All-solid-state Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for C-H oxidation and preparation method thereof

Abstract

The invention provides a preparation method of an all-solid-state Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for enhancing C-H oxidation and a preparation method of the all-solid-state Z-type heterojunction. By adopting a method of doping Au / g-C3N4 with metal halogenated perovskite, efficient catalytic activity and high stability of the metal halogenated perovskite material under an oxygen-enriched condition are realized; a benzyl substrate is irradiated by visible light at room temperature in an oxygen atmosphere, so that high-efficiency and high-selectivity synthesis of carboxylic acid, ketone and alcohol is realized.

Description

Technical Field

[0001] The present invention relates to the field of photocatalysts, and in particular to an all-solid-state Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for CH oxidation and a preparation method thereof. Background Art

[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 the synthesis of carboxylic acids, ketones, and alcohols are necessary to facilitate drug discovery.

[0003] Selective activation of saturated C-H bonds into high-value-added chemicals has great 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 oxygenated products. In general, conventional methods for activating C-H bonds require toxic and corrosive chemical oxidants (such as dichromates and permanganates) and harsh conditions, especially high temperature and high pressure. To overcome these obstacles, photocatalysis, as a green and mild technology, is considered to be a promising method for selective activation of C(sp3)-H bonds. Therefore, the development of catalytic systems with fast and efficient properties to achieve green and efficient conversion of C(sp3)-H bonds to carboxylic acids, ketones and alcohols has become a current research hotspot.

[0004] Metal halide perovskite materials (MHPs) are ideal visible light catalysts due to their sensitive visible light response, long carrier lifetime, easy structural control, and low cost and availability. However, since active oxygen species and water can easily penetrate into the MHPs lattice and cause skeleton degradation, the MHPs are structurally unstable in oxygen-rich and high-humidity environments, which limits their application research. Therefore, achieving high structural stability and high catalytic activity of MHPs under oxygen-rich conditions is still a difficult problem to be overcome. Summary of the invention

[0005] One of the objects of the present invention is to provide an all-solid-state Z-type heterojunction for enhancing CH oxidation

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

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

[0008] Add 1-3 parts of melamine to 100-200 parts of ultrapure water according to the g / m ratio, heat to 80°C, and stir 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, add sodium hydroxide solution to adjust the pH to 6.5-7, stir in air at 80°C for 5 hours and then dry, and after drying, calcine at 550°C in a reducing atmosphere for 2 hours to obtain gold-doped carbon nitride (Au / g-C3N4);

[0009] Wherein, the reducing atmosphere is 5% argon hydrogen atmosphere;

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

[0011] Mix oleylamine and hydrobromic acid to react, evacuate the obtained curing reaction mixture and heat it at 120°C, heat it for 2 hours under a nitrogen atmosphere, then increase the reaction temperature to 150°C and heat it for 30 minutes, then cool the solution and keep it at 80°C to obtain an ammonium bromide precursor for use;

[0012] Wherein, the volume ratio of oleylamine to hydrobromic acid is 10:1-1.5;

[0013] Cesium carbonate, gold-doped carbon nitride (Au / g-C3N4) and lead oxide, as well as octadecene and oleic acid were mixed, vacuumed and heated at 120°C in a nitrogen atmosphere for 1 hour. After the reaction temperature was raised to 220°C, an ammonium bromide precursor was immediately injected, annealed for 6 minutes, and then the solution was cooled in an ice-water bath for 10 minutes.

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

[0015] Among them, the precursors of cesium carbonate: Au / g-C3N4: lead oxide: octadecene: oleic acid: ammonium bromide are 0.2mmol: 45-55mg: 0.4mmol: 20mL: 1.5mL: 1-2mL.

[0016] Another object of the present invention is to provide the use of the above catalyst in the synthesis of carboxylic acids, ketones and alcohols using benzyl as a substrate, as follows:

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

[0018] 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;

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

[0020] Advantages of the present invention:

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

[0022] (2) The present invention uses a benzyl substrate as a raw material, 1,2-dichloroethane as a solvent, and CsPbBr3 / Au / g-C3N4 as a catalyst, and achieves efficient and highly selective synthesis of carboxylic acids, ketones, and alcohols by visible light irradiation at room temperature in an oxygen atmosphere. The method is economical and green, has high atomic utilization, simple post-processing, and low experimental cost, and is suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the synthesis of Au / g-C3N4 and CsPbBr3 / Au / g-C3N4 composite materials;

[0024] Figure 2 TEM spectrum and mapping element analysis of CsPbBr3 / Au / g-C3N4;

[0025] Figure 3 The NMR hydrogen spectrum and mass spectrum of benzoic acid after photocatalytic synthesis in Example 1;

[0026] Figure 4 The H NMR spectrum and mass spectrum of acetophenone after photocatalytic synthesis in Example 2;

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

[0028] Figure 6 These are the H NMR spectrum and mass spectrum of probenecid 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 10 mg / mL chloroauric acid aqueous solution under rapid stirring, stirred and cooled to room temperature, and the pH was adjusted to 6.5 with a NaOH solution. After heating at 80 ° C for 5 h on a table, it was dried overnight and placed in a tubular furnace under a 5% argon hydrogen atmosphere, 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] Preparation of 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 h under nitrogen purge. The reaction temperature was then raised to 150 °C and heated for 30 min. Finally, the solution was kept at 80 °C for further use;

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

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

[0037] Example 2

[0038] Ethylbenzene (21.2 mg, 0.02 mmol) was weighed and dissolved in 3 mL of 1,2-dichloroethane, and then 15 mg of CsPbBr3 / Au / g-C3N4 was added. The reaction system was irradiated with visible light for 10 hours in an air atmosphere; then, the photocatalyst was recovered by centrifugation, and the resulting solution was extracted with an organic solvent for 3 times, the organic phases were combined, dried, filtered, and concentrated to obtain the acetophenone product (isolation yield: 82%).

[0039] Example 3

[0040] Weigh p-nitroisopropylbenzene (33.0 mg, 0.2 mmol) and dissolve it in 3 mL 1,2-dichloroethane, then add 15 mg CsPbBr3 / Au / g-C3N4, and the reaction system is irradiated with visible light for 10 hours in an air atmosphere; then, the photocatalyst is recovered by centrifugation, and the resulting solution is extracted with an organic solvent for 3 times, the organic phases are combined, dried, filtered, and concentrated to obtain a 2-(4-nitrophenyl)propan-2-ol product (isolation yield: 76%).

[0041] Example 4

[0042] Detrolamide (51.0 g, 0.2 mmol) was weighed and dissolved in 3 mL of 1,2-dichloroethane, and then 15 mg of CsPbBr3 / Au / g-C3N4 was added. The reaction system was irradiated with visible light for 10 hours in an air atmosphere; then, the photocatalyst was recovered by centrifugation, and the resulting solution was extracted with an organic solvent for 3 times, the organic phases were combined, dried, filtered, and concentrated to obtain the probenecid product (isolation yield: 58%).

Claims

1. A method for preparing an all-solid-state Z-type heterojunction CsPbBr3 / Au / g-C3N4 photocatalyst for CH oxidation, characterized in that: 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 according to the g / ml ratio, heat to 80°C, and stir 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, add sodium hydroxide solution to adjust the pH to 6.5-7, stir in air at 80°C for 5 hours and then dry, and after drying, calcine 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 Mix oleylamine and hydrobromic acid to react, evacuate the obtained curing reaction mixture and heat it at 120°C, heat it for 2 hours under a nitrogen atmosphere, then increase the reaction temperature to 150°C and heat it for 30 minutes, then cool the solution and keep it 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 in a nitrogen atmosphere for 1 hour. After the reaction temperature was raised to 220°C, an ammonium bromide precursor was immediately injected, annealed for 6 minutes, and then the solution was cooled in an ice-water bath for 10 minutes. The obtained solution was centrifuged, the supernatant was discarded, and the obtained yellow solid was washed with n-hexane for 2-3 times and dried at 60° C. for 2 hours under vacuum to obtain the composite photocatalyst CsPbBr3 / Au / g-C3N4.

2. The method for preparing a 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 oleylamine to 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 0.2mmol: 45-55mg: 0.4mmol: 20mL: 1.5mL: 1-2mL.

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 in that: 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 in 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 with anhydrous sodium sulfate, filtered, and concentrated to obtain carboxylic acid, ketone and alcohol products.

6. The use 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 according to claim 5, characterized in that: The CsPbBr3 / Au / g-C3N4: benzyl substrate: 1,2-dichloroethane is 10-20 mg: 0.2mmol:3mL.

Images