CN109225282A - A kind of p-n junction CdWO4/ BiOCl heterojunction photocatalyst, preparation method and its usage - Google Patents
A kind of p-n junction CdWO4/ BiOCl heterojunction photocatalyst, preparation method and its usage Download PDFInfo
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- BWOROQSFKKODDR-UHFFFAOYSA-N oxobismuth;hydrochloride Chemical compound Cl.[Bi]=O BWOROQSFKKODDR-UHFFFAOYSA-N 0.000 title claims abstract description 158
- 239000011941 photocatalyst Substances 0.000 title claims abstract description 23
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000000725 suspension Substances 0.000 claims abstract description 41
- 239000002245 particle Substances 0.000 claims abstract description 24
- 239000003054 catalyst Substances 0.000 claims abstract description 19
- 239000007788 liquid Substances 0.000 claims abstract description 17
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims abstract description 16
- 238000000926 separation method Methods 0.000 claims abstract description 14
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 5
- 238000013033 photocatalytic degradation reaction Methods 0.000 claims abstract description 5
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 24
- 238000005406 washing Methods 0.000 claims description 13
- 238000003756 stirring Methods 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- YKYOUMDCQGMQQO-UHFFFAOYSA-L Cadmium chloride Inorganic materials Cl[Cd]Cl YKYOUMDCQGMQQO-UHFFFAOYSA-L 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 9
- 229910020350 Na2WO4 Inorganic materials 0.000 claims description 6
- 239000002244 precipitate Substances 0.000 claims description 6
- 239000013049 sediment Substances 0.000 claims description 6
- 239000000047 product Substances 0.000 claims description 4
- 239000000376 reactant Substances 0.000 claims description 4
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 3
- 238000003786 synthesis reaction Methods 0.000 claims description 3
- PPNKDDZCLDMRHS-UHFFFAOYSA-N bismuth(III) nitrate Inorganic materials [Bi+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O PPNKDDZCLDMRHS-UHFFFAOYSA-N 0.000 claims description 2
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 230000001699 photocatalysis Effects 0.000 abstract description 25
- 238000007146 photocatalysis Methods 0.000 abstract description 14
- PYWVYCXTNDRMGF-UHFFFAOYSA-N rhodamine B Chemical compound [Cl-].C=12C=CC(=[N+](CC)CC)C=C2OC2=CC(N(CC)CC)=CC=C2C=1C1=CC=CC=C1C(O)=O PYWVYCXTNDRMGF-UHFFFAOYSA-N 0.000 abstract description 14
- 229940043267 rhodamine b Drugs 0.000 abstract description 12
- 238000005215 recombination Methods 0.000 abstract description 7
- 230000006798 recombination Effects 0.000 abstract description 6
- 230000005284 excitation Effects 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 12
- 239000004065 semiconductor Substances 0.000 description 12
- 238000006731 degradation reaction Methods 0.000 description 9
- 230000015556 catabolic process Effects 0.000 description 8
- 239000012153 distilled water Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 239000013078 crystal Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000005684 electric field Effects 0.000 description 3
- 238000000921 elemental analysis Methods 0.000 description 3
- 238000005286 illumination Methods 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000001055 reflectance spectroscopy Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 238000004847 absorption spectroscopy Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000002800 charge carrier Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- ZXOKVTWPEIAYAB-UHFFFAOYSA-N dioxido(oxo)tungsten Chemical group [O-][W]([O-])=O ZXOKVTWPEIAYAB-UHFFFAOYSA-N 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000000724 energy-dispersive X-ray spectrum Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000003574 free electron Substances 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000005622 photoelectricity Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000005067 remediation Methods 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 238000001507 sample dispersion Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000002336 sorption--desorption measurement Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000002211 ultraviolet spectrum Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/06—Halogens; Compounds thereof
- B01J27/132—Halogens; Compounds thereof with chromium, molybdenum, tungsten or polonium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
-
- B01J35/30—
-
- B01J35/39—
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/308—Dyes; Colorants; Fluorescent agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/34—Organic compounds containing oxygen
- C02F2101/345—Phenols
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/10—Photocatalysts
Abstract
The present invention is supplied to a kind of p-n junction CdWO4/ BiOCl heterojunction photocatalyst and preparation method thereof, the catalyst includes CdWO4Particle and BiOCl particle；The CdWO4Particle is connect with the BiOCl particle, forms CdWO4/ BiOCl hetero-junctions.P-n junction CdWO4The formation tied in/BiOCl hetero-junctions advantageously reduces photo-generate electron-hole pairs recombination rate, improves photocatalysis performance, expands it in the application of photocatalysis field.When light irradiates CdWO4When/BiOCl hetero-junctions, photo-generate electron-hole pair is generated by photon excitation, the electronics (e-) on the CB of BiOCl can be transferred to CdWO by the internal electrostatic gesture of hetero-junctions4CB on.And CdWO4Hole then moves in the VB of BiOCl, so that photoelectron and hole can efficiently separate, promotes the raising of photocatalytic activity.Preparation method includes: that the first suspension is prepared, the first solution is prepared, CdWO4/ BiOCl suspension is prepared and solid-liquid separation step.The present invention provides p-n junction CdWO4/ BiOCl heterojunction photocatalyst is used for the purposes of Photocatalytic Degradation of Phenol and rhodamine B.
Description
Technical field
The present invention relates to technical field of material chemistry, in particular to a kind of p-n junction CdWO4/ BiOCl heterojunction photocatalyst, system
Preparation Method and application thereof.
Background technique
Photocatalytic semiconductor material causes widely at alleviation water resource pollution, environment remediation and the renewable aspect of the energy
Concern.N-type semiconductor CdWO4With stratiform monocline wolframite structure, it is considered as due to its chemistry, structure and thermal stability
A kind of excellent photochemical catalyst.However, due to its wider forbidden band gap (about 3.1eV), CdWO4It is only limitted in ultraviolet spectra area
It is used in domain.In addition, CdWO4Recombination rate in photocatalysis due to photo-generate electron-hole pairs is relatively high to be difficult to meet practical application
Demand.Therefore, CdWO4Practical application be still a stern challenge.In recent years, BiOCl photochemical catalyst is due to its conjunction
Suitable band gap and efficient photocatalytic activity are widely paid close attention in practical applications.BiOCl photochemical catalyst is that one kind has
The p-type semiconductor of layer structure, in each Cl halide layer and staggered [Bi2O2]2+Layer powerful internal electric field easy to form,
And this layer structure is conducive to enhance photocatalytic activity.However, the recombination rate due to photo-generate electron-hole pair is high, BiOCl's
Photocatalytic activity is still not fully up to expectations.Individual semiconductor light-catalyst photo-generate electron-hole pairs recombination rate with higher,
Photo-catalysis capability can not effectively degrade a variety of organic contaminations.
Summary of the invention
For this reason, it may be necessary to provide one kind in reducing photo-generate electron-hole pairs recombination rate, the photochemical catalyst of photocatalysis performance is improved.
To achieve the above object, a kind of p-n junction CdWO is inventor provided4/ BiOCl heterojunction photocatalyst, the catalyst include
CdWO4Particle and BiOCl particle；The CdWO4Particle forms p-n junction CdWO in conjunction with the BiOCl particle4/ BiOCl is heterogeneous
Knot.
Further, the CdWO4The molar ratio of particle and BiOCl particle is 5-35:65-95.
Further, the CdWO4The molar ratio of particle and BiOCl particle is 25:75.The CdWO of the ratio4/ BiOCl is different
Matter knot shows highest photocatalysis efficiency.
Further, the CdWO4Particle is club shaped structure, length 150-300nm, diameter 30-50nm；It is described
BiOCl particle is laminated structure, length 500nm-700nm, width 500nm-700nm, with a thickness of 80-120nm.
Inventor additionally provides above-mentioned p-n junction CdWO4The preparation method of/BiOCl heterojunction photocatalyst, the preparation side
Method the following steps are included:
First suspension is prepared: by CdWO4It is added to the water, is uniformly dispersed, obtains the first suspension；
First solution is prepared: by Bi (NO3)3·5H2O and KCl are dissolved in ethylene glycol, obtain the first solution；
CdWO4/ BiOCl suspension is prepared: the first solution is added dropwise into the first suspension, stirring first during being added dropwise
Suspension；After dropwise addition obtain mixture 60-100 DEG C water-bath 4-8 hours, be stirred during water-bath；Mixture water-bath
CdWO is obtained after being cooled to room temperature after the completion4/ BiOCl suspension；
It is separated by solid-liquid separation: the CdWO that will be obtained4/ BiOCl suspension is separated by solid-liquid separation, washing precipitate, and to washing after
Sediment is dried, and obtains CdWO4/ BiOCl heterojunction photocatalyst.
Further, the CdWO4、Bi(NO3)3Molar ratio with KCl is 5-35:65-95:65-95.
Further, the CdWO4For CdCl2With Na2WO4It is synthesized by hydro-thermal method, preparation process includes following step
It is rapid:
By Na2WO4Solution and CdCl2Solution is stirred mixing, obtains the second suspension；
Second suspension is put into autoclave, 150-200 DEG C reaction 10-15 hours, obtain reactant, reactant washed
CdWO is obtained after washing drying4Particle.
Further, the CdCl2With Na2WO4Molar ratio be 1:1.
Above-mentioned p-n junction CdWO4/ BiOCl heterojunction photocatalyst is used for the purposes of Photocatalytic Degradation of Phenol and rhodamine B.
Inventor further provides a kind of catalyst prod, and the product includes above-mentioned p-n junction CdWO4/BiOCl different
Matter knot photochemical catalyst.
It is different from the prior art, above-mentioned technical proposal provides a kind of novel p-n junction CdWO4/ BiOCl hetero-junctions light is urged
Agent.Because hetero-junctions has two or more different bandgap structures, this is conducive to photo-generate electron-hole to partly leading
It is migrated between body, and promotes the separative efficiency of its photo-generate electron-hole pairs.P-n junction CdWO4The formation tied in/BiOCl hetero-junctions has
Conducive to photo-generate electron-hole pairs recombination rate is reduced, photocatalysis performance is improved, expands it in the application of photocatalysis field.When light irradiates
P-n junction CdWO4When/BiOCl hetero-junctions, photo-generate electron-hole pair is generated by photon excitation.Electronics (e on the CB of BiOCl-)
CdWO can be transferred to by the internal electrostatic gesture of hetero-junctions4CB on.And CdWO4Hole then moves in the VB of BiOCl, from
And photoelectron and hole can efficiently separate, and promote the raising of photocatalytic activity.
Detailed description of the invention
Fig. 1 is CdWO4Scanning electron microscope (SEM) photograph；
Fig. 2 is the scanning electron microscope (SEM) photograph of BiOCl；
The CdWO that Fig. 3 is 25%4The scanning electron microscope (SEM) photograph of/BiOCl；
Fig. 4 is 25%CdWO4The transmission electron microscope picture of/BiOCl；
Fig. 5 is 25%CdWO4The elemental analysis figure of/BiOCl；
Fig. 6 is CdWO4, BiOCl and difference CdWO4The X ray diffracting spectrum of/BiOCl；
Fig. 7 is CdWO4, BiOCl and difference CdWO4The UV Diffuse Reflectance Spectroscopy figure of/BiOCl；
The CdWO that Fig. 8 is 25%4The band gap diagram of/BiOCl and BiOCl；
Fig. 9 is CdWO4/ BiOCl hetero-junctions separates photo-generate electron-hole to process schematic；
Figure 10 is BiOCl, CdWO4And 25%CdWO4The photoelectric current of/BiOCl is accordingly schemed；
Figure 11 is BiOCl, CdWO4, 15%CdWO4/ BiOCl, 25%CdWO4/ BiOCl and 35%CdWO4The light of/BiOCl
Catalytic degradation activity figure；
Figure 12 is the 25%CdWO of synthesis4Degradation of phenol the ultraviolet of/BiOCl hetero-junctions under simulated solar irradiation irradiation can
See abosrption spectrogram.
Specific embodiment
Technology contents, construction feature, the objects and the effects for detailed description technical solution, below in conjunction with specific reality
It applies example and attached drawing is cooperated to be explained in detail.
CdWO in present embodiment4It is all to be synthesized by hydro-thermal method, specific preparation process is as follows: by 10mmol's
CdCl2·2.5H2O (2.2836g) is dissolved in 20ml distilled water, obtains CdCl2Solution.
By the Na of 10mmol2WO4·2H2O (3.2988g) obtains Na in being dissolved in 20mL distilled water2WO4Solution.
By Na while stirring2WO4Solution instills CdCl2In solution, after being stirred for 30 minutes, the mixture that will obtain
It is transferred in the stainless steel autoclave of 50ml polytetrafluoroethyllining lining, 12h is reacted at 180 DEG C, is finally naturally cooling to room temperature,
Product is washed with distilled water, is dried, CdWO is obtained4Powder.
Embodiment 2:25%CdWO4/ BiOCl catalyst preparation
First suspension is prepared: by 1mmol CdWO4(0.3603g) is added in 20ml distilled water, is uniformly dispersed, and obtains the
One suspension；
First solution is prepared: by 3mmolBi (NO3)3·5H2O (1.4552g) and 3mmol KCl (0.2236g) is dissolved in
In 20ml ethylene glycol, the first solution is obtained；
KCl can sufficiently dissolve in water and ethylene glycol, and ethylene glycol and water can dissolve each other.
CdWO4/ BiOCl suspension is prepared: being added dropwise the first solution dropwise into the first suspension, stirring the during being added dropwise
One solution；The mixture that obtains after dropwise addition continuously stirs 5 hours in 80 DEG C of water-baths, obtains CdWO after being cooled to room temperature4/
BiOCl suspension；
It is separated by solid-liquid separation: the CdWO that will be obtained4/ BiOCl suspension is separated by solid-liquid separation, washing precipitate, and to washing after
Sediment is dried, and obtains 25%CdWO4/ BiOCl heterojunction photocatalyst.
The CdWO of embodiment 3:15%4/ BiOCl catalyst preparation
First suspension is prepared: by 1.5mmol CdWO4It is added in 30ml distilled water, is uniformly dispersed, it is suspended to obtain first
Liquid；
First solution is prepared: by 8.5mmolBi (NO3)3·5H2O and 8.5mmol KCl are dissolved in 30ml ethylene glycol, are obtained
First solution；
CdWO4/ BiOCl suspension is prepared: being added dropwise the first solution dropwise into the first suspension, stirring the during being added dropwise
One solution, the mixture that obtains after dropwise addition continuously stir 5 hours in 80 DEG C of water-baths, obtain CdWO after being cooled to room temperature4/
BiOCl suspension；
It is separated by solid-liquid separation: the CdWO that will be obtained4/ BiOCl suspension is separated by solid-liquid separation, washing precipitate, and to washing after
Sediment is dried, and obtains 15%CdWO4/ BiOCl heterojunction photocatalyst.
The CdWO of embodiment 4:35%4/ BiOCl catalyst preparation
First suspension is prepared: by 3.5mmol CdWO4It is added in 30ml distilled water, is uniformly dispersed, it is suspended to obtain first
Liquid；
First solution is prepared: by 6.5mmolBi (NO3)3·5H2O and 6.5mmol KCl are dissolved in 30ml ethylene glycol, are obtained
First solution；
CdWO4/ BiOCl suspension is prepared: being added dropwise the first solution dropwise into the first suspension, stirring the during being added dropwise
One solution,；The mixture that obtains after dropwise addition continuously stirs 5 hours in 80 DEG C of water-baths, obtains CdWO after being cooled to room temperature4/
BiOCl suspension；
It is separated by solid-liquid separation: the CdWO that will be obtained4/ BiOCl suspension is separated by solid-liquid separation, washing precipitate, and to washing after
Sediment is dried, and obtains 35%CdWO4/ BiOCl heterojunction photocatalyst.
The CdWO of embodiment 5:5%4/ BiOCl catalyst preparation
First suspension is prepared: by 0.5mmolCdWO4It is added in 10ml distilled water, is uniformly dispersed, it is suspended to obtain first
Liquid；
First solution is prepared: by 9.5mmolBi (NO3)3·5H2O and 9.5mmol KCl are dissolved in 30ml ethylene glycol, are obtained
First solution；
CdWO4/ BiOCl suspension is prepared: being added dropwise the first solution dropwise into the first suspension, stirring the during being added dropwise
One solution；The mixture that obtains after dropwise addition continuously stirs 10 hours in 60 DEG C of water-baths, obtains CdWO after being cooled to room temperature4/
BiOCl suspension；
It is separated by solid-liquid separation: the CdWO that will be obtained4/ BiOCl suspension is separated by solid-liquid separation, washing precipitate, and to washing after
Sediment is dried, and obtains 5%CdWO4/ BiOCl heterojunction photocatalyst.
Performance detection is carried out with various p-n junction CdWO4/BiOCl heterojunction photocatalysts prepared by embodiment:
1, scanning electron microscope and transmission electron microscope detection:
CdWO prepared by embodiment 14, the 25%CdWO for preparing of BiOCl and embodiment 24The pattern of/BiOCl hetero-junctions is big
Small and microstructure is characterized by scanning electron microscope and transmission electron microscope.
Fig. 1 is CdWO4The scanning electron microscope (SEM) photograph of particle, as seen from the figure CdWO4Particle length 150-300nm, diameter 30-
50nm。
From Fig. 2 be BiOCl scanning electron microscope (SEM) photograph, by figure it is observed that BiOCl be length and width be about 600nm, thickness
For the nanometer chip architecture of 100nm.
Fig. 3 is 25%CdWO4/ BiOCl scanning electron microscope (SEM) photograph shows CdWO in figure4Nanometer rods are connected with BiOCl nanometer sheet
Form heterojunction structure.
Fig. 4 is 25%CdWO4The transmission electron microscope picture of/BiOCl, TEM image further confirm CdWO4Nanometer rods are received with BiOCl
Rice piece surface connects and composes CdWO4/BiOCl hetero-junctions.
In order to further confirm that the component of synthetic product, elemental analysis has been carried out to sample.In Figure 52 5%CdWO4/
It is observed that CdWO in the elemental analysis figure of BiOCl4Contain Cd, W, Bi, O and Cl elemental characteristic in the EDS spectrum of/BiOCl
Peak, and do not detect other elements, show heterojunction structure by CdWO4It is constituted with BiOCl.
2, X-ray diffraction is tested:
Fig. 6 is CdWO4, BiOCl and difference CdWO4The X ray diffracting spectrum of/BiOCl；
By Fig. 6 it will be clear that CdWO4The crystal face (110), (- 111), (111), (020) and (021) showed
With monoclinic system CdWO4(JCPDS No.87-1114) height is consistent.For BiOCl, 24.50 °, 26.72 °, 32.69 °,
33.95 ° and 37.23 ° of diffraction maximum, correspond respectively to (002) of tetragonal crystal system BiOCl (JCPDS 06-0249), (101),
(110), the crystal face of (102) and (003).In CdWO4In/BiOCl hetero-junctions, XRD spectra shows CdWO4With the feature of BiOCl
Peak shows CdWO4/ BiOCl hetero-junctions is by CdWO4With BiOCl composition.
With CdWO4CdWO in/BiOCl compound4The increase of ratio, some characteristic peaks especially (- 111), (111) and
(021) relative intensity for (" ■ " being indicated in Fig. 6) is increased slightly, this further illustrates the CdWO in hetero-junctions4Presence.
3, UV-vis DRS detects:
Fig. 7 is CdWO4, BiOCl and difference CdWO4The UV Diffuse Reflectance Spectroscopy figure of/BiOCl.As shown in fig. 7, CdWO4It inhales
It receives at the about 370nm of side, and BiOCl ABSORPTION EDGE is at 390nm.CdWO4/ BiOCl hetero-junctions has and CdWO4It is similar with BiOCl
DRS.
With pure CdWO4It compares, CdWO4The optical absorption edge of/BiOCl hetero-junctions with the BiOCl content in hetero-junctions increasing
Add, ABSORPTION EDGE gradually happens red shift.Uv drs spectrogram based on semiconductor can calculate it by following formula
Band gap:
Ahv=A (hv-Eg)n/2 (1)
Wherein a is absorption coefficient, and h is Planck's constant, and v is the frequency of light, and A is constant, and Eg is band gap.In this public affairs
In formula, n is the coefficient determined by optics migration type (n=1 is direct transition, and n=4 is indirect transition).Therefore, for
Indirect band gap semiconductor CdWO4And BiOCl, n value are 4.
The band gap diagram of CdWO4/BiOCl and BiOCl that Fig. 8 is 25%；It is (ahv)n/2It maps to hv, can be obtained from figure
CdWO out4It calculates separately with the band gap of BiOCl as 3.08eV and 3.01eV.In addition, the current potential of valence band (VB) and conduction band (CB) can
It is obtained by Mulliken equation:
ECB=X-EC–0.5Eg (2)
EVB=ECB+Eg (3)
Wherein Eg、X、ECBe respectively the free electron energy of band-gap energy, the absolute electronegativity of semiconductor and hydrogen scale (about
4.5eV or so).EVBIndicate valence band, ECBIndicate conduction band.In addition, CdWO4X value with BiOCl is respectively 6.28eV and 6.36eV.
By above-mentioned equation, CdWO is calculated4VB and CB be respectively 3.32eV and 0.24eV, the VB and CB of BiOCl is respectively
3.36eV and 0.35eV.
Fig. 9 is CdWO4/ BiOCl hetero-junctions separates photo-generate electron-hole to process schematic；Wherein left side expression is
CdWO4With the band structure of BiOCl.As p-type semiconductor, the fermi level of BiOCl is located near VB.On the contrary, CdWO4It is one
Kind n-type semiconductor, fermi level are located near CB.
However, when forming type CdWO4When/BiOCl hetero-junctions, n-type semiconductor energy band will decline, and p-type semiconductor energy band will
It increases, until the fermi level of the two reaches equilibrium state.Therefore, when the fermi level of hetero-junctions reaches balance, interface
Internal electric field will be generated, this is conducive to the separation of photo-generated carrier.Due to the influence of internal electric field, positive charge is gathered in CdWO4Area
Domain, and negative electrical charge then concentrates on the region BiOCl.When light irradiates CdWO4When/BiOCl hetero-junctions, photoproduction is generated by photon excitation
Electron-hole pair.Electronics (e on the CB of BiOCl-) CdWO can be transferred to by the internal electrostatic gesture of hetero-junctions4CB on.
And CdWO4Hole then moves in the VB of BiOCl, so that photoelectron and hole can efficiently separate, promotes photocatalytic activity
Raising.
4, photoelectricity current test:
For photocatalytic degradation efficiency, the recombination rate in light induced electron and hole be the important influence of one of them because
Element.It is tested using photoelectric current, the CdWO under simulated solar irradiation irradiation can be measured4, BiOCl and 25%CdWO4/ BiOCl hetero-junctions
The separating effect of upper electric charge carrier.As a result such as Figure 10 BiOCl, CdWO4And 25%CdWO4The photoelectric current of/BiOCl accordingly schemes institute
Show.
It can be with as seen from Figure 10 25% CdWO4/ BiOCl hetero-junctions is than single CdWO4Have with BiOCl stronger
Photo-current intensity.Photo-current intensity can be used to speculate the separative efficiency of electron-hole pair, and this is largely urged with light
It is relevant for changing activity.The experimental results showed that 25%CdWO4/ BiOCl hetero-junctions can reduce the compound of light induced electron and hole,
To improve separative efficiency.
5, photocatalytic activity series of tests:
Using rhodamine B as organic dye pollutant, under simulated solar irradiation irradiation, to the photocatalytic activity of synthetic sample
It is assessed.
Method particularly includes: using rhodamine B and phenol as simulating pollution object, analyze the photocatalysis performance of photochemical catalyst.It is first
First by 0.05g or 0.1g sample dispersion in 100ml rhodamine B solution (2 × 10-5) or 50ml phenol solution (50mg/L) mol/L
In, it is protected from light and stirs 30min in the dark, sample and solution is made to reach adsorption-desorption balance.Then, suspension is placed in 300W xenon
It is irradiated under lamp.In irradiation process, it is taken out a sample every 3min (or 1h), and be centrifuged with separating catalyst powder.Finally,
Supernatant is analyzed with UV1902 ultraviolet-uisible spectrophotometer.The degradation state of rhodamine B and phenol can use C/C0Come
It indicates, wherein C0It is that the initial concentration of rhodamine B or phenol, C are that representative is a certain in illumination before illumination after reaching adsorption equilibrium
The concentration of moment rhodamine B or phenol.
(the C/C of rhodamine B solution0) and the degradation curve of radiated time it is as shown in figure 11.Figure 11 is BiOCl, CdWO4、
15%CdWO4The Photocatalytic activity figure of/BiOCl, 25%CdWO4/BiOCl and 35%CdWO4/BiOCl.
For pure CdWO4, after simulated solar irradiation irradiates 18min, the degradation efficiency of rhodamine B is very low, and BiOCl is in mould
Quasi- sunlight irradiation following table reveals very big degrading activity, degradable 90% rhodamine B in 18min.With individual CdWO4
It is compared with BiOCl, all hetero-junctions all show higher degradation efficiency.Work as CdWO4Content from 15% increase to 35% when,
CdWO4The catalytic efficiency of/BiOCl hetero-junctions first improves, when ratio reaches 25%, CdWO4/ BiOCl hetero-junctions shows highest
Photocatalysis efficiency, rhodamine B is degradable at 15 minutes, then as CdWO4Content further increase, photocatalysis effect
Rate and then decline.Therefore it can thus be seen that CdWO4The formation of/BiOCl hetero-junctions can significantly improve the photocatalysis of semiconductor
Activity.This phenomenon can be explained by the synergistic effect of heterojunction structure.With CdWO in hetero-junctions4The increase of content,
CdWO4More heterojunction boundaries are formd between BiOCl, to isolate more photo-generated carriers.However, with
CdWO4CdWO in/BiOCl hetero-junctions4Content further increases, and photocatalysis performance decline, this may be interpreted as the mistake in BiOCl
The CdWO of amount4Load can hinder the sunlight of BiOCl to capture.Therefore, the only CdWO of optimal proportion4Photocatalytic can be improved
Energy.
Under simulated solar irradiation irradiation, further using phenol solution as simulating pollution object to 25%CdWO4/
The photocatalytic activity of BiOCl hetero-junctions is assessed.The result is shown in Figure 12: the 25%CdWO4/BiOCl hetero-junctions of synthesis is being simulated
The ultraviolet-visible absorption spectroscopy figure of degradation of phenol under sunlight irradiation.
As shown in figure 12, absorption peak of the phenol at 270nm is as the extension of light application time declines and finally disappears.In 6h
After illumination, the degradation rate of phenol solution is close to 100%.The result shows that for the photocatalytic degradation of phenol, 25%CdWO4/
BiOCl hetero-junctions also presents excellent performance.
The result shows that compared to single CdWO4And BiOCl, all CdWO4The photocatalysis performance of/BiOCl hetero-junctions is all
It is significant to improve, as optimum mole ratio CdWO4When/BiOCl is 25%, respectively can 15min and 6h to rhodamine and phenol into
Row is fully degraded.
The CdWO prepared in present embodiment4/ BiOCl heterojunction photocatalyst can be mixed with other types catalyst
Or assembled together with controllable light source, constitute catalyst prod, the degradation for rhodamine in waste water and phenol.
It should be noted that, in this document, relational terms such as first and second and the like are used merely to a reality
Body or operation are distinguished with another entity or operation, are deposited without necessarily requiring or implying between these entities or operation
In any actual relationship or order or sequence.Moreover, the terms "include", "comprise" or its any other variant are intended to
Non-exclusive inclusion, so that the process, method, article or the terminal device that include a series of elements not only include those
Element, but also including other elements that are not explicitly listed, or further include for this process, method, article or end
The intrinsic element of end equipment.In the absence of more restrictions, being limited by sentence " including ... " or " including ... "
Element, it is not excluded that there is also other elements in process, method, article or the terminal device for including the element.This
Outside, herein, " being greater than ", " being less than ", " being more than " etc. are interpreted as not including this number；" more than ", " following ", " within " etc. understand
Being includes this number.
It should be noted that being not intended to limit although the various embodiments described above have been described herein
Scope of patent protection of the invention.Therefore, it based on innovative idea of the invention, change that embodiment described herein is carried out and is repaired
Change, or using equivalent structure or equivalent flow shift made by description of the invention and accompanying drawing content, it directly or indirectly will be with
Upper technical solution is used in other related technical areas, is included within scope of patent protection of the invention.
Claims (9)
1. a kind of p-n junction CdWO4/ BiOCl heterojunction photocatalyst, which is characterized in that the catalyst includes CdWO4Particle with
BiOCl particle；The CdWO4Particle forms CdWO in conjunction with the BiOCl particle4/ BiOCl hetero-junctions.
2. p-n junction CdWO according to claim 14/ BiOCl heterojunction photocatalyst, which is characterized in that the CdWO4Grain
The molar ratio of son and BiOCl particle is 5-35:65-95.
3. p-n junction CdWO according to claim 24/ BiOCl heterojunction photocatalyst, which is characterized in that the CdWO4Grain
The molar ratio of son and BiOCl particle is 25:75.
4. p-n junction CdWO according to claim 14/ BiOCl heterojunction photocatalyst, which is characterized in that the CdWO4Grain
Son is club shaped structure, length 150-300nm, diameter 30-50nm；The BiOCl particle is laminated structure, and length is
500nm-700nm, width 500nm-700nm, with a thickness of 80-120nm.
5. any p-n junction CdWO of claim 1-44The preparation method of/BiOCl heterojunction photocatalyst, feature exist
In the preparation method comprises the following steps:
First suspension is prepared: by CdWO4It is added to the water, is uniformly dispersed, obtains the first suspension；
First solution is prepared: by Bi (NO3)3·5H2O and KCl are dissolved in ethylene glycol, obtain the first solution；
CdWO4/ BiOCl suspension is prepared: the first solution is added dropwise into the first suspension, stirring first is suspended during being added dropwise
Liquid；After dropwise addition obtain mixture 60-100 DEG C water-bath 4-8 hours, be stirred during water-bath, mixed after the completion of water-bath
Object obtains CdWO after being cooled to room temperature4/ BiOCl suspension；
It is separated by solid-liquid separation: the CdWO that will be obtained4/ BiOCl suspension is separated by solid-liquid separation, washing precipitate, and to sediment after washing
It is dried, obtains p-n junction CdWO4/ BiOCl heterojunction photocatalyst.
6. preparation method according to claim 5, which is characterized in that the CdWO4、Bi(NO3)3Molar ratio with KCl is
5-35:65-95:65-95.
7. preparation method according to claim 5, which is characterized in that the CdWO4For CdCl2With Na2WO4Pass through hydro-thermal method
Synthesis, preparation process the following steps are included:
By Na2WO4Solution and CdCl2Solution is stirred mixing, obtains the second suspension；
Second suspension is put into autoclave, 150-200 DEG C reaction 10-15 hours, obtain reactant, reactant washed dry
CdWO is obtained after dry4, the CdCl2With Na2WO4Molar ratio be 1:1.
8. any p-n junction CdWO of claim 1-44/ BiOCl heterojunction photocatalyst is in Photocatalytic Degradation of Phenol and sieve
The purposes of red bright B.
9. a kind of catalyst prod, which is characterized in that the product includes any p-n junction CdWO of claim 1-44/
BiOCl heterojunction photocatalyst.
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