CN100406125C

CN100406125C - Method for preparing highly active Fe/Sn ion co-doped nano phtocatalyst of titanium dioxide

Info

Publication number: CN100406125C
Application number: CNB2006100112394A
Authority: CN
Inventors: 徐利华; 邸云萍; 王缓
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2006-01-19
Filing date: 2006-01-19
Publication date: 2008-07-30
Anticipated expiration: 2026-01-19
Also published as: CN1799693A

Abstract

The present invention provides a preparation method for a nanometer TiO2 photocatalyst with the codope of high-activity iron ions and stannum ions, which belongs to the technical field of photocatalyst material. The present invention has processing steps: firstly, TiO2 collosol with the codope of Fe<3+> and Sn<4+> is prepared; a TiO2 film with the codope of Fe<3+> and Sn<4+> is prepared. The present invention has the advantages that the prepared TiO2 film with the codope of Fe<3+> and Sn<4+> has the mixed crystal structure of an anatase phase and a rutile phase, the average size of the TiO2 film is 20 nm, the rutile phase is determined to be a solid solution crystal phase formed by that Fe<3+> and Sn<4+> are dissolved in TiO2 crystal lattices in a solid mode; the film plated on a glass basis is transparent and has a smooth surface; the codope of Fe<3+> and Sn<4+> causes the red shift of the absorption edge of a TiO2 photocatalyst film to incident light to a visible region so as to generate a visual light induced photocatalysis effect; the photocatalytic activity of the TiO2 film is obviously increased; compared with a pure nanometer TiO2 film, the photocatalytic degradation rate to methyl orange is increased by two times.

Description

The preparation method of highly active Fe/Sn ion co-doped nano phtocatalyst of titanium dioxide

Technical field

The invention belongs to the photocatalyst material technical field, a kind of preparation method of highly active Fe/Sn ion co-doped nano phtocatalyst of titanium dioxide particularly is provided, has related in particular to a kind of sol-gel preparation technology with iron/tin coblended nano TiO 2 of visible light effect, highlight catalytic active and mixed crystal effect.

Background technology

Nano titanium dioxide belongs to the inorganic new material in environmental protection field, also is the environmental type photocatalyst material that has the exploitation future most.By photochemical catalytic oxidation reduction effect degraded noxious pollutant, and non-secondary pollution, have functions such as wastewater treatment, air cleaning, kill virus and cancer cell, antibiotic, deodorizing, automatically cleaning.

Restriction TiO ₂The bottleneck of photocatalyst practical application: the one, the restriction of excitation wavelength is because TiO ₂Energy gap be 3.2eV, corresponding excitation wavelength belong to ultraviolet region, and ultraviolet light accounts for less than 5% in big positive energy at 387nm, the photocatalyst material of most economical practicality should be able to utilize visible light part abundant in the sunshine, substitutes expensive artificial ultraviolet source; The 2nd, TiO ₂The quick recombination probability height of semiconductor photoproduction electronics and photohole, and the interfacial migration rate of the photoproduction current-carrying that produces is low, has limited TiO ₂The photocatalytic activity of photocatalyst.The key technology that addresses the above problem is exactly to TiO ₂Photocatalyst carries out modification, and wherein one of the most noticeable method of modifying is exactly the doping of transition metal ions.Mixing of transition metal ions can be at TiO ₂Introduce defective locations in the lattice or change TiO ₂Degree of crystallinity etc. can be served as the captor of light induced electron or photohole, effectively stop electric charge compound in transfer process, improve quantum yield, thereby influence TiO ₂The catalytic activity of photocatalyst; Or at TiO ₂Can introduce new energy level in the band, reduce band gap, induce electron transition, make the photoresponse wavelength spread to visible region.

Suspended phase TiO ₂Particulate is easy to cohesion in the aqueous solution, be difficult to reclaim, and active ingredient loss is big, has also seriously limited the practicability of photocatalysis technology.Thereby nano-TiO ₂Photo-catalyst film again because it has nano effect and high activity, and has theoretical research and actual application value as having reaction and separating bifunctional new material and become the focus of new catalytic material.

Summary of the invention

The support type Fe that the purpose of this invention is to provide a kind of highlight catalytic active and mixed crystal effect ³⁺/ Sn ⁴⁺Ion co-doped nanocrystalline TiO ₂The preparation method of photo-catalyst film utilizes metal cations Fe ³⁺With Sn ⁴⁺Synergistic function obviously improve nanocrystalline TiO ₂The catalytic activity of photocatalyst.

Processing step of the present invention is:

A.Fe ³⁺/ Sn ⁴⁺The TiO of codope ₂The preparation of colloidal sol

With percent by volume is that 15%～20% butyl titanate, 22%～24% absolute ethyl alcohol and 10%～12% acetylacetone,2,4-pentanedione are mixed with homogeneous solution A, according to molar percentage M _Sn: M _Ti=11.41% and M _Fe: M _Ti=0.05%～5.00% calculates weighing stannic chloride pentahydrate and nine water ferric nitrates respectively, with the SnCl of aequum ₄5H ₂O and Fe (NO ₃) ₃9H ₂O is dissolved in the solution B of 43%～49% absolute ethyl alcohol and the preparation of 2%～3% distilled water, and the pH that drips red fuming nitric acid (RFNA) regulator solution B is 3.15～4.20, again solution B slowly is added drop-wise to the reaction that is hydrolyzed in the solution A, and the control reaction temperature is 30～40 ℃.With the Fe that forms ³⁺/ Sn ⁴⁺The TiO of ion codope ₂Colloidal sol was 10～35 ℃ of sealing ageings 4～10 days;

B.Fe ³⁺/ Sn ⁴⁺The TiO of codope ₂The preparation of film

Preliminary treatment glass basis before plated film: glass basis soaks with pickle behind 500～550 ℃ of following heat treatment 120～130min in chamber type electric resistance furnace, uses distilled water and absolute ethyl alcohol ultrasonic cleaning then, puts into the baking oven dry for standby at last; The glass basis of cleaning is immersed in the speed of 2～4cm/min in the sol solutions of preparation and leaves standstill 2～5min, treat to lift vertically upward with same pull rate behind the liquid level stabilizing, wet film is at room temperature placed 5～15min, 60～100 ℃ of down dry 10～20min and become gel mould in vacuum drying chamber take out and continue to be coated with a skim down behind 10～35 ℃ of cooling 5～10min again; Repeat above-mentioned coating process cycles prepare 1～10 layer film, plated last tunic after, the vacuum drying chamber of putting into 60～80 ℃ is dry; Speed with 1～2 ℃/min is warmed up to 500～550 ℃ of heat preservation hot processing 120～180min in chamber type electric resistance furnace then, naturally cools to room temperature in stove, obtains the Fe of different dopings ³⁺/ Sn ⁴⁺Ion co-doped TiO ₂Photo-catalyst film.

Fe ³⁺/ Sn ⁴⁺Ion co-doped nano-TiO ₂Photo-catalyst film photocatalytic activity method of testing:

Select dyestuff methyl orange as the degraded object, the methyl orange of azo structure is a kind of organic compound than difficult degradation, with the simulated wastewater of finished product methyl orange dye preparation as estimating nano-TiO ₂The reaction model of film light catalytic activity has certain representativeness.Using the 200ml conical flask as the easy reaction device, is excitation source with the 125W high pressure mercury fluorescent lamp, with the pure TiO of glass tube load ₂Film or Fe ³⁺/ Sn ⁴⁺Ion co-doped TiO ₂Film is as photochemical catalyst.Photocatalytic activity testing experiment process is: the TiO that puts into the glass tube load in the 200ml conical flask ₂The methyl orange aqueous solution of photo-catalyst film and 100ml variable concentrations, different pH, 125W from the ballast high pressure mercury fluorescent lamp apart from conical flask reactor 5～10cm.With air pump bubbling air in methyl orange solution, open light source irradiation different time after several minutes earlier.Measure the absorbance of methyl orange solution with ultraviolet-visible spectrophotometer, change the photocatalytic degradation rate of calculating methyl orange according to the absorbance of methyl orange solution in the maximum absorption wave strong point.Computing formula is

D % = \frac{A_{0} - A}{A_{0}} \times 100 %,

A in the formula ₀Be the initial absorbance of methyl orange dye solution, A is the reacted absorbance of methyl orange dye solution photocatalytic oxidation degradation.

Utilize X-ray diffraction, AFM, ultraviolet-visible spectrophotometer to study TiO ₂The surface topography of photo-catalyst film, phase structure and photocatalytic activity thereof.The invention has the advantages that: the Fe of preparation ³⁺/ Sn ⁴⁺The nano-TiO of codope ₂Film has anatase and rutile duplex grain structure mutually, and average grain size is 15～20nm, determines that by analysis rutile is Fe mutually ³⁺, Sn ⁴⁺Be solidly soluted into TiO ₂The solid solution crystalline phase that forms in the lattice; The film that is coated with on glass basis is transparent, and surfacing is smooth; Codope Fe ³⁺/ Sn ⁴⁺There is the effect of Synergistic, can produces the visible light-inducing photocatalytic effect, significantly improved TiO ₂The photocatalytic activity of film is compared pure nano-TiO ₂Film has improved 2 times to the photocatalytic degradation rate of methyl orange.

Description of drawings

Fig. 1 is 500 ℃ of heat treated 0.1%Fe ³⁺/ 11.41%Sn ⁴⁺The TiO of codope ₂The XRD figure spectrum of powder.The Fe that this figure explanation obtains through 500 ℃ of heat treatment 120min ³⁺/ Sn ⁴⁺The TiO of codope ₂Powder has the mixing crystal formation of Detitanium-ore-type and rutile-type, and TiO ₂Crystallite dimension obviously diminishes.

The 0.1%Fe of Fig. 2 on glass basis, being coated with ³⁺/ 11.41%Sn ⁴⁺The TiO of codope ₂The AFM photo of film.This figure illustrates that film is evenly smooth, the film surface smoother, and average grain size has hole about 20nm.

Fig. 3 is at doping 11.41%Sn ⁴⁺The basis on the mix Fe of different amounts ³⁺Influence curve to photocatalytic degradation methyl orange.This figure illustrates codope Fe ³⁺/ Sn ⁴⁺Make TiO ₂Film significantly strengthens the photocatalytic Degradation of methyl orange, has obviously improved TiO ₂The photocatalytic activity of film.

The specific embodiment

Embodiment 1

Drip the 17ml butyl titanate earlier in the 23ml absolute ethyl alcohol, continue magnetic agitation, the back slowly drips the 11ml acetylacetone,2,4-pentanedione as complexing agent, fully obtains homogeneous solution a after the reaction; With 2.00gSnCl ₄5H ₂O and 0.02g Fe (NO ₃) ₃9H ₂O is dissolved in the 47ml absolute ethyl alcohol, drips 2ml distilled water and 0.2ml nitric acid again, and magnetic agitation obtains homogeneous solution b.The control reaction temperature is 30 ℃, slowly drips the solution b reaction that is hydrolyzed in the solution a.At last with the Fe that forms ³⁺/ Sn ⁴⁺The TiO of ion codope ₂Colloidal sol seals ageing in room temperature.

(1cm * 2.5cm) is immersed in the speed of 4cm/min in the sol solutions of preparation and leaves standstill 2min with the glass tube of pretreated cleaning, treat to lift vertically upward with same pull rate behind the liquid level stabilizing, wet film is at room temperature placed 5min, 60 ℃ of following dryings 10min and become gel mould at least in vacuum drying chamber takes out behind room temperature cooling 5min and continues to be coated with a skim down again.Repeat above-mentioned coating process cycles prepare 3 layer films, plated last tunic after, the vacuum drying chamber of putting into 80 ℃ is dry.Speed with 2 ℃/min is warmed up to 500 ℃ of heat preservation hot processing 120min in chamber type electric resistance furnace then, naturally cools to room temperature in stove, can obtain 0.1%Fe ³⁺/ 11.41%Sn ⁴⁺The TiO of codope ₂Photo-catalyst film.

Photocatalytic activity testing experiment: the Fe that in the 200ml conical flask, puts into the glass tube load ³⁺/ Sn ⁴⁺Ion co-doped TiO ₂Photo-catalyst film and 100ml concentration are 0.76 * 10 ^-5The methyl orange aqueous solution of mol/L, pH=3.15 is light source with a 125W from the ballast high pressure mercury fluorescent lamp, and lamp is apart from conical flask reactor 5cm.Use air pump to the methyl orange solution bubbling air earlier, open light source irradiation 30min after several minutes.0.1%Fe in the present embodiment ³⁺/ 11.41%Sn ⁴⁺Codope TiO ₂Photo-catalyst film is 89.65% to the photocatalytic degradation rate of methyl orange solution.

Embodiment 2

The processing step of present embodiment is substantially the same manner as Example 1, and that different is Fe (NO ₃) ₃9H ₂The doping of O is 0.10g.The photocatalytic activity testing experiment shows the 0.5%Fe of present embodiment ³⁺/ 11.41%Sn ⁴⁺Codope TiO ₂Photo-catalyst film is 81.56% to the photocatalytic degradation rate of methyl orange solution.

Comparative example

Earlier drip the 17ml butyl titanate while stirring in the 23ml absolute ethyl alcohol, the back slowly drips the 11ml acetylacetone,2,4-pentanedione as complexing agent, and reacting completely obtains homogeneous solution a; 2ml distilled water and 0.2ml nitric acid are added drop-wise in the 47ml absolute ethyl alcohol, and magnetic agitation obtains homogeneous solution b.The control hydrolysising reacting temperature is 30 ℃, slowly drips the solution b reaction that is hydrolyzed in the solution a while stirring.The pure TiO that will form at last ₂Colloidal sol seals ageing in room temperature.

The coating process step is identical with embodiment 1, makes 3 layers of pure TiO at last ₂Photo-catalyst film.The photocatalytic activity testing experiment shows the pure TiO of this comparative example ₂Photo-catalyst film is 44.76% to the photocatalytic degradation rate of methyl orange solution.

Claims

1. highlight catalytic active Fe ³⁺/ Sn ⁴⁺Ion co-doped nano-TiO ₂The preparation method of photo-catalyst film is characterized in that: processing step is:

A.Fe ³⁺/ Sn ⁴⁺The TiO of codope ₂The preparation of colloidal sol

17ml butyl titanate, 23ml absolute ethyl alcohol and 11ml acetylacetone,2,4-pentanedione are mixed with homogeneous solution A, according to molar percentage M _Sn: M _Ti=11.41% and M _Fe: M _Ti=0.1% calculates weighing stannic chloride pentahydrate and nine water ferric nitrates respectively, with the SnCl of aequum ₄5H ₂O and Fe (NO ₃) ₃9H ₂O is dissolved in the 47ml absolute ethyl alcohol and 2ml distilled water is mixed with homogeneous solution B, and the pH that drips red fuming nitric acid (RFNA) regulator solution B is 3.15～4.20, and the control reaction temperature is 30 ℃, and solution B slowly is added drop-wise to the reaction that is hydrolyzed in the solution A, forms Fe ³⁺/ Sn ⁴⁺Ion co-doped TiO ₂Colloidal sol was 10～35 ℃ of sealing ageings 4～10 days;

B.Fe ³⁺/ Sn ⁴⁺The TiO of codope ₂The preparation of film

Preliminary treatment glass basis before plated film: glass basis soaks with pickle behind 500 ℃ of following heat treatment 120min in chamber type electric resistance furnace, uses distilled water and absolute ethyl alcohol ultrasonic cleaning then, puts into the baking oven dry for standby at last; The glass basis of cleaning is immersed in the speed of 4cm/min in the sol solutions of preparation and leaves standstill 2min, treat to lift vertically upward with same pull rate behind the liquid level stabilizing, wet film is at room temperature placed 5～15min, 60 ℃ of down dry 10～20min and become gel mould in vacuum drying chamber take out and continue to be coated with a skim down behind 10～35 ℃ of cooling 5min again; Repeat above-mentioned coating process cycles prepare 3 layer films, plated last tunic after, the vacuum drying chamber of putting into 80 ℃ is dry; Speed with 2 ℃/min is warmed up to 500 ℃ of heat preservation hot processing 120min in chamber type electric resistance furnace then, naturally cools to room temperature in stove, obtains Fe ³⁺/ Sn ⁴⁺Ion co-doped nano-TiO ₂Photo-catalyst film.