CN114950402A - TiO 2 /CeO 2 Heterojunction photocatalyst and preparation method thereof - Google Patents
TiO 2 /CeO 2 Heterojunction photocatalyst and preparation method thereof Download PDFInfo
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- 239000011941 photocatalyst Substances 0.000 title claims abstract description 55
- 229910010413 TiO 2 Inorganic materials 0.000 title claims abstract description 37
- 238000002360 preparation method Methods 0.000 title claims abstract description 30
- 238000006243 chemical reaction Methods 0.000 claims abstract description 42
- 239000000725 suspension Substances 0.000 claims abstract description 29
- 238000005406 washing Methods 0.000 claims abstract description 26
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims abstract description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 238000001035 drying Methods 0.000 claims abstract description 16
- 238000002156 mixing Methods 0.000 claims abstract description 13
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 8
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 60
- 229910052684 Cerium Inorganic materials 0.000 claims description 16
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 11
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 11
- 238000001354 calcination Methods 0.000 claims description 10
- 239000002105 nanoparticle Substances 0.000 claims description 9
- 238000001914 filtration Methods 0.000 claims description 7
- 238000000227 grinding Methods 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 24
- 239000001257 hydrogen Substances 0.000 abstract description 24
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 24
- 230000001699 photocatalysis Effects 0.000 abstract description 13
- 230000000694 effects Effects 0.000 abstract description 5
- 239000000243 solution Substances 0.000 description 28
- 239000000047 product Substances 0.000 description 19
- 229910021642 ultra pure water Inorganic materials 0.000 description 12
- 239000012498 ultrapure water Substances 0.000 description 12
- 239000003054 catalyst Substances 0.000 description 10
- 238000003756 stirring Methods 0.000 description 9
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- 230000000052 comparative effect Effects 0.000 description 6
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- 238000011068 loading method Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 5
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- 238000001816 cooling Methods 0.000 description 4
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- 150000001875 compounds Chemical class 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 2
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000031700 light absorption Effects 0.000 description 2
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- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 1
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- 238000011065 in-situ storage Methods 0.000 description 1
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- 238000006862 quantum yield reaction Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
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- 238000001308 synthesis method Methods 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
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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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
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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
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
- B01J21/063—Titanium; Oxides or hydroxides thereof
-
- 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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/002—Mixed oxides other than spinels, e.g. perovskite
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- B01J35/23—
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- B01J35/39—
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/04—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of inorganic compounds, e.g. ammonia
- C01B3/042—Decomposition of water
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/30—Wastewater or sewage treatment systems using renewable energies
- Y02W10/37—Wastewater or sewage treatment systems using renewable energies using solar energy
Abstract
The invention discloses a TiO2 2 /CeO 2 Heterojunction photocatalyst and preparation method thereof, and TiO 2 /CeO 2 The preparation method of the heterojunction photocatalyst comprises the following steps: s1, obtaining cubic CeO 2 And dissolving it in water to obtain CeO 2 A suspension; s2, mixing TiCl 4 Is added to CeO 2 In the suspension, obtaining a pre-product after reaction; s3, washing and drying the pre-product to obtain TiO 2 /CeO 2 A heterojunction photocatalyst. TiO of the invention 2 /CeO 2 The heterojunction photocatalyst has excellent photocatalytic hydrogen evolution effect.
Description
Technical Field
The invention relates to the preparation of photocatalystsIn particular to a TiO 2 /CeO 2 A heterojunction photocatalyst and a preparation method thereof.
Background
With the increasing global energy shortage problem, the search for new environmentally friendly energy sources to replace the traditional fossil energy sources is urgent. Solar energy is inexhaustible due to inexhaustibility of the solar energy, and is distinguished from a plurality of sustainable new energy sources, so that an environment purification technology and an energy conversion technology formed by converting the solar energy into chemical energy and the like are widely researched by various circles. In recent years, scientific research work for converting solar energy into hydrogen energy by using a photocatalyst is increasingly mature, the generated hydrogen is used as fuel, energy conversion and utilization can be realized, the byproduct water has no pollution to the environment, the problems of energy scarcity, environmental pollution and the like can be solved to a great extent, and the method has important application prospects in the fields of energy and environmental protection.
In order to develop the photocatalytic technology, the search for a semiconductor catalyst with excellent performance is the key of the attack. At present, TiO 2 The catalyst is an early-researched and widely-applied catalyst, but the band gap is wide, the catalyst is ultraviolet response type, and the single catalyst has the problem of high carrier recombination efficiency, so that the intrinsic photocatalytic activity is low, and the hydrogen production rate of photocatalytic hydrogen evolution is low.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The invention aims to provide TiO 2 /CeO 2 A heterojunction photocatalyst having an excellent photocatalytic hydrogen evolution effect.
Another object of the present invention is to provide a TiO compound 2 /CeO 2 A preparation method of a heterojunction photocatalyst.
To achieve the above object, embodiments of the present invention provide a TiO 2 /CeO 2 The preparation method of the heterojunction photocatalyst comprises the following steps:
s1, obtaining cubic CeO 2 And dissolving it in water to obtain CeO 2 A suspension;
s2, mixing TiCl 4 Is added to CeO 2 In the suspension, obtaining a pre-product after reaction;
s3, washing and drying the pre-product to obtain TiO 2 /CeO 2 A heterojunction photocatalyst.
In one or more embodiments of the invention, CeO is obtained in the form of cubes 2 Comprises the following steps:
s11, dissolving a cerium source in water, and uniformly mixing to obtain a cerium source solution;
s12, adding a sodium hydroxide solution into the cerium source solution, and reacting to obtain a reaction solution;
s13, filtering, washing, drying and grinding the reaction solution to obtain a primary product;
s14, placing the primary product in a muffle furnace to calcine to obtain cubic CeO 2 。
In one or more embodiments of the invention, the cerium source is Ce (NO) 3 ) 3 ·6H 2 O; and/or the presence of a gas in the gas,
the concentration of the sodium hydroxide solution is 4 mol/L.
In one or more embodiments of the present invention, the step S12 specifically includes: adding a sodium hydroxide solution into the cerium source solution, mixing, transferring to a high-pressure hydrothermal reaction kettle, and reacting for 11-13h at the temperature of 180-190 ℃ to obtain a reaction solution.
In one or more embodiments of the invention, the conditions of the calcination are:
heating to 450 ℃ at the heating rate of 4-6 ℃/min, wherein the calcining time is as follows: 3-3.5 h.
In one or more embodiments of the invention, the reaction conditions after the reaction to obtain the pre-product are:
the reaction time is 6-7h, and the reaction temperature is 115-125 ℃.
In one or more embodiments of the invention, the step of washing the pre-product comprises:
the pre-product was washed at least three times with water.
In one or more embodiments of the invention, the step of washing the pre-product further comprises:
the water-washed pre-product was washed at least twice with ethanol.
The embodiment of the invention also provides TiO 2 /CeO 2 The heterojunction photocatalyst is prepared by the preparation method.
In one or more embodiments of the invention, CeO in the form of cubes is included 2 And CeO supported on the cube 2 Surface TiO 2 The number of the nano-particles is,
wherein the TiO is 2 With the CeO 2 The mass ratio of (1-4): 10; preferably, the TiO is 2 With the CeO 2 The mass ratio of (A) to (B) is 3: 10.
TiO according to embodiments of the present invention, as compared to the prior art 2 /CeO 2 Heterojunction photocatalyst of CeO 2 Middle Ce 3+ And Ce 4+ The reversible conversion between the two can improve the mobility of electrons, inhibit the recombination of photo-generated charges and improve the photocatalytic hydrogen evolution activity. In addition, the structure of the heterojunction not only widens the visible light absorption range, but also improves the separation efficiency of the photon-generated carriers. In addition, the heterogeneous structure of the nano particles and the cube can fully expose catalytic active sites, and the catalytic efficiency is improved.
Drawings
FIG. 1 is a TiO according to an embodiment of the invention 2 /CeO 2 A flow diagram of a method of preparing a heterojunction photocatalyst;
FIG. 2 is a cubic CeO according to an embodiment of the present invention 2 A flow chart of the preparation method of (1);
FIG. 3 is a graph of photocatalytic hydrogen evolution test data for examples 1-4 according to the present invention and comparative examples 1 and 2;
FIG. 4 is a TiO embodiment according to the invention 2 /CeO 2 A hydrogen evolution yield cycle test data graph of the heterojunction photocatalyst;
FIG. 5 is a graph according toTiO of one embodiment of the invention 2 /CeO 2 An AQE measurement data graph of the heterojunction photocatalyst under different wavelengths;
FIG. 6 is an embodiment of a TiO compound in accordance with the invention 2 /CeO 2 The heterojunction photocatalyst is subjected to hydrogen evolution blank experiment tests under the conditions of no illumination and no catalyst.
Detailed Description
The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.
As shown in FIGS. 1 and 2, TiO according to a preferred embodiment of the present invention 2 /CeO 2 The preparation method of the heterojunction photocatalyst comprises the following steps:
s1, obtaining cubic CeO 2 And dissolving it in water, stirring the resulting CeO 2 And (3) suspension.
In step S1, cubic CeO is obtained 2 Comprises the following steps:
and S11, dissolving the cerium source in water, and uniformly mixing to obtain a cerium source solution.
Specifically, the cerium source is Ce (NO) 3 ) 3 ·6H 2 And O. The cerium source may also be other cerium salts.
And S12, adding a sodium hydroxide solution into the cerium source solution, and reacting to obtain a reaction solution.
Specifically, a sodium hydroxide solution is added into a cerium source solution, mixed and then transferred into a high-pressure hydrothermal reaction kettle, and the mixture is reacted for 11 to 13 hours at the temperature of 180-190 ℃ to obtain a reaction solution. Wherein the concentration of the sodium hydroxide solution (which can be understood as the aqueous solution of sodium hydroxide) is 2-8mol/L, and the concentration of the sodium hydroxide solution is preferably 4 mol/L.
S13, filtering, washing, drying and grinding the reaction solution to obtain a primary product.
S14, placing the primary product in a muffle furnace to calcine to obtain cubic CeO 2 。
Specifically, the conditions for calcination may be: heating to 450 ℃ at the heating rate of 4-6 ℃/min, wherein the calcining time is as follows: 3-3.5 h.
S2, mixing TiCl 4 Is added to CeO 2 In suspension, the pre-product is obtained after the reaction.
In S2, the reaction time is 6-7h, and the reaction temperature is 115-125 ℃.
S3, washing and drying the pre-product to obtain TiO 2 /CeO 2 A heterojunction photocatalyst.
In S3, the step of washing the pre-product comprises: washing the pre-product with water at least three times; and then washed at least twice with ethanol. The water washing is to remove a small amount of salts generated in the preparation process of the catalyst, and the ethanol washing is to remove water, so that the subsequent drying does not need to be heated to more than 100 ℃, and the energy consumption is saved.
The embodiment of the invention also provides TiO 2 /CeO 2 The heterojunction photocatalyst is prepared by the preparation method.
TiO 2 /CeO 2 The heterojunction photocatalyst comprises cubic CeO 2 And CeO supported on the cube 2 Surface TiO 2 Nanoparticles of which TiO is 2 With CeO 2 The mass ratio of (1-4): 10; preferably, TiO 2 With CeO 2 The mass ratio of (A) to (B) is 3: 10.
the TiO of the present invention will be explained in detail with reference to specific examples 2 /CeO 2 A heterojunction photocatalyst and a preparation method thereof.
Example 1
Cubic CeO 2 The preparation of (1):
a. 5.0459g of Ce (NO) are weighed out on an electronic balance 3 ) 3 ·6H 2 Placing the mixture in 30mL of ultrapure water for ultrasonic dissolution, and performing ultrasonic treatment for 5min to ensure that the salt solution is uniformly mixed for later use;
b. weighing 8.0000g of NaOH by an electronic balance to dissolve into 50mL of ultrapure water, wherein the concentration of NaOH alkali solution is 4mol/L, and ultrasonic dissolution is uniform for later use;
c. mixing the uniformly dissolved alkali solution with the salt solution and stirring for 1 h. Transferring the mixed solution to a high-pressure hydrothermal reaction kettle at 180 DEG CPerforming hydrothermal reaction in an oven for 12 hours. After the reaction is finished, cooling to room temperature, filtering, washing, drying and grinding to obtain CeO 2 And (5) obtaining an initial product. Calcining the CeO powder in a muffle furnace at 450 ℃ for 3h at the heating rate of 5 ℃/min to obtain the final sample cube CeO 2 。
TiO 2 /CeO 2 Preparation of heterojunction photocatalyst:
1g of prepared cubic CeO was weighed 2 Put into 25mL of ultrapure water and stirred to form a uniform suspension, and then 0.237g of anhydrous TiCl is added 4 Quickly adding into the suspension, stirring at room temperature under sealed condition for 30 min. Then placing the mixed suspension into a high-pressure reaction kettle for reaction for 6 hours at 120 ℃, washing the mixed suspension with water for three times and washing the mixed suspension with ethanol for two times after the reaction is finished, and placing the mixed suspension into a vacuum drying oven for drying at 60 ℃ to obtain TiO 2 /CeO 2 A heterojunction photocatalyst.
Example 2
Cubic form of CeO 2 The preparation of (1):
a. 5.0459g of Ce (NO) are weighed out on an electronic balance 3 ) 3 ·6H 2 Placing the mixture in 30mL of ultrapure water for ultrasonic dissolution, and performing ultrasonic treatment for 5min to ensure that the salt solution is uniformly mixed for later use;
b. 8.0000g of NaOH is weighed by an electronic balance and dissolved in 50mL of ultrapure water, the concentration of NaOH aqueous solution is 4mol/L, and the solution is uniformly dissolved by ultrasonic for standby;
c. mixing the uniformly dissolved alkali solution with the salt solution and stirring for 1 h. Transferring the mixed solution into a high-pressure hydrothermal reaction kettle, and carrying out hydrothermal reaction in an oven at 180 ℃ for 12 hours. After the reaction is finished, cooling to room temperature, filtering, washing, drying and grinding to obtain CeO 2 And (5) obtaining an initial product. Calcining the CeO powder in a muffle furnace at 450 ℃ for 3h at the heating rate of 5 ℃/min to obtain the final sample cube CeO 2 。
TiO 2 /CeO 2 Preparation of heterojunction photocatalyst:
1g of prepared cubic CeO was weighed 2 Put into 25mL of ultrapure water and stirred to form a uniform suspension, and then 0.474g of anhydrous TiCl is added 4 Quickly adding into the suspension, stirring at room temperature under sealed condition for 30 min. Then the mixed suspension is put into a high-pressure reactionReacting for 6 hours at 120 ℃ in a kettle, washing with water for three times and ethanol for two times after the reaction is finished, and drying in a vacuum drying oven at 60 ℃ to obtain TiO 2 /CeO 2 A heterojunction photocatalyst.
Example 3
Cubic CeO 2 The preparation of (1):
a. 5.0459g of Ce (NO) are weighed out on an electronic balance 3 ) 3 ·6H 2 Placing the mixture in 30mL of ultrapure water for ultrasonic dissolution, and performing ultrasonic treatment for 5min to ensure that the salt solution is uniformly mixed for later use;
b. weighing 8.0000g of NaOH by an electronic balance to dissolve into 50mL of ultrapure water, wherein the concentration of NaOH alkali solution is 4mol/L, and ultrasonic dissolution is uniform for later use;
c. mixing the uniformly dissolved alkali solution with the salt solution and stirring for 1 h. Transferring the mixed solution into a high-pressure hydrothermal reaction kettle, and carrying out hydrothermal reaction in an oven at 180 ℃ for 12 hours. After the reaction is finished, cooling to room temperature, filtering, washing, drying and grinding to obtain CeO 2 And (5) obtaining an initial product. Calcining the CeO powder in a muffle furnace at 450 ℃ for 3h at the heating rate of 5 ℃/min to obtain the final sample cube CeO 2 。
TiO 2 /CeO 2 Preparation of heterojunction photocatalyst:
1g of prepared cubic CeO was weighed 2 Put into 25mL of ultrapure water and stirred to form a uniform suspension, and then 0.711g of anhydrous TiCl is added 4 Quickly adding into the suspension, stirring at room temperature under sealed condition for 30 min. Then placing the mixed suspension into a high-pressure reaction kettle for reaction for 6 hours at 120 ℃, washing the mixed suspension with water for three times and washing the mixed suspension with ethanol for two times after the reaction is finished, and placing the mixed suspension into a vacuum drying oven for drying at 60 ℃ to obtain TiO 2 /CeO 2 A heterojunction photocatalyst.
Example 4
Cubic CeO 2 The preparation of (1):
a. 5.0459g of Ce (NO) are weighed out on an electronic balance 3 ) 3 ·6H 2 Placing the mixture into 30mL of ultrapure water for ultrasonic dissolution, and performing ultrasonic treatment for 5min to ensure that the salt solutions are uniformly mixed for later use;
b. 8.0000g of NaOH is weighed by an electronic balance and dissolved in 50mL of ultrapure water, the concentration of NaOH aqueous solution is 4mol/L, and the solution is uniformly dissolved by ultrasonic for standby;
c. mixing the uniformly dissolved alkali solution with the salt solution and stirring for 1 h. Transferring the mixed solution into a high-pressure hydrothermal reaction kettle, and carrying out hydrothermal reaction in an oven at 180 ℃ for 12 hours. After the reaction is finished, cooling to room temperature, filtering, washing, drying and grinding to obtain CeO 2 And (5) obtaining an initial product. Calcining the CeO powder in a muffle furnace at 450 ℃ for 3h at the heating rate of 5 ℃/min to obtain the final sample cube CeO 2 。
TiO 2 /CeO 2 Preparation of heterojunction photocatalyst:
1g of prepared cubic CeO was weighed 2 Put into 25mL of ultrapure water and stirred into a uniform suspension, and then 0.948g of anhydrous TiCl is added 4 Quickly adding into the suspension, stirring at room temperature under sealed condition for 30 min. Then placing the mixed suspension into a high-pressure reaction kettle for reaction for 6 hours at 120 ℃, washing the mixed suspension with water for three times and washing the mixed suspension with ethanol for two times after the reaction is finished, and placing the mixed suspension into a vacuum drying oven for drying at 60 ℃ to obtain TiO 2 /CeO 2 A heterojunction photocatalyst.
Comparative example 1
Using TiO 2 As a photocatalyst.
Comparative example 2
Using cubic CeO 2 As a photocatalyst (preparation method is shown in the examples).
The photocatalysts of examples 1 to 4 and comparative examples 1 and 2 were subjected to a photocatalytic hydrogen evolution test:
in a photocatalytic water splitting test system equipped with a 300W xenon lamp (microsporan 300). The 300mL Pyrex reaction vessel was connected to a closed gas circulation and evacuation system at ambient temperature. Using H 2 PtCl 6 As a platinum source, 3 wt.% Pt nanoparticles were deposited on the surface of the photocatalyst using an in-situ photo-deposition method. Generation of H 2 Passing through an on-line gas chromatograph (Techcomp GC-7900, N) with Thermal Conductivity Detector (TCD) 2 As a carrier gas) for analysis. Typically, 100mg of photocatalyst was placed in 100mL of an aqueous solution containing 10 vol% TEOA. TEOA is used as a sacrificial agent. To avoid heating the solution during the reaction, water is passed throughA cylindrical Pyrex jacket positioned around the light source was cycled. Before the reaction started, air in the system was removed by a pump and data was recorded during the photocatalytic reaction, once per hour. And the light irradiation power in the reaction cell was controlled to 50 mW.cm -2 。
The following table data were obtained:
as can be seen from the above table, the TiO of the present invention 2 /CeO 2 The heterojunction photocatalyst has excellent catalytic effect.
As shown in fig. 3, fig. 3 is a graph of the hydrogen evolution yield over time for the samples after the addition of 3 wt.% Pt photo-deposition. In comparison with CeO alone 2 And TiO 2 ，TiO 2 /CeO 2 Hydrogen evolution yield of heterojunction photocatalysts with TiO 2 The loading capacity of the nano particles is obviously increased, and TiO 2 When the loading is 30 wt% (i.e. example 3), the compound after adding 3 wt.% of Pt for light deposition has the highest hydrogen evolution yield, and the highest hydrogen evolution rate can reach 37.7 μmol/h. For the 40 wt.% loading of the composite (i.e., example 4), the photocatalytic hydrogen evolution yield is reduced because the loading of the nanoparticles is too large, the catalytically active sites are covered, and the agglomeration phenomenon of the nanoparticles is severe, so that the recombination rate of the photo-generated electron-hole pairs is increased, and therefore, the catalytic activity is lower than that of the 30 wt.% loading. Wherein, TiO 2 A loading of 30 wt.% is understood to mean TiO 2 /CeO 2 TiO in heterojunction photocatalyst 2 With CeO 2 The mass ratio of (A) to (B) is 3: 10.
the six data lines in fig. 3 correspond to example 3, example 4, example 2, example 1, comparative example 1, and comparative example 1 in this order from top to bottom.
For example 3 TiO 2 /CeO 2 The hydrogen evolution yield cycle test of the heterojunction photocatalyst is carried out, the result is shown in fig. 4, the hydrogen evolution yield is almost not changed when the sample 30 wt.% of TiO2/CeO2 is cycled for 5 times, the total time is 25h, and the stability of the photocatalyst is good.
For example 3 TiO 2 /CeO 2 The data of the data shown in figure 5 shows that the value of AQE is reduced along with the increase of the wavelength, the variation trend is almost consistent with the absorption spectrum, and the apparent quantum yield AQE of the sample at 380nm is 16.3%.
For example 3 TiO 2 /CeO 2 The heterojunction photocatalyst was subjected to hydrogen evolution blank test in the absence of light and catalyst, respectively, and the data is shown in fig. 6. Wherein, the yield of hydrogen is almost zero, and the blank experimental chart indicates that light and catalyst are needed to participate in the hydrogen evolution experiment.
In conclusion, the TiO of the invention 2 /CeO 2 The heterojunction photocatalyst has the beneficial effects that:
1)CeO 2 middle Ce 3+ And Ce 4+ The reversible conversion between the two can improve the mobility of electrons, inhibit the recombination of photo-generated charges and improve the photocatalytic hydrogen evolution activity;
2) the heterojunction not only widens the visible light absorption range, but also improves the separation efficiency of photon-generated carriers. In addition, the heterogeneous structure of the nano particles and the cube can fully expose catalytic active sites, so that the catalytic efficiency is improved;
3) the inorganic catalyst has easily obtained raw materials, rich reserves and simple synthesis method, and provides possibility for subsequent industrial mass production;
4)TiO 2 /CeO 2 the heterojunction photocatalyst has excellent photocatalytic hydrogen evolution effect, and can lay an experimental foundation for industrialization of photocatalytic hydrogen production.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (10)
1. TiO2 2 /CeO 2 The preparation method of the heterojunction photocatalyst is characterized by comprising the following steps:
s1, obtaining cubic CeO 2 And dissolving it in water to obtain CeO 2 A suspension;
s2, mixing TiCl 4 Is added to CeO 2 In the suspension, obtaining a pre-product after reaction;
s3, washing and drying the pre-product to obtain TiO 2 /CeO 2 A heterojunction photocatalyst.
2. The TiO of claim 1 2 /CeO 2 A method for preparing a heterojunction photocatalyst is characterized in that cubic CeO is obtained 2 Comprises the following steps:
s11, dissolving a cerium source in water, and uniformly mixing to obtain a cerium source solution;
s12, adding a sodium hydroxide solution into the cerium source solution, and reacting to obtain a reaction solution;
s13, filtering, washing, drying and grinding the reaction solution to obtain a primary product;
s14, placing the primary product in a muffle furnace to calcine to obtain cubic CeO 2 。
3. The TiO of claim 2 2 /CeO 2 The preparation method of the heterojunction photocatalyst is characterized in that the cerium source is Ce (NO) 3 ) 3 ·6H 2 O; and/or the presence of a gas in the gas,
the concentration of the sodium hydroxide solution is 2-8mol/L, preferably, the concentration of the sodium hydroxide solution is 4 mol/L.
4. The TiO of claim 2 2 /CeO 2 The preparation method of the heterojunction photocatalyst is characterized in that the step S12 specifically comprises the following steps: adding a sodium hydroxide solution into the cerium source solution, mixing, transferring to a high-pressure hydrothermal reaction kettle, and reacting for 11-13h at the temperature of 180-190 ℃ to obtain a reaction solution.
5. The TiO of claim 2 2 /CeO 2 The preparation method of the heterojunction photocatalyst is characterized in that the calcination conditions are as follows:
heating to 450 ℃ at the heating rate of 4-6 ℃/min, wherein the calcining time is as follows: 3-3.5 h.
6. The TiO of claim 1 2 /CeO 2 The preparation method of the heterojunction photocatalyst is characterized in that the reaction conditions of the pre-product obtained after the reaction are as follows:
the reaction time is 6-7h, and the reaction temperature is 115-125 ℃.
7. The TiO of claim 1 2 /CeO 2 The preparation method of the heterojunction photocatalyst is characterized in that the step of washing the pre-product comprises the following steps:
the pre-product was washed at least three times with water.
8. The TiO of claim 7 2 /CeO 2 The preparation method of the heterojunction photocatalyst is characterized in that the step of washing the pre-product further comprises the following steps:
the water-washed pre-product was washed at least twice with ethanol.
9. TiO2 2 /CeO 2 A heterojunction photocatalyst produced by the production method according to any one of claims 1 to 8.
10. The TiO of claim 9 2 /CeO 2 A heterojunction photocatalyst comprising cubic CeO 2 And CeO supported on the cube 2 Surface TiO 2 The number of the nano-particles is,
wherein the TiO is 2 With said CeO 2 The mass ratio of (1-4): 10; preferably, the TiO is 2 With the CeO 2 The mass ratio of (A) to (B) is 3: 10.
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