CN102836701A - Preparation method of Si@TiO2 heterojunction nanocomposite - Google Patents
Preparation method of Si@TiO2 heterojunction nanocomposite Download PDFInfo
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- CN102836701A CN102836701A CN2012102558422A CN201210255842A CN102836701A CN 102836701 A CN102836701 A CN 102836701A CN 2012102558422 A CN2012102558422 A CN 2012102558422A CN 201210255842 A CN201210255842 A CN 201210255842A CN 102836701 A CN102836701 A CN 102836701A
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Abstract
The invention discloses a preparation method of an Si@TiO2 heterojunction nanocomposite. The preparation method comprises the following steps of: preparing SiO2 microballoon firstly; thermally reducing SiO2 through Mg so as to obtain Si in form of microballoon; weighing 0 to 0.6g (more than 0) of Si powder, and transferring the Si powder into an 100ml of Teflon reaction kettle; adding 5ml of Ti(OBu)4 and 0.6ml of HF solution; keeping temperature for 5 to 24 hours at 180 to 250 DEG C; taking out the blue precipitate produced at the bottom of the kettle after the reaction; centrifugally cleaning through deionized water and ethanol; and drying in vacuum at 60 DEG C, and grinding to obtain the heterojunction Si@TiO2 nanocomposite with the heterojunction. The preparation method is simple in equipment, easy to operate, and is suitable for being applied to industrial production.
Description
Technical field
The invention belongs to field of photocatalytic material, be specifically related to a kind of SiTiO
2The preparation method of hetero-junctions nano composite material.
Background technology
Environmental pollution and energy shortage are the significant challenge that current mankind faces, and also are that China implements the necessary top-priority key subjects of the strategy of sustainable development.Photocatalytic process can convert inexhaustible low-density solar energy into highdensity chemical energy and electric energy; Physicochemical change degraded and mineralized water and airborne most pollutant that can also directly utilize sunshine and catalysis material effect to be taken place simultaneously, thereby photocatalysis demonstrates great potential at aspects such as the depollution of environment and new energy developments.Less than in the time in 40 years, people have obtained great successes in the research of catalysis material exploitation and application facet in the past.
TiO
2Semiconducting compound causes people's extensive concern in fields such as opto-electronic conversion and photocatalysis because it is stable preferably.Its main photocatalysis principle is: TiO
2Semiconductor is under the illumination of certain energy, and the valence band electronics that obtains energy can transit on the conduction band, on valence band, produces the hole and forms electron-hole pair, can be respectively and be adsorbed on the OH in the oxygen G&W of catalyst surface in light induced electron and hole
-Ion reacts and forms mistake/ultra oxygen radical ion and the hydroxyl radical free radical with oxidation.Although TiO
2Catalysis material shows great potential in degradable organic pollutant, but the energy gap of its broad (Eg=3.0-3.2 eV) has determined TiO
2Above-mentioned photocatalytic process can only take place in catalysis material under the irradiation of ultraviolet light, this part luminous energy only accounts for 3 ~ 4% of gross energy in solar energy, and the visible light energy in the sunshine has accounted for 40% more than of gross energy.Simultaneously, light induced electron-hole compound in catalyst also is to cause TiO
2The major reason that photocatalysis efficiency is lower.
Compare other semi-conducting material, silicon (Eg=1.12 eV) can be a large amount of utilizes the light photon energy in the sunshine, yet narrower energy gap has caused it still to exist light induced electron-hole very easily to take place compound and made the problem that photoelectric transformation efficiency reduces.As far back as 1976, people such as Mirisaki (APPLIED PHYSICS LETTERS 1976 the 29th the 6th phase of volume the 338th page) have deposited one deck TiO with the method for CVD on the Si electrode on the solar energy electrode of p-Si and n-Si composition
2Film has increased the photovoltage of electrode, has improved the efficient of photodissociation water.The Yang Peidong of University of California Berkeley etc. (NANO LETTER rolled up the 410th page in 2009 the 9th) have reported the coaxial Si/TiO of employing ald (ALD) technology preparation high density
2Nuclear-shell nano-wire array.Discover Si/TiO
2The structure of heterojunction structure can remedy TiO
2The shortcoming that light abstraction width is little, and the band curvature effect that on hetero-junctions, takes place can improve the separating power in electronics-hole, further improves photocatalysis performance.They also find Si/TiO
2The generation at interface can reduce the loss of photohole thereby further improve the light anode current, and this point has great significance on photoelectric catalysis degrading organic pollution or hydrogen production by water decomposition ability field and is worth.
Summary of the invention
The technical problem that solves: the present invention is directed to the Si/TiO that mentions in the prior art
2The advantage of boundary material provides a kind of SiTiO
2The preparation method of hetero-junctions nano composite material drops into lowly, has higher economic value.
Technical scheme:
The SiTiO that the present invention proposes
2The preparation method of hetero-junctions nano composite material is characterized in that may further comprise the steps:
1), SiO
2The preparation of microballoon
Prepare SiO2 microballoon document (the St ber W that sees reference with St ber method; Fink A.Controlled growth of monodisperse silica spheres in the micron size range [J] .J Colloid Interf Sci; 1968,26:62).
Concrete grammar is: measure 74 ml ethanol and place 200 ml beakers, add 10ml H then
2O drips 3.15 ml ammoniacal liquor at last.Mixed solution is stirred 15 min at normal temperatures to be made it fully to mix.Measure 6 ml TEOS and drip as in the above-mentioned mixed solution, normal temperature stirs 4 h down.After stirring end, standing demix is removed supernatant liquor.With deionized water and ethanol eccentric cleaning white depositions repeatedly, 60 ℃ of vacuum drying.2), Mg thermal reduction SiO
2Preparation Si powder
Adopt Mg thermal reduction SiO
2Preparation Si powder document (the Bao Z that sees reference; Weatherspoon M R; Shian S; Et al. Chemical reduction of three-dimensional silica micro-assemblies into microporous silicon replicas [J]. Nature, 2007,446:172 ~ 175).
Concrete grammar is: take by weighing SiO
2, the Mg weight ratio is the sample of 0.5:0.42, in agate mortar, fully grind.Ground mixture is put into tube furnace.Under blanket of nitrogen, 750 ℃ of insulation 5 h, programming rate is controlled at 10 ℃/min.Sample after the annealing in process is put in the beaker of 200 ml deionized waters, slowly added 60 ml 32%wt HCl, stir 24 h, excessive Mg and HCl are fully reacted.Standing demix is removed supernatant liquor.With deionized water and ethanol eccentric cleaning brownish black sediment, 60 ℃ of vacuum drying are ground.3), SiTiO
2The preparation of hetero-junctions nano composite material
The Si powder 0-0.6g that takes by weighing above-mentioned preparation places 100ml polytetrafluoroethylene (PTFE) agitated reactor, adds 5ml Ti (OBu)
4With 0.6ml HF solution, insulation 5-24 h under the 180-250 ℃ of condition.After reaction finishes, the blue sediment that generates is taken out, with deionized water and ethanol eccentric cleaning repeatedly, 60 ℃ of vacuum drying, grinding.
Wherein the Si powder is examined as Si, Ti (OBu)
4Mix the back with the Si powder to Si powder parcel, HF solution at high temperature impels Ti (OBu)
4Hydrolytic reactions generates TiO
2Be coated on the outside of Si nuclear.The band structure at this composite construction knot place can effectively reduce the compound of electron-hole pair under the illumination: TiO
2With Si after being excited under the illumination, because the conduction band current potential of Si compares TiO
2The conduction band current potential more negative, so light induced electron will be moved to TiO
2On the conduction band; Simultaneously because TiO
2The valence band current potential than the corrigendum of the valence band current potential of Si, then at TiO
2The interior photohole that produces more is prone to get in the valence band of Si, thereby has prolonged the photo-generated carrier life-span to a certain extent, has suppressed the compound of light induced electron-hole, has improved the photo-generated carrier separative efficiency, thereby its photocatalysis performance is improved.
Can obtain the SiTiO of different Si content and photocatalysis characteristic through the addition of regulating the Si powder
2The hetero-junctions nano composite material, materials are simple, and technology is easy, need not complex apparatus, and cost is low.When Si powder addition is 0, prepare the TiO of pure phase
2Nanometer sheet is as SiTiO
2The comparison sample of hetero-junctions nano composite material.
Description of drawings
Fig. 1 is SiO
2The microballoon scanning electron microscope diagram; Thus it is clear that, SiO
2The microballoon size is more even, and microsphere diameter is about 300nm.
Fig. 2 is a Si ball scanning electron microscope diagram; It is thus clear that Mg thermal reduction SiO
2The Si particle size and the SiO that obtain
2Basically identical, surface become coarse, are cellular.
Fig. 3 is TiO
2The nanometer sheet scanning electron microscope diagram; TiO
2Be the nano-sheet structure, the lamella size is less than 100 nm, and thickness is less than 10 nm.
Fig. 4 is SiTiO
2The scanning electron microscope diagram of hetero-junctions nano composite material; SiTiO
2The hetero-junctions nano composite material keeps the shape characteristic of Si powder basically, and microparticle surfaces is more coarse.
Wherein Fig. 4 a is the SiTiO of 0.15g for the Si content of embodiment 2 preparations
2The scanning electron microscope diagram of hetero-junctions nano composite material.
Fig. 4 b is the SiTiO of 0.3g for the Si content of embodiment 1 preparation
2The scanning electron microscope diagram of hetero-junctions nano composite material.
The Si content that Fig. 4 c prepares for embodiment 3 is 0.6 SiTiO
2The scanning electron microscope diagram of hetero-junctions nano composite material.
Fig. 5 is Si, TiO
2And SiTiO
2The x-ray diffraction pattern of composite, abscissa are the angle of diffraction, from figure, can obviously find out the pure TiO that hydro-thermal method is prepared
2At 25.3 ° of appearance (101) crystal face characteristic diffraction peaks (JCPDS:21-1272); The prepared Si powder of magnesium reduction process (111) of 28.4 ° of appearance crystal face characteristic diffraction peak with and narrower half-peak breadth, show that this method prepared Si purity and degree of crystallinity are higher; SiTiO
2There is TiO in the hetero-junctions nano composite material
2Characteristic diffraction peak (101) etc. and the characteristic diffraction peak (111) of Si, the photocatalysis performance that phase structure that forms thus and hetero-junctions all will improve this structure.SiTiO wherein
2-0.15 expression silicone content is 0.15g.
Fig. 6 is SiTiO
2The uv drs of hetero-junctions nano composite material; From figure, can obviously find out, at ultraviolet region (200-400 nm), TiO
2And SiTiO
2Composite is more or less the same to the absorption of light, and diffuse reflectance curve almost completely overlaps, but at visible region (400-800 nm), SiTiO
2Composite compares TiO
2Pure relative light be absorbed with tangible enhancing.Pure TiO is compared in this explanation
2, SiTiO
2Composite is more outstanding to the absorbability of light, shows better absorbing properties.Lifting on this absorbing properties is because SiTiO
2The cause that semiconductor Si exists in the composite.
Fig. 7 is the Si ball, TiO
2Nanometer sheet and SiTiO
2The photocatalytic degradation of hetero-junctions nano composite material; Preceding 30 min are absorption phase, can find out for three kinds of materials SiTiO
2The hetero-junctions nano composite material has best dyestuff adsorption capacity.In addition, can compare the photo-catalysis capability of three kinds of materials, SiTiO
2Hetero-junctions nano composite material photocatalysis effect best (Rh.B in the solution almost completely is degraded), TiO
2Take second place (90% degradation rate) Si powder the poorest (Rh.B in the solution is not degraded almost completely).
Fig. 8 is the Si ball, TiO
2Nanometer sheet and SiTiO
2Three kinds of material light catalysis dynamics research of hetero-junctions nano composite material; Can find that the Si powder is less to the degradation kinetics constant of Rh.B, approaches 0 in the material kinetics research from figure, and TiO
2Be 0.027, behind the structure hetero-junctions, SiTiO
2The kinetic constant of hetero-junctions nano composite material is greater than pure TiO
2SiTiO is described
2The hetero-junctions that makes up in the hetero-junctions nano composite material makes it have better photocatalysis performance.
Fig. 9 is that embodiment 4 is at 180 ℃ of SiTiO that hydro-thermal 5h is prepared
2-0.15-180-5 and embodiment 5 are at 250 ℃ of SiTiO that hydro-thermal 12h is prepared
2-0.15-250-12 is to the photocatalytic degradation figure of Rh.B, and is as shown in the figure, embodiment 4 and 5 prepared SiTiO
2Though hetero-junctions nano composite material hydrothermal temperature and asynchronism(-nization), it compares TiO
2All has better photocatalytic degradation performance.
Figure 10 is SiTiO
2The Si/TiO of hetero-junctions nano composite material
2Heterojunction boundary photocatalysis mechanism figure.Can know that by sketch map the existence of Si makes SiTiO
2Composite construction at visible region than pure TiO
2The absorption of Xiang Gengqiang, its utilization rate to light strengthens; Si and TiO
2The structure of heterojunction boundary can effectively separate photo-generated carrier, improves carrier separation efficient, thereby strengthens its photocatalysis performance.
The specific embodiment:
Below be the concrete embodiment of the present invention.
Embodiment 1:
1), SiO
2The preparation of microballoon
2), Mg thermal reduction SiO
2Preparation Si powder
3), SiTiO
2The preparation of hetero-junctions nano composite material
Si powder 0.3 g that takes by weighing above-mentioned preparation places 100 ml polytetrafluoroethylene (PTFE) agitated reactors, adds 5ml Ti (OBu)
4With 0.6ml HF solution.Insulation 24 h under 200 ℃ of conditions.After reaction finishes, the blue sediment that generates is taken out, with deionized water and ethanol eccentric cleaning repeatedly, 60 ℃ of vacuum drying, grinding.
Embodiment 2:
Be that with embodiment 1 difference step (3) Si powder consumption is 0.15g, reaction temperature does.
Embodiment 3:
Be that with embodiment 1 difference step (3) Si powder consumption is 0.6g.
Comparative Examples:
When preparation did not add the Si powder, similarity condition is the TiO of preparation down
2Pure phase, appearance as a comparison.
Embodiment 4
Be that with embodiment 2 differences step (3) reaction temperature is 180 ℃ of insulation 5 h.
Embodiment 5
Be that with embodiment 2 differences step (3) reaction temperature is 250 ℃ of insulation 12 h.
Claims (1)
1. SiTiO
2The preparation method of hetero-junctions nano composite material is characterized in that may further comprise the steps:
1), SiO
2The preparation of microballoon;
2), Mg thermal reduction SiO
2Preparation Si powder;
3), SiTiO
2The preparation of hetero-junctions nano composite material: the Si powder 0-0.6g that gets preparation places agitated reactor, adds 5ml Ti (OBu)
4With 0.6ml HF solution, insulation 5-24 h under the 180-250 ℃ of condition after reaction finishes, takes out the blue sediment that generates; With deionized water and ethanol eccentric cleaning, vacuum drying is ground; Promptly get composite, when Si powder addition is 0, prepare the TiO of pure phase
2Nanometer sheet.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103950972A (en) * | 2014-04-22 | 2014-07-30 | 浙江大学 | Preparation method of heterogeneous junction of perovskite phase lead titanate single crystal nanosheet and anatase phase titanium dioxide |
| CN112121781A (en) * | 2020-08-26 | 2020-12-25 | 太原科技大学 | Visible light response titanium-silicon composite oxide photocatalyst with chiral stacking structure and preparation and application thereof |
| CN113262818A (en) * | 2021-06-04 | 2021-08-17 | 北京中清和成新材料科技有限公司 | PVP-Si @ TiO applied to dye liquor degradation2Catalyst and preparation method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102306550A (en) * | 2011-06-03 | 2012-01-04 | 厦门大学 | Method for preparing nano-branched titanium dioxide photoanode of dye sensitized solar cell |
| CN102515270A (en) * | 2011-12-13 | 2012-06-27 | 武汉大学 | Preparation method of mixed crystal-type nanoscale TiO2 having exposed (001) crystal faces |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102306550A (en) * | 2011-06-03 | 2012-01-04 | 厦门大学 | Method for preparing nano-branched titanium dioxide photoanode of dye sensitized solar cell |
| CN102515270A (en) * | 2011-12-13 | 2012-06-27 | 武汉大学 | Preparation method of mixed crystal-type nanoscale TiO2 having exposed (001) crystal faces |
Non-Patent Citations (2)
| Title |
|---|
| 《Nano Letters》 20091231 Yun Jeong Hwang et al. "High Density n-Si/n-TiO2 Core/Shell Nanowire Arrays with Enhanced Photoactivity" 第410页 1 第9卷, 第1期 * |
| YUN JEONG HWANG ET AL.: ""High Density n-Si/n-TiO2 Core/Shell Nanowire Arrays with Enhanced Photoactivity"", 《NANO LETTERS》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103950972A (en) * | 2014-04-22 | 2014-07-30 | 浙江大学 | Preparation method of heterogeneous junction of perovskite phase lead titanate single crystal nanosheet and anatase phase titanium dioxide |
| CN103950972B (en) * | 2014-04-22 | 2015-10-07 | 浙江大学 | The preparation method of the heterojunction of a kind of Perovskite Phase lead titanate monocrystal nano sheet and anatase phase titanium dioxide |
| CN112121781A (en) * | 2020-08-26 | 2020-12-25 | 太原科技大学 | Visible light response titanium-silicon composite oxide photocatalyst with chiral stacking structure and preparation and application thereof |
| CN113262818A (en) * | 2021-06-04 | 2021-08-17 | 北京中清和成新材料科技有限公司 | PVP-Si @ TiO applied to dye liquor degradation2Catalyst and preparation method thereof |
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