Catechol derivative coordinated TiO2@metal phthalocyanine photoanode material and its preparation method and application

Abstract

The present invention discloses a catechol derivative-coordinated TiO2@metal phthalocyanine photoanode material, a preparation method thereof, and an application thereof. The material comprises a TiO2 nanoarray as a core, a catechol derivative coordinating agent as a bridge, and a metal phthalocyanine as a shell, forming a coordinating agent-bridged core-shell structure, and can be used in the photoelectrocatalytic selective oxidation of glycerol to synthesize glyceraldehyde. The material of the present invention effectively improves the separation efficiency of photogenerated carriers, thereby significantly improving the photoelectrocatalytic activity of glycerol, realizing the directional upgrading of biomass from glycerol to glyceraldehyde. At the same time, the photoelectrocatalytic reaction conditions are mild, which can effectively alleviate the problem of C-C bond breakage during the oxidation of multi-carbon organic matter, providing a new idea for the highly selective preparation of multi-carbon products, and is of great significance to the green development of the biodiesel industry.

Description

Technical Field

[0001] The present invention relates to the field of photoelectrocatalytic materials and organic synthesis, and in particular to a TiO2@metal phthalocyanine photoanode material coordinated with a catechol derivative having a core-shell structure, a preparation method thereof, and application thereof in the photoelectrocatalytic oxidation of glycerol into glyceraldehyde. Background Art

[0002] Photoelectrocatalysis (PEC) is a powerful strategy that combines the advantages of photocatalysis and electrocatalysis. It can achieve efficient charge separation with the help of low bias voltage, while saving energy, avoiding excessive oxidation of reaction substrates, reducing side reactions, and achieving higher selectivity. Glycerol, a major byproduct in the biodiesel production process, can be mildly converted into C3 value-added chemicals such as glyceraldehyde and 1,3-dihydroxyacetone (DHA) through photoelectrocatalytic oxidation strategies, achieving biomass upgrading. Among them, glyceraldehyde has a wide range of applications and is often used as a nutritional supplement, food preservative, and pharmaceutical intermediate. Therefore, the rational design and preparation of efficient and stable photoanode materials for the photoelectrocatalytic oxidation of glycerol to glyceraldehyde is of great significance to the development of the biodiesel industry.

[0003] Metallophthalocyanines are organic compounds composed of a planar macrocycle and a central metal ion, and exhibit good catalytic activity in many reactions. The electronic structure of metallophthalocyanines can be effectively regulated by coordinating the metal center of the metallophthalocyanine with a ligand. Catechol derivatives with bidirectional coordination functions can not only regulate the electronic structure of metallophthalocyanines, but also improve the carrier transport performance between the semiconductor catalyst and the metallophthalocyanine by bridging the oxide semiconductor at the other end, achieving a bidirectional coordination effect of the core-shell structure, improving PEC performance, and exhibiting better catalytic activity and product selectivity. Therefore, the rational design of a core-shell structure bridged by a ligand for the selective photocatalytic oxidation of glycerol to glyceraldehyde is a valuable photoanode design and preparation strategy. Summary of the Invention

[0004] The present invention provides a TiO2@metal phthalocyanine photoanode material coordinated with a catechol derivative and a preparation method thereof. The material can be used for photoelectrocatalytic oxidation of glycerol into glyceraldehyde, thereby realizing directional upgrading and conversion of biomass.

[0005] The technical solutions of the present invention are as follows:

[0006] A catechol derivative-coordinated TiO2@metal phthalocyanine photoanode material, with a TiO2 nanoarray as a core, a coordinating agent as a bridge, and a metal phthalocyanine as a shell, forming a coordinating agent-bridged core-shell structure;

[0007] Preferably, the TiO2 nanoarray is a nanorod array structure, and the diameter of the nanorods is 80 to 150 nm;

[0008] The ligand is a catechol derivative selected from: 3,4-dihydroxybenzonitrile, dopamine or caffeic acid;

[0009] The metal phthalocyanine is a single metal or multi-metal phthalocyanine selected from the group consisting of copper phthalocyanine (CuPc), iron phthalocyanine (FePc), cobalt phthalocyanine (CoPc), copper cobalt phthalocyanine (CuCoPc), copper zinc phthalocyanine (CuZnPc), copper iron phthalocyanine (CuFePc) or cobalt iron phthalocyanine (CoFePc);

[0010] The thickness of the metal phthalocyanine shell is 5 to 15 nm.

[0011] The method for preparing the catechol derivative-coordinated TiO2@metal phthalocyanine photoanode material of the present invention comprises the following steps:

[0012] (1) Preparation of TiO2 nanoarrays by hydrothermal reaction-calcination method;

[0013] (2) soaking the TiO2 nanoarray obtained in step (1) in an ethanol solution of a catechol derivative at a constant temperature of 20 to 50° C. for 2 to 5 hours to obtain a TiO2 nanoarray coordinated and modified by a catechol derivative;

[0014] The concentration of the ethanol solution of the catechol derivative is 0.1 to 0.5 mg / mL, preferably 0.25 mg / mL;

[0015] The preferred constant temperature soaking temperature is 30°C and the time is 2h;

[0016] (3) placing the catechol derivative-coordinated TiO2 nanoarray obtained in step (2) in an ethanol solution of metal phthalocyanine, and subjecting it to a solvothermal reaction at 100-150° C. for 3-12 hours to obtain the catechol derivative-coordinated TiO2@metal phthalocyanine photoanode material;

[0017] The concentration of the metal phthalocyanine ethanol solution is 1 to 5 mg / mL, preferably 1 mg / mL;

[0018] The preferred solvent thermal reaction temperature is 120° C. and the time is 6 h.

[0019] Specifically, the TiO2 nanoarray in the present invention has a nanorod array structure, and its preparation process is as follows:

[0020] Deionized water, concentrated hydrochloric acid (36.5-38 wt%), and tetrabutyl titanate were mixed in an autoclave, added to a cleaned FTO substrate with the conductive surface facing downward, heated to 150°C for hydrothermal reaction for 5 hours, then removed, rinsed, dried, and heated to 450°C in air at a rate of 2°C / min and kept warm for 30 minutes to obtain TiO2 nanoarrays grown on the FTO substrate;

[0021] Preferably, the volume ratio of deionized water, concentrated hydrochloric acid, and tetrabutyl titanate is 3:3:0.1.

[0022] The preparation method of metal phthalocyanine in the present invention is as follows:

[0023] Pyromellitic dianhydride, phthalic anhydride, urea, ammonium chloride, ammonium molybdate, and copper acetate were mixed and ground uniformly, and the mixture was placed in a muffle furnace, heated to 220°C at a rate of 3°C / min, kept warm for 3 hours, and then cooled to room temperature, washed, and vacuum-dried to obtain copper phthalocyanine (CuPc) in powder form;

[0024] Preferably, the mass molar ratio of pyromellitic dianhydride, phthalic anhydride, urea, ammonium chloride, ammonium molybdate, and copper acetate is 0.6098 g: 0.4740 g: 2.721 g: 0.6419 g: 1.1 mmol;

[0025] The preparation method of iron phthalocyanine (FePc) and cobalt phthalocyanine (CoPc) is the same as above, except that copper acetate is replaced by ferric chloride or cobalt chloride;

[0026] The preparation methods of copper cobalt phthalocyanine (CuCoPc), copper zinc phthalocyanine (CuZnPc), copper iron phthalocyanine (CuFePc), and cobalt iron phthalocyanine (CoFePc) are the same as those described above, except that copper acetate is replaced by the corresponding bimetallic chloride.

[0027] The catechol derivative-coordinated TiO2@metal phthalocyanine photoanode material of the present invention can be used in the photoelectrocatalytic oxidation reaction of glycerol to glyceraldehyde. The specific application method is as follows:

[0028] The research team used an H-shaped electrolytic cell with a quartz window on one side. The cathode and anode compartments were separated by a Nafion 117 proton exchange membrane. A photoelectrocatalytic reaction system was assembled using a TiO2@metal phthalocyanine photoanode material coordinated with a catechol derivative as the photoanode, platinum as the cathode, Ag / AgCl as the reference electrode, and sodium sulfate aqueous solution as the electrolyte. Glycerol was added to the electrolyte in the anode compartment. A xenon lamp (300W) equipped with an AM1.5G filter was used as the light source to simulate sunlight, which was irradiated onto the photoanode through the quartz window. A constant voltage was applied to the electrolytic reaction, resulting in the selective conversion of glycerol to glyceraldehyde.

[0029] The electrolyte sodium sulfate aqueous solution has a concentration of 0.1 to 1 M, preferably 0.5 M;

[0030] The glycerol concentration in the anode compartment electrolyte is 10 to 100 mM, preferably 100 mM;

[0031] The electrolysis potential is 0.8 to 1.2 V vs. RHE, preferably 1.0 V vs. RHE.

[0032] The beneficial effects of the present invention are:

[0033] This invention provides a TiO2@metal phthalocyanine photoanode material coordinated by a catechol derivative. This material utilizes catechol derivatives for coordination bridging, creating a core-shell structure through a solvothermal method. Compared to traditional methods, this method more effectively controls the microstructure of the composite photoanode material by adjusting the functional groups on the catechol derivatives, resulting in a unique core-shell structure. This improves carrier transport between the semiconductor and the metal phthalocyanine, increasing hole utilization and, consequently, enhancing the photoelectrocatalytic activity of glycerol.

[0034] At 1.0 V vs RHE, the photocurrent densities of TiO2@CuPc and TiO2@CuCoPc are 1.75 mA / cm 2 and 1.70 mA / cm 2 , which is 3.2 times that of TiO2; the yield of glyceraldehyde on TiO2@CuPc is 113.6mmol / m 2 / h, 2.4 times that of TiO2. This invention achieves the targeted upgrading of biomass from glycerol to glyceraldehyde, effectively alleviating the problem of CC bond cleavage during the oxidation of multi-carbon organic matter and providing a new approach for the highly selective preparation of multi-carbon products. Furthermore, the mild conditions of the photoelectrocatalytic reaction are of great significance to the green development of the biodiesel industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 : Transmission electron microscopy image of the TiO2@CuPc photoanode with core-shell structure in Example 1.

[0036] Figure 2 : Linear sweep voltammograms of TiO2@CuPc photoanode coordinated and bridged with different catechol derivatives in Example 2 in glycerol.

[0037] Figure 3 : The yield diagram of product glyceraldehyde in Example 2.

[0038] Figure 4 : Linear sweep voltammogram of TiO2@CuCoPc photoanode in glycerol in Example 3. DETAILED DESCRIPTION

[0039] To facilitate understanding of the present invention, the present invention will be further described below in conjunction with specific examples. These examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention. The professional terms used herein are merely for the purpose of describing specific examples and are not intended to limit the scope of the present invention.

[0040] In the following examples,

[0041] The preparation process of TiO2 nanoarray is as follows:

[0042] 3 mL of deionized water and 3 mL of concentrated hydrochloric acid were stirred and mixed in a Teflon-lined stainless steel autoclave (volume 25 mL), and then 100 μL of tetrabutyl titanate was added. The cleaned FTO substrate was added with the conductive side facing down and hydrothermally reacted at 150 ° C for 5 h. After synthesis, it was rinsed with deionized water and then dried in air. Finally, the sample was refrigerated in air at 2 ° C min -1 The TiO2 nanoarrays were obtained by heating the sample to 450℃ at a rate of 0.18 V and keeping it at 450℃ for 30 min.

[0043] The preparation method of metal phthalocyanine is as follows:

[0044] 0.6098 g of pyromellitic dianhydride, 0.4740 g of phthalic anhydride, 2.721 g of urea, 0.6419 g of ammonium chloride, 0.0034 g of ammonium molybdate, and 0.2196 g of copper acetate (1.1 mmol) were mixed and ground, and the mixture was heated in a muffle furnace at 3 ° C min -1 The temperature was raised to 220°C and kept at this temperature for 3 hours. After heating, the mixture was cooled to room temperature, washed three times with deionized water, acetone, and ethanol, and dried under vacuum at 60°C for 12 hours to obtain copper phthalocyanine (CuPc) powder.

[0045] The preparation methods of iron phthalocyanine (FePc) and cobalt phthalocyanine (CoPc) are the same, except that copper acetate is replaced with 1.1 mmol of ferric chloride and cobalt chloride.

[0046] Copper cobalt phthalocyanine (CuCoPc), copper zinc phthalocyanine (CuZnPc), copper iron phthalocyanine (CuFePc), and cobalt iron phthalocyanine (CoFePc) were prepared by adding 1.1 mmol of a double metal chloride.

[0047] Example 1

[0048] The preparation method of TiO2@CuPc-DHBN photoanode material coordinated by 3,4-dihydroxybenzonitrile is as follows:

[0049] (1) Dissolve 5 mg of 3,4-dihydroxybenzonitrile (DHBN) in 10 mL of ethanol, place the TiO2 nanoarray, and incubate in a water bath at 30°C for 2 h to obtain TiO2 coordinated with 3,4-dihydroxybenzonitrile.

[0050] (2) After ultrasonically dispersing 20 mg of copper phthalocyanine with 10 mL of ethanol, the coordinated TiO2 nanoarrays were placed in the solution and subjected to a solvothermal reaction at 120°C for 6 h. After the reaction, the excess metal phthalocyanine on the surface was rinsed with ethanol and then dried in air to obtain a TiO2@CuPc photoanode material with a core-shell structure.

[0051] Figure 1This is the transmission electron microscopy image of the prepared TiO2@CuPc photoanode. The obvious core-shell structure can be seen from the image. The diameter of TiO2 is 85nm and the thickness of the shell is 13nm.

[0052] An H-type electrolytic cell with a quartz window on one side was used, and a 0.5M sodium sulfate aqueous solution was added. 100mM glycerol was added to the anode chamber. TiO2@CuPc was used as the photoanode, platinum as the cathode, and Ag / AgCl as the reference electrode. A xenon lamp was turned on and irradiated through the quartz window onto the back of the FTO loaded with the photoanode material. A 1.0V bias was applied and electrolysis was carried out for 1h. After the reaction was completed, 1mL of the reaction solution was taken and the product was detected by high-performance liquid chromatography. The comparison results showed that the yield of glyceraldehyde on the TiO2@CuPc photoanode was 113.6mmol / m 2 / h, which is 2.4 times that of TiO2.

[0053] Example 2

[0054] The preparation of TiO2@CuPc with a core-shell structure follows the same operating steps as in Example 1, except that the ligand is changed from 3,4-dihydroxybenzonitrile to dopamine (DA) or caffeic acid (CA). The resulting composite photoanode material is TiO2@CuPc-DA or TiO2@CuPc-CA.

[0055] Perform linear voltammetric sweep test in the range of 0.2V to 1.8V vs RHE, such as Figure 2 As shown in Figure 2, the photocurrent density of the TiO2@CuPc photoanode materials with three different catechol derivatives coordinated and bridged is higher than that of TiO2. The best one is TiO2@CuPc-DHBN, with a photocurrent density of 1.75 mA / cm at 1.0 V vs. RHE. 2 , is TiO2(0.54mA / cm 2 ) is ~3.2 times.

[0056] The performance of three catechol-bridged TiO2@CuPc photoanode materials in photoelectrocatalytic glycerol oxidation reaction is shown in Figure 2. Figure 3 As shown, the best one is TiO2@CuPc-DHBN with a yield of 113.6mmol / m 2 / h, is TiO2 (46.6mmol / m 2 / h) is 2.4 times.

[0057] Example 3

[0058] The core-shell TiO2@CuCoPc was prepared by the same steps as in Example 1. Only 1.1 mmol of cobalt chloride was added during the preparation of monometallic copper phthalocyanine to form bimetallic copper-cobalt phthalocyanine. The other conditions remained unchanged. The cyclic voltammetry curve is shown in FIG. Figure 4 As shown, the photocurrent density of TiO2@CuCoPc is higher than that of TiO2, and the photocurrent density at 1.0V vs.RHE is 1.7mA / cm 2 , which is ~3.2 times that of TiO2.

Claims

1. A catechol derivative coordinated TiO2@metal phthalocyanine photoanode material, characterized in that: The material uses TiO2 nanoarray as core, coordination agent as bridge, and metal phthalocyanine as shell, forming a coordination agent-bridged core-shell structure. The ligand is a catechol derivative selected from: 3,4-dihydroxybenzonitrile; The metal phthalocyanine is selected from the group consisting of copper phthalocyanine, copper cobalt phthalocyanine, copper zinc phthalocyanine or copper iron phthalocyanine; The thickness of the metal phthalocyanine shell is 5~15 nm.

2. The method for preparing the catechol derivative-coordinated TiO2@metal phthalocyanine photoanode material according to claim 1, characterized in that: The steps include: (1) Preparation of TiO2 nanoarrays by hydrothermal reaction-calcination method; (2) Soaking the TiO2 nanoarray obtained in step (1) in an ethanol solution of a catechol derivative at a constant temperature of 20-50°C for 2-5 hours to obtain a TiO2 nanoarray coordinated and modified by a catechol derivative; (3) The catechol derivative-coordinated TiO2 nanoarray obtained in step (2) is placed in an ethanol solution of metal phthalocyanine, and subjected to a solvent thermal reaction at 100-150°C for 3-12 hours to obtain the catechol derivative-coordinated TiO2@metal phthalocyanine photoanode material.

3. The preparation method according to claim 2, wherein The operation process of step (1) is as follows: Deionized water, concentrated hydrochloric acid, and tetrabutyl titanate were mixed in an autoclave, added to a cleaned FTO substrate with the conductive surface facing down, and heated to 150 °C for hydrothermal reaction for 5 h. After that, the substrate was taken out, rinsed, and dried, and heated to 450 °C in air at a rate of 2 °C / min and kept warm for 30 min to obtain a TiO2 nanoarray grown on the FTO substrate.

4. The preparation method according to claim 2, wherein In step (2), the concentration of the ethanol solution of the catechol derivative is 0.1-0.5 mg / mL.

5. The preparation method according to claim 2, wherein In step (3), the concentration of the metal phthalocyanine ethanol solution is 1-5 mg / mL.

6. The preparation method according to claim 2, wherein In step (3), the preparation method of metal phthalocyanine is as follows: Pyromellitic dianhydride, phthalic anhydride, urea, ammonium chloride, ammonium molybdate, and copper acetate were mixed and ground uniformly. The mixture was placed in a muffle furnace and heated to 220°C at a rate of 3°C / min, kept at this temperature for 3 h, and then cooled to room temperature. The mixture was washed and vacuum-dried to obtain copper phthalocyanine. The preparation methods of copper-cobalt phthalocyanine, copper-zinc phthalocyanine and copper-iron phthalocyanine are the same as those described above, and cobalt chloride, zinc chloride or ferric chloride can be added during the preparation of monometallic copper phthalocyanine.

7. Use of the catechol derivative-coordinated TiO2@metal phthalocyanine photoanode material according to claim 1 in the photoelectrocatalytic oxidation reaction of glycerol to glyceraldehyde.

8. The use according to claim 7, characterized in that The application method is as follows: The researchers used an H-shaped electrolytic cell with a quartz window on one side. The cathode and anode compartments were separated by a Nafion 117 proton exchange membrane. A photoelectrocatalytic reaction system was assembled using a TiO2@metal phthalocyanine photoanode material coordinated with a catechol derivative as the photoanode, platinum as the cathode, Ag / AgCl as the reference electrode, and sodium sulfate aqueous solution as the electrolyte. Glycerol was added to the electrolyte in the anode compartment. Sunlight simulated by a xenon lamp equipped with an AM1.5G filter was irradiated onto the photoanode through the quartz window. A constant voltage was applied to the electrolytic reaction, resulting in the selective conversion of glycerol into glyceraldehyde. The electrolyte sodium sulfate aqueous solution concentration is 0.1~1 M; The glycerol concentration in the electrolyte of the anode chamber was 10–100 mM; Electrolysis potential 0.8~1.2 V vs. RHE.

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