A photothermal-pyroelectric-photocatalytic composite catalyst system and its preparation method and application

Abstract

The present invention discloses a photothermal-pyroelectric-photocatalytic composite catalyst system and its preparation method and application. The preparation method comprises the following steps: in situ derivatizing and growing a photocatalyst with a pyroelectric effect on a MXene surface to obtain a composite material, then loading a co-catalyst on the composite material, and finally mixing the composite material with a polymer matrix to form a thin film to obtain the photothermal-pyroelectric-photocatalytic composite catalyst system. The composite material has excellent photothermal conversion efficiency, good pyroelectric performance and photocatalytic water decomposition ability. The pyroelectric effect is introduced into photocatalysis, and compensating charges excited by temperature changes participate in the catalytic reaction. At the same time, the presence of the pyroelectric field improves the mobility of photogenerated charges. The photothermal, pyroelectric and photocatalytic methods can synergistically improve the performance of water decomposition and hydrogen production.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic materials, and in particular to a photothermal-pyroelectric-photocatalytic composite catalyst system and a preparation method and application thereof. Background Art

[0002] Photocatalytic technology is a key strategy for developing and utilizing solar energy, holding enormous potential for alleviating global environmental pollution and energy crises. Replacing fossil fuels with clean, renewable energy as the primary energy source is crucial for the sustainability of future energy supplies and global security. Hydrogen is a clean, renewable fuel with high energy density, and photocatalytic water splitting for hydrogen production is gaining increasing attention. Infrared light, which accounts for approximately 50% of the solar spectrum, has been neglected due to its low photon energy, making it incapable of directly stimulating photocatalytic reactions. Photothermal technology, however, can convert infrared light into heat. MXene is a promising photothermal material with high absorption capacity in the visible and near-infrared spectral ranges. Using MXene, the efficiency of infrared light conversion to heat can be significantly improved.

[0003] Temperature fluctuations are a natural energy source in our environment and can be considered a clean energy source similar to sunlight. Pyroelectric materials can effectively respond to temperature fluctuations, generating the pyroelectric effect. Temperature changes induce slight spatial motions of atoms within the crystal structure, leading to changes in the internal polarization of the pyroelectric body and changes in the induced pyroelectric charge on the surface of the pyroelectric material. In recent years, pyroelectric catalysis, a catalytic process that combines the pyroelectric effect with chemical redox reactions, has been widely used in catalysis, energy conversion, and environmental remediation, including water decomposition, the decomposition of hazardous organic matter, the generation of reactive oxygen species, and disinfection.

[0004] At present, there are many studies on the combination of pyroelectric effect and photocatalytic reaction. Chinese patent document CN202110229872.5 discloses a method and application of enhancing the photocatalytic performance of heterostructure composite materials by pyroelectric effect. Ba(CH3COO)2, Sr(CH3COO)2 and tetrabutyl titanate are used as raw materials. 1-x Sr x The stoichiometric ratio of TiO3 (0≤x≤1) is formed through hydrolysis and polycondensation to form a stable sol and then gradually transformed into a wet gel, which is then prepared into a hollow Ba by electrospinning and calcination. 1-x Sr x TiO3 nanotubes, and attached silver nanoparticles and silver oxide particles to Ba by ion adsorption 1-x Sr x After centrifugation, drying and heat treatment, S-type or Z-type heterogeneous structure composite materials Ba were obtained on TiO3 nanotubes. 1- x Srx TiO3 / Ag / Ag2O.

[0005] The present invention creatively combines photothermal materials and pyroelectric materials with photocatalysts to construct a photothermal-pyroelectric-photocatalytic composite system. While infrared light is effectively utilized, the synergistic effect of the pyroelectric effect and the photocatalytic reaction improves the performance of water decomposition and hydrogen production. Pyroelectric materials have spontaneous polarization. Under temperature changes, they release charge due to spontaneous polarization, converting H in the aqueous solution into hydrogen. + Reduced to H2. In addition, the built-in electric field generated by the pyroelectric effect can effectively promote the separation of photogenerated carriers and accelerate the migration speed of carriers, thereby improving the photocatalytic efficiency. Summary of the Invention

[0006] In order to address the deficiencies in the prior art, the present invention aims to provide a photothermal-pyroelectric-photocatalytic composite catalyst system, its preparation method, and application. MXene is used as a source for in-situ derivatization and growth of a photocatalyst with a pyroelectric effect, which is then loaded with a co-catalyst and mixed with a polymer matrix to form a thin film. Infrared light, which is often overlooked in photocatalytic reactions, can be utilized to achieve a series of energy conversions from light to heat to electricity to chemical energy.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a photothermal-pyroelectric-photocatalytic composite catalyst system comprises the following steps: in situ derivatizing and growing a photocatalyst with a pyroelectric effect on the surface of MXene to obtain a composite material, then loading a co-catalyst on the composite material, and finally mixing the composite material with a polymer matrix to form a thin film to obtain the photothermal-pyroelectric-photocatalytic composite catalyst system.

[0009] Preferably, the photocatalyst having pyroelectric effect is Ba x Sr 1-x TiO3, 0≤x≤1.

[0010] Preferably, the photocatalyst having pyroelectric effect is BaTiO3 and / or PbTiO3.

[0011] Preferably, the co-catalyst is one or more of Pt, Rh, Pd, and Au, and the loading amount of the co-catalyst on the composite material is 0.05 to 0.2 wt%.

[0012] Specifically, the loading amount of the co-catalyst on the composite material can be 0.05 wt%, 0.1 wt%, 0.15 wt%, or 0.2 wt%.

[0013] Preferably, the polymer matrix is ​​one or more of PVA, α-PVDF, PI, PDMS, and PE, and the mass ratio of the composite material to the polymer matrix is ​​0.05 to 0.15:1.

[0014] Specifically, the mass ratio of the composite material to the polymer matrix can be 0.05:1, 0.1:1, or 0.15:1.

[0015] Preferably, the preparation method of the composite material comprises the following steps: etching away the Al layer in the precursor MAX (Ti3AlC2), and obtaining MXene (Ti3C2) by centrifugal drying; adding NaBF4 and HCl solution, performing a hydrothermal reaction once, converting part of the Ti in the MXene (Ti3C2) substrate into TiO2, and in situ derivatizing and growing TiO2 on the MXene surface to obtain MXene-TiO2 composite powder, adding the MXene-TiO2 composite powder into deionized water, and then adding a pyroelectric metal salt, performing a secondary hydrothermal reaction, and reacting the TiO2 in the MXene-TiO2 composite powder into a photocatalyst with a pyroelectric effect to obtain the composite material.

[0016] Preferably, the usage ratio of MXene (Ti3C2), NaBF4, and HCl solution is 60-100 mg: 0.125-0.205 g: 10-20 mL.

[0017] Preferably, the pyroelectric metal salt is a soluble salt of Ba, Pb, or Sr, and the pyroelectric metal salt is in excess.

[0018] Preferably, the first hydrothermal reaction condition is 160-200° C. for 1-10 h, and the second hydrothermal reaction condition is 160-200° C. for 60-84 h.

[0019] Specifically, under the premise of an excess of pyroelectric metal salt, the loading amount of the photocatalyst having the pyroelectric effect is proportional to the duration of the hydrothermal reaction.

[0020] Specifically, the primary hydrothermal reaction temperature can be 160°C, 170°C, 180°C, 190°C, or 200°C, and the reaction time can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h.

[0021] Specifically, the secondary hydrothermal reaction temperature can be 160°C, 170°C, 180°C, 190°C, or 200°C, and the reaction time can be 60h, 64h, 68h, 72h, 76h, 80h, or 84h.

[0022] Preferably, the co-catalyst is loaded by one or more of photodeposition, impregnation, reduction and microwave methods.

[0023] The present invention also claims protection for a photothermal-pyroelectric-photocatalytic composite catalyst system prepared by the preparation method.

[0024] The present invention also claims to protect the use of the photothermal-pyroelectric-photocatalytic composite catalyst system in high-efficiency photothermal-photoelectric-photocatalytic decomposition of water to produce hydrogen.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a photothermal-pyroelectric-photocatalytic composite catalyst system, which uses MXene as a source to locate the photocatalytic reaction on the surface and interface of the film. The film interface has high photothermal conversion efficiency, and rapid local heat collection can be used to achieve rapid interface temperature increase, forming a significant temperature difference, which generates a strong driving force for the pyroelectric effect. At the same time, the film material is easy to recycle and expand, and it can be easily integrated into an immobilized photocatalytic system. In this composite catalyst system, the photothermal material is MXene, and BaTiO3 is a pyroelectric material and photocatalyst. Under simulated solar light, the MXene in the system absorbs light and is first heated, and then the photocatalyst grown in situ on the surface of the MXene is heated. The photocatalyst is also a pyroelectric material. Under temperature change conditions, it releases charge due to spontaneous polarization, converting H in the aqueous solution into + Reduced to H2, in addition, a pyroelectric field is formed on its surface, and electrons migrate toward the direction with positive pyroelectric potential and further migrate to the noble metal co-catalyst to react with water molecules to generate hydrogen, and positively charged holes migrate toward the direction with negative pyroelectric potential; on the one hand, the pyroelectric effect excites the photocatalyst to generate pyroelectric charges, which convert H2 in water into + On the other hand, the pyroelectric effect promotes the migration of photogenerated carriers in the photocatalytic water splitting reaction. The synergistic effect of photothermal, pyroelectric and photocatalysis greatly improves the hydrogen production performance of the catalytic reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only show schematic diagrams of certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 This is a diagram of the catalyst structure of the pyroelectric-photothermal-photocatalytic composite system provided by the present invention; in the figure: 1. Thin film carrier; 2. MXene; 3. Photocatalyst with pyroelectric effect;

[0029] Figure 2This is the Pt-loaded MXene-BaTiO3-PE composite material prepared in Example 4 of the present invention; in the figure: 1. Pt-loaded MXene-BaTiO3; 2. PE film;

[0030] Figure 3 The performance diagram of the composite system catalyst prepared in Examples 1 to 11 and Comparative Examples 1 to 2 for decomposing water and producing hydrogen under visible light. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0032] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0033] The present invention will be further described below with reference to specific examples.

[0034] Example 1

[0035] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0036] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0037] (2) Using 80 mg of MXene (Ti3C2) prepared in step (1) as a substrate, 0.165 g of crystal plane control agent NaBF4 and 15 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally reacted at 180 ° C for 10 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain a Ti3C2-TiO2 composite powder, which was added to deionized water, and then 5 g of Ba(OH)2·8H2O and 5 g of KOH were added, and the mixture was hydrothermally reacted at 180 ° C for 72 h to convert the TiO2 in the Ti3C2-TiO2 composite powder into BaTiO3 to obtain a MXene-BaTiO3 composite material;

[0038] (3) The MXene-BaTiO3 composite material obtained in step (2) was placed in a Pyrex reaction cell filled with deionized water, connected to a photocatalytic water splitting hydrogen production system (Labsolar-6A), and the system was evacuated to remove the air in the system. The composite material was subjected to photodeposition to load the hydrogen production co-catalyst Pt. 0.1 wt% Pt was deposited on the MXene-BaTiO3 composite material using a solution of H2PtCl6. The reaction time was 3 h, and a 300 W xenon lamp was used as a light source to obtain a Pt-loaded MXene-BaTiO3 composite material.

[0039] (4) Polyvinyl alcohol (PVA) and gelatin were mixed in distilled water to obtain a PVA-gelatin solution, and then polyvinyl alcohol pyridone was dissolved in a solution of ethanol and water, mixed with the PVA-gelatin solution, and reacted at 50°C for 3 hours to obtain a mixed solution, and then the composite material powder obtained in step (3) was dispersed in the mixed solution, the mass ratio of the composite material to PVA was 0.1:1, cross-linked by physical cross-linking method, and stored at low temperature to obtain a thin film of Pt-loaded MXene-BaTiO3-PVA composite material.

[0040] Example 2

[0041] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0042] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0043] (2) Using 80 mg of MXene (Ti3C2) prepared in step (1) as the substrate, 0.165 g of crystal plane control agent NaBF4 and 15 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally reacted at 180 ° C for 3 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain a Ti3C2-TiO2 composite powder, which was added to deionized water, and then 5 g of Ba(OH)2·8H2O and 5 g of KOH were added, and the mixture was hydrothermally reacted at 180 ° C for 72 h to convert the TiO2 in the Ti3C2-TiO2 composite powder into BaTiO3 to obtain a MXene-BaTiO3 composite material;

[0044] (3) The MXene-BaTiO3 composite material obtained in step (2) was placed in a Pyrex reaction cell filled with deionized water, connected to a photocatalytic water splitting hydrogen production system (Labsolar-6A), and the system was evacuated to remove the air in the system. The composite material was subjected to photodeposition to load the hydrogen production co-catalyst Pt. 0.2 wt% Pt was deposited on the MXene-BaTiO3 composite material using a solution of H2PtCl6. The reaction time was 3 h. A 300 W xenon lamp was used as a light source to obtain a Pt-loaded MXene-BaTiO3 composite material.

[0045] (4) Polyvinyl alcohol (PVA) and gelatin were mixed in distilled water to obtain a PVA-gelatin solution, and then polyvinyl alcohol pyridone was dissolved in a solution of ethanol and water, mixed with the PVA-gelatin solution, and reacted at 50°C for 3 hours to obtain a mixed solution, and then the composite material powder obtained in step (3) was dispersed in the mixed solution, the mass ratio of the composite material to PVA was 0.1:1, cross-linked by physical cross-linking method, and stored at low temperature to obtain a thin film of Pt-loaded MXene-BaTiO3-PVA composite material.

[0046] Example 3

[0047] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0048] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0049] (2) Using 100 mg of MXene (Ti3C2) prepared in step (1) as the substrate, 0.205 g of crystal plane control agent NaBF4 and 20 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally reacted at 180 ° C for 1 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain a Ti3C2-TiO2 composite powder, which was added to deionized water, and then 5 g of Ba(OH)2·8H2O and 5 g of KOH were added, and the mixture was hydrothermally reacted at 180 ° C for 72 h to convert the TiO2 in the Ti3C2-TiO2 composite powder into BaTiO3 to obtain a MXene-BaTiO3 composite material;

[0050] (3) The MXene-BaTiO3 composite material obtained in step (2) was placed in a Pyrex reaction cell filled with deionized water, connected to a photocatalytic water splitting hydrogen production system (Labsolar-6A), and the system was evacuated to remove the air in the system. The composite material was subjected to photodeposition to load the hydrogen production co-catalyst Pt. 0.05 wt% Pt was deposited on the MXene-BaTiO3 composite material using a solution of H2PtCl6. The reaction time was 3 h, and a 300 W xenon lamp was used as a light source to obtain a Pt-loaded MXene-BaTiO3 composite material.

[0051] (4) Polyvinyl alcohol (PVA) and gelatin were mixed in distilled water to obtain a PVA-gelatin solution, and then polyvinyl alcohol pyridone was dissolved in a solution of ethanol and water, mixed with the PVA-gelatin solution, and reacted at 50°C for 3 hours to obtain a mixed solution, and then the composite material powder obtained in step (3) was dispersed in the mixed solution, the mass ratio of the composite material to PVA was 0.1:1, cross-linked by physical cross-linking method, and stored at low temperature to obtain a thin film of Pt-loaded MXene-BaTiO3-PVA composite material.

[0052] Example 4

[0053] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0054] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0055] (2) Using 60 mg of MXene (Ti3C2) prepared in step (1) as a substrate, 0.125 g of crystal plane control agent NaBF4 and 10 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally reacted at 180 ° C for 10 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain a Ti3C2-TiO2 composite powder, which was added to deionized water, and then 5 g of Ba(OH)2·8H2O and 5 g of KOH were added, and the mixture was hydrothermally reacted at 180 ° C for 72 h to convert the TiO2 in the Ti3C2-TiO2 composite powder into BaTiO3 to obtain a MXene-BaTiO3 composite material;

[0056] (3) The MXene-BaTiO3 composite material obtained in step (2) was placed in a Pyrex reaction cell filled with deionized water, connected to a photocatalytic water splitting hydrogen production system (Labsolar-6A), and the system was evacuated to remove the air in the system. The composite material was subjected to photodeposition to load the hydrogen production co-catalyst Pt. 0.1 wt% Pt was deposited on the MXene-BaTiO3 composite material using a solution of H2PtCl6. The reaction time was 3 h, and a 300 W xenon lamp was used as a light source to obtain a Pt-loaded MXene-BaTiO3 composite material.

[0057] (4) Low-density polyethylene (LDPE), high-density polyethylene (HDPE) and the composite material prepared in step (3) were mixed uniformly in a sealed bag and added to a small twin-screw extruder for melt blending. The mixing temperature was set to 180°C at a maximum speed of 130 r / min. After granulation, the pellets were placed in an oven at 80°C and dried for 12 hours to obtain a PE / composite blend. The blend was blown into a film in a single-screw film blowing machine, and the screw section and die head temperatures were set to 170-180°C. The mass ratio of the composite material to PE was 0.1:1, and a Pt-loaded MXene-BaTiO3-PE composite material was obtained.

[0058] Example 5

[0059] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0060] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0061] (2) Using 80 mg of MXene (Ti3C2) prepared in step (1) as a substrate, 0.165 g of crystal plane control agent NaBF4 and 15 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally reacted at 180 ° C for 10 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain a Ti3C2-TiO2 composite powder, which was added to deionized water, and then 5 g of Ba(OH)2·8H2O and 5 g of KOH were added, and the mixture was hydrothermally reacted at 180 ° C for 72 h to convert the TiO2 in the Ti3C2-TiO2 composite powder into BaTiO3 to obtain a MXene-BaTiO3 composite material;

[0062] (3) The MXene-BaTiO3 composite material obtained in step (2) was placed in a Pyrex reaction cell filled with deionized water, connected to a photocatalytic water splitting hydrogen production system (Labsolar-6A), and the system was evacuated to remove the air in the system. The composite material was subjected to photodeposition to load the hydrogen production co-catalyst Pt. 0.1 wt% Pt was deposited on the MXene-BaTiO3 composite material using a solution of H2PtCl6. The reaction time was 3 h, and a 300 W xenon lamp was used as a light source to obtain a Pt-loaded MXene-BaTiO3 composite material.

[0063] (4) PMDA and ODA were weighed in a molar ratio of 1:1. ODA was first added to a 50 mL beaker, and 30 mL of DMF was added and stirred to dissolve. Under ice-water bath and stirring conditions, argon was introduced for protection. PMDA was divided into 10 portions and added to the above solution every 10 min. The reaction conditions were kept dry and the water content in the reagent was as low as possible. The timing was started from the beginning of the addition of ODA, and the addition time was controlled. After 5 to 6 hours of reaction, a yellow viscous, clear and transparent polyamic acid (PAA) solution with a mass fraction of 15% was obtained. After sealing with plastic wrap, it was placed in a refrigerator for storage. The prepared spinning solution was injected into a syringe with a needle for electrospinning. The propulsion speed set in the electrospinning was 0.5 mL / h, the voltage was 15.0 kV, and the needle and The distance between the collecting plates is 12 cm and is received by a copper mesh; the PAA membrane sample prepared above is placed in a tubular furnace, and the temperature is increased from 30°C to 280°C at a heating rate of 1°C / h, and kept at 280°C for 1 hour to obtain PI microfibers; using water as a solvent, a Pt-loaded MXene-BaTiO3 composite material solution and a ligand solution of 2-methylimidazole are prepared respectively; then the PI microfiber membrane is first immersed in the Pt-loaded MXene-BaTiO3 composite material solution, and then immersed in the ligand solution containing 2-methylimidazole. After repeating 3 cycles, the PI microfiber membrane is taken out and vacuum dried at 80°C for 12 hours. The mass ratio of the composite material to PI is 0.1:1, and a Pt-loaded MXene-BaTiO3-PI composite material is obtained.

[0064] Example 6

[0065] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0066] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0067] (2) 80 mg of MXene (Ti3C2) prepared in step (1) was used as the substrate, 0.165 g of crystal plane control agent NaBF4 and 15 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally reacted at 180 ° C for 10 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain Ti3C2-TiO2 composite powder, which was added to deionized water, and then 3.61 g of Ba(OH)2·8H2O, 1.39 g of Sr(OH)2 and 5 g of KOH were added, and the mixture was hydrothermally reacted at 180 ° C for 72 h to obtain MXene-Ba 0.7 Sr 0.3 TiO3 composite materials;

[0068] (3) The MXene-Ba obtained in step (2) 0.7 Sr 0.3 The TiO3 composite material was placed in a Pyrex reaction tank filled with deionized water, connected to a photocatalytic water splitting hydrogen production system (Labsolar-6A), and the system was evacuated to remove the air in the system. The composite material was subjected to photodeposition to load the hydrogen production catalyst Pt, and a solution of H2PtCl6 was used to react with the MXene-BaO3 composite material. 0.7 Sr 0.3 0.1wt% Pt was deposited on the TiO3 composite material, the reaction time was 3h, and a 300W xenon lamp was used as the light source to obtain Pt-loaded MXene-Ba 0.7 Sr 0.3 TiO3 composite materials;

[0069] (4) Polyvinyl alcohol (PVA) and gelatin were mixed in distilled water to obtain a PVA-gelatin solution, and then polyvinyl alcohol pyridone was dissolved in an ethanol and water solution, mixed with the PVA-gelatin solution, and reacted at 50°C for 3 hours to obtain a mixed solution, and then the composite material powder obtained in step (3) was dispersed in the mixed solution, the mass ratio of the composite material to PVA was 0.05:1, cross-linked by physical cross-linking method, and stored at low temperature to obtain a thin film of Pt-loaded MXene-Ba 0.7 Ti 0.3 O3-PVA composite material.

[0070] Example 7

[0071] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0072] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0073] (2) Using 80 mg of MXene (Ti3C2) prepared in step (1) as a substrate, 0.165 g of crystal plane control agent NaBF4 and 15 mL of 1 mol / L HCl solution were added, and a hydrothermal reaction was carried out at 180 ° C for 10 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain a Ti3C2-TiO2 composite powder; the Ti3C2-TiO2 composite powder and lead monoxide were placed in a ball mill for crushing and mixing, and then placed in a muffle furnace for calcination at 400 ° C. The sample was ground and pulverized, centrifuged to remove impurities, and dried to obtain a MXene-PbTiO3 composite material;

[0074] (3) The MXene-PbTiO3 composite material obtained in step (2) was placed in a Pyrex reaction cell filled with deionized water, connected to a photocatalytic water splitting hydrogen production system (Labsolar-6A), and the system was evacuated to remove the air in the system. The composite material was subjected to photodeposition to load the hydrogen production co-catalyst Pt. 0.1 wt% Pt was deposited on the MXene-PbTiO3 composite material using a solution of H2PtCl6. The reaction time was 3 h, and a 300 W xenon lamp was used as a light source to obtain a Pt-loaded MXene-PbTiO3 composite material.

[0075] (4) Polyvinyl alcohol (PVA) and gelatin were mixed in distilled water to obtain a PVA-gelatin solution, and then polyvinyl alcohol pyridone was dissolved in a solution of ethanol and water, mixed with the PVA-gelatin solution, and reacted at 50°C for 3 hours to obtain a mixed solution, and then the composite material powder obtained in step (3) was dispersed in the mixed solution, the mass ratio of the composite material to PVA was 0.05:1, cross-linked by physical cross-linking method, and stored at low temperature to obtain a thin film of Pt-loaded MXene-PbTiO3-PVA composite material.

[0076] Example 8

[0077] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0078] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0079] (2) Using 80 mg of MXene (Ti3C2) prepared in step (1) as a substrate, 0.165 g of crystal plane control agent NaBF4 and 15 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally reacted at 180 ° C for 10 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain a Ti3C2-TiO2 composite powder, which was added to deionized water, and then 5 g of Ba(OH)2·8H2O and 5 g of KOH were added, and the mixture was hydrothermally reacted at 180 ° C for 72 h to convert the TiO2 in the Ti3C2-TiO2 composite powder into BaTiO3 to obtain a MXene-BaTiO3 composite material;

[0080] (3) The MXene-BaTiO3 composite material prepared in step (2) was poured into deionized water and ultrasonically obtained to obtain a uniform dispersion. The H2PtCl6 solution dissolved in ethylene glycol was added dropwise to the stirred carrier uniform dispersion. After the addition, ultrasonic stirring was continued. The pH was adjusted to 8.5 with a KOH solution dissolved in ethylene glycol. The mixture was continuously stirred at 60°C, cooled to room temperature, and filtered. After the filtered sample was dried and ground, it was reduced with 40% H2 at 250°C and cooled to obtain a Pt-loaded MXene-BaTiO3 composite material.

[0081] (4) Polyvinyl alcohol (PVA) and gelatin were mixed in distilled water to obtain a PVA-gelatin solution, and then polyvinyl alcohol pyridone was dissolved in a solution of ethanol and water, mixed with the PVA-gelatin solution, and reacted at 50°C for 3 hours to obtain a mixed solution, and then the composite material powder obtained in step (3) was dispersed in the mixed solution, the mass ratio of the composite material to PVA was 0.1:1, cross-linked by physical cross-linking method, and stored at low temperature to obtain a thin film of Pt-loaded MXene-BaTiO3-PVA composite material.

[0082] Example 9

[0083] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0084] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0085] (2) Using 80 mg of MXene (Ti3C2) prepared in step (1) as a substrate, 0.165 g of crystal plane control agent NaBF4 and 15 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally reacted at 180 ° C for 10 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain a Ti3C2-TiO2 composite powder, which was added to deionized water, and then 5 g of Ba(OH)2·8H2O and 5 g of KOH were added, and the mixture was hydrothermally reacted at 180 ° C for 72 h to convert the TiO2 in the Ti3C2-TiO2 composite powder into BaTiO3 to obtain a MXene-BaTiO3 composite material;

[0086] (3) At room temperature, the MXene-BaTiO3 composite material obtained in step (2) was added to a beaker containing deionized water, stirred evenly, and a certain amount of H2PtCl6 solution was added to load 0.1 wt% of Pt, stirred, and evaporated in an 80°C water bath. The mixture was then dried in a vacuum oven at 80°C, ground and sieved, and reduced with H2 at 300°C for 2 h to obtain a Pt-loaded MXene-BaTiO3 composite material.

[0087] (4) Polyvinyl alcohol (PVA) and gelatin were mixed in distilled water to obtain a PVA-gelatin solution, and then polyvinyl alcohol pyridone was dissolved in a solution of ethanol and water, mixed with the PVA-gelatin solution, and reacted at 50°C for 3 hours to obtain a mixed solution, and then the composite material powder obtained in step (3) was dispersed in the mixed solution, the mass ratio of the composite material to PVA was 0.1:1, cross-linked by physical cross-linking method, and stored at low temperature to obtain a thin film of Pt-loaded MXene-BaTiO3-PVA composite material.

[0088] Example 10

[0089] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0090] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0091] (2) Using 80 mg of MXene (Ti3C2) prepared in step (1) as a substrate, 0.165 g of crystal plane control agent NaBF4 and 15 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally reacted at 180 ° C for 10 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain a Ti3C2-TiO2 composite powder, which was added to deionized water, and then 5 g of Ba(OH)2·8H2O and 5 g of KOH were added, and the mixture was hydrothermally reacted at 180 ° C for 72 h to convert the TiO2 in the Ti3C2-TiO2 composite powder into BaTiO3 to obtain a MXene-BaTiO3 composite material;

[0092] (3) At room temperature, the MXene-BaTiO3 composite material obtained in step (2) was added to a beaker containing deionized water, stirred evenly, and a certain amount of H2PtCl6 solution was added to load 0.1 wt% of Pt, and then NaBH4 (NaBH4, Pt molar ratio is 20:1) was added, stirred, and evaporated by stirring in an 80°C water bath, and then placed in a vacuum oven at 80°C for drying to obtain a Pt-loaded MXene-BaTiO3 composite material;

[0093] (4) Polyvinyl alcohol (PVA) and gelatin were mixed in distilled water to obtain a PVA-gelatin solution, and then polyvinyl alcohol pyridone was dissolved in a solution of ethanol and water, mixed with the PVA-gelatin solution, and reacted at 50°C for 3 hours to obtain a mixed solution, and then the composite material powder obtained in step (3) was dispersed in the mixed solution, the mass ratio of the composite material to PVA was 0.1:1, cross-linked by physical cross-linking method, and stored at low temperature to obtain a thin film of Pt-loaded MXene-BaTiO3-PVA composite material.

[0094] Example 11

[0095] A method for preparing a photothermal-pyroelectric-photocatalytic composite system catalyst comprises the following steps:

[0096] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0097] (2) Using 80 mg of MXene (Ti3C2) prepared in step (1) as a substrate, 0.165 g of crystal plane control agent NaBF4 and 15 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally reacted at 180 ° C for 10 h to convert part of the Ti in the MXene (Ti3C2) substrate into TiO2, and TiO2 was in situ derived and grown on the MXene surface to obtain a Ti3C2-TiO2 composite powder, which was added to deionized water, and then 5 g of Ba(OH)2·8H2O and 5 g of KOH were added, and the mixture was hydrothermally reacted at 180 ° C for 72 h to convert the TiO2 in the Ti3C2-TiO2 composite powder into BaTiO3 to obtain a MXene-BaTiO3 composite material;

[0098] (3) The MXene-BaTiO3 composite material obtained in step (2) was placed in a Pyrex reaction cell filled with deionized water, connected to a photocatalytic water splitting hydrogen production system (Labsolar-6A), and the system was evacuated to remove the air in the system. The composite material was subjected to photodeposition to load the hydrogen production co-catalyst Pt. 0.1 wt% Pt was deposited on the MXene-BaTiO3 composite material using a solution of H2PtCl6. The reaction time was 3 h, and a 300 W xenon lamp was used as a light source to obtain a Pt-loaded MXene-BaTiO3 composite material.

[0099] (4) α-PVDF powder, N,N-dimethylformamide (DMF) solution and acetone solution were mixed and magnetically stirred at 60°C for 40 minutes. After the solution was placed in the air to cool to room temperature, the composite material prepared in step (3) was added. The mass ratio of the composite material to α-PVDF was 0.1:1. The mixture was magnetically stirred until uniformly mixed. The mixture was spin-coated on a clean glass slide at a speed of 2000 rpm and dried. The PVDF film was initially solidified into a film. Finally, the sample was quickly placed in deionized water at 10°C and allowed to cool. The PVDF composite film was peeled off from the glass slide to obtain a Pt-loaded MXene-BaTiO3-PVDF (α phase) composite film.

[0100] Comparative Example 1

[0101] A method for preparing a pyroelectric-photocatalytic composite catalyst comprises the following steps:

[0102] (1) 5 g of KOH was dissolved in deionized water, 1 g of P25 and 5 g of Ba(OH)2·8H2O were added and stirred thoroughly. The mixture was then transferred to a polytetrafluoroethylene-lined reactor and subjected to hydrothermal reaction at 180°C for 72 h. BaTiO3 was obtained after centrifugation, washing, and drying.

[0103] (2) The BaTiO3 obtained in step (1) was placed in a Pyrex reaction cell filled with deionized water, connected to a photocatalytic water splitting hydrogen production system (Labsolar-6A), and the system was evacuated to remove the air in the system. The composite material was subjected to photodeposition to load the hydrogen production co-catalyst Pt. 0.1 wt% Pt was deposited on the BaTiO3 using a solution of H2PtCl6. The reaction time was 3 h. A 300 W xenon lamp was used as a light source to obtain a Pt-loaded BaTiO3 material.

[0104] (3) Polyvinyl alcohol (PVA) and gelatin are mixed in distilled water to obtain a PVA-gelatin solution, and then polyvinyl alcohol pyridone is dissolved in a solution of ethanol and water, mixed with the PVA-gelatin solution, and reacted at 50°C for 3 hours to obtain a mixed solution, and then the BaTiO3 powder obtained in step (2) is dispersed in the mixed solution, the mass ratio of the composite material to PVA is 0.1:1, cross-linked by a physical cross-linking method, and stored at low temperature to obtain a thin film of Pt-loaded BaTiO3-PVA composite material.

[0105] Comparative Example 2

[0106] A method for preparing a photothermal-photocatalytic composite system catalyst comprises the following steps:

[0107] (1) The Al layer in the precursor MAX (Ti3AlC2) was etched away, and MAX was reacted with HF at 50°C for 46 hours, and then centrifugally dried to obtain MXene (Ti3C2);

[0108] (2) Using 80 mg of MXene prepared in step (1) as the substrate, 0.165 g of crystal plane control agent NaBF4 and 15 mL of 1 mol / L HCl solution were added, and the mixture was hydrothermally heated at 180 ° C for 10 h to in situ derivatize TiO2 on the MXene surface to obtain a MXene-TiO2 composite material;

[0109] (3) The MXene-TiO2 composite material obtained in step (2) was placed in a Pyrex reaction cell filled with deionized water, connected to a photocatalytic water splitting hydrogen production system (Labsolar-6A), and the system was evacuated to remove the air in the system. The composite material was subjected to photodeposition to load the hydrogen production co-catalyst Pt. 0.1 wt% Pt was deposited on the MXene-TiO2 composite material using a solution of H2PtCl6. The reaction time was 3 h. A 300 W xenon lamp was used as a light source to obtain a Pt-loaded MXene-TiO2 composite material.

[0110] (4) Polyvinyl alcohol (PVA) and gelatin were mixed in distilled water to obtain a PVA-gelatin solution, and then polyvinyl alcohol pyridone was dissolved in a solution of ethanol and water, mixed with the PVA-gelatin solution, and reacted at 50°C for 3 hours to obtain a mixed solution, and then the composite material powder obtained in step (3) was dispersed in the mixed solution, the mass ratio of the composite material to α-PVDF was 0.1:1, cross-linked by physical cross-linking method, and stored at low temperature to obtain a thin film Pt-loaded MXene-TiO2 composite material.

[0111] The composite films prepared in Examples 1 to 11 and Comparative Examples 1 to 2 were cut into slices of a certain radius and placed in a Pyrex reaction cell filled with a certain amount of deionized water. The cells were connected to a photocatalytic water decomposition hydrogen production system (Labsolar-6A). Before the photocatalytic reaction, the system was evacuated to remove air from the system. A 300W xenon lamp (PLS-SXE300) was used as the light source to test the photocatalytic water decomposition hydrogen production performance. The specific data are shown in FIG. Figure 3 .

[0112] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a photothermal-pyroelectric-photocatalytic composite catalyst system, characterized in that: The method comprises the following steps: in situ deriving and growing a photocatalyst with a pyroelectric effect on the surface of MXene to obtain a composite material, then loading a co-catalyst on the composite material, and finally mixing the composite material with a polymer matrix to form a thin film to obtain the photothermal-pyroelectric-photocatalytic composite catalyst system; The photocatalyst with pyroelectric effect is BaTiO3, PbTiO3, Ba 0.7 Ti 0.3 One of O3; The co-catalyst is one or more of Pt, Rh, Pd, and Au; The MXene is Ti3C2.

2. The preparation method according to claim 1, characterized in that The photocatalyst with pyroelectric effect is BaTiO3 and / or PbTiO3.

3. The preparation method according to claim 1, characterized in that The co-catalyst is one or more of Pt, Rh, Pd, and Au, and the loading amount of the co-catalyst on the composite material is 0.05-0.2 wt %.

4. The preparation method according to claim 1, characterized in that The polymer matrix is ​​one or more of PVA, α-PVDF, PI, PDMS, and PE, and the mass ratio of the composite material to the polymer matrix is ​​0.05-0.15:

1.

5. The preparation method according to claim 1, characterized in that The preparation method of the composite material comprises the following steps: etching away the Al layer in the precursor MAX and obtaining MXene by centrifugal drying; adding NaBF4 and HCl solution, performing a primary hydrothermal reaction to convert part of the Ti in the MXene substrate into TiO2, in-situ derivatizing and growing TiO2 on the MXene surface to obtain a MXene-TiO2 composite powder; adding the MXene-TiO2 composite powder into deionized water, and then adding a pyroelectric metal salt, performing a secondary hydrothermal reaction to convert the TiO2 in the MXene-TiO2 composite powder into a photocatalyst with a pyroelectric effect, thereby obtaining the composite material.

6. The preparation method according to claim 5, characterized in that The conditions for the first hydrothermal reaction are 160~200℃ for 1~10h, and the conditions for the second hydrothermal reaction are 160~200℃ for 60~84h; under the premise of excess pyroelectric metal salt, the length of the hydrothermal reaction controls the loading amount of the photocatalyst with pyroelectric effect.

7. The preparation method according to claim 5, characterized in that The usage ratio of MXene, NaBF4, and HCl solution is 60~100 mg: 0.125~0.205 g: 10~20 mL; the pyroelectric metal salt is a soluble salt of Ba, Pb, and Sr, and the pyroelectric metal salt is in excess.

8. A photothermal-pyroelectric-photocatalytic composite catalyst system prepared by the preparation method according to any one of claims 1 to 7.

9. An application of the photothermal-pyroelectric-photocatalytic composite catalyst system according to claim 8, characterized in that: It is used in efficient photothermal-photoelectrochemical-photocatalytic water decomposition to produce hydrogen.

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