Tantalum pentoxide, also known as “tantalum anhydride”, is a white rhombic crystal. Its chemical properties are more stable, resistant to general acid and alkali, when heated by hydrogen chloride or hydrogen bromide erosion. The corresponding insoluble tantalate can be obtained by co-melting with the hydroxide of alkali metal or carbonate, which is hydrolyzed by washing with water to produce hydrated tantalum pentoxide precipitate. At present, the traditional high purity tantalum pentaoxide is prepared by the tantalum liquid in the liquid-liquid extraction process of tantalum and niobium separation. First, the tantalum liquid is driven into the neutralization precipitation tank, and NH3 gas is passed through under agitation to make the solution PH = 8-9 to generate Ta(OH)5 precipitation, and then it is filtered through the filter press or vacuum. Then, the tantalum hydroxide is put back into the decomposition tank, adding hydrofluoric acid and sulfuric acid to dissolve, and the high purity tantalum liquid is obtained by secondary extraction with organic matter. The high purity tantalum liquid is neutralized with purified ammonia to obtain high purity tantalum hydroxide. High purity tantalum hydroxide is calcined, cooled and sieved in muffle furnace to obtain high purity tantalum pentaoxide products.
1) preparation of tantalum pentoxide/graphene composite photocatalyst nanoparticles, using graphite oxide as matrix, using commercial tantalum pentoxide is configured with catalyst precursor, described by hydrogen peroxide and other reagents on the regulation of tantalum pentoxide precursor solution, the auxiliary of the ultrasonic method, realized the tantalum pentoxide nanoparticles in the growth of the graphene surface, Tantalum pentoxide nanoparticles/graphene composite photocatalyst was obtained. The prepared tantalum pentoxide nanoparticles/graphene composite photocatalyst has a broad application prospect in the photocatalytic decomposition of organic pollutants and the photocatalytic production of hydrogen from water due to the electron receiving effect of graphene and the ultraviolet photocatalytic property of tantalum pentoxide nanoparticles.
2) Perovskite solar cells using tantalum pentoxide as electron transport layer: tantalum pentoxide was dissolved in alcohol to prepare precursor solution with concentration of 0.01mol/L to 0.06mol/L; The precursor solution was coated on the transparent conductive substrate, and then annealed at 500-600℃ to form a layer of 5nm-60nm thin tantalum pentoxide film on the surface of the conductive substrate. The perovskite precursor solution was coated on the surface of tantalum pentoxide thin film, and then annealed at 100-110℃ to form a perovskite absorbent layer with thickness of 400nm-500nm on the surface of tantalum pentoxide thin film. A perovskite solar cell was prepared by modifying a hole transport layer and a metal electrode on the surface of the perovskite absorption layer. The method has the advantages of simple process and low cost, and adopts tantalum pentoxide thin film as the electron transport layer, which can accelerate the electron migration ability and improve the utilization rate of light.
3) Prepare high density tantalum pentoxide film material and put the tantalum pentoxide powder into vacuum graphite furnace for hot pressing; It includes the following steps :(1) vacuum to 1×103 ~ 5×103Pa by mechanical pump, and then open the diffusion pump to vacuum to 1×10-3 ~ 5× 10-3pa; Then it was filled with argon gas for protection and heated to 1300 ~ 1600℃. (2) Keep the temperature at 1300 ~ 1600℃, and pressure to 18 ~
25MPa, the holding time is 25-35min, during the holding period, the inert gas argon is used to protect the sintering environment pressure between 1×103 ~ 1×104Pa; (3) High density tantalum pentoxide membrane material can be obtained by cooling to room temperature at a cooling rate of 3-7 ℃/min. The invention realizes further densification of materials by means of high temperature pressure, simplifies the traditional tantalum pentoxide production process, and can prepare coating materials with higher density and purity by means of high temperature pressure.
4) Preparation of a spindle tantalum pentoxide photocatalyst, including: dispersed tantalum powder in ultra-pure water placed in the first lining, hydrofluoric acid and hydrogen peroxide solution evenly mixed in the second lining, hydrothermal reaction; After the reaction is over, the suspension in the first lining is centrifuged, cleaned and dried. The prepared spindle tantalum pentoxide has the advantages of simple preparation method, good repeatability, high crystallinity, controllable morphology and high photocatalytic efficiency, and has broad application prospects in photowater hydrogen production and water treatment.