CN101182033A - Method for preparing titanium dioxide nano-tube - Google Patents

Abstract

The invention discloses a preparation method of TiO2 nanotubes, which comprises the following steps: an appropriate amount of sodium titanate nanotubes obtained by a hydrothermal synthesis method is dispensed to be fully dipped in mixed solution of ammonium fluorotitanate and boric acid with the filtered molar concentration ratio of 1:1-1:5 for deposition with the deposition time of 10-120mins; the mixed solution is reacted to obtain the sodium titanate nanotubes with TiO2 films formed which are then dried in an oven and next treated with heat treatment in a muffle furnace and cooled naturally so as to obtain the anatase type TiO2 nanotubes. The TiO2 nanotubes prepared by the method has anatase crystal form and relatively high catalytic activity, so the hydrogen yield of photocatalysis hydrogen production can be increased and the photoelectric transformation efficiency of dye-sensitized solar cells can be improved.

Description

The preparation method of titania nanotube

Technical field

The present invention relates to photochemical catalysis and areas of information technology, relate to a kind of preparation method of titania nanotube specifically.

Background technology

1996, Hoyer P adopted the porous anodic alumina films template successfully to make titania nanotube; 1998, the simple hydrothermal synthesis methods of human such as Kasuga T successfully made Powdered " titanium dioxide " nanotube, had from then on drawn back the prelude of " titanium dioxide " nanotube research.The preparation method of titania nanotube is based on template synthesis method and hydrothermal synthesis method at present, and electrochemical process, oxidation reduction process, atomic deposition method etc. also have bibliographical information.

By template gained TiO ₂Nanotube has uniform distribution, perpendicular to film surface, the intensive nanoporous that is parallel to each other, and length, aperture and thickness of pipe can be controlled by electrochemical means.But the obtained TiO of this method ₂The caliber of nanotube big (about 200nm), easily form corpus fibrosum, and be subjected to the restriction of template pattern, and preparation process and complex process.

" titanium dioxide " nanotube tube wall that hydrothermal synthesis method obtains is thin, caliber is little, specific surface area is big, and this synthetic method is fairly simple.Therefore these class methods are mostly adopted in present international research.But the nanotube that this method of chemical treatment obtains is formed very big-difference is arranged, mainly form by other oxide compounds of metatitanic acid or titanium, even the different nanotube O/Ti in same sample also have nothing in common with each other, so in fact " titanium dioxide " nanotube that hydrothermal synthesis method makes should be called titanate radical nanopipe.Because this nanotube tube wall is thinner, along with the continuous rising of maturing temperature, titanate radical nanopipe loses water of constitution gradually, the wall layers spacing is dwindled, in the time of 300 ℃ tubular structure begin destroyed, thereby can't carry out pyroprocessing, obtain tubular structure anatase octahedrite TiO preferably ₂Nanotube is so its photocatalytic activity is lower.

Summary of the invention

The technical issues that need to address of the present invention provide a kind of TiO ₂The preparation method of nanotube, the TiO for preparing by this method ₂Nanotube has higher photocatalytic activity.

The technical scheme that solves the problems of the technologies described above is as follows:

A kind of TiO ₂The preparation method of nanotube may further comprise the steps,

1. prepare ammonium titanium fluoride [(NH respectively ₄) ₂TiF ₆] solution and boric acid [H ₃BO ₃] solution, stand-by after filtering;

2. get an amount of titanate radical nanopipe that makes with hydrothermal synthesis method, being immersed in molar concentration rate fully is 1: 1-1: deposit in 5 ammonium titanium fluoride and the boric acid mixing solutions, depositing time is 10min-120min;

3. mixing solutions reacts, and obtains being formed with on it TiO ₂The titanate radical nanopipe of film;

4. be formed with TiO with on it ₂The titanate radical nanopipe of film is dried in baking oven;

5. in retort furnace, heat-treat then;

6. naturally cooling promptly obtains Detitanium-ore-type TiO again ₂Nanotube.

Wherein, the molar concentration rate of 2. middle ammonium titanium fluoride of step and boric acid is preferably 1: 3; Depositing time is preferably 40-50 minute.

Preferably, heat-treat in the described retort furnace for: at first be warmed up to 250 ℃, 2 ℃/min of temperature rise rate is warming up to 300 ℃ again, 0.2 ℃/min of temperature rise rate, insulation 1h is warmed up to 350 ℃, 0.2 ℃/min of temperature rise rate then, be warming up to 600 ℃ at last, 2 ℃/min of temperature rise rate, insulation 1h; Or processing 1h under being preferably 500 ℃, 2 ℃/min of temperature rise rate; Or processing 1h under being preferably 600 ℃, 2 ℃/min of temperature rise rate.

Preferably, the preparation of titanate radical nanopipe may further comprise the steps:

A is with 2g TiO ₂Put into the tetrafluoroethylene flask that is equipped with condensing works with the 10mol/L NaOH 40ml NaOH solution for preparing;

B heated and stirred, control reaction temperature are about 100 ℃, and the reaction times is 12h;

The C reaction finishes postcooling to room temperature, takes out white depositions;

D is lower than 70us/cm until the supernatant liquor specific conductivity for several times with deionized water wash;

E cleans white depositions with the 0.1mol/L HCl for preparing, and leaves standstill 5h;

F is lower than 5us/cm until the supernatant liquor specific conductivity for several times with deionized water wash again; Promptly obtain fresh titanate radical nanopipe.

The present invention is directed to the hydrothermal synthesis method subzero treatment and fail to obtain the Detitanium-ore-type TiO of highlight catalytic active ₂Nanotube, the titanate radical nanopipe that proposes to make with hydrothermal synthesis method is a template, by liquid deposition method epitaxy TiO thereon ₂Nanotube, because what form nanotube is titanium dioxide than multicomponent, further caving in because of dehydration or dislocation will can not appear in thermal treatment, can be so that titania nanotube carries out the transition to anatase crystal naturally in the condition of high temperature.Finally can obtain having the Detitanium-ore-type TiO of high light catalytic activity by pyroprocessing ₂Nanotube.This titania nanotube is a foraminate hexahedral shape in the middle of the one side.The titania nanotube of this kind method preparation is compared titanate radical nanopipe, has the high light catalytic activity.

The high light photocatalysis activity titanium dioxide nano pipe of this method preparation can be applied to photocatalysis hydrogen production, dye sensitization solar battery, because this nanotube has the anatase octahedrite crystalline form, photocatalytic activity is higher, so can improve the hydrogen yield of photocatalysis hydrogen production, improve the photoelectric transformation efficiency of dye sensitization solar battery.Simultaneously, because the titania nanotube light transmission is better, and titanium dioxide has excellent self-cleaning function, can be used for building exterior wall glass.In addition, in areas of information technology, after titania nanotube is filled littler metal or magnetic nano-particle, have the magnetic recording ability, can be used for the high density information storage.

Description of drawings

Fig. 1 is 110 ℃ of titanate radical nanopipe TEM figure among the embodiment one;

Fig. 2 is the TEM figure of the titania nanotube among the embodiment one;

Fig. 3 is that titanate radical nanopipe and the titania nanotube photocatalytic activity among the embodiment one compares synoptic diagram.

Embodiment

Embodiment 1

(1) preparation titanate radical nanopipe

(1) takes by weighing Detitanium-ore-type TiO ₂2g;

(2) preparation 10mol/L NaOH 40ml;

(3) preparation 0.1mol/L HCl;

(4) 2g TiO2 is put into the tetrafluoroethylene flask that is equipped with condensing works with the NaOH solution for preparing;

(5) heated and stirred, control reaction temperature are about 100 ℃, and the reaction times is 12h;

(6) reaction finishes postcooling to room temperature, takes out white depositions;

(7) be lower than 70us/cm until the supernatant liquor specific conductivity for several times with deionized water wash;

(8) clean white depositions with the 0.1mol/LHCl for preparing, leave standstill 5h (hour);

(9) be lower than 5us/cm until the supernatant liquor specific conductivity for several times with deionized water wash again;

(10) promptly obtain fresh titanate radical nanopipe, be designated as sample A.

(2) preparation titania nanotube

1. prepare the ammonium titanium fluoride [(NH of 0.1mol/L respectively ₄) ₂TiF ₆] boric acid [H of solution and 0.3mol/L ₃BO ₃] solution, stand-by after filtering;

2. get the titanate radical nanopipe A of proper amount of fresh, be immersed in fully in ammonium titanium fluoride after the filtration and the boric acid mixing solutions and deposit depositing time 40min;

3. (NH ₄) ₂TiF ₆The reaction of coordination exchange equilibrium takes place in the aqueous solution:

${\left[{\mathrm{TiF}}_6\right]}^{2-}+n{H}_{2}O\⇔{\mathrm{TiF}}_{6-n}{\left(\mathrm{OH}\right)}_n^{2-}+\mathrm{nHF}$

The boric acid and the F that add ^-Reaction forms the permutoid reaction that complex ion moves right this balanced reaction and quickened ligand:

$H_3{\mathrm{BO}}_3+4\mathrm{HF}\⇔{\mathrm{BF}}_4^{-}+H_3{O}^{+}+2H_{2}O$

Finally consumed not coordinate F ^-, quickened the carrying out of hydrolysis reaction, by [TiF ₆] ^2-[the Ti (OH) that forms of hydrolysis ₆] ^2-Dehydration makes TiO ₂Film forms on sample A, is designated as sample B;

4. sample B is dried in 80 ℃ of baking ovens sample C;

5. sample C is heat-treated, the retort furnace temperature program is: at first be warmed up to 250 ℃, 2 ℃/min of temperature rise rate is warming up to 300 ℃ again, 0.2 ℃/min of temperature rise rate, insulation 1h, be warmed up to 350 ℃ then, 0.2 ℃/min of temperature rise rate is warming up to 600 ℃ at last, 2 ℃/min of temperature rise rate, insulation 1h;

6. naturally cooling promptly obtains Detitanium-ore-type TiO ₂Nanotube.

7. sample A is heat-treated, handle 1h down for 110 ℃ in retort furnace, 2 ℃/min of temperature rise rate obtains the exsiccant titanate radical nanopipe, is used for degradation effect and measures.

From accompanying drawing 1, can know and see that titanate radical nanopipe has both ends open, the hollow tubular structure of pattern homogeneous, can see that under high-resolution-ration transmission electric-lens all titanate radical nanopipes are multilayered tube, no single-walled pipe, tube wall does not wait at 3～5 layers, nanotube wall thickness 2～3nm, bore 4～6nm, external diameter 8～12nm.

As shown in accompanying drawing 2, titania nanotube is foraminate hexahedral shape in the middle of the one side, and bore is about 5nm, and external diameter is about 20nm, and thickness of pipe is about 10～15nm, and pipe range is about 20nm.

(3) degradation effect is measured

The experiment of photocatalytic degradation tropeolin-D: make light source with 125W straight pipe type high voltage mercury lamp (ultraviolet predominant wavelength is 365nm), adopt the self-control photo catalysis reactor, this reactor is made up of condensation sleeve pipe, reactor, air agitation head, ultraviolet lamp.Adding concentration in reactor is methyl orange solution 400ml and 0.4g titanate radical nanopipe or the titania nanotube of 20mg/l.Under unglazed photograph, fill air 30min and make catalyzer and reaction solution thorough mixing, reach absorption/desorption balance.Simultaneously high voltage mercury lamp is placed homemade tap water condensing works, open the ultraviolet lamp preheating, so that illumination is basicly stable when the experiment beginning.

During degradation experiment, sampling at regular intervals, centrifugation 30min measures organic degradation effect by the absorbancy of reaction solution.Referring to Fig. 3.

Fig. 3 be titanate radical nanopipe and titania nanotube photocatalytic degradation 20mg/l methyl orange solution specific activity.The degradation efficiency of titanate radical nanopipe 60min is 40.2%, and 20 minutes degradation efficiencies of modified Nano pipe are 71.6%.

Generally speaking, the dynamics research of TiO2 photocatalysis to degrade organic matter generally adopts Langmuir-Hinshelwood (L-H) model to describe, and in the dynamics data analytical procedure, usually adopts the pseudo-first-order reaction kinetics equation to analyze light-catalyzed reaction:

$\frac{\mathrm{dC}}{\mathrm{dt}}=K_{B}C$ Integration gets $\ln \left(\frac{C_0}{C}\right)=K_{B}t$

C in the formula ₀, C is respectively the starting point concentration of reactant and arrives the concentration of t time, and KB is the apparent speed constant.

According to (C/C ₀) the vs.t linear regression titanate radical nanopipe of trying to achieve and the apparent speed constant of titania nanotube photocatalytic degradation methyl orange solution be respectively: 0.00842,0.08687, the activity of titania nanotube improves more than 10 times.

Embodiment 2

(1) prepares the method for titanate radical nanopipe with embodiment 1.

(2) preparation titania nanotube

1. prepare the ammonium titanium fluoride [(NH of 0.01mol/L respectively ₄) ₂TiF ₆] boric acid [H of solution and 0.03mol/L ₃BO ₃] solution, stand-by after filtering;

2. get the titanate radical nanopipe A of proper amount of fresh, be immersed in fully in ammonium titanium fluoride after the filtration and the boric acid mixing solutions and deposit;

3. (NH ₄) ₂TiF ₆The reaction of coordination exchange equilibrium takes place in the aqueous solution:

${\left[{\mathrm{TiF}}_6\right]}^{2-}+n{H}_{2}O\⇔{\mathrm{TiF}}_{6-n}{\left(\mathrm{OH}\right)}_n^{2-}+\mathrm{nHF}$

The boric acid and the F that add ^-Reaction forms the permutoid reaction that complex ion moves right this balanced reaction and quickened ligand:

$H_3{\mathrm{BO}}_3+4\mathrm{HF}\⇔{\mathrm{BF}}_4^{-}+H_3{O}^{+}+2H_{2}O$

Finally consumed not coordinate F ^-, quickened the carrying out of hydrolysis reaction, by [TiF ₆] ^2-[the Ti (OH) that forms of hydrolysis ₆] ^2-Dehydration makes TiO ₂Film forms on sample A, is designated as sample B;

4. sample B is dried in baking oven sample C;

5. sample C is heat-treated, handle 1h down for 600 ℃ in retort furnace, 2 ℃/min of temperature rise rate, naturally cooling promptly obtain Detitanium-ore-type TiO ₂Nanotube.

(3) result and the embodiment of degradation effect mensuration are basic identical.

Claims (7)

1. TiO ₂The preparation method of nanotube is characterized in that, may further comprise the steps,

1. prepare ammonium titanium fluoride solution and boric acid solution respectively, stand-by after filtering;

2. get an amount of titanate radical nanopipe that makes with hydrothermal synthesis method, being immersed in molar concentration rate fully is 1: 1-1: deposit in 5 ammonium titanium fluoride and the boric acid mixing solutions, depositing time is 10-120min;

3. mixing solutions reacts, and obtains forming on it TiO ₂The titanate radical nanopipe of film;

4. TiO will be formed on it ₂The titanate radical nanopipe of film is dried in baking oven;

5. in retort furnace, heat-treat then;

6. naturally cooling promptly obtains Detitanium-ore-type TiO again ₂Nanotube.

2. TiO according to claim 1 ₂The preparation method of nanotube, it is characterized in that, heat-treat in the described step retort furnace 5. for: at first be warmed up to 250 ℃, 2 ℃/min of temperature rise rate, be warming up to 300 ℃ again, 0.2 ℃/min of temperature rise rate, insulation 1h is warmed up to 350 ℃ then, 0.2 ℃/min of temperature rise rate, be warming up to 600 ℃ at last, 2 ℃/min of temperature rise rate, insulation 1h.

3. TiO according to claim 1 ₂The preparation method of nanotube is characterized in that, heat-treat in the described step retort furnace 5. into: handle down 1h, 2 ℃/min of temperature rise rate for 500 ℃.

4. TiO according to claim 1 ₂The preparation method of nanotube is characterized in that, heat-treat in the described step retort furnace 5. into: handle down 1h, 2 ℃/min of temperature rise rate for 600 ℃.

5. TiO according to claim 1 ₂The preparation method of nanotube is characterized in that, the molar concentration rate of step (2) ammonium titanium fluoride and boric acid is 1: 3.

6. TiO according to claim 1 ₂The preparation method of nanotube is characterized in that, depositing time is 50-60min. in the step (2)

7. according to each described TiO of claim 1-6 ₂The preparation method of nanotube is characterized in that, the preparation of titanate radical nanopipe comprises:

A is with 2g TiO ₂Put into the tetrafluoroethylene flask that is equipped with condensing works with the 10mol/L NaOH 40ml NaOH solution for preparing;

B heated and stirred, control reaction temperature are about 100 ℃, and the reaction times is 12h;

The C reaction finishes postcooling to room temperature, takes out white depositions;

D is lower than 70us/cm until the supernatant liquor specific conductivity for several times with deionized water wash;

E cleans white depositions with the 0.1mol/L HCl for preparing, and leaves standstill 5h;

F is lower than 5us/cm until the supernatant liquor specific conductivity for several times with deionized water wash again; Promptly obtain titanate radical nanopipe.

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