An oxide-sulfide S-type heterojunction composite photocatalyst and a preparation method and application thereof
By preparing an oxide-sulfide S-type heterojunction composite photocatalyst, the problems of reduced economic benefits and environmental pollution caused by hole sacrificial agents in the photocatalytic hydrogen production system were solved, and efficient photocatalytic hydrogen production and benzyl alcohol oxidation were achieved, with good photocatalytic activity and selectivity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-29
- Publication Date
- 2026-03-27
AI Technical Summary
The use of hole sacrificial agents in existing photocatalytic hydrogen production systems leads to reduced economic efficiency and environmental pollution, and the selective oxidation of benzyl alcohol is difficult to control.
An oxide-sulfide S-type heterojunction composite photocatalyst was used to prepare WOx and CdS by hydrothermal and precipitation methods to form a heterojunction, which was then supported with a Ni co-catalyst for photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol.
It achieves highly efficient photocatalytic hydrogen production and benzyl alcohol oxidation, exhibiting high activity, high selectivity, and stability. The photocatalytic hydrogen production rate reaches ~198 μmol h⁻¹, and the benzyl alcohol conversion rate and benzaldehyde selectivity are as high as ~91% and ~100%, respectively.
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Figure CN117643901B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the field of hydrogen energy preparation, and relates to a photocatalytic clean hydrogen energy preparation technology, in particular to an oxide-sulfide S-type heterojunction composite photocatalyst and a preparation method and application thereof. BACKGROUND
[0002] Under the background of environmental pollution, abuse of natural resources, shortage of fossil energy and greenhouse effect, the conversion of renewable energy into high-value organic chemicals has attracted widespread attention. Photocatalytic water splitting for hydrogen production is considered as an effective way of solar energy conversion. In order to improve the hydrogen production efficiency, a hole sacrificial agent (lactic acid, triethanolamine and Na2S / Na2SO3) is usually added to the photocatalytic system. However, the use of these sacrificial agents will reduce the economic benefit of photocatalytic hydrogen production and cause environmental pollution. Therefore, the use of high-value organic conversion products instead of sacrificial agents in the photocatalytic hydrogen production system is an important solution to obtain green energy and fine chemicals at the same time. Benzaldehyde is a valuable industrial compound, which is mainly used as an important intermediate for the synthesis of various fine chemicals, pharmaceuticals and pesticides. Benzaldehyde can be obtained by mild oxidation of benzyl alcohol, but it is still a great challenge to control the selective oxidation of benzyl alcohol. Compared with traditional organic synthesis methods, the coupling of photocatalytic hydrogen production and benzyl alcohol oxidation has great potential in future production. Therefore, it is crucial to develop a recyclable and efficient photocatalytic hydrogen production and benzyl alcohol oxidation system. SUMMARY
[0003] The application aims to provide an oxide-sulfide S-type heterojunction composite photocatalyst and a preparation method and application thereof, so as to realize efficient photocatalytic preparation of green clean energy and high-value organic compounds.
[0004] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:
[0005] A preparation method of an oxide-sulfide S-type heterojunction composite photocatalyst, comprising the following steps:
[0006] WO x CdS is added to ethanol, ultrasonically dispersed uniformly, and then heated and dried to obtain the oxide-sulfide S-type heterojunction composite photocatalyst.
[0007] Further, the amount ratio of WO x to ethanol is 5mg-10mg:60mL.
[0008] Further, the amount ratio of WO x to CdS is 5mg-10mg:100mg.
[0009] Further, the amount ratio of WO xThe oxide-sulfide S-type heterojunction composite photocatalyst is prepared according to the method. x .
[0010] Further, the millimolar ratio of Na2WO4·2H2O powder, Na2SO4, glycine and hydroxylamine hydrochloride powder is 2.5:12.5:7.5:1.5.
[0011] Further, the CdS is prepared by the following process: Na2S solution is added to Cd(NO3)2 solution, after stirring the reaction, the yellow precipitate is filtered and dried to obtain CdS.
[0012] Further, the molar ratio of Cd(NO3)2 and Na2S is 7:14.
[0013] An oxide-sulfide S-type heterojunction composite photocatalyst prepared according to the method.
[0014] An application of an oxide-sulfide S-type heterojunction composite photocatalyst prepared according to the method in photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol under visible light.
[0015] Further, the oxide-sulfide S-type heterojunction composite photocatalyst is added to the reactor, then the benzyl alcohol aqueous solution and the nickel chloride aqueous solution are added, and the photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol is carried out under visible light.
[0016] The mass of Ni in the nickel chloride aqueous solution is 1wt%-2.5wt% of the mass of the oxide-sulfide S-type heterojunction composite photocatalyst.
[0017] Compared with the prior art, the present application has the following beneficial effects:
[0018] The present application utilizes the ability of cadmium sulfide to generate photo-generated carriers and the unique reactive sites of tungsten oxide, so that the prepared tungsten oxide and cadmium sulfide S-type heterojunction composite material has excellent photocatalytic hydrogen production activity, the heterojunction interface formed by cadmium sulfide and tungsten oxide has a synergistic effect, which promotes the selective oxidation of benzyl alcohol and realizes the efficient conversion of benzyl alcohol in the system. While improving the photocatalytic hydrogen production capacity, the strong light utilization and redox capacity are retained, and the present application has high activity, high selectivity and high stability. The raw materials of the present application are cheap and easy to obtain, the operation is simple, and the preparation method has good repeatability.
[0019] The prepared tungsten oxide and cadmium sulfide S-type heterojunction composite material has excellent light-generated carrier generation capacity of cadmium sulfide, and provides a basis for efficient photocatalytic hydrogen production. When the tungsten oxide and cadmium sulfide are constructed into an S-type heterojunction composite material, an internal electric field is formed between the two, which promotes the separation of electrons and holes in the photo-generated carriers generated by cadmium sulfide, avoids carrier recombination, and enhances the redox capacity of the system, thereby further improving the photocatalytic performance. The composite material has good light response, can realize hydrogen production and benzaldehyde production under visible light irradiation, and shows good photocatalytic activity, high conversion rate and high selectivity. After loading a Ni cocatalyst, the photocatalytic hydrogen production rate is ~ 198 μmol h -1 , the benzyl alcohol conversion rate and benzaldehyde selectivity are as high as ~ 91% and ~ 100%, and the system has good stability. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 are X-ray diffraction (XRD) patterns of tungsten oxide (WO x ), cadmium sulfide (CdS) and tungsten oxide and cadmium sulfide S-type heterojunction composite material (WO x / CdS) of Example 2.
[0021] Figure 2 are transmission electron microscope (TEM) photos of tungsten oxide and cadmium sulfide S-type heterojunction composite material of Example 2.
[0022] Figure 3 are photocatalytic hydrogen production rate diagrams of tungsten oxide and cadmium sulfide S-type heterojunction composite material of Examples 1-3 under visible light.
[0023] Figure 4 are photocatalytic hydrogen production rate diagrams of tungsten oxide and cadmium sulfide S-type heterojunction composite material of Examples 4-7 under visible light after loading a Ni cocatalyst.
[0024] Figure 5 are photocatalytic stability test diagrams of tungsten oxide and cadmium sulfide S-type heterojunction composite material of Example 6.
[0025] Figure 6 are photocatalytic benzyl alcohol conversion rate and selectivity test diagrams of tungsten oxide and cadmium sulfide S-type heterojunction composite material of Examples 4-7 after loading a Ni cocatalyst. DETAILED DESCRIPTION
[0026] For the purpose of facilitating the understanding of the present application, a more complete description of the present application will be given below with reference to the relevant drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the disclosure of the present application can be more thoroughly and completely understood.
[0027] The present application relates to the preparation of clean energy coupled with high additional organic conversion technology, the provided tungsten oxide and cadmium sulfide S type heterojunction composite material can realize photocatalytic hydrogen production and preparation of benzaldehyde, for realizing the efficient photocatalytic hydrogen production and the selective oxidation of benzyl alcohol provides an effective feasible system.
[0028] The present application relates to the preparation of clean energy coupled with high additional organic conversion technology, the provided tungsten oxide and cadmium sulfide S type heterojunction composite material can realize photocatalytic hydrogen production and preparation of benzaldehyde, for realizing the efficient photocatalytic hydrogen production and the selective oxidation of benzyl alcohol provides an effective feasible system.
[0029] Step one: first, the hydrothermal method is used to synthesize tungsten oxide nanostructure. 2.5mmol sodium tungstate Na2WO4·2H2O, 12.5mmol anhydrous sodium sulfate Na2SO4, 7.5mmol glycine and 1.5mmol hydroxylamine hydrochloride powder are added in 50mL deionized water in turn, further stirring for 30 minutes, then adding 2mL hydrochloric acid with a concentration of about 6mol / L for acidification, and continuing to stir for 30 minutes, sealing in a high pressure kettle with a capacity of 100mL, heating to 180℃ and keeping for 12 hours. After cooling, the product is centrifuged and washed with deionized water and ethanol several times, and then dried in a vacuum oven at 60℃ for 10 hours, obtaining WO x .
[0030] Step two: cadmium sulfide nanostructure is synthesized by precipitation method. Cd(NO3)2 . 4H2O powder is added to deionized water and stirred for 1 hour to obtain Cd(NO3)2 solution, and then Na2S . 9H2O is ultrasonically dissolved in another deionized water to obtain Na2S solution. Then the Na2S solution is slowly added to the Cd(NO3)2 solution. After stirring for 3 hours, yellow precipitate is obtained by filtration, which is washed with deionized water and ethanol several times, and then dried at 60℃ for 10 hours to obtain CdS. The molar ratio of Cd(NO3)2 . 4H2O powder to Na2S . 9H2O is 7:14; the amount of deionized water is 20mL.
[0031] Step three: 5mg-10mg WO xand 100 mg of CdS obtained in step two were dispersed into 60 mL of ethanol solution and ultrasonicated for 30 minutes. Then the oil bath was heated to 85 °C for 4-6 hours until the ethanol was evaporated completely to obtain the oxide-sulfide S-type heterojunction composite photocatalyst.
[0032] WO x Different oxide-sulfide S-type heterojunction composite photocatalysts (WO x were prepared using different amounts (5 mg-10 mg, preferably 5 mg, 8 mg and 10 mg) of WO
[0033] The application of an oxide-sulfide S-type heterojunction composite photocatalyst in photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol, wherein the oxide-sulfide S-type heterojunction photocatalyst of tungsten oxide and cadmium sulfide is added to a reactor, then 10 mmol / L of an aqueous solution of benzyl alcohol is added, after purging with argon, under stirring, light irradiation is carried out, and 1 wt%-2.5 wt% of Ni is loaded by light reduction method for photocatalytic hydrogen production and selective oxidation of benzyl alcohol to realize hydrogen production and benzaldehyde production. The specific steps are as follows:
[0034] The oxide-sulfide S-type heterojunction composite photocatalyst is added to a reactor, then an aqueous solution of benzyl alcohol and an aqueous solution of nickel chloride are added, and photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol is carried out under visible light.
[0035] The mass of Ni in the aqueous solution of nickel chloride is 1-2.5% of the mass of the oxide-sulfide S-type heterojunction composite photocatalyst.
[0036] Example 1
[0037] Step one: first, 2.5 mmol of sodium tungstate dihydrate, 12.5 mmol of anhydrous sodium sulfate, 7.5 mmol of glycine and 1.5 mmol of hydroxylamine hydrochloride were sequentially added to 50 mL of deionized water, and further stirred for 30 minutes, then 2 mL of hydrochloric acid with a concentration of about 6 mol / L was added for acidification. The aqueous solution was continuously stirred for 30 minutes, sealed in a high-pressure kettle with a capacity of 100 mL, and heated to 180 °C for 12 hours. After cooling, the product was separated by centrifugation, washed with deionized water and ethanol several times, and then dried in a vacuum oven at 60 °C for 10 hours to obtain WO x .
[0038] Step two: Cd(NO3)2 . 4H2O powder was added to deionized water and stirred for 1 hour, then Na2S .9H2O was dissolved in another deionized water. Then the Na2S solution was slowly added into the Cd(NO3)2 solution. After stirring for 3 hours, a yellow precipitate was obtained by filtration, washed with deionized water and ethanol for several times, and then dried at 60 C for 10 hours to obtain CdS.
[0039] Step three: 5 mg of WO x and 100 mg of CdS obtained in step two were dispersed into 60 mL of ethanol solution and ultrasonicated for 30 minutes. Then the solution was heated in an oil bath at 85 C for 4-6 hours until the ethanol was completely evaporated to obtain the WOx / CdS heterojunction composite. It was named as 5-WCDS.
[0040] Step four: the WOx / CdS S-type heterojunction composite prepared in step three was added into a benzyl alcohol aqueous solution for photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol. The specific steps are as follows:
[0041] 1) 10 mg of WOx / CdS S-type heterojunction photocatalyst was added into a reactor with a volume of 55 mL, and 45 mL of 10 mmol / L benzyl alcohol aqueous solution was added;
[0042] 2) Before illumination, the reactor was purged with argon for 10 minutes to remove air in the system;
[0043] 3) The magnetic stirrer was turned on, and the xenon lamp power was turned on.
[0044] Example 2
[0045] Step one: first, 2.5 mmol of sodium tungstate dihydrate, 12.5 mmol of anhydrous sodium sulfate, 7.5 mmol of glycine and 1.5 mmol of hydroxylamine hydrochloride were sequentially added into 50 mL of deionized water, and further stirred for 30 minutes, and then 2 mL of hydrochloric acid with a concentration of about 6 mol / L was added for acidification. The aqueous solution was continuously stirred for 30 minutes, sealed in a high-pressure kettle with a volume of 100 mL, heated to 180 C and kept for 12 hours. After cooling, the product was separated by centrifugation, washed with deionized water and ethanol for several times, and then dried in a vacuum oven at 60 C for 10 hours to obtain WO x .
[0046] Step two: Cd(NO3)2 . 4H2O powder was added into 20 mL of deionized water and stirred for 1 hour, and then Na2S . 9H2O was dissolved in another deionized water. Then the Na2S solution was slowly added into the Cd(NO3)2 solution. After stirring for 3 hours, a yellow precipitate was obtained by filtration, washed with deionized water and ethanol for several times, and then dried at 60 C for 10 hours to obtain CdS. Cd(NO3)2 . 4H2O powder and Na2S. 9H2O in a molar ratio of 7:14.
[0047] Step three: 8 mg of WO x and 100 mg of CdS obtained in step two were dispersed into 60 mL of ethanol solution and ultrasonicated for 30 minutes. Then the solution was heated in an oil bath at 85°C for 4-6 hours until the ethanol was completely evaporated, obtaining a WOx-CdS heterojunction composite. It was named as 8-WCDS.
[0048] Step four: the WOx-CdS S-type heterojunction composite prepared in step three was added into a benzyl alcohol aqueous solution for photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol. The specific steps are as follows:
[0049] 1) 10 mg of WOx-CdS S-type heterojunction photocatalyst was added into a reactor with a volume of 55 mL, and 45 mL of 10 mmol / L benzyl alcohol aqueous solution was added;
[0050] 2) Before illumination, the reactor was purged with argon for 10 minutes to remove air in the system;
[0051] 3) Turn on the magnetic stirrer and the xenon lamp power supply.
[0052] Example 3
[0053] Step one: first, 2.5 mmol of sodium tungstate dihydrate, 12.5 mmol of anhydrous sodium sulfate, 7.5 mmol of glycine and 1.5 mmol of hydroxylamine hydrochloride were sequentially added into 50 mL of deionized water, and further stirred for 30 minutes, and then 2 mL of hydrochloric acid with a concentration of about 6 mol / L was added for acidification. The aqueous solution was continuously stirred for 30 minutes, sealed in a high-pressure kettle with a volume of 100 mL, and heated to 180°C for 12 hours. After cooling, the product was separated by centrifugation, washed with deionized water and ethanol for several times, and then dried in a vacuum oven at 60°C for 10 hours, obtaining WO x .
[0054] Step two: Cd(NO3)2 . 4H2O powder was added into 20 mL of deionized water and stirred for 1 hour, and then Na2S . 9H2O was ultrasonically dissolved in 20 mL of deionized water. Then the Na2S solution was slowly added into the Cd(NO3)2 solution. After stirring for 3 hours, a yellow precipitate was obtained by filtration, which was washed with deionized water and ethanol for several times, and then dried at 60°C for 10 hours, obtaining CdS.
[0055] Step three: 10 mg of WO xand 100 mg of CdS obtained in step two were dispersed into 60 mL of ethanol solution and ultrasonicated for 30 minutes. Then the oil bath was heated to 85 °C for 4-6 hours until the ethanol was evaporated completely to obtain the tungsten oxide and cadmium sulfide heterojunction composite. It was named as 10-WCDS.
[0056] Step four: The tungsten oxide and cadmium sulfide S-type heterojunction composite prepared in step three was added into the aqueous solution of benzyl alcohol for photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol. The specific steps were as follows:
[0057] 1) 10 mg of the tungsten oxide and cadmium sulfide S-type heterojunction photocatalyst was added into a reactor with a volume of 55 mL, and 45 mL of 10 mmol / L aqueous solution of benzyl alcohol was added;
[0058] 2) The reactor was purged with argon for 10 minutes before illumination to remove air in the system;
[0059] 3) The magnetic stirrer was turned on, and the xenon lamp power was turned on.
[0060] Example 4
[0061] Step one: First, 2.5 mmol of sodium tungstate dihydrate, 12.5 mmol of anhydrous sodium sulfate, 7.5 mmol of glycine and 1.5 mmol of hydroxylamine hydrochloride were sequentially added into 50 mL of deionized water, and further stirred for 30 minutes, and then 2 mL of hydrochloric acid with a concentration of about 6 mol / L was added for acidification. The aqueous solution was continuously stirred for 30 minutes, sealed in a high-pressure kettle with a volume of 100 mL, and heated to 180 °C for 12 hours. After cooling, the product was separated by centrifugation, washed with deionized water and ethanol for several times, and then dried in a vacuum oven at 60 °C for 10 hours to obtain WO x .
[0062] Step two: Cd(NO3)2 . 4H2O powder was added into 20 mL of deionized water and stirred for 1 hour, and then Na2S . 9H2O was ultrasonically dissolved in 20 mL of deionized water. Then the Na2S solution was slowly added dropwise into the Cd(NO3)2 solution. After stirring for 3 hours, a yellow precipitate was obtained by filtration, which was washed with deionized water and ethanol for several times, and then dried at 60 °C for 10 hours to obtain CdS.
[0063] Step three: 8 mg of WO x and 100 mg of CdS obtained in step two were dispersed into 60 mL of ethanol solution and ultrasonicated for 30 minutes. Then the oil bath was heated to 85 °C for 4-6 hours until the ethanol was evaporated completely to obtain the tungsten oxide and cadmium sulfide heterojunction composite. It was named as 10-WCDS.
[0064] Step four: The prepared tungsten oxide and cadmium sulfide S-type heterojunction composite material in step three was added into the aqueous solution of benzyl alcohol, and the photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol was tested by loading 1wt% Ni cocatalyst by photoreduction method. The specific steps are as follows:
[0065] 1) 10 mg of tungsten oxide and cadmium sulfide S-type heterojunction photocatalyst was added into a reactor with a volume of 55 mL, 45 mL of 10 mmol / L aqueous solution of benzyl alcohol was added, and 395 μL of 1 mg / mL NiCl2 aqueous solution was added;
[0066] 2) Before illumination, the reactor was purged with argon for 10 min to remove air in the system;
[0067] 3) Turn on the magnetic stirrer and the xenon lamp power supply.
[0068] Example 5
[0069] Step one: First, 2.5 mmol of sodium tungstate dihydrate, 12.5 mmol of anhydrous sodium sulfate, 7.5 mmol of glycine and 1.5 mmol of hydroxylamine hydrochloride were sequentially added into 50 mL of deionized water, and further stirred for 30 minutes, then 2 mL of hydrochloric acid with a concentration of about 6 mol / L was added for acidification. The aqueous solution was continuously stirred for 30 minutes, sealed in a high-pressure kettle with a volume of 100 mL, heated to 180C and kept for 12 hours. After cooling, the product was separated by centrifugation, washed with deionized water and ethanol several times, and then dried in a vacuum oven at 60C for 10 hours to obtain WO x .
[0070] Step two: Cd(NO3)2 . 4H2O powder was added into 20 mL of deionized water and stirred for 1 hour, then Na2S . 9H2O was ultrasonically dissolved in 20 mL of deionized water. Then the Na2S solution was slowly added to the Cd(NO3)2 solution. After stirring for 3 hours, a yellow precipitate was obtained by filtration, which was washed with deionized water and ethanol several times, and then dried at 60C for 10 hours to obtain CdS.
[0071] Step three: 8 mg of WO x obtained in step one and 100 mg of CdS obtained in step two were dispersed into 60 mL of ethanol solution and ultrasonicated for 30 minutes. Then heated in an oil bath to 85℃ for 4-6 hours until the ethanol evaporated completely to obtain a tungsten oxide and cadmium sulfide heterojunction composite material. Named as 8-WCDS.
[0072] Step four: The prepared tungsten oxide and cadmium sulfide S-type heterojunction composite material in step three was added into the aqueous solution of benzyl alcohol, and the photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol was tested by loading 1.5wt% Ni cocatalyst by photoreduction method. The specific steps are as follows:
[0073] 1) In a 55 mL reactor, 10 mg of WO3 / CdS type S heterojunction photocatalyst was added, 45 mL of 10 mmol / L benzyl alcohol aqueous solution was added, and 593 μL of 1 mg / mL NiCl2 aqueous solution was added;
[0074] 2) The reactor was purged with argon for 10 min before irradiation to remove air in the system;
[0075] 3) The magnetic stirrer was turned on, and the xenon lamp power was turned on.
[0076] Example 6
[0077] Step 1: First, 2.5 mmol of sodium tungstate dihydrate, 12.5 mmol of anhydrous sodium sulfate, 7.5 mmol of glycine and 1.5 mmol of hydroxylamine hydrochloride were sequentially added to 50 mL of deionized water, and further stirred for 30 minutes, then 2 mL of 6 mol / L hydrochloric acid was added for acidification. The aqueous solution was continuously stirred for 30 minutes, sealed in a 100 mL capacity autoclave, heated to 180C for 12 hours. After cooling, the product was separated by centrifugation, washed with deionized water and ethanol several times, and then dried in a vacuum oven at 60C for 10 hours to obtain WO3 x .
[0078] Step 2: Cd(NO3)2 . 4H2O powder was added to 20 mL of deionized water and stirred for 1 hour, then Na2S . 9H2O was ultrasonically dissolved in 20 mL of deionized water. Then the Na2S solution was slowly added to the Cd(NO3)2 solution. After stirring for 3 hours, a yellow precipitate was obtained by filtration, which was washed with deionized water and ethanol several times, and then dried at 60C for 10 hours to obtain CdS.
[0079] Step 3: 8 mg of WO3 obtained in step 1 and 100 mg of CdS obtained in step 2 were dispersed in 60 mL of ethanol solution and ultrasonicated for 30 minutes. Then heated to 85C in an oil bath for 4-6 hours until the ethanol evaporated completely to obtain a tungsten oxide / cadmium sulfide heterojunction composite material. Named 8-WCDS. x
[0080] Step 4: The tungsten oxide / cadmium sulfide type S heterojunction composite material prepared in step 3 was added to a benzyl alcohol aqueous solution, and a 2wt% Ni cocatalyst was loaded by a photoreduction method for a photocatalytic hydrogen production and selective oxidation of benzyl alcohol test. The specific steps are as follows:
[0081] 1) In a 55 mL reactor, 10 mg of WO3 / CdS type S heterojunction photocatalyst was added, 45 mL of 10 mmol / L benzyl alcohol aqueous solution was added, and 790 μL of 1 mg / mL NiCl2 aqueous solution was added;
[0082] 2) Before light irradiation, the reactor was purged with argon for 10 min to remove air in the system;
[0083] 3) The magnetic stirrer was turned on, and the xenon lamp power was turned on.
[0084] Example 7
[0085] Step 1: First, 2.5 mmol of sodium tungstate dihydrate, 12.5 mmol of anhydrous sodium sulfate, 7.5 mmol of glycine and 1.5 mmol of hydroxylamine hydrochloride were sequentially added to 50 mL of deionized water, and further stirred for 30 minutes, and then 2 mL of 6 mol / L hydrochloric acid was added for acidification. The aqueous solution was continuously stirred for 30 minutes, sealed in a 100 mL capacity autoclave, heated to 180C and kept for 12 hours. After cooling, the product was separated by centrifugation, washed with deionized water and ethanol several times, and then dried in a vacuum oven at 60C for 10 hours to obtain WO3 x .
[0086] Step 2: Cd(NO3)2 . 4H2O powder was added to 20 mL of deionized water and stirred for 1 hour, and then Na2S . 9H2O was ultrasonically dissolved in 20 mL of deionized water. Then the Na2S solution was slowly added to the Cd(NO3)2 solution. After stirring for 3 hours, a yellow precipitate was obtained by filtration, washed with deionized water and ethanol several times, and then dried at 60C for 10 hours to obtain CdS.
[0087] Step 3: 8 mg of WO3 obtained in step 1 and 100 mg of CdS obtained in step 2 were dispersed in 60 mL of ethanol solution and ultrasonicated for 30 minutes. Then heated to 85C in an oil bath for 4-6 hours until the ethanol was completely evaporated to obtain a tungsten oxide / cadmium sulfide heterojunction composite material. Named 8-WCDS. x
[0088] Step 4: The tungsten oxide / cadmium sulfide type S heterojunction composite material prepared in step 3 was added to a benzyl alcohol aqueous solution, and a 2.5 wt% Ni cocatalyst was loaded by a photo-reduction method to test the photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol. The specific steps are as follows:
[0089] 1) In a 55 mL volume reactor, 10 mg of tungsten oxide and cadmium sulfide S-type heterojunction photocatalyst was added, 45 mL of 10 mmol / L benzyl alcohol aqueous solution was added, and 988 μL of 1 mg / mL NiCl2 aqueous solution was added;
[0090] 2) Before light irradiation, the reactor was purged with argon for 10 min to remove air in the system;
[0091] 3) The magnetic stirrer was turned on, and the xenon lamp power was turned on.
[0092] Figure 1 is the X-ray diffraction (XRD) pattern of tungsten oxide (WO x ), cadmium sulfide (CdS), and tungsten oxide and cadmium sulfide S-type heterojunction composite (WO x / CdS). The resulting composite has characteristic peaks of both tungsten oxide (WO x ) and cadmium sulfide (CdS). The XRD results show that the composite is composed of tungsten oxide and cadmium sulfide.
[0093] Figure 2 is the transmission electron microscopy (TEM) image of the tungsten oxide and cadmium sulfide S-type heterojunction composite. Further evidence that the resulting composite is composed of tungsten oxide and cadmium sulfide, and that the two are in contact to form a heterojunction.
[0094] Figure 3 is the photocatalytic hydrogen production rate graph of the tungsten oxide and cadmium sulfide S-type heterojunction composite under visible light. The photocatalytic hydrogen evolution rate of sample 8-WCDS is the highest.
[0095] Figure 4 is the photocatalytic hydrogen production rate graph of the tungsten oxide and cadmium sulfide S-type heterojunction composite after loading Ni cocatalyst under visible light. After loading 2 wt% Ni cocatalyst, the photocatalytic hydrogen production rate of the composite reaches ~198 μmol h -1 .
[0096] Figure 5 is the photocatalytic stability test graph of the tungsten oxide and cadmium sulfide S-type heterojunction composite, which shows that the catalyst has good stability.
[0097] Figure 6 is the photocatalytic benzyl alcohol conversion rate and selectivity test graph of the tungsten oxide and cadmium sulfide S-type heterojunction composite after loading Ni cocatalyst. After loading 2 wt% Ni cocatalyst, the benzyl alcohol conversion rate and benzaldehyde selectivity of the composite are as high as ~91% and ~100%.
[0098] The tungsten oxide and cadmium sulfide S-type heterojunction is successfully constructed, the prepared tungsten oxide and cadmium sulfide S-type heterojunction composite material has good light response, can generate hydrogen under visible light irradiation and realize efficient conversion of benzyl alcohol, and has good photocatalytic activity and superior reaction selectivity.
[0099] The application has good repeatability and simple operation, and provides a reliable scheme for development and application of a new photocatalyst for improving photocatalytic hydrogen production coupled with selective oxidation efficiency of benzyl alcohol.
[0100] The above only describes the best embodiments of the present application, but cannot be understood as limiting the claims. The present application is not limited to the above embodiments, and the specific structure allows changes. Any changes made within the protection scope of the independent claims of the present application are within the protection scope of the present application.
[0101] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.
Claims
1. The application of an oxide-sulfide S-type heterojunction composite photocatalyst in photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol under visible light; characterized in that, The oxide-sulfide S-type heterojunction composite photocatalyst was prepared by the following steps: Will WO x CdS was added to ethanol, ultrasonically dispersed until uniform, and then heated to dryness to obtain an oxide-sulfide S-type heterojunction composite photocatalyst. WO x The WO4 was prepared by the following process: Na2WO4·2H2O powder, Na2SO4, glycine, and hydroxylamine hydrochloride powder were mixed evenly in deionized water, acidified with hydrochloric acid, and stirred evenly. The mixture was then hydrothermally heated at 180°C for 12 hours to obtain WO4. x The WO x For WO3 . 0.33H2O; The millimolecular ratio of Na2WO4·2H2O powder to Na2SO4, glycine, and hydroxylamine hydrochloride powder is 2.5:12.5:7.5:1.5; CdS is prepared by the following process: Na2S solution is added to Cd(NO3)2 solution, the mixture is stirred and reacted, filtered to obtain a yellow precipitate, and dried to obtain CdS.
2. The application of the oxide-sulfide S-type heterojunction composite photocatalyst according to claim 1 in photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol under visible light, characterized in that, WO x The dosage ratio of ethanol to ethanol is 5 mg-10 mg: 60 mL.
3. The application of the oxide-sulfide S-type heterojunction composite photocatalyst according to claim 1 in photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol under visible light, characterized in that... WO x The dosage ratio to CdS is 5 mg-10 mg: 100 mg.
4. The application of the oxide-sulfide S-type heterojunction composite photocatalyst according to claim 1 in photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol under visible light, characterized in that, The molar ratio of Cd(NO3)2 to Na2S is 7:
14.
5. The application of the oxide-sulfide S-type heterojunction composite photocatalyst according to claim 1 in photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol under visible light, characterized in that, An oxide-sulfide S-type heterojunction composite photocatalyst was added to the reactor, followed by an aqueous solution of benzyl alcohol and an aqueous solution of nickel chloride. Photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol was carried out under visible light. In this process, the mass of Ni in the nickel chloride aqueous solution is 1 wt% to 2.5 wt% of the mass of the oxide-sulfide S-type heterojunction composite photocatalyst.