Low energy consumption and high catalytic efficiency of photothermal synergy M(OH) x / TiO2 / PVP composite material and preparation method thereof

Abstract

The present invention relates to a photothermal synergistic M(OH) x / TiO2 / PVP composite material and preparation method thereof, the present invention adds nickel, cobalt, iron metal salt aqueous solution to TiO2 colloidal solution, and then adds alkaline aqueous solution to obtain M(OH) x / TiO2 mixed solution; to M(OH) x Polyvinyl pyrrolidone was added to the mixed solution of TiO2 in batches to obtain photothermal synergistic M(OH) x / TiO2 / PVP composite material. The M(OH) x The TiO2 / PVP composite material not only overcomes the high energy consumption of traditional thermal catalysis and the expensive price of precious metal-loaded catalysts, but also overcomes the low quantum efficiency and narrow spectral range of photocatalysis (photocatalysis primarily utilizes ultraviolet and visible light, ignoring near-infrared and infrared light), maximizing the use of solar energy. This enables thermally assisted photocatalysis to efficiently remove harmful pollutants from water or the atmosphere using only sunlight, without the need for external energy.

Description

Technical Field

[0001] The present invention relates to a photothermal synergistic M(OH) x The invention relates to a / TiO2 / PVP composite material and a preparation method thereof, belonging to the field of solar energy and its application. Background Art

[0002] In recent years, carbon emissions caused by fossil fuel consumption have become a widespread concern in human society, leading to a growing consensus on the development of renewable clean energy. Solar energy, as the most ideal clean energy source on Earth, has become a research priority. The development of photothermal catalysts with a wide absorption range, excellent photothermal conversion, and high catalytic activity is crucial for solar energy utilization and catalytic reactions.

[0003] The widely used TiO2 photocatalyst has the advantages of good stability, high catalytic activity, and non-toxicity. However, due to its large band gap (3.2eV), it only responds to ultraviolet light. This part of light radiation accounts for about 4% to 6% of the total sunlight radiation reaching the ground. The utilization rate is low and varies significantly over time. Therefore, current research uses artificial light sources that are expensive, short-lived, and consume a lot of electricity. During use, the light source must be placed in a quartz cold trap to avoid damage to the instrument due to excessive temperatures. It is not suitable for large-scale application. Photothermal catalysis can solve the problems of high energy consumption of thermal catalysis and low photocatalytic efficiency by effectively combining photocatalysis and thermal catalysis technologies. It is a sustainable and green catalytic technology.

[0004] In the photothermal catalytic reaction using natural sunlight as the light source, electrons and holes are generated on the catalyst surface due to the excitation of solar energy; at the same time, part of the light energy is converted into heat energy in this process, which increases the temperature of the reaction system and drives the reaction. Whether from the theoretical and economic benefits or from the perspective of energy saving and environmental protection, the study of semiconductor materials with photothermal catalytic synergistic effects using natural sunlight as a semiconductor excitation light source has far-reaching significance and has broad application prospects in the fields of energy conversion, environmental protection and sustainable development. Existing photothermal catalysts are mainly concentrated on precious metal catalysts. Although they have excellent performance, they are expensive and easily poisoned. Non-precious metal photothermal catalysts have great potential for future industrial applications due to their abundant output and low cost. For example, the literature Chemical Engineering Journal, 2023, 459, 141549 reported a Co3O4 / ZnIn2S4 photocatalytic system that constructs a full-spectrum S-type heterojunction to promote photothermal-assisted photocatalytic hydrogen production.

[0005] Professor Xu Yijun of Fuzhou University used a series of different transition metal hydroxides as co-catalysts for solar photocatalytic CO2 reduction on a two-dimensional conductive graphene platform [Nature Communications, 2020, 11, 1581]. Because different transition metal hydroxides have different electronic structures and infrared absorption capabilities, photocatalytic reactions can absorb light energy and convert it into chemical energy. As passivators, transition metal hydroxides passivate the recombination centers at the interface, increasing charge separation and the kinetics of water oxidation. As charge collectors / storage layers, they collect photogenerated holes to drive water oxidation, reducing the kinetic energy barrier of the initial water dissociation process. In recent years, the coupling of semiconductor materials and transition metal hydroxides has been viewed by many scientists as an effective strategy to improve the performance of electrocatalytic materials [Angew. Chem. Int. Ed. 2021, 60, 3504-3509].

[0006] Iron-based (Group VIII) hydroxides are formed by the combination of transition metal elements (Fe, Co, Ni) with hydrogen and oxygen atoms. They have the advantages of large specific surface area, easy regulation of surface components, surface charge properties and surface catalytic active centers, and can be used as substrate materials to load and anchor nanoparticles, thereby improving the dispersion and stability of active components.

[0007] In summary, existing photothermal catalysts have the following defects: 1) Precious metal catalysts have excellent performance but are expensive and easily poisoned; 2) Non-precious metal photothermal catalysts have high catalytic energy consumption and a narrow spectrum; 3) There are few reports on the use of hydroxides of Group VIII elements (iron, cobalt, and nickel) for photothermal catalytic degradation of pollutants, and the types are limited. Summary of the Invention

[0008] In view of the shortcomings of the existing technology, the present invention provides a low energy consumption, high catalytic efficiency photothermal synergistic M (OH) x / TiO2 / PVP composite material and preparation method thereof.

[0009] Terminology Notes:

[0010] Room temperature: The room temperature mentioned in the present invention has a meaning well known in the art, generally referring to 20-25°C.

[0011] The present invention is achieved through the following technical solutions:

[0012] A photothermal synergistic M(OH) with low energy consumption and high catalytic efficiency x The preparation method of the / TiO2 / PVP composite material comprises the following steps:

[0013] (1) Mix TiO2 nanopowder in deionized water or distilled water and stir to obtain a uniform and transparent TiO2 colloidal solution;

[0014] (2) adding the metal salt aqueous solution to the TiO2 colloidal solution and stirring for 5-30 minutes to obtain a mixture;

[0015] (3) Add alkaline aqueous solution to the mixture and stir for 5-30 minutes to obtain M(OH) x / TiO2 mixed solution;

[0016] (4) Towards M(OH) x Polyvinyl pyrrolidone was added to the mixed solution of TiO2 in batches and stirred for 24-36 hours to obtain the photothermal synergistic M(OH) with low energy consumption and high catalytic efficiency. x / TiO2 / PVP composite material.

[0017] Preferably, according to the present invention, in step (1), the mass volume ratio of TiO2 nanopowder to deionized water or distilled water is (1-10): (0.1-1), unit: g / L.

[0018] Preferably according to the present invention, in step (2), the metal salt is nitrate or acetate.

[0019] Preferably according to the present invention, in step (2), the metal salt is ferric acetate, nickel acetate, cobalt acetate, ferric nitrate, nickel nitrate or cobalt nitrate.

[0020] Further preferably, in step (2), the metal salt is nickel acetate, cobalt acetate, nickel nitrate or cobalt nitrate.

[0021] Preferably, according to the present invention, in step (2), the concentration of the aqueous solution of the metal acetate is 0.1-10 mol / L, and the concentration of the aqueous solution of the metal nitrate is 0.1-10 mol / L.

[0022] According to the preferred embodiment of the present invention, in step (2), the mass volume ratio of TiO2 nanopowder to metal salt aqueous solution is (0.1-200): (0.01-20), unit: g / mL.

[0023] Further preferably, the mass volume ratio of TiO2 nanopowder to metal salt aqueous solution is (0.1-10): (0.01-1), unit: g / mL.

[0024] According to the preferred embodiment of the present invention, in step (3), the alkaline aqueous solution is a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution with a concentration of 0.1-10 mol / L.

[0025] Preferably, according to the present invention, in step (3), the mass volume ratio of TiO2 nanopowder to alkaline aqueous solution is (0.1-50): (0.02-100), unit: g / mL.

[0026] Further preferably, in step (3), the mass volume ratio of TiO2 nanopowder to alkaline aqueous solution is (0.1-15): (0.1-5), unit: g / mL.

[0027] According to the present invention, preferably, in step (3), M(OH) x / M in TiO2 = Fe, Co, Ni, which is the same as the metal of the metal salt in step (2).

[0028] According to the preferred embodiment of the present invention, in step (4), the polyvinyl pyrrolidone is K88-K90 polyvinyl pyrrolidone.

[0029] Preferably according to the present invention, in step (4), the weight average molecular weight of polyvinyl pyrrolidone is 1-1.5 million.

[0030] According to the preferred embodiment of the present invention, in step (4), the amount of polyvinyl pyrrolidone added is proportional to the amount of M(OH) x The mass ratio of the TiO2 mixed solution is (5-50): (0.5-100).

[0031] According to the present invention, when the metal salt is a nickel salt, a Ni(OH)2 / TiO2 / PVP composite material is prepared; when the metal salt is an iron salt, a Fe(OH)3 / TiO2 / PVP composite material is prepared; when the metal salt is a cobalt salt, a Co(OH)2 / TiO2 / PVP composite material is prepared.

[0032] According to a preferred embodiment of the present invention, in step (4), when adding polyvinyl pyrrolidone, it is evenly divided into 3-5 parts and added to the system in batches of 3-5 times.

[0033] Polyvinylpyrrolidone must be added in batches. If it is added in large quantities at one time, stratification and agglomeration will occur.

[0034] A photothermal synergistic M(OH) with low energy consumption and high catalytic efficiency x / TiO2 / PVP composite material is prepared by the above method.

[0035] M(OH) x The microscopic morphology of the TiO2 / PVP composite material is composed of fine particles with roughly the same shape and narrow size distribution. The size of the particles is 3-5nm, which is within the range of colloidal particles. The surface is coated with PVP, which is uniformly dispersed in the aqueous solution and has colloidal properties.

[0036] The present invention adopts a simple and efficient one-step precipitation method to prepare highly stable and high catalytic efficiency M(OH) x / TiO2 / PVP(M=Fe,Co,Ni) composite materials. M(OH) xThe introduction of (M=Fe, Co, Ni) improves the light response ability of the catalyst, while the synergistic effect of heat further promotes the photocatalytic redox reaction, realizing the efficient removal of harmful pollutants in water or the atmosphere with the help of sunlight in the heat-assisted photocatalytic mode without the need for external energy. The addition of polyvinyl pyrrolidone not only makes the fine particles dispersed evenly in the aqueous solution, but also enhances the photothermal synergistic catalytic efficiency. Among them, the thermal energy comes from the photothermal conversion of sunlight. The catalytic process has a low activation energy barrier and high carrier mobility, providing a sustainable development solution for the efficient use of solar energy.

[0037] Low energy consumption and high catalytic efficiency of photothermal synergy M(OH) x The application of / TiO2 / PVP composite materials has a photothermal catalytic effect under natural sunlight, and is used for the efficient thermal effect synergistic photocatalytic degradation of organic pollutant wastewater.

[0038] Low energy consumption and high catalytic efficiency of photothermal synergy M(OH) x The application of / TiO2 / PVP composite materials is based on the fact that metal hydroxides with alkaline surfaces have the ability to strongly adsorb acidic gas molecules. Spraying them on the outer walls of buildings can effectively remove ozone, formaldehyde, nitrogen oxides, and sulfur oxides from the air.

[0039] The M(OH) x The TiO2 / PVP nano-hydrosol is a photothermal synergistic catalytic oxidation system with a strong light response capability. Heat energy is derived from the photothermal conversion of sunlight. This synergistic effect further promotes the photocatalytic redox reaction, achieving a heat-assisted photocatalytic mode that efficiently removes harmful pollutants from water or the atmosphere using only sunlight, without the need for external energy. This not only overcomes the high energy consumption of traditional thermal catalysis and the expensive price of precious metal-loaded catalysts, but also overcomes the low photocatalytic quantum efficiency and narrow spectral range (photocatalysis primarily utilizes ultraviolet and visible light, ignoring near-infrared and infrared light), maximizing the use of solar energy.

[0040] The present invention adopts precipitation method to prepare M(OH) x / TiO2 / PVP (M=Fe, Co, Ni) nanocomposite materials have the advantages of large specific surface area, multiple reaction active sites, low recombination rate of photogenerated electron-hole pairs and high light energy utilization rate. They can effectively inhibit the recombination of photogenerated carriers, improve quantum efficiency, and thus efficiently carry out photothermal catalytic degradation reactions.

[0041] This invention pioneers the upgrade from a laboratory photocatalytic reaction system to an outdoor photocatalytic reaction system exposed to direct sunlight. Transition metal hydroxides, with their high light absorption and electron conductivity, serve as co-catalysts for the photothermal degradation of organic pollutants and acidic gases such as nitrogen oxides and sulfur oxides under natural sunlight. This system combines excellent photoresponsiveness with thermal catalytic activity, offering advantages such as low cost, ease of preparation, and efficient use of solar energy.

[0042] The M(OH) x / TiO2 / PVP composite material can directly use sunlight as an activation catalyst and drive redox reactions. It has a strong full solar spectrum response capability and can effectively convert the absorbed photon energy into active oxygen species and thermal energy. It has good photothermal catalytic properties. In addition, it can react at room temperature and has a green and simple preparation method. It is an ideal low-energy technology that can be promoted and utilized on a large scale.

[0043] The technical features and advantages of the present invention are as follows:

[0044] 1. M(OH) of the present invention x / TiO2 / PVP composite materials not only overcome the problems of high energy consumption of traditional thermal catalysis and expensive price of precious metal-loaded catalysts, but also overcome the problems of low photocatalytic quantum efficiency and narrow spectral corresponding range (photocatalysis mainly uses ultraviolet and visible light, ignoring near-infrared and infrared light), maximizing the use of solar energy.

[0045] 2. M(OH) of the present invention x / TiO2 / PVP composite material is a photothermal synergistic catalytic oxidation system with strong light response ability. The heat energy comes from the photothermal conversion of sunlight. The synergistic effect of heat further promotes the photocatalytic redox reaction, realizing the efficient removal of harmful pollutants in water or air by relying only on sunlight without adding external energy in the heat-assisted photocatalytic mode. In addition, M(OH) x / TiO2 / PVP (M=Fe, Co, Ni) composite materials can be sprayed on the interior and exterior walls of buildings of various colors to efficiently remove harmful acidic gases such as nitrogen oxides and sulfur oxides from the air.

[0046] 3. The addition of polyvinyl pyrrolidone in the present invention not only makes the fine particles dispersed evenly in the aqueous solution, but also enhances the photothermal synergistic catalytic effect. Polyvinyl pyrrolidone (K88-K90) is soluble in M(OH) x / TiO2 (M=Fe, Co, Ni) is completely transparent in aqueous solution and can be sprayed on the interior and exterior walls of buildings of various colors. It forms a uniform film in 10-60 minutes. After film formation, it is colorless and odorless and easy to use.

[0047] 4. M(OH) of the present inventionx / TiO2 / PVP (M=Fe, Co, Ni) composite materials are stable and do not contain auxiliary components, which can effectively remove harmful pollutants in water or atmosphere under natural sunlight, and M(OH) x / TiO2 / PVP (M=Fe, Co, Ni) composite materials can be produced on a large scale, greatly improving the application efficiency and are expected to promote related research on solar thermal catalysis.

[0048] 5. The present invention uses the simplest method to obtain M(OH) with thermal effect synergistic photocatalysis and excellent performance. x / TiO2 / PVP (M=Fe, Co, Ni) composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 XRD spectra of the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1, the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2, the 0.1% Fe(OH)3 / TiO2 / PVP composite material prepared in Example 3, and the TiO2 / PVP composite material prepared in Comparative Example 1.

[0050] Figure 2 The low-magnification TEM photograph (a) and high-magnification TEM photograph (b) of the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1; the low-magnification TEM photograph (c) and high-magnification TEM photograph (d) of the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2.

[0051] Figure 3 SEM photos and EDS spectra of film materials obtained by coating the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1 and the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2 on a glass substrate;

[0052] a is the SEM photo of Example 1, b is the EDS spectrum of Example 1, c is the SEM photo of Example 2, b is the EDS spectrum of Example 2;

[0053] Figure 4 These are the N2 adsorption-desorption isotherms of the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1, the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2, and the TiO2 / PVP composite material prepared in Comparative Example 1.

[0054] Figure 5These are diffuse reflection absorption spectra of the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1, the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2, the 0.1% Fe(OH)3 / TiO2 / PVP composite material prepared in Example 3, and the TiO2 / PVP composite material prepared in Comparative Example 1; the inset is an enlarged view of the area.

[0055] Figure 6 The following is a graph showing the photothermal catalytic degradation of Rhodamine B (RhB) by the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1, the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2, the 0.1% Fe(OH)3 / TiO2 / PVP composite material prepared in Example 3, the TiO2 / PVP composite material prepared in Comparative Example 1, the 1% Ni(OH)2 / TiO2 / PVP composite material prepared in Comparative Example 2, the 1% Co(OH)2 / TiO2 / PVP composite material prepared in Comparative Example 3 and the 1% Fe(OH)3 / TiO2 / PVP composite material prepared in Comparative Example 4 under natural sunlight.

[0056] Figure 7 These are the degradation curves of RhB degradation of the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1 and the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2 under natural sunlight and 800W xenon lamp irradiation in a laboratory with circulating water, where a is Example 1 and b is Example 2.

[0057] Figure 8 The photocurrent curves of the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1, the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2, the 0.1% Fe(OH)3 / TiO2 / PVP composite material prepared in Example 3 and the TiO2 / PVP composite material prepared in Comparative Example 1.

[0058] Figure 9 Impedance curves of the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1, the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2, the 0.1% Fe(OH)3 / TiO2 / PVP composite material prepared in Example 3, and the TiO2 / PVP composite material prepared in Comparative Example 1.

[0059] Figure 10Surface images of the composite film layers obtained by water droplets and oil droplets in Examples 1-3 and Comparative Example 1, a is a surface image of the composite film layer of water droplets in Example 1, b is a surface image of the composite film layer of water droplets in Example 2, c is a surface image of the composite film layer of water droplets in Example 3, d is a surface image of the composite film layer of water droplets in Comparative Example 1, e is a surface image of the composite film layer of oil droplets in Example 1, f is a surface image of the composite film layer of oil droplets in Example 2, g is a surface image of the composite film layer of oil droplets in Example 3, and h is a surface image of the composite film layer of oil droplets in Comparative Example 1.

[0060] Figure 11 Infrared thermal images of the photothermal catalytic degradation of RhB by the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1, the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2, the 0.1% Fe(OH)3 / TiO2 / PVP composite material prepared in Example 3, and the TiO2 / PVP composite material prepared in Comparative Example 1, as well as pure RhB solution.

[0061] Figure 12 Infrared thermal imaging of the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1, the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2, the 0.1% Fe(OH)3 / TiO2 / PVP composite material prepared in Example 3, the TiO2 / PVP composite material prepared in Comparative Example 1, as well as the 0.1% Ni(OH)2 / TiO2 composite material, 0.2% Co(OH)2 / TiO2 composite material, 0.1% Fe(OH)3 / TiO2 composite material and the TiO2 / PVP composite material under irradiation with an 800W xenon lamp in a laboratory with circulating water. DETAILED DESCRIPTION

[0062] The present invention will be described in detail below. Before describing, it should be understood that the terms used in this specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present invention on the basis of the principle that allows the inventor to appropriately define the terms for the best interpretation. Therefore, the descriptions presented here are merely preferred examples for illustrative purposes and are not intended to limit the scope of the present invention. It should be understood that other equivalents or improvements can be obtained therefrom without departing from the spirit and scope of the present invention.

[0063] The following examples are merely examples of embodiments of the present invention and do not constitute any limitation to the present invention. Those skilled in the art will appreciate that modifications without departing from the spirit and scope of the present invention fall within the scope of protection of the present invention. The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are all commercially available unless otherwise specified; and the equipment used is all conventional equipment. Among them: polyvinyl pyrrolidone is polyvinyl pyrrolidone K88-90, with a weight-average molecular weight of 1.3 million.

[0064] Example 1

[0065] The preparation method of the photothermal synergistic 0.1% Ni(OH)2 / TiO2 / PVP composite material with low energy consumption and high catalytic efficiency is as follows:

[0066] (1) Prepare 1 M nickel acetate solution and 1 M sodium hydroxide solution respectively;

[0067] (2) Dissolve 10 g of TiO2 in 1 L of deionized water and stir for 20 min to obtain a TiO2 colloidal solution;

[0068] (3) 1 mL of 1 M nickel acetate solution and 2 mL of 1 M sodium hydroxide solution were added to the TiO2 colloid solution and stirred for 20 min to obtain 0.1% Ni(OH)2 / TiO2 colloid;

[0069] (4) Weigh 50 g of polyvinylpyrrolidone K90 with a weight-average molecular weight of 1.3 million, divide it into 5 equal parts, add it into 50 g of 0.1% Ni(OH)2 / TiO2 colloid in batches of 5 times, and stir for 10 h to obtain 0.1% Ni(OH)2 / TiO2 / PVP composite material.

[0070] Example 2

[0071] The preparation method of the photothermal synergistic 0.2% Co(OH)2 / TiO2 / PVP composite material with low energy consumption and high catalytic efficiency is as follows:

[0072] (1) Prepare 1 M cobalt acetate solution and 1 M sodium hydroxide solution respectively;

[0073] (2) Dissolve 10 g of TiO2 in 1 L of deionized water and stir for 20 min to obtain a TiO2 colloidal solution;

[0074] (3) 2 mL of 1 M cobalt acetate solution and 4 mL of 1 M sodium hydroxide solution were added to the TiO2 colloidal solution and stirred for 20 min to obtain 0.2% Co(OH)2 / TiO2 colloid;

[0075] (4) Weigh 50 g of polyvinylpyrrolidone K90 with a weight-average molecular weight of 1.3 million and divide it into 5 equal parts. Add it into 50 g of 0.2% Co(OH)2 / TiO2 colloid in batches of 5 times and stir for 10 h to obtain 0.2% Co(OH)2 / TiO2 / PVP composite material.

[0076] Example 3

[0077] The method for preparing a photothermal synergistic 0.1% Fe(OH)3 / TiO2 / PVP composite material with low energy consumption and high catalytic efficiency comprises the following steps:

[0078] (1) Prepare 1 M ferric acetate solution and 1 M sodium hydroxide solution respectively;

[0079] (2) Dissolve 10 g of TiO2 in 1 L of deionized water and stir for 20 min to obtain a TiO2 colloidal solution;

[0080] (3) 10 mL of 1 M ferric acetate solution and 30 mL of 1 M sodium hydroxide solution were added to the TiO2 colloidal solution and stirred for 20 min to obtain 0.1% Fe(OH)3 / TiO2 colloid;

[0081] (4) Weigh 50 g of polyvinylpyrrolidone K90 with a weight-average molecular weight of 1.3 million and divide it into 5 equal parts. Add it into 50 g of 0.1% Fe(OH)3 / TiO2 colloid in batches of 5 times and stir for 10 h to obtain 0.1% Fe(OH)3 / TiO2 / PVP composite material.

[0082] Comparative Example 1

[0083] The preparation method of TiO2 / PVP composite material comprises the following steps:

[0084] (1) Dissolve 10 g of TiO2 in 1 L of deionized water and stir for 30 min to obtain a TiO2 colloidal solution;

[0085] (2) Weigh 50 g of polyvinylpyrrolidone K90 with a weight average molecular weight of 1.3 million and divide it into 5 equal parts. Add it into 50 g of TiO2 colloidal solution in batches of 5 times and stir for 10 hours to form TiO2 / PVP composite material.

[0086] Comparative Example 2

[0087] The preparation method of 1% Ni(OH)2 / TiO2 / PVP is the same as that of Example 1, except that:

[0088] Step (3) was to add 10 mL of 1 M nickel acetate solution and 2 mL of 1 M sodium hydroxide solution to the TiO2 colloid solution and stir for 20 min to obtain 1% Ni(OH)2 / TiO2 colloid. Other steps were carried out as in Example 1.

[0089] Comparative Example 3

[0090] The preparation method of 1% Co(OH)2 / TiO2 / PVP is the same as that of Example 2, except that:

[0091] Step (3) was to add 10 mL of 1 M cobalt acetate solution and 20 mL of 1 M sodium hydroxide solution to the TiO2 colloidal solution and stir for 20 min to obtain a 1% Co(OH)2 / TiO2 colloid. Other steps were carried out as in Example 2.

[0092] Comparative Example 4

[0093] The preparation method of 0.5% Fe(OH)3 / TiO2 / PVP is the same as that of Example 3, except that:

[0094] In step (3), 5 mL of 1 M ferric acetate solution and 10 mL of 1 M sodium hydroxide solution were added to the TiO2 colloidal solution and stirred for 20 minutes to obtain a 0.5% Fe(OH)3 / TiO2 colloid. Other steps were carried out as in Example 3.

[0095] Application Experiment Example 1

[0096] Photocatalytic degradation of Rhodamine B (RhB)

[0097] The composite materials prepared in Examples 1-3 and Comparative Example 1 were applied to the photocatalytic degradation of a Rhodamine B (RhB) solution having a concentration of 10 mg / L. The specific steps were as follows:

[0098] At room temperature, 15 mL of the composite material was added to 45 mL of rhodamine B (RhB) solution and magnetically stirred in a dark box for 30 minutes to achieve adsorption-desorption equilibrium. An 800W xenon lamp was used to simulate reference sunlight, and the solution was collected every 3 minutes without centrifugation. Absorbance was measured using a UV-2550 spectrophotometer.

[0099] Application Experiment Example 2

[0100] Photothermal catalytic degradation of Rhodamine B (RhB)

[0101] The composite materials prepared in Examples 1-3 and Comparative Example 1 were applied to the photothermal catalytic degradation of a Rhodamine B (RhB) solution having a concentration of 10 mg / L. The specific steps were as follows:

[0102] At room temperature, 15 mL of the composite material was added to 45 mL of rhodamine B (RhB) solution and magnetically stirred in a dark box for 30 minutes to achieve adsorption-desorption equilibrium. The solution was irradiated with natural sunlight, and the radiation intensity was tracked using a solar radiation meter. The solution was collected every 3 minutes without centrifugation. Absorbance was measured using a UV-2550 spectrophotometer.

[0103] Application Experiment Example 3

[0104] The degradation rate, degradation time and temperature difference generated by the thermal effect of photothermal catalytic degradation of RhB by composite materials obtained with different contents of Ni(OH)2, Co(OH)2 and Fe(OH)3 under natural sunlight are compared. The results are shown in Table 1.

[0105] Table 1 Comparison of degradation rate, degradation time and temperature difference caused by thermal effect of photothermal catalytic degradation of RhB of different samples under natural sunlight

[0106]

[0107]

[0108] It can be seen from Table 1 that in the Ni(OH)2 / TiO2 / PVP system, 0.1% Ni(OH)2 / TiO2 / PVP composite material has the best photothermal catalytic performance; in the Co(OH)2 / TiO2 / PVP system, 0.2% Co(OH)2 / TiO2 / PVP composite material has the best photothermal catalytic performance; in the Fe(OH)3 / TiO2 / PVP system, 0.1% Fe(OH)3 / TiO2 / PVP composite material has the best photothermal catalytic degradation efficiency; moreover, under the same hydroxide content conditions, the degree of photothermal catalytic performance is Ni(OH)2 / TiO2 / PVP>Co(OH)2 / TiO2 / PVP>Fe(OH)3 / TiO2 / PVP.

[0109] Experimental Example 1

[0110] Figure 1 The XRD spectra of the 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1, the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2, the 0.1% Fe(OH)3 / TiO2 / PVP composite material prepared in Example 3 and the TiO2 / PVP composite material prepared in Comparative Example 1 are shown in FIG. )2The crystal phase structure of / TiO2 / PVP and 0.1%Fe(OH)3 / TiO2 / PVP composite materials is consistent with the anatase TiO2 phase in Comparative Example 1, and no relevant diffraction peaks of Ni(OH)2, Co(OH)2 and Fe(OH)3 are detected, which may be due to the low content and high dispersion of Ni(OH)2, Co(OH)2 and Fe(OH)3 in the composite material system.

[0111] The 0.1% Ni(OH)2 / TiO2 / PVP composite materials prepared in Example 1 and the 0.2% Co(OH)2 / TiO2 / PVP composite materials prepared in Example 2 were directly scooped up using a support net. No ethanol or water was added again during the sample preparation process, and no additional ultrasonic dispersion was required. Transmission electron microscopy (TEM) observation showed that the 0.1% Ni(OH)2 / TiO2 / PVP composite materials prepared in Example 1 and the 0.2% Co(OH)2 / TiO2 / PVP composite materials prepared in Example 2 were directly scooped up using a support net. No ethanol or water was added again during the sample preparation process, and no additional ultrasonic dispersion was required. Figure 2 It can be found that the samples obtained in Example 1 and Example 2 are distributed with nanoparticles with a particle size of 3-5 nm, high size uniformity and good dispersibility.

[0112] The 0.1% Ni(OH)2 / TiO2 / PVP composite material prepared in Example 1 and the 0.2% Co(OH)2 / TiO2 / PVP composite material prepared in Example 2 were coated on a glass substrate to obtain a film material. The film material was subjected to SEM and EDS tests. Figure 3 The results show that the hydrosol coated on the glass substrate forms a dense and uniform Ni(OH)2 / TiO2 / PVP and Co(OH)2 / TiO2 / PVP nanofilm. EDS spectra confirm the presence of various elements in the samples. PVP, a water-soluble polymer surfactant, exhibits excellent dispersibility. Its dispersibility mechanism is primarily due to steric hindrance and electrostatic stabilization. In the PVP structure, the methylene groups that form the chain and pyrrolidone ring are non-polar and lipophilic groups, while the lactam groups in the PVP molecule are highly polar and hydrophilic. PVP can form a dissolved or dispersed system through interaction with water. It also interacts with the particle surface or chemical functional groups to form an adsorption film, which modifies the hydrophilic and lipophilic properties of the particle surface. This adsorption film can envelop the particles, creating repulsive forces between them, effectively preventing aggregation and precipitation and achieving uniform particle dispersion.

[0113] Experimental Example 2

[0114] According to the N2 adsorption-desorption isotherm of the composite material ( Figure 4 ), calculate the specific surface area, the specific surface area of 0.1% Ni(OH)2 / TiO2 / PVP prepared in Example 1 is 169.479m 2 / g, the specific surface area of 0.2% Co(OH)2 / TiO2 / PVP prepared in Example 2 is 168.601m 2 / g, the specific surface area of TiO2 / PVP prepared in Comparative Example 1 is 149.678m 2 / g. By comparison, it can be seen that the introduction of Ni(OH)2 and Co(OH)2 increases the specific surface area, increases the active sites, promotes the generation of reactive species, and ensures the smooth progress of the photocatalytic redox reaction.

[0115] Figure 5 The UV-Vis DRS analysis results show that compared with the diffuse reflectance absorption spectrum of pure TiO2, the introduction of Fe(OH)3, Ni(OH)2 and Co(OH)2 broadens the absorption spectrum range of TiO2 / PVP composite materials, and the introduction of Ni(OH)2 and Co(OH)2 broadens the absorption of TiO2 / PVP composite materials in the visible light region, thereby achieving more efficient use of sunlight to excite electrons / holes and maximizing the use of solar energy.

[0116] from Figure 6 It can be seen that the samples prepared in Example 1 and Example 2 have a high photothermal catalytic degradation rate, indicating that Ni(OH)2 and Co(OH)2 can form a relatively good interface effect with TiO2, and as hole storage components, effectively alleviate the charge recombination phenomenon, thereby providing highly active and highly selective sites for the entire reaction; and Ni(OH)2 and Co(OH)2 can be in situ oxidized to NiOOH and CoOOH, lowering the Fermi level and generating a Helmholtz potential layer, thereby accelerating the photocatalytic reaction rate; and the system can utilize the energy storage properties of Ni(OH)2 and Co(OH)2 to store the redox energy generated by the system during illumination, ensuring that the catalytic activity is released and continues to be exhibited under dark conditions.

[0117] from Figure 7 It can be seen that there is a significant difference in the degradation effect of RhB between Example 1 and Example 2 under the conditions of Application Experiment 1 and Application Experiment 2. This result proves the superiority of photothermal catalysis in improving the degradation efficiency of RhB. Compared with simple photocatalysis, photothermal catalysis shows a more outstanding effect.

[0118] The steps of different heights reflect the separation ability of photocatalyst photogenerated carriers. Figure 8 It can be seen that the 0.1% Ni(OH)2 / TiO2 / PVP material prepared in Example 1 has the largest photocurrent and the highest quantum efficiency, followed by Example 2.

[0119] The size of the arc reflects the electron transmission ability of the photocatalyst. The smaller the radius, the easier it is for electrons to be transmitted. Figure 9It can be seen that the 0.1% Ni(OH)2 / TiO2 / PVP hydrosol material prepared in Example 1 has the smallest impedance and the largest electron transmission capacity, followed by Example 2. Therefore, the M(OH)2 / TiO2 / PVP hydrosol material prepared in the present invention has the smallest impedance and the largest electron transmission capacity. x The electron transmission ability of the / TiO2 / PVP (M=Fe, Co, Ni) composite material photocatalyst is better than that of the TiO2 / PVP hydrosol material prepared in Comparative Example 1.

[0120] from Figure 10 It can be seen that the water and oil contact angles of Examples 1-3 are significantly smaller than those of Comparative Example 1, indicating that M(OH) x The hydrophilicity of / TiO2 / PVP (M=Fe, Co, Ni) is enhanced, and the material has both hydrophilicity and super lipophilicity.

[0121] The temperature change of liquid during the photocatalytic degradation of RhB was recorded using an infrared thermal imaging camera. Figure 11 It can be seen that the liquid temperature of the 0.1% Ni(OH)2 / TiO2 / PVP hydrosol photocatalytic degradation system prepared in Example 1 increased from 24.0°C to 33.2°C after 18 minutes of sunlight irradiation, indicating that the strong photothermal effect of the 0.1% Ni(OH)2 / TiO2 / PVP hydrosol photocatalyst prepared in Example 1 caused the solution temperature to increase. The figure also shows that the liquid temperature of the degradation system in Example 1 increased by a maximum of 9.2°C within 18 minutes, demonstrating the best photothermal synergistic effect.

[0122] Under sunlight, TiO2 / PVP can absorb light energy and convert it into electron excitation and hole generation. These photoinduced electrons and holes are usually excited to the conduction band and valence band of the material. The M(OH) x (M=Fe, Co, Ni) can produce photothermal effect under light conditions. This means that when sunlight is irradiated, M(OH) x (M=Fe, Co, Ni) can absorb light energy and convert it into heat, thereby increasing the temperature of the composite system. This photothermal effect causes the composite system's temperature to rise, which facilitates the separation and transfer of electrons. Increasing the temperature increases the kinetic energy of electrons, thereby facilitating the photoinduced transition of electrons from the conduction band to higher energy levels or the conductor surface, where they participate in the photocatalytic reaction at the interface. Furthermore, increasing the temperature promotes the effective separation of electrons and holes, reducing their recombination rate, thereby improving photocatalytic efficiency.

[0123] from Figure 12As can be seen, after 12 minutes of irradiation with an 800W xenon lamp in a laboratory with circulating water, the liquid temperature of the 0.1% Ni(OH)2 / TiO2 / PVP composite prepared in Example 1 reached 38.0°C, higher than the system temperature without PVP. The final system temperatures of Examples 1-3 and Comparative Example 1 were all higher than those without PVP, demonstrating that the addition of polyvinylpyrrolidone not only uniformly disperses the fine particles in the aqueous solution but also enhances the photothermal synergistic catalytic efficiency.

Claims

1. Low energy consumption and high catalytic efficiency of photothermal synergy M(OH) x / TiO2 / PVP composite materials, under natural sunlight, M(OH) x The TiO2 / PVP composite material can directly use sunlight as an activation catalyst and drive redox reactions. It has a strong full solar spectrum response capability and can effectively convert the absorbed photon energy into active oxygen species and thermal energy. It has good photothermal catalytic performance and can be used for efficient thermal effect synergistic photocatalytic degradation of organic pollutant wastewater. The low energy consumption and high catalytic efficiency photothermal synergistic M(OH) x The / TiO2 / PVP composite material is prepared as follows: (1) Mix TiO2 nanopowder in deionized water or distilled water and stir to obtain a uniform and transparent TiO2 colloidal solution; (2) adding a metal salt aqueous solution to a TiO2 colloidal solution and stirring for 5-30 minutes to obtain a mixture; the metal salt is a nitrate or acetate, the concentration of the acetate metal salt aqueous solution is 0.1-10 mol / L, and the concentration of the nitrate metal salt aqueous solution is 0.1-10 mol / L; the metal salt is nickel acetate, cobalt acetate, nickel nitrate or cobalt nitrate; the mass volume ratio of the TiO2 nanopowder to the metal salt aqueous solution is (1-10):1, unit: g / mL; (3) Add alkaline aqueous solution to the mixture and stir for 5-30 minutes to obtain M(OH) x / TiO2 mixed solution; (4) Towards M(OH) x Polyvinyl pyrrolidone was added to the mixed solution of TiO2 in batches and stirred for 24-36 hours to obtain the photothermal synergistic M(OH) with low energy consumption and high catalytic efficiency. x / TiO2 / PVP composite materials, M(OH) x The TiO2 / PVP composite material is a photothermal synergistic catalytic oxidation system with strong light response ability. The heat energy comes from the photothermal conversion of sunlight. The synergistic effect of heat further promotes the photocatalytic redox reaction, realizing the efficient removal of harmful pollutants in water or air with only sunlight in the heat-assisted photocatalytic mode without the need for external energy. The polyvinyl pyrrolidone is K88-K90 polyvinyl pyrrolidone, the weight average molecular weight of polyvinyl pyrrolidone is 1 million to 1.5 million, and the amount of polyvinyl pyrrolidone added is proportional to the M(OH) x The mass ratio of the mixed solution of TiO2 is (5-50): (0.5-100); When adding polyvinyl pyrrolidone, divide it into 3-5 equal parts and add it to the system in batches of 3-5 times.

2. The use according to claim 1, characterized in that In step (1), the mass volume ratio of TiO2 nanopowder to deionized water or distilled water is (1-10): (0.1-1), unit is g / L.

3. The use according to claim 1, characterized in that In step (3), the alkaline aqueous solution is a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution with a concentration of 0.1-10 mol / L, and the mass volume ratio of TiO2 powder to alkaline aqueous solution is (0.1-15): (0.1-5), unit: g / mL.

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