Composite photocatalyst, preparation method and application thereof, and method for photocatalytic cycloaddition reaction of dicyclopentadiene

Abstract

The invention relates to the technical field of catalysts, and discloses a composite photocatalyst, a preparation method and application thereof, and a method for photocatalytic cycloaddition reaction of dicyclopentadiene, the composite photocatalyst comprises a carrier and an active metal component loaded on the carrier; wherein the carrier comprises alkali metal titanate and titanium dioxide; the active metal component is selected from at least one of IIIB group metal elements, IVB group metal elements, VB group metal elements, VIB group metal elements, VIIB group metal elements, VIII group metal elements, IB group metal elements and IIB group metal elements; the composite photocatalyst is rod-shaped, and the specific surface area is not less than 45m < 2 > / g. The composite photocatalyst has relatively high photocatalytic activity and photocatalytic efficiency.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of photocatalysts, in particular to a composite photocatalyst and a preparation method and application thereof, and a method for photocatalytic dicyclopentadiene cycloaddition. BACKGROUND

[0002] Photocatalysis technology has been widely concerned in recent years due to its characteristics such as high efficiency, flexibility, mild reaction conditions, easy control, low cost, cleanness and recyclability. Among them, titanium dioxide is a photocatalyst material with excellent performance. Titanium dioxide has the advantages of rich source, safety, non-toxicity, strong ultraviolet absorption ability, good chemical stability and low price, and has broad application prospects in solar cells, photocatalysis, water splitting, air pollutant treatment, sensors, food packaging, coatings, functional ceramics and the like. However, there are still some problems in the practical application of titanium dioxide photocatalysis technology, such as narrow spectral response range, low quantum efficiency, low solar energy utilization rate, easy agglomeration of powder and difficult recycling.

[0003] Depositing noble metal nanoparticles on the surface of titanium dioxide is an important means to improve the activity of photocatalysts. CN114042451A discloses a method for loading metal clusters on a photocatalyst, which uses metal particles and photocatalyst particles as precursors. After mixing, the composite photocatalyst loaded with metal clusters is obtained under hydrothermal conditions. The size of the loaded metal clusters is less than 2nm, and they are uniformly distributed on the photocatalyst particles, which greatly improves the catalytic activity of the photocatalyst. However, the metal particles in this method need to be pre-prepared as nano metal particles, and the overall process is still cumbersome, energy-consuming and has a small loadable amount.

[0004] CN103157477A discloses a nickel oxide doped sodium titanate-titanium dioxide composite photocatalyst and a preparation method thereof. Titanium salt is used as a precursor to grow a titanium dioxide nanofilm loaded on a nickel foam substrate in situ, and then a sodium titanate-titanium dioxide is prepared by hydrothermal reaction with a sodium hydroxide aqueous solution after drying and calcination. The sodium titanate-titanium dioxide exists in the form of nanosheets or nanotube arrays, and nickel oxide nanoparticles are uniformly dispersed on the surface thereof. However, this method requires the use of organic alcohol solvents, and the nickel foam sheet needs to be calcined and pre-oxidized in advance before each use, which is cumbersome to operate.

[0005] CN107081150A discloses a platinum-loaded sodium titanate mixed crystal nanowire assembly and a preparation method thereof. The catalyst is assembled by platinum-loaded sodium titanate mixed crystal nanowires, which is used as a high-efficiency photocatalyst. The platinum-loaded sodium titanate mixed crystal nanowire assembly photocatalyst is prepared by using inorganic titanium sulfate, hydrogen peroxide and noble metal salt as raw materials through hydrothermal reaction and calcination. Hydrogen peroxide is used in the experimental process, and the reaction operation is dangerous. 0.23 TiO2 / Na2Ti x O 2x+1 The mixed crystal nanowire assembly photocatalyst is prepared by using inorganic titanium sulfate, hydrogen peroxide and noble metal salt as raw materials through hydrothermal reaction and calcination. Hydrogen peroxide is used in the experimental process, and the reaction operation is dangerous.

[0006] In addition, in the prior art, the reaction time of the titanium dioxide photocatalyst in catalyzing the dicyclopentadiene cycloaddition reaction is long, and the efficiency is low. Therefore, it is necessary to develop a photocatalyst which is simple to prepare, low in cost, good in chemical stability, easy to recycle, and has high photocatalytic efficiency and activity. SUMMARY

[0007] The purpose of the present application is to overcome the problems of insufficient catalytic activity and low catalytic efficiency of the titanium dioxide photocatalyst in the prior art, and to provide a composite photocatalyst, a preparation method and application thereof, and a method for photocatalyzing dicyclopentadiene cycloaddition reaction, which has high photocatalytic activity.

[0008] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a composite photocatalyst, which comprises a carrier and an active metal component loaded on the carrier; wherein the carrier comprises an alkali metal titanate and titanium dioxide; and the active metal component is selected from at least one of group IIIB, group IVB, group VB, group VIB, group VIIB, group VIII, group IB and group IIB metal elements.

[0009] The composite photocatalyst is in the form of a rod, and the specific surface area is not less than 45 m 2 / g.

[0010] Preferably, the length of the composite photocatalyst is 0.1-3 μm, and the aspect ratio is 3-200:1.

[0011] Preferably, based on the total mass of the composite photocatalyst, the content of the active metal component is 0.001-15 wt%, the content of the alkali metal is 0.1-3.5 wt%, and the content of titanium element is 40-70 wt%.

[0012] The second aspect of the present application provides a preparation method of a composite photocatalyst, which comprises the following steps:

[0013] (1) mixing a titanium source and an alkali metal source, and performing a hydrothermal reaction to obtain alkali metal titanate micro-nano rods; the conditions of the hydrothermal reaction include: first reacting at 60-140℃ for 12-96h, and then reacting at 160-240℃ for 12-96h;

[0014] (2) activating the alkali metal titanate micro-nano rods by contacting them with an acid;

[0015] (3) contacting the product obtained in step (2) with a precursor of an active metal component, and then performing drying and calcination; the active metal component is selected from at least one of group IIIB, group IVB, group VB, group VIB, group VIIB, group VIII, group IB and group IIB metal elements.

[0016] The third aspect of the present application provides the composite photocatalyst prepared by the above preparation method.

[0017] The fourth aspect of the present application provides the application of the above composite photocatalyst in solar cells, photocatalysis, water splitting, sensors, nano-electronic or optoelectronic nano-devices.

[0018] The fifth aspect of the present application provides a method for photocatalytic dicyclopentadiene cycloaddition reaction, comprising: contacting dicyclopentadiene with a catalyst under light conditions, wherein the catalyst is the composite photocatalyst of the first aspect or the third aspect.

[0019] The composite photocatalyst provided by the present application has a rod-like morphology, titanium dioxide and alkali metal titanate exist in the form of micro-nano rod array, and the active metal component is uniformly compounded in the form of nanoparticles on the surface of the rod array. The micro-nano rod array form of the catalyst is beneficial to the transfer of electric charge and reduces the recombination probability of photo-generated electrons and holes. On the other hand, the composite photocatalyst has a larger specific surface area, and through the special rod-like structure and the appropriate number of pores, the metal loading capacity is improved, and the active sites are increased. Through the synergistic effect of the active metal component and the carrier, the recombination of photo-generated electrons and holes can be prevented, and the photocatalytic efficiency is further improved.

[0020] The present application can prepare alkali metal titanate micro-nano rods with large specific surface area, regular size arrangement and good crystallinity through two-stage hydrothermal reaction, and then perform acid activation treatment. On the one hand, the alkali metal titanate micro-nano rods can be partially dissolved to form part of oxide species, thereby increasing the active sites of the composite catalyst. On the other hand, the surface of the micro-nano rods is etched by acid, which is beneficial to improve the loading effect of the active metal component, improve the interaction between the active metal component and the carrier, and further improve the photocatalytic efficiency. The preparation process is simple and easy to operate, has low cost, and has good industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 FIG. 3 is a high-resolution transmission electron microscope (TEM) image of the composite photocatalyst prepared in Example 3 of the present application;

[0022] Figure 2 FIG. 4 is a high-resolution transmission electron microscope energy spectrum test (TEM-EDS) image of the composite photocatalyst prepared in Example 3 of the present application. DETAILED DESCRIPTION

[0023] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not to be understood as being crucial to the invention. Any numeric range recited is intended to include all values from the lower value to the upper value. For numeric ranges recited as "from X to Y", it is intended that the range include X and Y. For numeric ranges recited as "X or more" or "Y or less", it is intended that the range include X and Y. Numeric ranges can be combined to form new numeric ranges, which are to be construed in accordance with the above rules.

[0024] The first aspect of the present application provides a composite photocatalyst, comprising a carrier and an active metal component loaded on the carrier; wherein the carrier comprises an alkali titanate and titanium dioxide; the active metal component is selected from at least one of the group consisting of group IIIB, group IVB, group VB, group VIB, group VIIB, group VIII, group IB and group IIB metal elements;

[0025] The composite photocatalyst is rod-shaped, and the specific surface area is not less than 50 m 2 / g.

[0026] According to the present application, the composite photocatalyst has a rod-shaped morphology, titanium dioxide and alkali titanate exist in the form of a micro-nano rod array, and the active metal component is uniformly compounded in the form of nanoparticles on the surface thereof. On the one hand, the rod-shaped array form of the catalyst is beneficial to the transfer of electric charges, and reduces the recombination probability of photo-generated electrons and holes. On the other hand, the catalyst has a high specific surface area, and through the special rod-shaped structure and the appropriate number of pores, the metal loading capacity is improved, and the catalytic active sites are increased. Through the synergistic effect of the active metal component and the carrier, the recombination of photo-generated electrons and holes can be prevented, and the photocatalytic efficiency is further improved.

[0027] According to the present application, preferably, the length of the composite photocatalyst is 0.1-3 μm, preferably 0.5-2.5 μm, and the aspect ratio is 3-200:1, preferably 80-150:1. In the present application, the "length" of the composite photocatalyst refers to the longest diameter through the interior of the composite photocatalyst particle; and the "aspect ratio" refers to the ratio of the longest diameter through the interior of the composite photocatalyst particle, and the longest diameter perpendicular thereto. In the present application, the length and diameter of the rod-shaped particle of the composite photocatalyst are measured by high-resolution transmission electron microscopy (TEM), and the aspect ratio is calculated.

[0028] According to the present application, the composite photocatalyst has a large specific surface area, and the specific surface area is not less than 50 m 2 / g. Preferably, the specific surface area of the composite photocatalyst is 50-200 m 2 / g, preferably 65-150 m 2 / g. In the above preferred case, it is beneficial to further improve the utilization rate of the active metal, and improve the photocatalytic efficiency.

[0029] In the present application, the carrier can be proved to comprise alkali titanate, titanium dioxide and active metal component by high resolution transmission electron microscopy (HRTEM) characterization.

[0030] According to the present application, preferably, the alkali titanate is selected from sodium titanate and / or potassium titanate, and further preferably is sodium titanate.

[0031] Preferably, the content of active metal component is 0.001-15 wt% by element, the content of alkali metal is 0.1-3.5 wt%, and the content of titanium element is 40-70 wt% based on the total mass of the composite photocatalyst. In the present application, the element content in the composite photocatalyst is tested by inductively coupled plasma optical emission spectrometer (ICP-OES).

[0032] In a further preferred embodiment, the mass ratio of titanium element to alkali metal element in the carrier is (4-50):1, preferably (25-48):1. In the above preferred composition, the carrier has suitable titanium dioxide and alkali titanate content, which synergizes with the active metal component to further improve the activity and catalytic efficiency of the catalyst.

[0033] According to the present application, the active metal component is selected from at least one of Group IIIB, Group IVB, Group VB, Group VIIB, Group VIII, Group IB and Group IIB metal elements, which can be noble metal, non-noble metal or rare earth metal, etc. Preferably, the active metal component is selected from at least one of Pd, Pt, Rh, Ni, Co, Zn, Cu, Cd, Hg, Mn, Ag, Fe, Cr, La, Ce, Ru, Zr, Nb and W.

[0034] According to some preferred embodiments of the present application, the active metal component is selected from at least one of Pd, Pt, Rh, Ag and Ru, and the content of active metal component is 0.001-0.5 wt% by element, the content of alkali metal is 0.1-3.5 wt%, and the content of titanium element is 55-70 wt% based on the total mass of the composite photocatalyst.

[0035] According to some other preferred embodiments of the present application, the active metal component is selected from at least one of Ni, Co, Zn, Cu, Cd, Hg, Mn, Fe, Cr, La, Ce, Zr, Nb and W, and the content of active metal component is 1-10 wt% by element, the content of alkali metal is 0.1-3.5 wt%, and the content of titanium element is 50-65 wt% based on the total mass of the composite photocatalyst.

[0036] In the above preferred embodiment, by controlling the content of each component in the composite photocatalyst within the above preferred range, the photocatalytic efficiency of the composite photocatalyst can be further improved.

[0037] In the present application, preferably, at least part of the active metal component exists in the form of an oxide, for example, at least part of Pd exists in the form of PdO, Ce can exist in the form of CeO, and Fe can exist in the form of Fe2O3.

[0038] The second aspect of the present application provides a preparation method of a composite photocatalyst, comprising the following steps:

[0039] (1) mixing a titanium source and an alkali metal source, and performing a hydrothermal reaction to obtain alkali metal titanate micro-nano rods; the hydrothermal reaction conditions include: first reacting at 60-140℃ for 12-96h, and then reacting at 160-240℃ for 12-96h;

[0040] (2) activating the alkali metal titanate micro-nano rods by contacting them with an acid;

[0041] (3) contacting the product obtained in step (2) with a precursor of an active metal component, and then performing drying and calcination; the active metal component is selected from at least one of the following: metal elements in Group IIIB, Group IVB, Group VB, Group VIB, Group VIIB, Group VIII, Group IB and Group IIB.

[0042] In the present application, by two-stage hydrothermal reaction, alkali metal titanate micro-nano rods with large specific surface area, regular size arrangement and good crystallinity can be prepared, and then acid activation treatment is performed, which can on one hand partially dissolve the alkali metal titanate micro-nano rods to form part of oxide species, increase the active sites of the composite catalyst, and on the other hand etch the surface of the micro-nano rods with the acid, which is beneficial to improve the loading effect of the active metal component, improve the interaction between the active metal component and the carrier, and further improve the photocatalytic efficiency.

[0043] In a further preferred embodiment, the hydrothermal reaction conditions include: first reacting at 100-130℃ for 24-48h, and then reacting at 170-200℃ for 12-24h. By using the above preferred embodiment, nanorods with good thermal stability, regular size arrangement and good crystallinity can be obtained, and at the same time, first low-temperature reaction and then high-temperature reaction are beneficial to improve the specific surface area of the micro-nano rods, improve their photocatalytic efficiency and metal loading, and thus the photocatalytic activity is better.

[0044] The present application has a wide range of selection for the titanium source. The titanium-containing compounds in the art can be applied to the present application as long as they can provide titanium element. Preferably, the titanium source is selected from at least one of titanium dioxide, metatitanic acid, orthotitanic acid, tetrabutyl titanate, titanium sulfate, titanyl sulfate, titanium tetrachloride, and titanium isopropoxide.

[0045] The present application also has no particular limitation for the selection of the alkali metal source. The alkali metal source can be selected from at least one of alkali metal hydroxide, alkali metal hydride, and alkali metal salt. According to some preferred embodiments of the present application, the alkali metal is selected from sodium and / or potassium, and the alkali metal source is selected from at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium hydride, potassium hydroxide, potassium carbonate, potassium bicarbonate, and potassium hydride.

[0046] According to some preferred embodiments of the present application, the alkali metal source is provided by an alkali metal source solution, and the concentration of the alkali metal source solution is 5-30 mol / L, preferably 8-15 mol / L.

[0047] The present application has no particular limitation for the amount of the titanium source and the alkali metal source, which can be selected by the person skilled in the art according to actual needs as long as it can form the alkali metal titanate. Preferably, the amount of the titanium source is calculated based on titanium dioxide. For 1 g of the titanium source, the volume of the alkali metal source solution is 5-100 mL, preferably 10-80 mL.

[0048] According to the present application, the step (1) further comprises: performing solid-liquid separation, washing, and drying on the product obtained by the hydrothermal reaction, and then obtaining the alkali metal titanate micro-nanorod. The present application has no particular limitation for the specific operation mode and conditions of the solid-liquid separation, washing, and drying, which can be performed by the conventional mode in the art. For example, the mode of the solid-liquid separation can be filtration or centrifugation. The washing can be performed by distilled water, and the washing is performed until the pH is 6-8. The drying temperature can be 60-120°C, preferably 80-100°C, and the drying time can be 6-24 h, preferably 10-15 h.

[0049] In the present application, the activation treatment in the step (2) can partially dissolve the alkali metal titanate micro-nanorod to form part of the oxide species, increase the active site of the composite catalyst, and etch the surface of the micro-nanorod by the acid, which is beneficial to improve the loading effect of the active metal component and improve the interaction between the active metal component and the carrier.

[0050] The present application has no particular limitation for the type of the acid, which can be an organic acid and / or an inorganic acid. Preferably, the acid is selected from at least one of formic acid, acetic acid, propionic acid, phosphoric acid, oxalic acid, hydrochloric acid, sulfuric acid, and nitric acid, preferably at least one of formic acid, acetic acid, and phosphoric acid.

[0051] The present application does not have particular limitation on the way of contacting the alkali titanate micro-nanorods with the acid, for example, the alkali titanate micro-nanorods can be added into an aqueous solution of the acid for the contacting.

[0052] According to some preferred embodiments of the present application, the acid is provided by an aqueous solution of the acid, and the concentration of the aqueous solution of the acid is 0.05-1.5 mol / L, preferably 0.1-1 mol / L.

[0053] According to the present application, preferably, the amount of the aqueous solution of the acid is 20-300 mL, preferably 40-200 mL, relative to 1 g of the alkali titanate micro-nanorods.

[0054] According to some preferred embodiments of the present application, the contacting in step (2) is carried out under stirring, and preferably, the contacting is carried out for 1-5 h.

[0055] According to the present application, the active metal component is selected from at least one of the group consisting of group IIIB, group IVB, group VB, group VIB, group VIIB, group VIII, group IB and group IIB metal elements, for example, can be noble metal, non-noble metal or rare earth metal, etc., and preferably, the active metal component is selected from at least one of Pd, Pt, Rh, Ni, Co, Zn, Cu, Cd, Hg, Mn, Ag, Fe, Cr, La, Ce, Ru, Zr, Nb and W. The present application does not have particular limitation on the kind of the precursor of the active metal component, and a soluble compound of the metal can be used conventionally in the art, for example, can be chloride, nitrate, oxalate, acetate, etc., or can be a coordination compound of the metal, for example, dichlorotetraamine palladium, etc. The precursor of the active metal component can also contain crystal water, which is well known to those skilled in the art.

[0056] According to the present application, preferably, the amount of the product obtained in step (2) and the precursor of the active metal component is such that the content of the active metal component in the composite photocatalyst prepared is 0.001-15 wt% in terms of element.

[0057] According to some preferred embodiments of the present application, the active metal component is selected from at least one of Pd, Pt, Rh, Ag and Ru, and the amount of the product obtained in step (2) and the precursor of the active metal component is such that the content of the active metal component in the composite photocatalyst prepared is 0.001-0.5 wt% in terms of element.

[0058] According to another preferred embodiment of the present application, the active metal component is selected from at least one of Ni, Co, Zn, Cu, Cd, Hg, Mn, Fe, Cr, La, Ce, Zr, Nb and W, the active metal component is selected from at least one of Pd, Pt, Rh, Ag and Ru, and the amount of the product obtained in step (2) and the precursor of the active metal component is such that the content of the active metal component in the composite photocatalyst prepared is 1-10 wt% in terms of element.

[0059] According to the present application, preferably, the contacting in step (3) is carried out under stirring, and preferably, the contacting is carried out for 12-24 h.

[0060] According to the present application, step (3) further comprises: subjecting the product of the contacting to solid-liquid separation and washing, and then to the drying and calcination. The present application does not particularly limit the specific operation mode and conditions for the solid-liquid separation and washing, which can be the same as described above for step (1).

[0061] According to the present application, preferably, the drying is carried out at a temperature of 60-120°C, preferably 80-100°C, for 6-24 h, preferably 10-15 h.

[0062] According to the present application, preferably, the calcination is carried out at a temperature of 300-700°C, preferably 400-600°C, for 1-7 h, preferably 2-4 h.

[0063] The third aspect of the present application provides a composite photocatalyst prepared by the above preparation method.

[0064] The fourth aspect of the present application provides the use of the above composite photocatalyst in solar cells, photocatalysis, water splitting, sensors, nano-electronic or optoelectronic nano-devices.

[0065] The fifth aspect of the present application provides a method for photocatalytic dicyclopentadiene cycloaddition, which comprises: contacting dicyclopentadiene with a catalyst under light, wherein the catalyst is the composite photocatalyst according to the first or third aspect of the present application.

[0066] Preferably, the mass ratio of the catalyst to dicyclopentadiene is 0.1-5:100, preferably 0.5-3:100.

[0067] Preferably, the light condition comprises: a temperature of 20-40°C and a 100W-400W medium-pressure mercury lamp.

[0068] Preferably, the contacting is carried out in the presence of a solvent, and the present application has a wide selection range for the solvent, which is capable of dissolving dicyclopentadiene. Preferably, the solvent is ketone, preferably acetone and / or butanone.

[0069] The amount of the solvent is not particularly limited, and the amount of the solvent is preferably 20-60 mL with respect to 1 g of the dicyclopentadiene, in order to dissolve the dicyclopentadiene.

[0070] The present application will be described in detail below by way of examples.

[0071] The raw materials used in the following examples and comparative examples are commercially available, unless otherwise specified.

[0072] Example 1

[0073] 2 g of TiO2 and 60 mL of an aqueous NaOH solution (concentration: 10 M) were placed in a 100 mL polytetrafluoroethylene-stainless steel reactor inner liner, stirred at room temperature to form a suspension, and then the reactor containing the dispersion was sealed and allowed to react in a hydrothermal reactor at 100°C for 48 h, and then allowed to react in a hydrothermal reactor at 160°C for 24 h. After the reaction, the reactor was cooled to room temperature, filtered, washed with deionized water until the pH was 8, and then dried at 90°C for 12 h to obtain sodium titanate nanorods.

[0074] The prepared 0.3 g of sodium titanate nanorods was added to 60 mL of an aqueous phosphoric acid solution (concentration: 0.1 M), mixed and stirred for 1 h, and then 1.0 mg of dichlorotetraammine palladium salt was added, and the reaction solution was stirred at room temperature for 12 h. After the reaction, the precipitate was separated by filtration, washed with deionized water until the pH was 7, and then dried at 110°C for 12 h. After that, it was calcined in a muffle furnace at 400°C for 3 h, and after the reaction, it was naturally cooled to room temperature to obtain a white solid powder catalyst, which was named Cat-1.

[0075] The composition of the catalyst was measured by ICP-OES and is shown in Table 1. It can be seen from the TEM test that the composite photocatalyst is rod-shaped, and the length of the composite photocatalyst is 0.5-2 μm, and the aspect ratio is 10-100:1. The specific surface area of the composite photocatalyst was 63.79 m 2 / g, which was obtained by BET test.

[0076] Example 2

[0077] 2g of Ti02and 80 mL of NaOH aqueous solution (concentration 10 M) were placed in a 100 mL polytetrafluoroethylene inner liner of a stainless steel autoclave, stirred at room temperature to form a suspension, and then the autoclave containing the dispersion was sealed and allowed to react in a hydrothermal reactor at 110°C for 48 h and then at 170°C for 24 h. After the reaction, the product was filtered, washed with deionized water several times until the pH was 8, and then dried at 100°C for 12 h to obtain sodium titanate nanorods.

[0078] The prepared 0.3 g of sodium titanate nanorods were added to 20 mL of an acetic acid aqueous solution (concentration: 0.2 M), mixed and stirred for 2 h, and then 1.9 mg of palladium acetate was added. The reaction solution was stirred at room temperature for 15 h. After the reaction, the precipitate was separated by filtration, washed with deionized water until the pH was 7, and then dried at 110°C for 12 h. Subsequently, calcination was performed in a muffle furnace at 500°C for 3 h, and after the reaction, the product was naturally cooled to room temperature and taken out as a light brown powder catalyst, which was named Cat-2. The composition of the catalyst is shown in Table 1.

[0079] It can be seen from the TEM test that the composite photocatalyst is rod-shaped, and the length of the composite photocatalyst is 0.3-2.2 μm, and the aspect ratio is 10-120:1. The BET test showed that the specific surface area of the composite photocatalyst was 75.02 m 2 / g.

[0080] Example 3

[0081] 2g of Ti02and 70 mL of NaOH aqueous solution (concentration 8 M) were placed in a 100 mL polytetrafluoroethylene inner liner of a stainless steel autoclave, stirred at room temperature to form a suspension, and then the autoclave containing the dispersion was sealed and allowed to react in a hydrothermal reactor at 130°C for 48 h and then at 170°C for 24 h. After the reaction, the product was filtered, washed with deionized water several times until the pH was 8, and then dried at 110°C for 15 h to obtain sodium titanate nanorods.

[0082] The prepared 0.3 g of sodium titanate nanorods were added to 20 mL of an acetic acid aqueous solution (concentration: 0.2 M), mixed and stirred for 2 h, and then 1.9 mg of palladium acetate was added. The reaction solution was stirred at room temperature for 15 h. After the reaction, the precipitate was separated by filtration, washed with deionized water until the pH was 7, and then dried at 110°C for 12 h. Subsequently, calcination was performed in a muffle furnace at 500°C for 3 h, and after the reaction, the product was naturally cooled to room temperature and taken out as a light brown powder catalyst, which was named Cat-2. The composition of the catalyst is shown in Table 1.

[0083] The high-resolution transmission electron microscopy (HRTEM) image of the composite photocatalyst is shown in Figure 2. Figure 1As shown, it can be seen that the composite photocatalyst contains three different lattice fringes, wherein the diffraction fringes with a lattice spacing of 0.80 nm match the lattice spacing of sodium titanate; the diffraction fringes with a lattice spacing of 0.35 nm match the lattice spacing of titanium dioxide; and the diffraction fringes with a lattice spacing of 0.2 nm match the lattice spacing of cerium oxide, Figure 2 The TEM-EDS picture is a high-resolution transmission electron microscopy energy dispersive spectroscopy test (TEM-EDS) picture, further verifying that the prepared catalyst contains Ce, Ti, Na, and O elements. The structure of the composite photocatalyst is further proved by HRTEM and TEM-EDS characterization analysis. The composition of the catalyst is shown in Table 1.

[0084] It can be seen from the TEM test that the composite photocatalyst is rod-shaped, and the length of the composite photocatalyst is 0.6-2 μm, and the aspect ratio is 3-100:1. The BET test shows that the specific surface area of the composite photocatalyst is 96.39 m 2 / g.

[0085] Example 4

[0086] 2 g of TiO2 and 60 mL of NaOH aqueous solution (concentration 12 M) were placed in a 100 mL polytetrafluoroethylene stainless steel autoclave inner liner, stirred at room temperature to form a suspension, and then the autoclave containing the above dispersion was sealed and allowed to react in a hydrothermal reactor at 130°C for 48 h, and then allowed to react in a hydrothermal reactor at 170°C for 24 h. After the reaction was completed, it was cooled to room temperature and filtered, washed with deionized water several times until the pH was 8, and finally dried at 110°C for 12 h to obtain sodium titanate nanorods.

[0087] The prepared 0.3 g of sodium titanate nanorods was added to 20 mL of aqueous acetic acid solution (concentration 0.1 M), mixed and stirred for 2 h, then 144.3 mg of ferric nitrate was added, and the reaction solution was stirred at room temperature for 12 h. After the reaction was completed, the precipitate was separated by filtration, washed with deionized water until the pH was 7, and then dried at 110°C for 12 h. Then it was calcined in a muffle furnace at 500°C for 3 h, and after the reaction was completed, it was naturally cooled to room temperature and taken out as a red-brown powder catalyst, named Cat-4. The composition of the catalyst is shown in Table 1.

[0088] It can be seen from the TEM test that the composite photocatalyst is rod-shaped, and the length of the composite photocatalyst is 0.5-1.5 μm, and the aspect ratio is 20-150:1. The BET test shows that the specific surface area of the composite photocatalyst is 67.28 m 2 / g.

[0089] Example 5

[0090] The method of Example 1 was followed except that the concentration of the aqueous phosphoric acid solution was 0.05 mol / L.

[0091] The obtained composite photocatalyst was named Cat-5. The composition of the catalyst is shown in Table 1.

[0092] It can be seen from the TEM test that the composite photocatalyst is rod-shaped, the length of the composite photocatalyst is 0.4-1.9 μm, and the length-diameter ratio is 10-90:1. The BET test shows that the specific surface area of the composite photocatalyst is 46.30 m 2 / g.

[0093] Comparative Example 1

[0094] The method of Example 1 was followed except that no palladium salt was added, and the catalyst prepared was named Cat-1-A. The composite photocatalyst was rod-shaped, and the BET test showed that the specific surface area of the composite photocatalyst was 50.22 m 2 / g.

[0095] Comparative Example 2

[0096] The method of Example 1 was followed except that commercially available nano-titanium dioxide (brand: anatase nano-TiO2, size 10-25 nm) was used instead of the prepared sodium titanate nanorods, and the catalyst prepared was named Cat-1-B.

[0097] The composite photocatalyst was spherical, and the BET test showed that the specific surface area of the composite photocatalyst was 60.52 m 2 / g.

[0098] Comparative Example 3

[0099] The method of Example 1 was followed except that the hydrothermal reaction conditions were 130°C for 96 h. The catalyst prepared was named Cat-1-C. The composition of the catalyst is shown in Table 1.

[0100] The composite photocatalyst was rod-shaped, and the BET test showed that the specific surface area of the composite photocatalyst was 32.09 m 2 / g.

[0101] Comparative Example 4

[0102] The method of Example 1 was followed except that the hydrothermal reaction conditions were 170°C for 96 h. The catalyst prepared was named Cat-1-D. The composition of the catalyst is shown in Table 1.

[0103] The composite photocatalyst was rod-shaped, and the BET test showed that the specific surface area of the composite photocatalyst was 30.59 m 2 / g.

[0104] Comparative Example 5

[0105] Following the method of Example 1, except that acid treatment was not performed, 0.3 g of the prepared sodium titanate nanorods, 1 mg of dichlorotetraamminepalladium salt, and 60 mL of water were directly mixed, and the reaction solution was stirred at room temperature for 12 h. After the reaction was completed, the precipitate was filtered and separated, washed with deionized water until pH = 7, and then dried at 110 °C for 12 h. Afterwards, it was calcined in a muffle furnace at 400 °C for 3 h, and after the reaction was completed, it was naturally cooled to room temperature and removed. The obtained catalyst was designated Cat-1-E.

[0106] Comparative Example 6

[0107] Commercially available nano-titanium dioxide (brand name: anatase nano-TiO2, size 10-25nm) was used as a catalyst, denoted as Cat-TiO2.

[0108] Table 1

[0109]

[0110] Test case

[0111] In a 250 mL single-port jacketed glass reactor, 10 g of dicyclopentadiene, 200 mL of acetone, and a photocatalyst were added. The amount of photocatalyst used in the above examples and comparative examples is shown in Table 2. The reactor was then sealed, wrapped with aluminum foil, and condenser was turned on. It was irradiated for a certain period using a medium-pressure mercury lamp (400 W). The reaction solution was analyzed using gas chromatography-mass spectrometry (GC-MS) to qualitatively identify the products and calculate the reaction conversion rate and yield. The reaction was terminated when the raw material conversion rate was greater than 99.9% or the reaction time reached 24 h. The total reaction time and the yield of the target product were recorded at this point. The results are shown in Table 2.

[0112] The target product is a pentacyclic ring [5.2.1.0]. 2.5 .0 3.9 .0 4.8 Decane,

[0113] Product yield (%) = A1*m2*200*100% / (A2*V1*10) (internal standard method);

[0114] Where A1 is the peak area of ​​the target product; A2 is the peak area of ​​adamantane; m2 is the mass of adamantane; and V1 is the sampling volume.

[0115] Raw material conversion rate (%) = (A0 - A) i )*100% / A0;

[0116] Where A0 is the initial peak area of ​​the raw material; A i The peak area of ​​the sampled raw material at a certain moment.

[0117] Table 2

[0118] Catalyst Catalyst dosage / mg Reaction time / h Feed conversion / % Product yield / % Cat-1 300 8 >99.9 92 Cat-2 150 5 >99.9 93 Cat-3 300 4 >99.9 96 Cat-4 300 5 >99.9 95 Cat-5 300 15 >99.9 93 Cat-1-A 300 18 >99.9 90 Cat-1-B 300 24 90 83 Cat-1-C 300 12 >99.9 92 Cat-1-D 300 15 >99.9 90 Cat-1-E 300 24 88 81 Cat-TiO2 300 24 84 75

[0119] As can be seen from the results in Table 2, the composite photocatalyst provided by this invention has high photocatalytic efficiency, with nearly complete conversion of raw materials in a short time and a high product yield. Using the prepared metal nanoparticle composite photocatalyst to catalyze the intramolecular [2+2] cycloaddition of dicyclopentadiene to prepare pentacyclodecane, the complete conversion time of the raw materials can be reduced by up to half, and the product yield can reach 96%. A comparison of Example 1 and Comparative Examples 3 and 4 shows that the photocatalyst prepared using a two-stage hydrothermal method has a higher specific surface area, resulting in higher photocatalytic efficiency and activity.

[0120] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composite photocatalyst, characterized in that, The composite photocatalyst comprises a support and an active metal component supported on the support; wherein the support comprises an alkali metal titanate and titanium dioxide; and the active metal component is selected from at least one metal element selected from Group IIIB, Group IVB, Group VB, Group VIB, Group VIIB, Group VIII, Group IB, and Group IIB. The composite photocatalyst is rod-shaped with a specific surface area of ​​not less than 45 m². 2 / g.

2. The composite photocatalyst according to claim 1, wherein, The length of the composite photocatalyst is 0.1-3 μm, preferably 0.5-2.5 μm; Preferably, the aspect ratio of the composite photocatalyst is 3-200:1, and more preferably 80-150:1; Preferably, the specific surface area of ​​the composite photocatalyst is 50-200 m². 2 / g, preferably 65-150m 2 / g.

3. The composite photocatalyst according to claim 1 or 2, wherein, The active metal component is selected from at least one of Pd, Pt, Rh, Ni, Co, Zn, Cu, Cd, Hg, Mn, Ag, Fe, Cr, La, Ce, Ru, Zr, Nb, and W; Preferably, at least a portion of the active metal component exists in the form of an oxide; Preferably, the alkali metal titanate is selected from sodium titanate and / or potassium titanate; Preferably, based on the total mass of the composite photocatalyst, the content of the active metal component is 0.001-15 wt%, the content of the alkali metal is 0.1-3.5 wt%, and the content of titanium is 40-70 wt%. Preferably, in the carrier, the mass ratio of titanium to alkali metal is (4-50):1, more preferably (25-48):

1.

4. The composite photocatalyst according to claim 3, wherein, The active metal component is selected from at least one of Pd, Pt, Rh, Ag, and Ru. Based on the total mass of the composite photocatalyst, the content of the active metal component, by element, is 0.001-0.5 wt%, the content of the alkali metal is 0.1-3.5 wt%, and the content of titanium is 55-70 wt%; or, The active metal component is selected from at least one of Ni, Co, Zn, Cu, Cd, Hg, Mn, Fe, Cr, La, Ce, Zr, Nb and W. Based on the total mass of the composite photocatalyst, the content of the active metal component is 1-10 wt%, the content of the alkali metal is 0.1-3.5 wt%, and the content of titanium is 50-65 wt%.

5. A method for preparing a composite photocatalyst, characterized in that, Includes the following steps: (1) Mix titanium source and alkali metal source and carry out hydrothermal reaction to obtain alkali metal titanate micro-nano rods; the conditions of the hydrothermal reaction include: first reacting at 60-140℃ for 12-96h, and then reacting at 160-240℃ for 12-96h. (2) The alkali metal titanate micro / nano rods are activated by contacting acid; (3) The product obtained in step (2) is contacted with the precursor of the active metal component, and then dried and calcined; the active metal component is selected from at least one of the metal elements of Group IIIB, Group IVB, Group VB, Group VIB, Group VIIB, Group VIII, Group IB and Group IIB.

6. The preparation method according to claim 5, wherein, The conditions for the hydrothermal reaction include: first reacting at 100-130℃ for 24-48 hours, and then reacting at 170-200℃ for 12-24 hours; Preferably, the titanium source is selected from at least one of titanium dioxide, metatitanic acid, orthotitanic acid, tetrabutyl titanate, titanium sulfate, titanium oxysulfate, titanium tetrachloride, and titanium isopropoxide. Preferably, the alkali metal source is selected from at least one of alkali metal hydroxides, alkali metal hydrides, and alkali metal salts; Preferably, the alkali metal is selected from sodium and / or potassium, and the alkali metal source is selected from at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium hydride, potassium hydroxide, potassium carbonate, potassium bicarbonate, and potassium hydride. Preferably, the alkali metal source is provided by an alkali metal source solution, and the concentration of the alkali metal source solution is 5-30 mol / L, preferably 8-15 mol / L; Preferably, the mass of the titanium source is calculated as titanium dioxide, and the volume of the alkali metal source solution used is 5-100 mL, more preferably 10-80 mL, relative to 1 g of the titanium source.

7. The preparation method according to claim 5 or 6, wherein, In step (2), the acid is selected from organic acids and / or inorganic acids, preferably at least one of formic acid, acetic acid, propionic acid, phosphoric acid, oxalic acid, hydrochloric acid, sulfuric acid and nitric acid; Preferably, the acid is provided by an aqueous solution of the acid, the concentration of which is 0.05-1.5 mol / L; Preferably, the amount of aqueous solution of acid used is 20-300 mL relative to 1 g of the alkali metal titanate nanorod.

8. The preparation method according to any one of claims 5-7, wherein, The active metal component is selected from at least one of Pd, Pt, Rh, Ni, Co, Zn, Cu, Cd, Hg, Mn, Ag, Fe, Cr, La, Ce, Ru, Zr, Nb, and W; Preferably, the amount of the product obtained in step (2) and the precursor of the active metal component is such that the content of the active metal component in the prepared composite photocatalyst is 0.001-15 wt% by element. Preferably, the active metal component is selected from at least one of Pd, Pt, Rh, Ag, and Ru, and the amount of the product obtained in step (2) and the precursor of the active metal component is such that the content of the active metal component in the prepared composite photocatalyst is 0.001-0.5 wt% (elementally); or, The active metal component is selected from at least one of Ni, Co, Zn, Cu, Cd, Hg, Mn, Fe, Cr, La, Ce, Zr, Nb and W, and the active metal component is selected from at least one of Pd, Pt, Rh, Ag and Ru. The amount of the product obtained in step (2) and the precursor of the active metal component is such that the content of the active metal component in the prepared composite photocatalyst is 1-10 wt% by element. Preferably, the roasting temperature is 300-700℃, more preferably 400-600℃, and the time is 1-7h, more preferably 2-4h.

9. The composite photocatalyst prepared by the preparation method according to any one of claims 5-8.

10. The application of the composite photocatalyst according to any one of claims 1-4 and 9 in solar cells, photocatalysis, photocatalytic water splitting, sensors, nanoelectronics or optoelectronic nanodevices.

11. A method for photocatalytic cycloaddition reaction of dicyclopentadiene, characterized in that, The method includes: contacting dicyclopentadiene with a catalyst under light irradiation conditions, wherein the catalyst is a composite photocatalyst according to any one of claims 1-4 and 9; Preferably, the mass ratio of the catalyst to dicyclopentadiene is 0.1-5:100, more preferably 0.5-3:100.

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