizing sunlight as light source.Irradiate the sunlight medium wavelength maximum intensity of visible ray near 500nm to earth's surface, wavelength is that the energy of the visible region of 400nm ~ 750nm is about the 43% of sunlight gross energy, so in order to utilize efficiently, the R and D of bismuth series photocatalyst have been achieved for a series of great achievement, bismuthous complex such as BiVO4、Bi2MoO6、Bi2Mo2O9、Bi2Mo3O12And Bi2WO4It is in the news and there is good absorption under visible light.A series of niobiums (tantalum) hydrochlorate photocatalyst is widely studied owing to having higher photocatalytic activity.Such as, niobate photocatalyst Pb3Nb4O13、BiNbO4And Bi2MNbO7(M=Al, Ga, In, Y, rare earth element and Fe) etc. and niobium potassium compound oxide photocatalyst such as KNbO3、KNb3O8、K4Nb6O17And K6Nb10.6O30Deng all having preferable photocatalysis performance, but in visible-range, its intrinsic photocatalytic effect is the most weak or does not has activity.
Although photocatalysis research has been carried out the several years, but at present report to have visible light-responded photocatalyst kind the most limited, there are still that light conversion efficiency is low, poor stability and the problem such as spectral response range is narrow, so it is the most necessary for researching and developing the new visible light-responded high efficiency photocatalyst that has.We are to consisting of Li2Bi3Nb7O23、Li2Bi3V7O23、Li2Bi3Ta7O23Compound carried out Photocatalytic Performance Study, found that Li2Bi3Nb7O23Band gap be 2.68eV, have excellence visible light-responded photocatalysis performance, the band gap width of other sample is both greater than 3.1eV, just can only can show activity under ultraviolet irradiation.
Summary of the invention
It is an object of the invention to provide and a kind of there is visible light-responded photocatalyst Li2Bi3Nb7O23And preparation method thereof.
The chemical constitution formula with visible light-responded photocatalyst that the present invention relates to is: Li2Bi3Nb7O23。
The preparation method of above-mentioned visible light-responded photocatalyst concretely comprises the following steps:
(1) by 99.9% analytically pure chemical raw material Li2O、Bi2O3And Nb2O5Starting powder press Li2Bi3Nb7O23Composition weigh dispensing.
(2) raw material mixing step (1) prepared, puts in ball grinder, adds zirconia ball and distilled water, ball milling 8 hours, be mixed and finely ground, take out and dry, cross 200 mesh sieves.
(3) by the powder of step (2) mix homogeneously 850 ~ 900 DEG C of pre-burnings, and it is incubated 6 hours, naturally cools to room temperature, then pulverized by ball mill and make average diameter of particles diminish, less than 2 μm, i.e. obtain Li2Bi3Nb7O23Powder.
The spectral response range width of the photocatalyst that the present invention obtains, light conversion efficiency height and good stability, there is decomposition harmful chemical, organic-biological matter and the effect of sterilization under visible light illumination;Additionally preparation method is simple, synthesis temperature is low, low cost, is suitable for commercial production and application.
Detailed description of the invention
Present invention will be described in detail below:
1, in order to obtain the composite oxides used in the present invention, prepare powder first by solid-phase synthesis, i.e. various oxides or the carbonate as raw material is mixed according to target constitutional chemistry metering ratio, then synthesize in air atmosphere at ambient pressure.
2 in order to effectively utilize light, the size of the photocatalyst in the present invention preferably in micron level, even nanoparticle, and specific surface area is bigger.The oxide powder prepared with solid-phase synthesis, its particle is relatively big and surface area is less, but can be by ball mill pulverizing means and make particle diameter diminish.
3, the photocatalysis experiment of the present invention is using methyl orange as simulation organic pollution, and its concentration is 20mg/L;Photocatalyst Li2Bi3Nb7O23Addition be 1g/L;Light source uses the xenon lamp of 300W, and reactive tank uses the vessel that pyrex is made, and obtains the wavelength light more than 420nm by wave filter, then irradiates photocatalyst;Catalysis time is set as 60 minutes.
Embodiment 1:
(1) by 99.9% analytically pure chemical raw material Li2O、Bi2O3And Nb2O5Starting powder press Li2Bi3Nb7O23Composition weigh dispensing.
(2) raw material mixing step (1) prepared, puts in ball grinder, adds zirconia ball and distilled water, ball milling 8 hours, be mixed and finely ground, take out and dry, cross 200 mesh sieves.
(3) by the powder of step (2) mix homogeneously 850 DEG C of pre-burnings, and it is incubated 6 hours, naturally cools to room temperature, then pulverized by ball mill and make average diameter of particles diminish, less than 2 μm, i.e. obtain Li2Bi3Nb7O23Powder.
Prepared photocatalyst, under the wavelength radiation of visible light more than 420nm, reaches 97.3% to methyl orange clearance in 60 minutes.
Embodiment 2:
(1) by 99.9% analytically pure chemical raw material Li2O、Bi2O3And Nb2O5Starting powder press Li2Bi3Nb7O23Composition weigh dispensing.
(2) raw material mixing step (1) prepared, puts in ball grinder, adds zirconia ball and distilled water, ball milling 8 hours, be mixed and finely ground, take out and dry, cross 200 mesh sieves.
(3) by the powder of step (2) mix homogeneously 880 DEG C of pre-burnings, and it is incubated 6 hours, naturally cools to room temperature, then pulverized by ball mill and make average diameter of particles diminish, less than 2 μm, i.e. obtain Li2Bi3Nb7O23Powder.
Prepared photocatalyst, under the wavelength radiation of visible light more than 420nm, reaches 98.4% to methyl orange clearance in 60 minutes.
Embodiment 3:
(1) by 99.9% analytically pure chemical raw material Li2O、Bi2O3And Nb2O5Starting powder press Li2Bi3Nb7O23Composition weigh dispensing.
(2) raw material mixing step (1) prepared, puts in ball grinder, adds zirconia ball and distilled water, ball milling 8 hours, be mixed and finely ground, take out and dry, cross 200 mesh sieves.
(3) by the powder of step (2) mix homogeneously 900 DEG C of pre-burnings, and it is incubated 6 hours, naturally cools to room temperature, then pulverized by ball mill and make average diameter of particles diminish, less than 2 μm, i.e. obtain Li2Bi3Nb7O23Powder.
Prepared photocatalyst, under the wavelength radiation of visible light more than 420nm, 60min reaches 97.9% to methyl orange clearance.
The present invention is never limited to above example.The bound of each temperature, interval value can realize the present invention, embodiment numerous to list herein.
The made photocatalyst powder of above inventive embodiments can be carried on multiple matrix surface.Matrix can be glass, pottery, activated carbon or quartz sand etc., and photocatalyst can be carried on matrix surface in the form of a film.