CN1686609A

CN1686609A - Iron oxide sensitized lamellar titanium oxide visible light catalyst and its preparation method

Info

Publication number: CN1686609A
Application number: CN 200510023961
Authority: CN
Inventors: 高濂; 刘红艳
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2005-02-18
Filing date: 2005-02-18
Publication date: 2005-10-26
Anticipated expiration: 2025-02-18
Also published as: CN100346875C

Abstract

An alpha-Fe2O3 sensitized titanium oxide nanoflake as the photocatalyst for visual light is prepared through synthesizing the nanoflaky titanium oxide, using mercaptoacetic acid to in-situ synthesize alpha-Fe2O3 nanoparticles adhered on the surface of titanium oxide nanoflakes and hydrothermal treating for crystallizing the alpha-Fe2O3 nanoparticles.

Description

Iron oxide sensitized lamellar titanium oxide visible light catalyst and preparation method

Technical field

The invention relates to the synthetic preparation method of iron oxide sensitized TiOx nano sheet visible light catalyst of low-gap semiconductor and original position thereof, prepared catalyst can be used for the degraded of organic dyestuff and pollutant in industrial wastewater or the environment, belongs to field of nanometer material technology.

Technical background

TiO ₂Chemical property is stable, catalytic activity is high, inexpensive owing to have, do not produce advantage such as secondary pollution and handling (the A.Fujishima that has broad application prospects aspect the low concentration bio-refractory organic wastewater, T.N.Rao, and D.A.Tryk, J.Phochem.Phobiol.C:Phochem.Review 1 (2000) 1-21).Under greater than its band-gap energy illumination condition, TiO ₂The harmful organic substance that photochemical catalyst can not only be degraded in the environment fully generates CO ₂And H ₂O, and can remove the oxynitride NO of low concentration in the atmosphere _xWith sulfide H ₂S, SO ₂Deng toxic gas.Seriously restrict at present TiO ₂A restriction that reason is exactly excitation wavelength of photocatalytic applications is because TiO ₂Energy gap be 3.0 to 3.2eV, corresponding excitation wavelength belong to ultraviolet region, and ultraviolet light accounts in solar energy less than 5% at 387nm, from utilizing the angle of solar energy, economical and practical photochemical catalyst should be to utilize visible light part abundant in the sunshine.

In order to overcome titanium oxide photochemical catalyst solar energy is utilized low problem, people use a lot of means to TiO ₂Carry out finishing, recently, TiO ₂The research of photocatalysis to degrade organic matter is by nonmetal S element (T.Umebayashi, T.Yamaki, H.Itoh, and K.Asai, Appl.Phys.Lett., 81,2002,454) and N element (H.Irie, S.Washizuka, N.Yoshino, and K.Hashimoto, Chem.Commun., 2003,1298) etc. anion dopedly obtained key progress, exciting light has moved on to visible region by UV.

Summary of the invention

The object of the present invention is to provide titania photocatalyst and the synthesis preparation method of the high-specific surface area of the enough visible light catalytics of a kind of energy, utilize more precisely the synthetic method of original position to synthesize particle α-Fe ₂O ₃The TiOx nano sheet visible light catalyst of modification.The improvement of pollutant is the final radiation energy that requires with the sunshine, is conversion of solar energy that chemical energy is used, and is a kind of power-saving technology.

Characteristics of the present invention are: prepared α-Fe ₂O ₃The TiOx nano sheet of sensitization modification is so that the efficient of absorption and Visible Light Induced Photocatalytic organic industry dyestuff methylene blue is improved.

Concrete steps are:

(1) with TiCl ₄Analyze pure as the Ti source under ice-water bath with distilled water diluting to 0.8mol/L, add surfactant polyethylene, mass content is 1%-2% (is benchmark with the Ti element), magnetic agitation is even, puts into 180 ℃ of hydrothermal treatment consists of autoclave then 2 hours; The rutile TiO of gained ₂Powder washs with distilled water, until AgNO ₃Till checking no chlorion to exist, then with 60 ℃ of dryings of alcohol 3 final vacuums of washing 6～8 hours, adopt above method and the titanium oxide powder that makes of filling a prescription be rutile mutually, pattern is a corynebacterium.

(2) TiO that step (1) is made ₂In the NaOH of 10M solution 120 ℃ hydro-thermal 10-12 hour, washing and the watery hydrochloric acid of 0.1M are washed alcohol wash then;

(3) with the prepared TiO of step (2) ₂Nanometer sheet adds distilled water and TGA, adds ferric nitrate after the ultrasonic dispersion, and regulating pH with ammoniacal liquor is 8-10, stirs 8-10 hour under the room temperature.Then suspension is put into 150 ℃ of hydro-thermal 2-4 of autoclave hours further crystallization, calcined 4 hours for 250 ℃ after gained powder washing 4-5 time and alcohol are washed 3 times.The addition of ferric nitrate is with TiO ₂α-the Fe of surface adhesion ₂O ₃Content is that 8-12mol% is as the criterion.

α-Fe that said method is made ₂O ₃Modification gold redrock nano TiO ₂Powder carries out the visible light catalytic performance test, and light-catalyzed reaction is in the self-control reactor.

Under magnetic agitation with catalyst powder and 20-50mg/L methylene blue solution, adopt strong stirring to keep particles dispersed therein even, uviol lamp is clock reaction after preheating, pass into oxygen from the reactor bottom tracheae with certain flow, with the residue percentage of methylene blue after reaction a period of time, i.e. the rear methylene blue concentration C of reaction and initial concentration C ₀recently weigh the particle photocatalytic activity.Centrifugal elimination TiO ₂Particle is analyzed the methylene blue solution change in concentration.

Lamellar titanium oxide visible light catalyst with the iron oxide sensitized modification of above-mentioned in-situ synthetic method preparation is characterized in that TiO ₂Powder in the form of sheets, α-Fe ₂O ₃Particle attaches to nano-TiO ₂The surface of sheet, α-Fe ₂O ₃Content be 8-10mol%, it forms mechanism as shown in Figure 3, at first TiO ₂The nanometer sheet surface after the NaOH hydrothermal treatment consists, surface band OH ^-Key (3a) adds Thioglycolic acid rear surface absorption Thioglycolic acid (3b), processes through ferric nitrate again, and surface in situ synthesizes α-Fe ₂O ₃Nano particle (3c), and to the composite nano-catalyst after the sensitization modification with the further crystallization of hydro-thermal method (3d).

The synthetic visible light catalyst of this method not only can be applicable to the processing of pollutant in the environment, also in solar energy conversion and optoelectronic device very big application potential is arranged.α-Fe provided by the invention ₂O ₃The TiOx nano sheet catalyst of modification and preparation method's characteristics are:

(1) utilizes the TGA in-situ synthetic method, so that α-Fe ₂O ₃Attach to TiO ₂The nanometer sheet surface, the α-Fe that makes ₂O ₃The TiO of sensitization modification ₂The catalyst high adsorption capacity can excited by visible light.α-the Fe that sticks ₂O ₃Particle is spherical in shape.

(2) realized under the radiation of visible light degraded, and better application potential arranged in solar energy conversion, environmental protection, photocatalysis the industrial dye methylene blue.

Description of drawings

Fig. 1 rutile powder, TiOx nano thin slice, α-Fe ₂O ₃The TiO of sensitization ₂The X ray diffracting spectrum of nanometer sheet shows among the figure that the pure zirconia titanium is Rutile Type.Sheet TiO ₂Has orientation.

(a), rutile (b) TiO ₂Nanometer sheet (b), α-Fe ₂O ₃The TiO of sensitization ₂Nanometer sheet

Fig. 2 rutile, sheet TiO ₂And α-Fe ₂O ₃Sheet TiO after the sensitization ₂Catalyst TEM pattern and α-Fe ₂O ₃Sheet TiO after the sensitization ₂Power spectrum.TiO after the alkali treatment ₂In the form of sheets, α-Fe ₂O ₃Be graininess.

(a) rutile TiO ₂, (b) pure TiO ₂Nanometer sheet (c), α-Fe ₂O ₃The TiO of sensitization ₂Sheet, (d), α-Fe ₂O ₃The TiO of sensitization ₂The EDS collection of illustrative plates.

Fig. 3 α-Fe ₂O ₃Particle is attached to sheet TiO ₂On formation mechanism figure.

Fig. 4 methylene blue degradation rate is with the variation of degradation time.

Absorbance behind the made photocatalyst for degrading methylene blue of Fig. 5 changes.

(a) pure TiO ₂Sheet, (b) the pure TiO behind the degraded methylene blue ₂α-Fe behind sheet (c) the degraded methylene blue ₂O ₃The TiO of sensitization ₂Nanometer sheet, (d) α-Fe ₂O ₃Sensitization TiO ₂Nanometer sheet, (e) α-Fe ₂O ₃, (f) the 20mg/L methylene blue absorbance for degrading.

Fig. 6 catalyst is to the infrared spectrum before and after the catalysis methylene blue.

(a) pure TiO ₂Nanometer sheet, (b) α-Fe ₂O ₃Sensitization TiO ₂Nanometer sheet, (c) the pure TiO of degraded behind the methylene blue ₂Nanometer sheet, (d) α-Fe behind the degraded methylene blue ₂O ₃Sensitization TiO ₂Nanometer sheet.

The specific embodiment

Further specify embodiment and effect with following non-limiting embodiment:

By the following examples, further set forth substantive distinguishing features of the present invention and obvious improvement, but the present invention only is confined to embodiment by no means.

Embodiment 1

Nanometer rutile TiO ₂Be to utilize TiCl ₄Carry out hydro-thermal under 180 ℃ made in 2 hours.To rutile TiO ₂Powder is used 10mol%NaOH solution 120 hydro-thermals 10 hours, obtains the TiO of sheet ₂, the washing back is to its rare nitric acid washing with 0.1mol%, washing then; With the sheet TiO that makes ₂Ultrasonic being scattered in the distilled water adds TGA, and be ultrasonic, adds ferric nitrate then, about ammoniacal liquor adjust pH 8-10, stirs, and then suspension put into 150 ℃ of hydro-thermals of autoclave 3 hours.The washing of gained catalyst, ethanol are washed back 250 ℃ of calcinings in 4 hours and are formed.Obtained iron oxide sensitized sheet TiO ₂Catalyst, surface adhesion have 10mol% α-Fe ₂O ₃

The photocatalysis performance of prepared catalyst can be tested in three layers of concentric circles tubular glass reactor and carry out, middle 300W medium pressure mercury lamp, the inner logical recirculated cooling water of inner sleeve, the outside filter plate that pastes one deck 400nm, so that only have wavelength can see through filter plate greater than the visible light of 400nm, be reactor in the middle of the inner-outer sleeve.Under magnetic agitation, catalyst joined 450ml initial concentration C ₀The methylene blue solution of=20mg/L, catalyst powder bulk concentration 1.5g/L, adopt powerful the stirring to keep particle to be uniformly dispersed, uviol lamp is clock reaction after preheating, from the reactor bottom gas distribution pipe with the certain flow aerating oxygen, oxygen flow is 10mL/min, with the residue percentage of methylene blue after reaction a period of time, promptly reacts back methylene blue concentration C and initial concentration C ₀recently weigh the particle photocatalytic activity.Concrete grammar for ease of the concentration of test methylene blue, dilutes 5 times, centrifugal elimination TiO for getting at regular intervals 4ml solution ₂Particle is analyzed over time rate of methylene blue solution concentration.Measured result shown in Fig. 4-6, α-Fe of providing of present embodiment as seen from the figure ₂O ₃Sensitization TiO ₂The nanometer sheet absorption region has moved on to visible region, and Absorption Characteristics is shown as TiO ₂And α-Fe ₂O ₃Total Absorption Characteristics.

Embodiment 2

Prepare earlier nano-TiO ₂Sheet is then at sheet TiO ₂Surface adhesion α-Fe ₂O ₃, its preparation process is identical with embodiment 1, the α-Fe that only sticks ₂O ₃Content is 8mol%, and its performance is similar to Fig. 4-6.

Embodiment 3

α-Fe ₂O ₃Attach to nano-TiO ₂The dose,surface of sheet is 11.5mol%, and its processing step is identical with embodiment 1, and performance is mutually identical with Fig. 4-6.

Claims

1. an iron oxide sensitized lamellar titanium oxide visible light catalyst is characterized in that titanium oxide in the form of sheets, α-Fe ₂O ₃Particle attaches to nano-TiO ₂The surface of sheet; α-Fe ₂O ₃Content be 8-12mol%.

2. by the described α-Fe of claim 1 ₂O ₃The lamellar titanium oxide photochemical catalyst of sensitization is characterized in that attaching to TiO ₂α-the Fe on sheet surface ₂O ₃Particle is spherical.

3. prepare α-Fe as claimed in claim 1 ₂O ₃The synthetic method of the lamellar titanium oxide photochemical catalyst of sensitization is characterized in that preparing earlier the nano-titanium oxide sheet, then at the synthetic α-Fe of lamellar titanium oxide surface in situ ₂O ₃Nano particle, and to the further crystallization of the application hydrothermal method of the composite nano-catalyst after the sensitization modification, concrete building-up process is:

(1) with TiCl ₄Analyze pure as the Ti source under ice-water bath with distilled water diluting to 0.8mol/L, add surfactant polyethylene, magnetic agitation is even, puts into 180 ℃ of hydrothermal treatment consists of autoclave then 2 hours; The rutile TiO of gained ₂With the distilled water washing, until AgNO ₃Till checking no chlorion to exist, then with alcohol washing final vacuum drying;

(2) TiO that step (1) is made ₂In the NaOH of 10M solution 120 ℃ hydro-thermal 10-12 hour, washing and the watery hydrochloric acid of 0.1M are washed then, alcohol is washed;

(3) the sheet TiO that step (2) is made ₂Be scattered in the distilled water with TGA is ultrasonic, add ammoniacal liquor and ferric nitrate, stir under the room temperature after 8～10 hours in autoclave, at 150 ℃ of hydro-thermal 2-4 hours, obtain α-Fe again ₂O ₃The sheet TiO of sensitization modification ₂Powder;

(4) the prepared powder of step (3) is rear with the alcohol washing with the distilled water washing, calcined 4 hours for 250 ℃; The ferric nitrate amount that adds in the step (3) is TiO ₂α-Fe of surface adhesion 8-12mol% ₂O ₃Be as the criterion; The ammoniacal liquor addition makes pH between 8-10.

4. by the described α-Fe of claim 3 ₂O ₃The sheet TiO of sensitization ₂The synthetic method of photochemical catalyst is characterized in that the 1-2% of quality addition take the Ti element as benchmark of surfactant polyethylene.

5. by the described α-Fe of claim 3 ₂O ₃The sheet TiO of sensitization ₂The synthetic method of photochemical catalyst is characterized in that α-Fe ₂O ₃The powder of hydro-thermal method crystallization stone is earlier with distilled water washing 4-5 time, again with alcohol washing 3 times.

6. an iron oxide sensitized lamellar titanium oxide visible light catalyst is characterized in that being used for the degraded of industrial dye methylene blue.