CN101000356A - Method for deciding coating (or not) titanium dioxide type optical catalyst on metal surface - Google Patents
Method for deciding coating (or not) titanium dioxide type optical catalyst on metal surface Download PDFInfo
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- CN101000356A CN101000356A CN 200710008409 CN200710008409A CN101000356A CN 101000356 A CN101000356 A CN 101000356A CN 200710008409 CN200710008409 CN 200710008409 CN 200710008409 A CN200710008409 A CN 200710008409A CN 101000356 A CN101000356 A CN 101000356A
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Abstract
A method for judging whether it is suitable to coat titanium dioxide catalyst on metal surface or not includes comparing work function of metal with work function of titanium dioxide catalyst, confirming that it is suitable to coat titanium dioxide catalyst on metal surface if metal work function is less than work function of titanium dioxide catalyst or otherwise confirming that it is not suitable to coat titanium dioxide catalyst on metal surface.
Description
Technical field
The present invention relates to the technology that various metal building material surface-coated titanium dioxide type optical catalysts make its surface light catalysisization, be specifically related to a kind ofly judge that whether the metal surface is fit to the method for titanium dioxide coating type photocatalyst.
Background technology
Titanium dioxide type optical catalyst is because of possessing photochemical catalytic oxidation pollutant function and the light self-cleaning action is used widely on surfaces such as building, building materials.Apply the last layer titanium deoxid film at the outdoor tile of buildings, exterior coating, cladding glass and not only can play automatic cleaning action, but and photocatalysis remove airborne NO
2And SO
2Apply the layer of titanium dioxide film at floor tile, concrete surface and can play the effect of removing air pollutants equally.Above-mentioned these buildings substrates all often can be called inert material as nonmetallic materials, and are little for its surperficial titanium deoxid film performance impact usually.Metal materials such as aluminium alloy, iron and steel, copper also are commonly used for building materials, if make it have sterilization, self-cleaning, function such as removal organism etc. at its surface-coated layer of titanium dioxide film, will greatly promote light-catalysed range of application.At present, relevant research and patent report are also arranged.Yet,, when its surface-coated layer of titanium dioxide film, may have the electron transfer effect between itself and the film, and then might cause the variation of metal surface because metal material surface is easily active.The metal surface change to exist two kinds may: the one, the metal surface loses electronics and oxidized, the 2nd, the metal surface obtains electronics and is reduced.The former can be regarded as the process of corrosion, and this moment, the metal surface was unfavorable for the titanium dioxide coating film; The latter then is the process of surface anticorrosive, and the titanium deoxid film that apply this moment not only has photocatalysis, even also has antisepsis.This shows that not all metal material all helps the titanium dioxide coating film and makes its surface light catalysisization, must consider the character of metal itself during metal material surface titanium dioxide coating film.At present, do not consider the corrosive attack of film to metallic substrates at metal material surface spraying titanium deoxid film, thus the phenomenon that occurs running counter to desire.
Summary of the invention
The object of the invention provides a kind ofly judges that whether the metal surface is fit to the method for titanium dioxide coating type photocatalyst, to avoid the generation because of problems such as the metallic substrates that causes at metal substrate surface blindness titanium dioxide coating type photocatalyst are corroded.
Determination methods of the present invention is: by the work function value size of metal work function and titanium dioxide type optical catalyst relatively, when the work function of metal during greater than the work function of titanium dioxide type optical catalyst, this metal surface is fit to titanium dioxide coating type photocatalyst; When the work function of metal during less than the work function of titania, this metal surface is not suitable for titanium dioxide coating type photocatalyst.
The present invention utilizes the principle of electron transfer acting to judge whether the metal surface is fit to titanium dioxide coating type photocatalyst: when the work function of metal during less than the work function of titanium dioxide type optical catalyst, electronics is transferred to surperficial institute work from metal inside and is less than electronics shifts institute's work from titanium dioxide type optical catalyst, therefore electronics is easier shifts out from metal, metal loses electronics and oxidized, and this metal is not suitable for titanium dioxide coating type photocatalyst.In like manner, when the work function of metal during greater than the work function of titanium dioxide type optical catalyst, electronics is transferred to surperficial institute work from metal inside and is greater than electronics shifts institute's work from titanium dioxide type optical catalyst, therefore electronics easily shifts out from titanium dioxide type optical catalyst, metal obtains electronics and is reduced, and this metal is fit to titanium dioxide coating type photocatalyst.
Effect of the present invention and superiority are: the metallic substrates that (1) the present invention proposes can have been remedied the deficiency that is considered a problem in original titanium dioxide type optical catalyst actual application by the possibility that the titanium dioxide type optical catalyst film light corrodes, the clear and definite range of application of titanium dioxide type optical catalyst; (2) the present invention infers that by the height of work function relatively certain metallic substrate surface could titanium dioxide coating type photocatalyst film, can realize that for judging arbitrary metal base photo-catalysis functionization provides a kind of comparatively simple and practicable method, can remove the difficulty that a series of experiment brings from; The interface electron transfer that is produced when (3) the present invention contacts metal with semiconductor is used as theoretical foundation, and do not consider the chemical composition of metal itself, for the repercussion study between substrate and the titanium dioxide type optical catalyst film provides a new method.The application of the technology of the present invention will improve the validity of titanium dioxide type optical catalyst coating in various metal building material surface applications greatly.
Embodiment
Titanium dioxide type optical catalyst is pure titinium dioxide photocatalyst or the composite titanium dioxide type photocatalyst that contains other material.
(1) direct comparison method: be mainly used in and judge whether the metal surface is fit to apply the pure titinium dioxide photocatalytic method.The directly work function of the metal of finding and the work function of titania from document, both numerical values recited of comparison, when the work function of metal during greater than the work function of titania, this metal surface is fit to the titanium dioxide coating photocatalyst; When the work function of metal during less than the work function of titania, this metal surface is not suitable for the titanium dioxide coating photocatalyst.
The method emphasizes that the work function value measured with under Same Way or the identical conditions, the range of application of this determination methods depend on that can the work function of metal base find.Because work function is meant the value of pure single metallic element material mostly in the document, can only judge roughly whether certain class simple metal base material (as aluminium, iron, titanium, copper) surface is fit to the titanium dioxide coating film.In fact, various metal building materials are normally based on the alloy material of certain metal, multiple other element dopings, its work function value changes to some extent than the simple metal element, and can't directly from document, find, and, can not directly find the size of its work function for the composite titanium dioxide type photocatalyst that contains other material from document, can directly record this moment by following second method.
(2) test relative method: the titanium dioxide type optical catalyst film that applies one deck nanometer grade thickness in the metal surface, then measure the work function of metallic substrates and titanium dioxide type optical catalyst film sample, the size that compares both work function values, when the work function of metal during greater than the work function of titanium dioxide type optical catalyst film sample, this metal surface is fit to titanium dioxide coating type photocatalyst; When the work function of metal during less than the work function of titanium dioxide type optical catalyst film sample, this metal surface is not suitable for titanium dioxide coating type photocatalyst.
Specifically undertaken: select arbitrary metal base, metal substrate surface is handled totally, titanium dioxide type optical catalyst is coated in dry metal surface, dry the titanium dioxide type optical catalyst film that forms one deck nanometer grade thickness by following process; Then record the work function of titanium dioxide type optical catalyst film sample and substrate sample by physical method, the size that compares both work functions, when the work function of metal during greater than the work function of titanium dioxide type optical catalyst film sample, this metal surface is fit to titanium dioxide coating type photocatalyst; When the work function of metal during less than the work function of titanium dioxide type optical catalyst film sample, this metal surface is not suitable for titanium dioxide coating type photocatalyst.
The invention will be further described below in conjunction with embodiment.
Embodiment 1
(1) preparation TiO 2 sol type photocatalyst
Be made into homogeneous solution in the deionized water with 1.1ml red fuming nitric acid (RFNA) (68%) adding 150ml, tetraisopropyl titanate with 17.0ml under strong agitation slowly splashes in the acidic aqueous solution, the suspending liquid that contains white precipitate that hydrolysis obtains continues to stir the colloidal sol that forms homogeneous transparent until the white precipitate dissolving with suspending liquid down at 40 ℃.Colloidal sol packed into carry out dialysis with the 2L deionized water in the dialysis membrane bag and handle, changing water to the final pH value of dialysis water every 12 hours is 3.2.Colloidal sol is taken out from dialysis bag, make the TiO 2 sol type photocatalyst that concentration is about 2.5wt%.
(2) prepare the titanium deoxid film sample at aluminium alloy and stainless steel surfaces
With the stainless steel sample surfaces of the aluminium alloy of a certain trade mark and a certain trade mark clean up, drying, make pure aluminum alloy and stainless steel substrate sample, then this substrate sample is flooded in the TiO 2 sol that makes and lift, make the titanium deoxid film sample that thickness is about 300～500nm after drying.
(3) work function value of specimen
Aluminium alloy, stainless steel, the titanium deoxid film of aluminum alloy surface and four kinds of samples of titanium deoxid film of stainless steel surfaces of making are carried out the test of work function respectively.Test is to carry out on ultraviolet photo-electron spectrometer (UPS), and four kinds of sample work function values that record are as follows: aluminium alloy is 3.8eV, and stainless steel is 4.4eV, and the titanium deoxid film of aluminum alloy surface is 4.1eV, and the titanium deoxid film of stainless steel surfaces is 4.1eV.
Work function value size by more above-mentioned four kinds of samples is judged: the work function of aluminium alloy is less than the work function of its surface titanium dioxide film, the unsuitable titanium dioxide coating film in its surface; Stainless steel has higher work function than its surface titanium dioxide film, but its surface titanium dioxide coating film.
Should be noted that, this aluminum alloy surface does not have anodic oxide coating, the aluminium alloy extrusions by anodized for the surface, the anodic oxide coating that the surface forms can not conduct electricity, can not produce the electron transfer effect when it contacts with titanium deoxid film, thus with this embodiment in the sample that makes show different results.
The corrosivity test of titanium deoxid film sample
To carry out the illumination test under the water droplet existence by four kinds of samples that embodiment makes.Ultraviolet light (254nm, 2mW/cm
2) illumination sample surfaces 2min, drip water droplet then and carry out illumination again, carry out the appearance change on observation sample surface repeatedly 5 times.The result shows, the titanium deoxid film sample surfaces of simple aluminium alloy, stainless steel and stainless steel surfaces does not all have obvious variation, and the brown hot spot of drop-shaped has appearred in the titanium deoxid film sample of aluminum alloy surface, shows that aluminium alloy has produced corrosion phenomenon because of its surface titanium dioxide film is subjected to illumination.This result is to be consistent with the narration that utilizes work function to judge whether metallic substrates is corroded because of the titanium dioxide coating film.
Embodiment 2
(the titania weight content is 2.3% to utilize silica containing composite titanium dioxide type liquid photocatalyst, silica weight content is 1.1%), press embodiment 1 method at aluminium alloy and stainless steel (this material with embodiment 1 in consistent) surface-coated last layer composite titanium dioxide type photocatalysis film, the work function that records aluminium alloy and stainless steel sample surfaces photocatalysis film respectively is 4.20eV and 4.25eV.Further the work function with this photocatalysis film compares with the base metal sample respectively, and judge: the work function of aluminium alloy is less than the work function of its surface light catalytic film, and its surface should not apply this photocatalyst; Stainless steel has higher work function than its surface light catalytic film, and its surface can apply this photocatalyst.
Press the surperficial decay resistance of the method test light catalytic film sample of embodiment 1.Found that, the photocatalysis film sample surfaces of simple aluminium alloy, stainless steel and stainless steel surfaces does not all have obvious variation, and the brown hot spot of drop-shaped has appearred in the photocatalysis film sample of aluminum alloy surface, shows that aluminium alloy has produced corrosion phenomenon because of its surface light catalytic film is subjected to illumination.
Embodiment 3
(the titania weight content is 2.5% to utilize salic composite titanium dioxide type photocatalyst, alumina weight content is 0.2%), the method of pressing among the embodiment 1 applies last layer composite titanium dioxide type photocatalysis film at a kind of brass (ormolu), and the work function that records brass metal and its sample surfaces photocatalysis film respectively is 4.5eV and 4.2eV.The size of both work functions relatively, because the work function of brass metal is greater than the work function of its surface light catalytic film, its surface can apply this photocatalysis film, thereby realizes photo-catalysis functionization.
Further test the surperficial decay resistance of above-mentioned photocatalysis film sample by embodiment 1 method.Found that the photocatalysis film sample surfaces of brass surfaces does not change, show that brass surfaces can corrosion phenomenon not take place because of this photocatalysis film of its surface-coated.
Embodiment 4
(model is SLOST-250A with the commodity photocatalyst, Korea S produces), be coated in aluminium alloy and stainless steel (this material with embodiment 1 in consistent) surface by embodiment 1 method, the work function that records aluminium alloy and stainless steel sample surfaces photocatalysis film respectively is 4.15eV and 4.20eV.The work function value of photocatalysis film is compared with the base metal sample respectively, and judge: the work function of aluminium alloy is less than the work function of its surface light catalytic film, and its surface should not apply this photocatalyst; Stainless steel has higher work function than its surface light catalytic film, and its surface can apply this photocatalyst.
Press the surperficial decay resistance of the method test light catalytic film sample of embodiment 1.Found that, the photocatalysis film sample surfaces of simple aluminium alloy, stainless steel and stainless steel surfaces does not all have obvious variation, and the brown hot spot of drop-shaped has appearred in the photocatalysis film sample of aluminum alloy surface, shows that aluminium alloy has produced corrosion phenomenon because of its surface light catalytic film is subjected to illumination.
Embodiment 5
With commodity photocatalyst (CG101, Sanglais Science ﹠ Tech Development Co Ltd, Fuzhou) be coated in aluminium alloy and stainless steel (this material with embodiment 1 in consistent) surface by embodiment 1 method, the work function that records aluminium alloy and stainless steel sample surfaces photocatalysis film respectively is 4.05eV and 4.10eV.The work function value of photocatalysis film is compared with the base metal sample respectively, and judge: the work function of aluminium alloy is less than the work function of its surface light catalytic film, and its surface should not apply this photocatalyst; Stainless steel has higher work function than its surface light catalytic film, and its surface can apply this photocatalyst.
Press the surperficial decay resistance of the method test light catalytic film sample of embodiment 1.Found that, the photocatalysis film sample surfaces of simple aluminium alloy, stainless steel and stainless steel surfaces does not all have obvious variation, and the brown hot spot of drop-shaped has appearred in the photocatalysis film sample of aluminum alloy surface, shows that aluminium alloy has produced corrosion phenomenon because of its surface light catalytic film is subjected to illumination.
Claims (6)
1. judge whether the metal surface is fit to the method for titanium dioxide coating type photocatalyst for one kind, it is characterized in that: by comparing the work function value size of metal work function and titanium dioxide type optical catalyst, when the work function of metal during greater than the work function of titanium dioxide type optical catalyst, this metal surface is fit to titanium dioxide coating type photocatalyst; When the work function of metal during less than the work function of titania, this metal surface is not suitable for titanium dioxide coating type photocatalyst.
2. according to claim 1ly judge that whether the metal surface is fit to the method for titanium dioxide coating type photocatalyst, it is characterized in that: the titanium dioxide type optical catalyst in the described method is pure titinium dioxide photocatalysis or the composite titanium dioxide type photocatalyst that contains other material.
3. according to claim 1ly judge that whether the metal surface is fit to the method for titanium dioxide coating type photocatalyst, it is characterized in that: describedly judge that whether the metal surface is fit to apply the pure titinium dioxide photocatalytic method is direct comparison method: the directly work function of the metal of finding and the work function of titania from document, compare both numerical values recited, when the work function of metal during greater than the work function of titania, this metal surface is fit to the titanium dioxide coating photocatalyst; When the work function of metal during less than the work function of titania, this metal surface is not suitable for the titanium dioxide coating photocatalyst.
4. according to claim 1ly judge that whether the metal surface is fit to the method for titanium dioxide coating type photocatalyst, it is characterized in that: described method is the test relative method: the titanium dioxide type optical catalyst film that applies one deck nanometer grade thickness in the metal surface, then measure the work function of metallic substrates and titanium dioxide type optical catalyst film sample, the size that compares both work function values, when the work function of metal during greater than the work function of titanium dioxide type optical catalyst film sample, this metal surface is fit to titanium dioxide coating type photocatalyst; When the work function of metal during less than the work function of titanium dioxide type optical catalyst film sample, this metal surface is not suitable for titanium dioxide coating type photocatalyst.
5. according to claim 4ly judge that whether the metal surface is fit to the method for titanium dioxide coating photocatalyst, it is characterized in that: described test relative method is undertaken by following process: select arbitrary metal base, metal substrate surface is handled clean, titanium dioxide type optical catalyst is coated in dry metal surface, dries the titanium dioxide type optical catalyst film that forms one deck nanometer grade thickness; Then record the work function of titanium dioxide type optical catalyst film sample and metallic substrates sample by physical method, the size that compares both work functions, when the work function of metal during greater than the work function of titanium dioxide type optical catalyst film sample, this metal surface is fit to titanium dioxide coating type photocatalyst; When the work function of metal during less than the work function of titanium dioxide type optical catalyst film sample, this metal surface is not suitable for titanium dioxide coating type photocatalyst.
6. according to claim 5ly judge that whether the metal surface is fit to the method for titanium dioxide coating photocatalyst, it is characterized in that: described physical method is ultraviolet photoelectron spectroscopy or Kelvin probe method.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101855180A (en) * | 2007-11-16 | 2010-10-06 | 水体检测有限公司 | Photo electrodes |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101855180A (en) * | 2007-11-16 | 2010-10-06 | 水体检测有限公司 | Photo electrodes |
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Application publication date: 20070718 |