All-solid-state z-type heterojunction csPbBr3 / Au / g-c3n4 photocatalyst for c-h oxidation and preparation method thereof

Abstract

The application provides a preparation method of a full-solid Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for enhancing C-H oxidation; the method of doping metal halide perovskite with Au / g-C3N4 is adopted, high efficient catalytic activity and high stability of the metal halide perovskite material under the condition of oxygen enrichment are realized; and the high efficient and high selective synthesis of carboxylic acid, ketone and alcohol is realized by visible light irradiation under an oxygen atmosphere at room temperature with a benzyl substrate.

Description

TECHNICAL FIELD

[0001] The application relates to the field of photocatalysts, in particular to a full-solid Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for C-H oxidation and a preparation method thereof. BACKGROUND

[0002] Carboxylic acids, ketones and alcohols are commonly found in many pharmaceuticals, agrochemicals and natural products. Due to the importance of their pharmacological activities, efficient methods for synthesizing carboxylic acids, ketones and alcohols are necessary to facilitate drug discovery.

[0003] Selective activation of saturated C-H bonds into high-value chemicals has full potential in the pharmaceutical, chemical and food industries. However, the reaction also faces significant obstacles, one of which is that C(sp3)-H bonds are very stable and require high energy to dissociate. The thermodynamic stability of C(sp3)-H bonds makes it difficult to convert them into useful oxygen-containing products. In general, conventional methods for activating C-H bonds require toxic and corrosive chemical oxidants (such as dichromate and permanganate) and harsh conditions, especially high temperature and high pressure. In order to overcome these obstacles, photocatalysis is considered as a promising method for selective activation of C(sp3)-H bonds as a green and mild technology. Therefore, it has become a current research hotspot to develop a fast and efficient catalytic system to realize the green and efficient conversion of C(sp3)-H bonds to carboxylic acids, ketones and alcohols.

[0004] Metal halide perovskite materials (MHPs) have the characteristics of visible light response sensitivity, long carrier lifetime, easy to control structure and low cost, and are an ideal visible light catalyst. However, due to the penetration of active oxygen species and water into the MHPs lattice leading to lattice degradation, the MHPs are not structurally stable in environments rich in oxygen and high humidity, which limits their application research. Therefore, it is still a difficult problem to be solved to realize high structural stability and high catalytic activity of MHPs under rich oxygen conditions. SUMMARY

[0005] One of the purposes of the application is to provide a full-solid Z-type heterojunction photocatalyst for enhancing C-H oxidation

[0006] The preparation method of the CsPbBr3 / Au / g-C3N4 photocatalyst is as follows:

[0007] 1) Preparation of Au-doped carbon nitride

[0008] 1-3 parts of melamine is added to 100-200 parts of ultrapure water in a g / m ratio, heated to 80 DEG C, and stirred rapidly until completely dissolved; continue stirring and add 1-5 parts of 10 mg / mL chloroauric acid aqueous solution, continue stirring and cool to room temperature, then add sodium hydroxide solution to adjust the pH to 6.5-7, and dry at 80 DEG C in air for 5 hours, then calcine in a reducing atmosphere at 550 DEG C for 2 hours to obtain gold-doped carbon nitride (Au / g-C3N4);

[0009] wherein the reducing atmosphere is a 5% argon-hydrogen atmosphere;

[0010] 2) Preparation of Au / g-C3N4 doped metal halide perovskite

[0011] Oleylamine is mixed with hydrobromic acid to obtain a solidified reaction mixture, which is vacuumed and heated at 120 DEG C for 2 hours in a nitrogen atmosphere, then the reaction temperature is increased to 150 DEG C and heated for 30 min, and then the solution is cooled to 80 DEG C to obtain an ammonium bromide precursor for standby;

[0012] wherein the oleylamine and hydrobromic acid are in a volume ratio of 10:1-1.5;

[0013] Cesium carbonate, gold-doped carbon nitride (Au / g-C3N4) and lead oxide, and octadecene and oleic acid are mixed, vacuumed and heated at 120 DEG C for 1 hour in a nitrogen atmosphere, then the reaction temperature is increased to 220 DEG C, and immediately the ammonium bromide precursor is injected, and annealed for 6 min, and then the solution is cooled in an ice water bath for 10 min;

[0014] The above obtained solution is centrifuged, and the supernatant is discarded, and the obtained yellow solid is washed with n-hexane for 2-3 times, and dried at 60 DEG C under vacuum for 2 hours to obtain a composite photocatalyst CsPbBr3 / Au / g-C3N4.

[0015] wherein the cesium carbonate: Au / g-C3N4: lead oxide: octadecene: oleic acid: ammonium bromide precursor is 0.2 mmol: 45-55 mg: 0.4 mmol: 20 mL: 1.5 mL: 1-2 mL.

[0016] Another object of the present application is to provide the use of the above-mentioned catalyst in the synthesis of carboxylic acid, ketone and alcohol with benzyl as a substrate, as follows:

[0017] CsPbBr3 / Au / g-C3N4 and benzyl substrate are dispersed in 1,2-dichloroethane, and the obtained system is irradiated with visible light in an oxygen atmosphere until the substrate is completely converted;

[0018] The above reaction system is centrifuged to recover the photocatalyst for recycling; the obtained solution is extracted with an organic solvent, the organic phases are combined, dried with anhydrous sodium sulfate, filtered, and concentrated to obtain carboxylic acid, ketone and alcohol products;

[0019] Wherein, CsPbBr3 / Au / g-C3N4: benzyl substrate: 1,2-dichloroethane is 10-20 mg: 0.2 mmol: 3 mL.

[0020] Advantages of the present application:

[0021] (1) The present application adopts the method of Au / g-C3N4 doped metal halide perovskite to realize the high efficient catalytic activity and high stability of metal halide perovskite material under oxygen-rich conditions.

[0022] (2) The present application takes benzyl substrate as raw material, 1,2-dichloroethane as solvent, and CsPbBr3 / Au / g-C3N4 as catalyst to realize the high efficient and high selective synthesis of carboxylic acid, ketone and alcohol under visible light irradiation at room temperature in oxygen atmosphere. The method is economical and green, high in atom utilization, simple in post-treatment, low in experimental cost, and suitable for large-scale application. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a synthesis diagram of Au / g-C3N4 and CsPbBr3 / Au / g-C3N4 composite material;

[0024] Figure 2 It is a TEM spectrum and Mapping element analysis of CsPbBr3 / Au / g-C3N4;

[0025] Figure 3 It is the nuclear magnetic hydrogen spectrum and mass spectrum of benzoic acid after photocatalytic synthesis in Example 1;

[0026] Figure 4 It is the nuclear magnetic hydrogen spectrum and mass spectrum of phenylacetone after photocatalytic synthesis in Example 2;

[0027] Figure 5 It is the nuclear magnetic hydrogen spectrum and mass spectrum of 2-(4-nitrophenyl)propan-2-ol after photocatalytic synthesis in Example 3;

[0028] Figure 6 It is the nuclear magnetic hydrogen spectrum and mass spectrum of propene sulfone after photocatalytic synthesis in Example 4. DETAILED DESCRIPTION

[0029] 1) Preparation of Au doped carbon nitride

[0030] First, 3 g of melamine was added to 150 mL of ultrapure water, heated to 80 ° C, and stirred until completely dissolved. The resulting solution was added with 3 mL of a 10 mg / mL aqueous solution of chloroauric acid under rapid stirring, and the mixture was cooled to room temperature with stirring. The pH was adjusted to 6.5 with a NaOH solution. After heating at 80 ° C on a plate for 5 h, it was dried overnight and placed in a tube furnace under a 5% argon-hydrogen atmosphere. It was heated to 550 ° C at a rate of 5 ° C / min and calcined for 2 h to obtain gold-doped carbon nitride (Au / g-C3N4);

[0031] 2) Preparation of Au / g-C3N4-doped metal halide perovskite

[0032] To prepare the amine bromide precursor, 10 mL of oleylamine and 1.3 mL of hydrobromic acid were placed in a 50 mL three-necked round-bottom flask. The resulting curing reaction mixture was evacuated and heated at 120°C for 2 hours under a nitrogen purge. The reaction temperature was then raised to 150°C and heated for 30 minutes. Finally, the solution was maintained at 80°C for further use.

[0033] 0.2 mmol of cesium carbonate, 50 mg of Au / g-C3N4, 0.4 mmol of lead oxide, 20 mL of octadecene, and 1.5 mL of oleic acid were placed in a 50 mL three-necked reaction flask. After evacuation, nitrogen was purged at 120°C for 1 hour. After the reaction temperature was raised to 220°C, 1.6 mL of ammonium bromide precursor was immediately injected. After annealing for 6 minutes, the solution was cooled in an ice-water bath for 10 minutes. After washing three times with n-hexane by centrifugation, the composite photocatalyst (CsPbBr3 / Au / g-C3N4) was collected and dried in a vacuum oven at 60°C for 2 hours.

[0034] The prepared composite photocatalyst is used for the following applications:

[0035] Example 1

[0036] Thioanisole (18.4 mg, 0.2 mmol) was weighed and dissolved in 3 mL of 1,2-dichloroethane, and 15 mg of CsPbBr3 / Au / g-C3N4 was added. The reaction system was irradiated with visible light in an air atmosphere for 10 hours; then, the photocatalyst was recovered by centrifugation, and the resulting solution was extracted with an organic solvent three times. The organic phases were combined, dried, filtered, and concentrated to obtain the benzoic acid product (isolation yield: 92%).

[0037] Example 2

[0038] Ethylbenzene (21.2 mg, 0.02 mmol) was weighed into 3 mL of 1,2-dichloroethane, 15 mg of CsPbBr3 / Au / g-C3N4 was added, and the reaction system was irradiated with visible light for 10 hours under an air atmosphere; subsequently, the photocatalyst was recovered by centrifugation, the obtained solution was extracted with an organic solvent 3 times, the organic phase was combined, dried, filtered, concentrated, and the acetophenone product was obtained (separation yield: 82%).

[0039] Example 3

[0040] p-Nitroisopropylbenzene (33.0 mg, 0.2 mmol) was weighed into 3 mL of 1,2-dichloroethane, 15 mg of CsPbBr3 / Au / g-C3N4 was added, and the reaction system was irradiated with visible light for 10 hours under an air atmosphere; subsequently, the photocatalyst was recovered by centrifugation, the obtained solution was extracted with an organic solvent 3 times, the organic phase was combined, dried, filtered, concentrated, and the 2-(4-nitrophenyl)propan-2-ol product was obtained (separation yield: 76%).

[0041] Example 4

[0042] Ditoline (51.0 g, 0.2 mmol) was weighed into 3 mL of 1,2-dichloroethane, 15 mg of CsPbBr3 / Au / g-C3N4 was added, and the reaction system was irradiated with visible light for 10 hours under an air atmosphere; subsequently, the photocatalyst was recovered by centrifugation, the obtained solution was extracted with an organic solvent 3 times, the organic phase was combined, dried, filtered, concentrated, and the probenecid product was obtained (separation yield: 58%).

Claims

1. A method for preparing an all-solid-state Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for CH oxidation, characterized by: The synthetic route is as follows: 1) Preparation of Au-doped carbon nitride Add 1-3 parts of melamine to 100-200 parts of ultrapure water at a g / ml ratio, heat to 80°C, and stir until completely dissolved; continue stirring and add 1-5 parts of a 10 mg / mL aqueous solution of chloroauric acid, continue stirring, cool to room temperature, add sodium hydroxide solution to adjust the pH to 6.5-7, stir in air at 80°C for 5 hours, and then dry. After drying, calcinate at 550°C in a reducing atmosphere for 2 hours to obtain Au / g-C3N4; 2) Preparation of Au / g-C3N4-doped metal halide perovskite The oleylamine and hydrobromic acid were mixed and reacted, and the obtained curing reaction mixture was vacuumed and heated at 120°C for 2 hours under a nitrogen atmosphere. The reaction temperature was then increased to 150°C and heated for 30 minutes. The solution was then cooled and maintained at 80°C to obtain an ammonium bromide precursor for use. Cesium carbonate, Au / g-C3N4, and lead oxide, as well as octadecene and oleic acid, were mixed, evacuated, and heated at 120°C under a nitrogen atmosphere for 1 hour. After the reaction temperature was raised to 220°C, an ammonium bromide precursor was immediately injected. After annealing for 6 minutes, the solution was cooled in an ice-water bath for 10 minutes. The obtained solution was centrifuged, and the supernatant was discarded. The obtained yellow solid was washed with n-hexane 2-3 times and dried at 60° C. under vacuum for 2 hours to obtain the composite photocatalyst CsPbBr 3 / Au / g-C 3 N 4 .

2. The method for preparing an all-solid-state Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for CH oxidation according to claim 1, characterized in that: The reducing atmosphere is a 5% argon-hydrogen atmosphere.

3. The method for preparing an all-solid-state Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for CH oxidation according to claim 1, characterized in that: The volume ratio of the oleylamine to the hydrobromic acid is 10:1-1.

5.

4. The method for preparing an all-solid-state Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for CH oxidation according to claim 1, characterized in that: The cesium carbonate: Au / g-C3N4: lead oxide: octadecene: oleic acid: ammonium bromide precursor is 0.2 mmol: 45-55 mg: 0.4 mmol: 20 mL: 1.5 mL: 1-2 mL.

5. Application of an all-solid-state Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for CH oxidation in the synthesis of carboxylic acids, ketones, and alcohols, characterized by: The application is as follows: CsPbBr3 / Au / g-C3N4 and benzyl substrate were dispersed in 1,2-dichloroethane, and the resulting system was irradiated with visible light under an oxygen atmosphere until the substrate was completely converted; The reaction system is centrifuged to recover the photocatalyst for recycling; the obtained solution is extracted with an organic solvent, the organic phases are combined, dried over anhydrous sodium sulfate, filtered, and concentrated to obtain carboxylic acid, ketone, and alcohol products.

6. Use of the all-solid-state Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for CH oxidation in the synthesis of carboxylic acids, ketones and alcohols according to claim 5, characterized in that: The CsPbBr3 / Au / g-C3N4: benzyl substrate: 1,2-dichloroethane is 10-20 mg: 0.2mmol:3mL.

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