FeVO₄ New Photocatalyst Preparation And Its Performance Study

Photocatalyst can use clean energy to solve environmental pollution.So photocatalyst becomes one of the hot spots.FeVO4 as new photocatalyst causes the concern of scholars due to its narrow bandgap width,magnetic property,recoverable utilization,low price of raw materials and other advantages.In this paper,three-inclined FeVO4 photocatalysts were prepared by soft template method.The influence of the type of templates and the reaction conditions on FeVO4 photocatalyst were studied.The samples were characterized by X-ray diffractometer,thermal field emission scanning electron microscopy,UV-visible diffuse reflectance spectroscopy and fluorescence spectroscopy.The photocatalytic activity of FeVO4 was evaluated by the degradation of methylene blue(MB)under visible light.The results are as follows:1.The effect of the type of templates on the performance of FeVO4 photocatalyst was discussed.Chelating agent EDTA,anionic surfactant SDBS and SDS,cationic surfactant CTAB and polymer organic polymer PEG and PVP were selected as templates.The experimental results showed that the FeVO4 photocatalyst prepared by SDBS is the best.Because SDBS can change the morphology of FeVO4.And the FeVO4 crystal is changed from a smooth rod-like structure to a rod-like structure with many small holes.Furthermore,in the calcination process,SDBS can capture the oxygen of catalyst,due to a long organic chain.Thus oxygen empty points were formed.Oxygen empty points effectively restrained the recombination of electron-hole pairs.It improved the photocatalytic activity.The sample was prepared by using SDBS as template.Its photodegradation rate of MB was 2.9 times higher than that of other templates.2.The effect of process conditions on the FeVO4 photocatalyst was studied by the single factor experiments.The effects of hydrothermal time,hydrothermal temperature,hydrothermal pH,addition of templating agent,calcination time and calcination temperature were investigated through single factor experiments.The results of single factor experiments showed that hydrothermal time,hydrothermal temperature,calcination time and calcination temperature influence the crystal form,crystallinity and purity of FeVO4 crystal.The morphology of FeVO4 can be controlled by changing the amount of SDBS.And the best performance photocatalysis of FeVO4 was prepared at the hydrothermal time 48 h,n(NH4VO3):n(SDBS)= 1:0.50,the pH value of the precursor fluid between 3 and 4.The optimal amount of fevo4 in photocatalytic experiment was 0.03 g.The degradation of MB solution with FeVO4 can reach 81.25%.3.In order to further improve the photocatalytic performance of FeVO4,orthogonal experiment was designed.According to the single factor experiment results,four important factors were selected.And then four appropriate levels were selected for each factor to make the orthogonal experiments.The effect of hydrothermal temperature is the largest.The time of hydrothermal time is the second.And then the effect of calcination time is greater than that of SDBS.The optimum preparation conditions were as following:n(NH4VO3):n(SDBS)= 1:0.65,the pH value of the precursor between 3 and 4,the water heated at 180 ? for 40 h,and calcined at 500 ?for 4.5 h.The degradation of MB solution with FeVO4 can reach 91.38%.4.Characterization and photocatalytic principle analysis of samples.The samples were tested by XRD and the results showed that the samples were three oblique FeVO4 crystals which have photocatalytic activity.The SEM analysis showed that the crystals were rod like and had many annular pores.More MB molecules can be adsorbed.The characterization of UV-vsi showed that the absorption valve is about 495 nm,which shows that the sample has a strong ability to absorb visible light,and the band gap is about 2.16 eV,which means that the energy needed to excite the photoelectron transition is small.So the photogenerated electron-hole pairs are easy to generate and the photocatalytic reaction is easy to occur.The PL test showed that the maximum emission wavelength was 536.5 nm and the overall fluorescence effect of the samples in the range of 490?620 nm was weak,which shows that the recombination rate of photogenerated electron-hole pairs is slow and the photocatalytic effect is strong.The photocatalytic degradation rate of MB solution increased from the lowest 7.69%to the highest 91.38%.