Preparation method and application of one-dimensional iron-gold / oxygen-deficient strontium titanate hollow nanotube composite photocatalyst

Abstract

A preparation method and application of an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst, which relates to a preparation method and application of a photocatalyst. The present invention is to solve the problem that the prior art prepares a strontium titanate-based composite photocatalyst with low photogenerated carrier separation efficiency and lacks methane adsorption sites and catalytic active centers for activating oxidants. In the present invention, strontium ions in strontium nitrate are first coordinated with a complexing agent acetylacetone to form a strontium acetylacetonate intermediate, and then reacted with tetrabutyl titanate to form a strontium titanate precursor, and then the precursor solution is electrostatically spun in combination with subsequent calcination treatment to form a strontium titanate one-dimensional hollow nanotube, and then a sodium borohydride vacuum hydrogen reduction treatment is performed to obtain a strontium titanate one-dimensional hollow nanotube with surface oxygen defects, and finally a step-by-step freezing photoreduction method is used to induce metal gold and iron to be modified on the surface of oxygen-deficient strontium carbonate to obtain an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst.

Description

Technical Field

[0001] The invention relates to a preparation method and application of a photocatalyst. Background Art

[0002] Methane reserves are huge, and directly burning it as a fuel or emitting it into the environment will cause energy waste or environmental problems. The catalytic conversion of methane into high-value-added oxidation products such as methanol is the holy grail reaction in the field of catalysis. At present, the conversion of methane in industry is often accompanied by high temperature, high pressure and high energy consumption, which is not conducive to sustainable development. Semiconductor photocatalytic technology can realize the direct conversion of methane into methanol under mild conditions, which is a feasible strategy to solve the above problems.

[0003] It is of great significance to rationally design and prepare efficient, cheap and stable photocatalysts for methane oxidation. Among the many photocatalysts, SrTiO3 has attracted extensive attention due to its abundant sources, stable chemical properties and non-toxicity. However, the wide band gap of SrTiO3 (~3.2eV) makes its photogenerated carrier separation efficiency low; its adsorption capacity for CH4 is weak; and it lacks surface catalytic active centers of activated oxidants and generally exhibits poor photocatalytic methane oxidation activity. Based on this, a metal / semiconductor composite system can be constructed by modifying the co-catalyst to promote the charge separation and transfer process. In addition, the active center of the activated oxidant is further introduced to improve its methane oxidation activity.

[0004] However, the current design of strontium titanate-based composite photocatalysts usually lacks the design of methane adsorption activation sites. In addition, the introduction of catalytic active sites and activated oxidants (hydrogen peroxide, oxygen) are often ignored in the rational design of promoting the separation and transfer of photogenerated charges in strontium titanate, resulting in the still unsatisfactory performance of photocatalytic methane oxidation. Summary of the invention

[0005] The present invention aims to solve the problems of low photogenerated carrier separation efficiency and lack of methane adsorption sites and catalytic active centers for activating oxidants in the prior art of preparing strontium titanate-based composite photocatalysts, and to provide a preparation method and application of an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst.

[0006] A method for preparing an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst is specifically completed by the following steps:

[0007] 1. Preparation of strontium titanate hollow nanotubes:

[0008] ① First, add the strontium source and the complexing agent into the organic solvent, then stir until completely dissolved, then add tetrabutyl titanate, continue stirring for a period of time to obtain a clear solution, then add the polymer to form a uniform and stable precursor sol;

[0009] ②, transferring the precursor sol to an electrospinning syringe, spinning it at 12kv to 14kv for 10h to 12h to obtain a precursor, and drying the precursor to obtain a reaction product;

[0010] ③, calcining the reaction product at 550°C to 650°C for a period of time, then adding low-concentration hydrochloric acid for pickling, removing the supernatant after centrifugation to obtain a precipitate; washing the precipitate with deionized water until it is neutral, and then drying to obtain strontium titanate hollow nanotubes;

[0011] 2. Preparation of oxygen defects on the surface of strontium titanate hollow nanotubes:

[0012] Placing strontium titanate hollow nanotubes and sodium borohydride solid powder in layers in a vacuum tube furnace, heating to 450° C. to 550° C., and calcining under vacuum and at a temperature of 450° C. to 550° C. to obtain oxygen-deficient strontium titanate;

[0013] 3. Dispersing the oxygen-deficient strontium titanate and chloroauric acid solution into a methanol-water solution, freezing with liquid nitrogen, reducing with light, then washing with deionized water by centrifugation, and drying to obtain a gold-modified oxygen-deficient strontium titanate complex;

[0014] 4. Dispersing the gold-modified oxygen-deficient strontium titanate complex and the ferric nitrate aqueous solution in a methanol aqueous solution, stirring evenly to obtain a dispersion; freezing the dispersion under liquid nitrogen, and then reducing it under light to obtain an iron-gold / oxygen-deficient strontium titanate complex; using deionized water to centrifugally wash the iron-gold / oxygen-deficient strontium titanate complex, and then drying it to obtain an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube complex photocatalyst.

[0015] Principle of the present invention:

[0016] First, the strontium ions in strontium nitrate are coordinated with the complexing agent acetylacetone to form a strontium acetylacetonate intermediate, which then reacts with tetrabutyl titanate to form a strontium titanate precursor. The precursor solution is then subjected to electrospinning combined with subsequent calcination to form one-dimensional strontium titanate hollow nanotubes, which are then subjected to vacuum hydrogen reduction with sodium borohydride to obtain one-dimensional strontium titanate hollow nanotubes with surface oxygen defects. Finally, a step-by-step cryo-photoreduction method is used to induce metallic gold and iron to be modified on the surface of oxygen-deficient strontium carbonate to obtain an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst.

[0017] Advantages of the present invention:

[0018] 1. The iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared by the present invention has abundant surface oxygen defects and can adsorb methane;

[0019] 2. Compared with the existing strontium titanate-based composite photocatalyst, the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared by the present invention is beneficial to the directional transfer and separation of photogenerated electrons by the regulation of the interface by gold nanoparticles; the iron species can activate the oxidant (hydrogen peroxide) to improve the methane oxidation activity;

[0020] 3. The iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared by the present invention is suitable for use as a photocatalytic methane oxidation and photocatalytic reduction of carbon dioxide catalyst. Each gram of iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst can generate 3.16 mmol to 8.22 mmol of methanol by photocatalytic oxidation of methane.

[0021] An iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst is used as a photocatalyst to catalyze the oxidation of methane or as a photocatalyst to reduce carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is an X-ray diffraction pattern of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1;

[0023] Figure 2 is a transmission electron microscope image of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1;

[0024] Figure 3 is the fluorescence spectrum of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1;

[0025] Figure 4 is a photocatalytic methane oxidation activity diagram of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1;

[0026] Figure 5 is a photocatalytic carbon dioxide reduction activity diagram of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1;

[0027] Figure 6 is the surface photovoltage spectrum of the copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 2;

[0028] Figure 7 is the UV solid absorption graph of the copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 2;

[0029] Figure 8It is a bar chart of the oxidation of methane by the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1, the copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 2, and the nickel-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 3. DETAILED DESCRIPTION

[0030] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention.

[0031] Specific implementation method 1: This implementation method is a method for preparing an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst, which is specifically completed according to the following steps:

[0032] 1. Preparation of strontium titanate hollow nanotubes:

[0033] ① First, add the strontium source and the complexing agent into the organic solvent, then stir until completely dissolved, then add tetrabutyl titanate, continue stirring for a period of time to obtain a clear solution, then add the polymer to form a uniform and stable precursor sol;

[0034] ②, transferring the precursor sol to an electrospinning syringe, spinning it at 12kv to 14kv for 10h to 12h to obtain a precursor, and drying the precursor to obtain a reaction product;

[0035] ③, calcining the reaction product at 550°C to 650°C for a period of time, then adding low-concentration hydrochloric acid for pickling, removing the supernatant after centrifugation to obtain a precipitate; washing the precipitate with deionized water until it is neutral, and then drying to obtain strontium titanate hollow nanotubes;

[0036] 2. Preparation of oxygen defects on the surface of strontium titanate hollow nanotubes:

[0037] Placing strontium titanate hollow nanotubes and sodium borohydride solid powder in layers in a vacuum tube furnace, heating to 450° C. to 550° C., and calcining under vacuum and at a temperature of 450° C. to 550° C. to obtain oxygen-deficient strontium titanate;

[0038] 3. Dispersing the oxygen-deficient strontium titanate and chloroauric acid solution into a methanol-water solution, freezing with liquid nitrogen, reducing with light, then washing with deionized water by centrifugation, and drying to obtain a gold-modified oxygen-deficient strontium titanate complex;

[0039] 4. Dispersing the gold-modified oxygen-deficient strontium titanate complex and the ferric nitrate aqueous solution in a methanol aqueous solution, stirring evenly to obtain a dispersion; freezing the dispersion under liquid nitrogen, and then reducing it under light to obtain an iron-gold / oxygen-deficient strontium titanate complex; using deionized water to centrifugally wash the iron-gold / oxygen-deficient strontium titanate complex, and then drying it to obtain an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube complex photocatalyst.

[0040] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that: the strontium source in step 1① is strontium nitrate; the organic solvent in step 1① is N,N-dimethylformamide; the complexing agent in step 1① is acetylacetone; the high molecular polymer in step 1① is polyacrylonitrile. The other steps are the same as those in specific implementation method 1.

[0041] Specific implementation method three: This implementation method is different from specific implementation method one or two in that: the mass ratio of the strontium source described in step one ① to the volume ratio of the organic solvent is (1.06g-2.12g): (50mL-100mL); the mass ratio of the complexing agent described in step one ① to the volume ratio of the organic solvent is (2g-4g): (50mL-100mL); the mass ratio of the tetrabutyl titanate described in step one ① to the volume ratio of the organic solvent is (3.4g-6.8g): (50mL-100mL); the mass ratio of the high molecular polymer described in step one ① to the volume ratio of the organic solvent is (4g-5g): (50mL-100mL); the stirring speed described in step one ① is 300r / min-500r / min; the stirring time in step one ① is 2h-3h. The other steps are the same as specific implementation method one or two.

[0042] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that: the drying temperature in step 1 ② is 60℃~80℃, and the drying time is 6h~8h; the drying temperature in step 1 ③ is 60℃~80℃, and the drying time is 8h~12h; the calcination time in step 1 ③ is 0.5h~1.5h; the concentration of low-concentration hydrochloric acid in step 1 ③ is 0.06mol / L~0.12mol / L. The other steps are the same as those in specific embodiments 1 to 3.

[0043] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that: the mass ratio of sodium borohydride to strontium titanate hollow nanotubes in step 2 is (0.02g-0.06g):(0.06g-0.18g); the heating rate in step 2 is 5°C / min-10°C / min; the calcination time in step 2 is 1h-3h. The other steps are the same as those in specific embodiments 1 to 4.

[0044] Specific embodiment 6: The difference between this embodiment and specific embodiments 1 to 5 is that: the concentration of the chloroauric acid solution described in step 3 is 4g / L; the volume ratio of the mass of the oxygen-deficient strontium titanate described in step 3 to the chloroauric acid solution is (0.04g~0.08g):(0.05mL~0.1mL); the volume ratio of methanol to water in the methanol aqueous solution described in step 3 is (10mL~20mL):(10mL~20mL); the volume ratio of the mass of the oxygen-deficient strontium titanate described in step 3 to the methanol aqueous solution is (0.04g~0.08g):(20mL~40mL). The other steps are the same as specific embodiments 1 to 5.

[0045] Specific embodiment 7: The difference between this embodiment and specific embodiments 1 to 6 is that: the freezing time with liquid nitrogen in step 3 is 5min to 10min; the light reduction time described in step 3 is 5min to 10min, and the wavelength of light is 200nm to 780nm; the speed of centrifugal washing described in step 3 is 4000r / min to 5000r / min, the number of centrifugal washing is 3 to 5 times, and the time of each centrifugal washing is 5min to 10min; the drying temperature described in step 3 is 60℃ to 80℃, and the drying time is 8h to 12h. The other steps are the same as specific embodiments 1 to 6.

[0046] Specific embodiment eight: The difference between this embodiment and specific embodiments one to seven is that: the concentration of the ferric nitrate aqueous solution described in step four is 4g / L; the mass ratio of the oxygen-deficient strontium titanate complex modified by gold in step four to the ferric nitrate aqueous solution is (0.04g-0.08g):(0.05mL-0.1mL); the volume ratio of methanol to water in the methanol aqueous solution described in step four is (10mL-20mL):(10mL-20mL); the mass ratio of the oxygen-deficient strontium titanate complex modified by gold in step four to the methanol aqueous solution is (0.04g-0.08g):(20mL-40mL); the freezing time described in step four is 3min-5min; the light reduction time described in step four is 5min-10min, and the wavelength of light is 200nm-780nm. The other steps are the same as specific embodiments one to seven.

[0047] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that: in step 4, the iron-gold / oxygen-deficient strontium titanate composite is centrifugally cleaned 2 to 3 times using deionized water, and then dried at 60° C. to 80° C. for 8 h to 12 h. The other steps are the same as those of specific embodiments 1 to 8.

[0048] Specific embodiment ten: This embodiment is an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst used as a photocatalyst to catalyze the oxidation of methane or as a photocatalyst to reduce carbon dioxide.

[0049] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0050] Example 1: A method for preparing an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst is specifically completed by the following steps:

[0051] 1. Preparation of strontium titanate hollow nanotubes:

[0052] ① First, add 2.12g of strontium nitrate and 4g of acetylacetone to 100mL of N,N-dimethylformamide, then stir until completely dissolved, then add 6.8g of tetrabutyl titanate, continue stirring for 2h to obtain a clear solution, then add 8g of polyacrylonitrile to form a uniform and stable precursor sol;

[0053] The stirring speed described in step 1① is 500r / min;

[0054] ②, transferring the precursor sol to an electrospinning syringe, spinning it at 14 kV for 12 h to obtain a precursor, and drying the precursor at 80 ° C for 12 h to obtain a reaction product;

[0055] ③. The reaction product was heated to 600°C at a heating rate of 1°C / min, calcined at 600°C for 1 hour, and then acid-washed once with low-concentration hydrochloric acid. The supernatant was removed after centrifugation to obtain a precipitate; the precipitate was washed with deionized water until neutral, and then dried at 60°C for 12 hours to obtain strontium titanate hollow nanotubes;

[0056] The concentration of the low concentration hydrochloric acid described in step 1③ is 0.06 mol / L;

[0057] 2. Preparation of oxygen defects on the surface of strontium titanate hollow nanotubes:

[0058] 0.06 g of strontium titanate hollow nanotubes and 0.02 g of sodium borohydride solid powder were placed in layers in a vacuum tube furnace, heated to 500°C at a heating rate of 5°C / min, and calcined at 500°C for 2 h in a vacuum to obtain oxygen-deficient strontium titanate.

[0059] 3. Disperse 0.04g of oxygen-deficient strontium titanate and 0.1mL of 4g / L chloroauric acid solution into 20mL of methanol-water solution, freeze with liquid nitrogen for 5min, reduce with light for 5min, wash with deionized water by centrifugation, and dry at 60°C for 12h to obtain gold-modified oxygen-deficient strontium titanate complex;

[0060] The speed of the centrifugal washing in step 3 is 5000 r / min, the number of centrifugal washing is 3 times, and the time of each centrifugal washing is 5 min;

[0061] The volume ratio of methanol to water in the methanol-water solution described in step 3 is 10 mL:10 mL;

[0062] 4. Disperse 0.04 g of gold-modified oxygen-deficient strontium titanate complex and 0.05 mL of a metal precursor solution with a concentration of 4 g / L in 20 mL of methanol-water solution, stir evenly to obtain a dispersion; freeze the dispersion under liquid nitrogen for 5 minutes, and then reduce it under light for 5 minutes to obtain an iron-gold / oxygen-deficient strontium titanate complex; use deionized water to centrifuge and wash the iron-gold / oxygen-deficient strontium titanate complex three times, and then dry it at 60°C for 12 hours to obtain an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube complex photocatalyst.

[0063] The metal precursor solution described in step 4 is an aqueous solution of ferric nitrate;

[0064] The volume ratio of methanol to water in the methanol-water solution described in step 4 is 10 mL:10 mL.

[0065] Figure 1 is an X-ray diffraction pattern of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1;

[0066] Depend on Figure 1 It can be seen that the introduction of gold nanoparticles and iron clusters did not change the crystal phase and degree of crystallinity of strontium titanate.

[0067] Figure 2 is a transmission electron microscope image of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1;

[0068] Depend on Figure 2 It can be seen that the iron-gold / oxygen-deficient strontium titanate composite nanophotocatalyst prepared in this experiment has a hollow one-dimensional tubular structure, which is beneficial to the adsorption of gas and the increase of mass transfer rate.

[0069] Figure 3 is the fluorescence spectrum of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1;

[0070] Depend on Figure 3 It can be seen that the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1 is beneficial to the transfer and separation of photogenerated charges.

[0071] 0.02 g of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1 was added to 20 mL of distilled water containing saturated CH4 gas and 2 mmol H2O2, and then transferred to a 100 mL quartz glass reactor. The photocatalyst was heated to 400 mW / cm 2 The quartz glass reactor was irradiated with ultraviolet-visible light for 3 hours, and then the liquid in the quartz glass reactor was extracted. Finally, the chromatogram was equipped with a headspace sampler for detection. The detection results are shown in Figure 4 As shown;

[0072] Figure 4 is a photocatalytic methane oxidation activity diagram of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1;

[0073] Depend on Figure 4 It can be seen that the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1 is beneficial to photocatalytic methane oxidation.

[0074] The photocatalytic reduction of carbon dioxide using the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Experiment 1 is specifically carried out in the following steps:

[0075] 0.02 g of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1 was added to 20 mL of ultrapure water and then transferred to a 100 mL quartz glass reactor. The photocatalyst was heated to 400 mW / cm 2 The quartz glass reactor was irradiated with ultraviolet-visible light for 3 hours, and the gases in the quartz glass reactor were extracted respectively. Finally, the gases were detected by chromatography. The test results are shown in Figure 5 As shown;

[0076] Figure 5 is a photocatalytic carbon dioxide reduction activity diagram of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1;

[0077] Depend on Figure 5 It can be seen that the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1 is beneficial to the photocatalytic reduction of carbon dioxide.

[0078] Example 2: This example differs from Example 1 in that the metal precursor solution in step 4 is a copper nitrate aqueous solution, and a copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst is obtained. Other steps and parameters are the same as those in Example 1.

[0079] The copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example was detected by surface photovoltage spectrometer. The detection results are as follows: Figure 6 As shown;

[0080] Figure 6 is the surface photovoltage spectrum of the copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 2;

[0081] Depend on Figure 6 It can be seen that the copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in this experiment has a high charge separation performance, proving that this hollow structured one-dimensional nanotube composite is beneficial to photocatalytic methane oxidation.

[0082] The copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in this experiment was tested by UV-visible absorption spectrometer. The test results are as follows: Figure 7 As shown;

[0083] Figure 7 is the UV solid absorption graph of the copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 2;

[0084] Depend on Figure 7 It can be seen that the copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 2 has a strong ultraviolet light response and an extended visible light response, proving that this hollow structured one-dimensional nanotube is beneficial for enhancing light absorption.

[0085] Example 3: This example differs from Example 1 in that the metal precursor solution in step 4 is a nickel nitrate aqueous solution, and a nickel-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst is obtained. The other steps and parameters are the same as those in Example 1.

[0086] 0.02 g of the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1, 0.02 g of the copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 2, and 0.02 g of the nickel-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 3 were added to 20 mL of distilled water containing saturated CH4 gas and 2 mmol H2O2, and then transferred to a 100 mL quartz glass reactor and heated at a light intensity of 400 mW / cm 2 The quartz glass reactor was irradiated with ultraviolet-visible light for 3 hours, and then the liquid in the quartz glass reactor was extracted. Finally, the chromatogram was equipped with a headspace sampler for detection. The detection results are shown in Figure 8 As shown;

[0087] Figure 8It is a bar chart of the oxidation of methane by the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1, the copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 2, and the nickel-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 3.

[0088] from Figure 8 It can be seen that the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 1 has higher photocatalytic methane oxidation performance than the copper-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 2 and the nickel-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared in Example 3, and the main product is methanol.

Claims

1. A method for preparing a one-dimensional iron-gold / oxygen-deficient strontium titanate hollow nanotube composite photocatalyst, characterized in that The method is specifically completed in the following steps:

1. Preparation of strontium titanate hollow nanotubes: ① First, add the strontium source and the complexing agent into the organic solvent, then stir until completely dissolved, then add tetrabutyl titanate, continue stirring for a period of time to obtain a clear solution, then add the polymer to form a uniform and stable precursor sol; ②, transferring the precursor sol to an electrospinning syringe, spinning it at 12kv to 14kv for 10h to 12h to obtain a precursor, and drying the precursor to obtain a reaction product; ③, calcining the reaction product at 550°C to 650°C for a period of time, then adding low-concentration hydrochloric acid for pickling, removing the supernatant after centrifugation to obtain a precipitate; washing the precipitate with deionized water until it is neutral, and then drying to obtain strontium titanate hollow nanotubes; 2. Preparation of oxygen defects on the surface of strontium titanate hollow nanotubes: Placing strontium titanate hollow nanotubes and sodium borohydride solid powder in layers in a vacuum tube furnace, heating to 450° C. to 550° C., and calcining under vacuum and at a temperature of 450° C. to 550° C. to obtain oxygen-deficient strontium titanate; 3. Dispersing the oxygen-deficient strontium titanate and chloroauric acid solution into a methanol-water solution, freezing with liquid nitrogen, reducing with light, then washing with deionized water by centrifugation, and drying to obtain a gold-modified oxygen-deficient strontium titanate complex; 4. Dispersing the gold-modified oxygen-deficient strontium titanate complex and the ferric nitrate aqueous solution in a methanol aqueous solution, stirring evenly to obtain a dispersion; freezing the dispersion under liquid nitrogen, and then reducing it under light to obtain an iron-gold / oxygen-deficient strontium titanate complex; using deionized water to centrifugally wash the iron-gold / oxygen-deficient strontium titanate complex, and then drying it to obtain an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube complex photocatalyst.

2. The method for preparing a one-dimensional iron-gold / oxygen-deficient strontium titanate hollow nanotube composite photocatalyst according to claim 1, characterized in that The strontium source described in step 1① is strontium nitrate; the organic solvent described in step 1① is N,N-dimethylformamide; the complexing agent described in step 1① is acetylacetone; the high molecular polymer described in step 1① is polyacrylonitrile.

3. The method for preparing a one-dimensional iron-gold / oxygen-deficient strontium titanate hollow nanotube composite photocatalyst according to claim 1, characterized in that The mass ratio of the strontium source described in step 1① to the volume ratio of the organic solvent is (1.06g~2.12g):(50mL~100mL); the mass ratio of the complexing agent described in step 1① to the volume ratio of the organic solvent is (2g~4g):(50mL~100mL); the mass ratio of the tetrabutyl titanate described in step 1① to the volume ratio of the organic solvent is (3.4g~6.8g):(50mL~100mL); the mass ratio of the high molecular polymer described in step 1① to the volume ratio of the organic solvent is (4g~5g):(50mL~100mL); the stirring speed described in step 1① is 300r / min~500r / min; the stirring time in step 1① is 2h~3h.

4. The method for preparing a one-dimensional iron-gold / oxygen-deficient strontium titanate hollow nanotube composite photocatalyst according to claim 1, characterized in that The drying temperature described in step 1② is 60℃~80℃, and the drying time is 6h~8h; the drying temperature described in step 1③ is 60℃~80℃, and the drying time is 8h~12h; the calcination time described in step 1③ is 0.5h~1.5h; the concentration of the low concentration hydrochloric acid described in step 1③ is 0.06mol / L~0.12mol / L.

5. The method for preparing a one-dimensional iron-gold / oxygen-deficient strontium titanate hollow nanotube composite photocatalyst according to claim 1, characterized in that The mass ratio of sodium borohydride to strontium titanate hollow nanotubes described in step 2 is (0.02g~0.06g):(0.06g~0.18g); the heating rate described in step 2 is 5℃ / min~10℃ / min; the calcination time described in step 2 is 1h~3h.

6. The method for preparing a one-dimensional iron-gold / oxygen-deficient strontium titanate hollow nanotube composite photocatalyst according to claim 1, characterized in that The concentration of the chloroauric acid solution described in step three is 4g / L; the volume ratio of the mass of the oxygen-deficient strontium titanate described in step three to the chloroauric acid solution is (0.04g~0.08g):(0.05mL~0.1mL); the volume ratio of methanol to water in the methanol-water solution described in step three is (10mL~20mL):(10mL~20mL); the volume ratio of the mass of the oxygen-deficient strontium titanate described in step three to the methanol-water solution is (0.04g~0.08g):(20mL~40mL).

7. The method for preparing a one-dimensional iron-gold / oxygen-deficient strontium titanate hollow nanotube composite photocatalyst according to claim 1, characterized in that The time for freezing with liquid nitrogen in step three is 5min to 10min; the time for light reduction described in step three is 5min to 10min, and the wavelength of light is 200nm to 780nm; the speed of centrifugal washing described in step three is 4000r / min to 5000r / min, the number of centrifugal washing is 3 to 5 times, and the time for each centrifugal washing is 5min to 10min; the temperature of drying described in step three is 60℃ to 80℃, and the drying time is 8h to 12h.

8. The method for preparing the iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst according to claim 1, characterized in that The concentration of the ferric nitrate aqueous solution described in step 4 is 4g / L; the volume ratio of the mass of the gold-modified oxygen-deficient strontium titanate complex described in step 4 to the ferric nitrate aqueous solution is (0.04g~0.08g):(0.05mL~0.1mL); the volume ratio of methanol to water in the methanol aqueous solution described in step 4 is (10mL~20mL):(10mL~20mL); the volume ratio of the mass of the gold-modified oxygen-deficient strontium titanate complex described in step 4 to the methanol aqueous solution is (0.04g~0.08g):(20mL~40mL); the freezing time described in step 4 is 3min~5min; the light reduction time described in step 4 is 5min~10min, and the wavelength of the light is 200nm~780nm.

9. The method for preparing a one-dimensional iron-gold / oxygen-deficient strontium titanate hollow nanotube composite photocatalyst according to claim 1, characterized in that In step 4, the iron-gold / oxygen-deficient strontium titanate complex is centrifugally cleaned 2 to 3 times using deionized water, and then dried at 60° C. to 80° C. for 8 h to 12 h.

10. Use of an iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst prepared by the preparation method according to claim 1, characterized in that An iron-gold / oxygen-deficient strontium titanate one-dimensional hollow nanotube composite photocatalyst is used as a photocatalyst to catalyze the oxidation of methane or as a photocatalyst to reduce carbon dioxide.

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