A strontium titanate photoanode film, its preparation method and application

Abstract

This invention discloses a strontium titanate photoanode film, its preparation method, and its application, comprising the following steps: Cleaning and drying conductive glass, then calcining it with the conductive side facing upwards; chelating tetrabutyl titanate with acetylacetone, adding it to a strontium acetate solution, stirring, then adding acetonitrile, continuing stirring for a set time, and aging to obtain a precursor solution; covering a pre-reserved area on the conductive surface of the calcined conductive glass with tape, then coating the conductive surface with the precursor solution layer by layer, calcining the conductive glass at 550-650℃ for 5-15 min after each layer is coated, and calcining the conductive glass at 550-650℃ for 0.8-1.2 h after coating, and obtaining the strontium titanate photoanode film after cooling. The prepared SrTiO3 photoanode film can not only be used for photoelectrocatalytic water splitting to produce oxygen, but can also be recycled and reused.

Description

Technical Field

[0001] This invention relates to the field of photoanode material preparation, specifically to a strontium titanate photoanode film, its preparation method, and its application. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] The current global energy shortage and ensuing environmental crisis are caused by the depletion of fossil fuels. Converting abundant natural solar energy directly into chemical energy in a sustainable manner is one of the most promising solutions to future energy crises and environmental pollution. As solar energy accounts for an increasing share of global energy consumption, the storage of energy converted from solar radiation will become increasingly important. Photoelectrochemical (PEC) oxidation reactions using semiconductor photoelectrodes are central to solar energy conversion and storage applications.

[0004] Strontium titanate (SrTiO3) is an n-type semiconductor with a typical perovskite (ABO3) structure, exhibiting strong redox properties (band gap of 3.2 eV) and high resistance to photocorrosion in aqueous media. Furthermore, it possesses a band edge that matches the redox level of water well, enabling SrTiO3 to photocatalytically split water without an external voltage.

[0005] Most existing SrTiO3 photocatalysts are in powder form, making them difficult to recycle and reuse. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a strontium titanate photoanode film, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a strontium titanate photoanode film, comprising the following steps:

[0009] After cleaning and drying the conductive glass, it is calcined with the conductive side facing up.

[0010] Tetrabutyl titanate was chelated with acetylacetone, then added to a strontium acetate solution, diluted with ethylene glycol methyl ether, stirred, and then acetonitrile was added. After stirring for a set time, the precursor solution was obtained after aging.

[0011] The conductive surface of the calcined conductive glass is covered with tape to cover the reserved area. Then, the precursor solution is coated layer by layer onto the conductive surface. After each layer is coated, the conductive glass is calcined at 550-650℃ for 5-15 minutes. After coating is completed, the conductive glass is calcined at 550-650℃ for 0.8-1.2 hours. After cooling, the strontium titanate photoanode film is obtained.

[0012] The purpose of cleaning and drying the conductive glass before calcination is to make the drying process more thorough, remove residual solvents and impurities from the surface, and make the FTO surface of the conductive glass smoother after calcination, thereby improving the adhesion between the film produced by subsequent calcination and the conductive glass.

[0013] Acetylacetone acts as a chelating agent to inhibit the hydrolysis of tetrabutyl titanate.

[0014] The molar ratio of strontium in strontium acetate to that in tetrabutyl titanate is 1:1. The resulting solution is diluted with ethylene glycol methyl ether to approximately 0.3 M. The strontium acetate solution is unstable. Ethylene glycol methyl ether (i.e., 2-methoxyethanol) acts as both a solvent and stabilizer, forming a chelate with the titanium alkoxide, which stabilizes the acetate solution.

[0015] Adding a small amount of acetonitrile promotes chelation.

[0016] The aging process allows the system sufficient time to fully crosslink and form a stable strontium titanate precursor solution.

[0017] The tape is removed after spin coating and before firing; no tape remains during the firing process. Tape is reapplied before the next spin coating.

[0018] Each layer of conductive glass is calcined to dry each film and to make the deposition between each layer more tightly bonded.

[0019] In some embodiments, the cleaning method for conductive glass is as follows: immerse the conductive glass in an aqueous solution of glass cleaner, perform ultrasonic cleaning, rinse off the residual glass cleaner on the surface with water, and then immerse it in ethanol for ultrasonic cleaning.

[0020] Preferably, the concentration of the aqueous solution of the glass cleaner is 0.3-0.7 v / v%.

[0021] In some embodiments, the conductive glass is calcined at a temperature of 400-500°C for 2-4 hours.

[0022] In some embodiments, the concentration of strontium acetate in the precursor solution is 0.2-0.4 mol / L, the concentration of tetrabutyl titanate is 0.2-0.4 mol / L, and the concentration of acetylacetone is 0.1-0.2 mol / L.

[0023] Preferably, the concentration of acetonitrile in the precursor solution is 0.3-0.6 mol / L.

[0024] In some embodiments, the stirring time after adding acetonitrile is 0.8-1.2 h.

[0025] In some embodiments, the aging time is 6-10 hours.

[0026] Secondly, the present invention provides a strontium titanate photoanode film, which is prepared by the aforementioned preparation method.

[0027] Thirdly, the present invention provides the application of strontium titanate photoanode membrane in photoelectrocatalytic water splitting to produce oxygen.

[0028] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0029] The SrTiO3 photoanode film was prepared by metal-organic chemical deposition, where SrTiO3 was synthesized in solution on conductive glass FTO. The process was carried out under normal pressure and the thickness of the electrode film could be controlled. Compared with SrTiO3 powder photocatalyst (which can only be used for photocatalysis), the SrTiO3 photoanode film prepared by this invention can not only be used for photoelectrocatalytic water splitting to produce oxygen, but also for photoelectrocatalytic systems and for device fabrication. Attached Figure Description

[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0031] Figure 1 These are X-ray diffraction (XRD) patterns of SrTiO3 / FTO and blank FTO prepared at different calcination temperatures.

[0032] Figure 2 The UV-Vis spectra of SrTiO3 / FTO photoanodes prepared at three calcination temperatures are shown.

[0033] Figure 3 (a) is a scanning electron microscope image of the SrTiO3 nanoparticle layer on a conductive glass FTO substrate; Figure 3 (b) is a cross-sectional view of the SrTiO3 / FTO electrode.

[0034] Figure 4 XPS spectra of the SrTiO3 / FTO photoanode: (a) overall spectrum, (b) Sr 3d, (c) Ti 2p, (d) O 1s.

[0035] Figure 5 The curves are linear sweep voltammetry curves for SrTiO3 / FTO as the photoanode. Detailed Implementation

[0036] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] The present invention will be further described below with reference to the embodiments.

[0038] Example 1

[0039] The SrTiO3 photoanode film was prepared by a method comprising the following steps:

[0040] (1) Pretreatment of conductive glass: FTO conductive glass with dimensions of 2.5cm×3cm was ultrasonically cleaned for 30min in deionized water with glass cleaner (0.5v / v%), the residual glass cleaner was rinsed off with deionized water, and then ultrasonically cleaned in 95% ethanol for 30min. The cleaned and dried glass was placed in a muffle furnace with the conductive side facing up and calcined at 450℃ for 3h.

[0041] (2) Preparation of a precursor solution containing strontium acetate and tetrabutyl titanate: Dissolve 25 mmol of strontium acetate in 42 mL of acetic acid, and chelate 25 mmol of tetrabutyl titanate with 12.5 mmol of acetylacetone. After mixing the two, dilute the resulting clear solution with 42 mL of ethylene glycol monomethyl ether to approximately 0.3 M. After stirring for 1 h, add 40 mmol of acetonitrile, continue stirring for 1 h, and age overnight to obtain the precursor solution.

[0042] (3) After the pretreatment in step (1), a 0.5cm × 2.5cm area was reserved on the conductive glass FTO as a pure fluorine-doped tin oxide surface for connecting the electrode. The area used to coat the precursor solution in step (2) was 2.5cm × 2.5cm. The reserved area was covered with tape, and the FTO conductive surface was coated layer by layer using a spin coater. Each layer of solution was 100μL, the spin coater parameters were 1000rpm, and the duration was 30s. After each layer was coated, it was placed in a muffle furnace and calcined at 600℃ for 10min, and then cooled to room temperature. After the coating was repeated, it was placed in a muffle furnace and calcined at 600℃ for 1h, and then naturally cooled to room temperature to obtain the SrTiO3 photoanode film.

[0043] All electrochemical tests used a three-electrode system, with Pt as the counter electrode, Ag / AgCl as the reference electrode, and the prepared series of photoanodes as the working electrodes. The test solution was 1M NaOH (pH=14).

[0044] Example 2

[0045] The difference from Example 1 is that in step (3), the calcination temperature in the precursor solution spin-coated is changed from 600℃ to 650℃, while the others remain unchanged.

[0046] Example 3

[0047] The difference from Example 1 is that in step (3), the calcination temperature in the precursor solution spin-coated is changed from 600℃ to 700℃, while the others remain unchanged.

[0048] Figure 1 The X-ray diffraction patterns of SrTiO3 / FTO and blank FTO prepared at different calcination temperatures in Examples 1-3 are shown. In the XRD patterns, 22.78°, 32.38°, 39.98°, 46.48°, 57.73°, and 67.80° correspond to the six characteristic diffraction planes of SrTiO3 (100), (110), (111), (200), (211), and (220), respectively (PDF#35-0734). The photoanodes prepared at the three calcination temperatures are consistent with the blank FTO and the sample card, and there are no other impurity mineral phase peaks, which confirms that SrTiO3 was synthesized on conductive glass FTO.

[0049] Figure 2 The images show the UV-Vis spectra of SrTiO3 / FTO photoanodes prepared at the three calcination temperatures in Examples 1-3. The absorption band edge of SrTiO3 / FTO is around 380 nm.

[0050] Figure 3 (a) is a scanning electron microscope image of the SrTiO3 nanoparticle layer on the conductive glass FTO substrate in Example 1. It can be seen that the deposition of the nano SrTiO3 layer is dense and uniform, and the particles are spherical with a size distribution between 10-40 nm. Figure 3 (b) is a cross-sectional view of the SrTiO3 / FTO electrode in Example 1. The thickness of the SrTiO3 layer is 1.41 μm. The dense structure of the electrode can be clearly seen from the cross-sectional view.

[0051] To investigate the presence of each element, XPS tests were performed on the SrTiO3 photoanode film prepared in Example 1. Figure 4 (a) is the overall spectrum, showing the Sr, Ti, and O elements in SrTiO3. Figure 4 (b) shows the broad spectrum of Sr, with Sr 3d⁻ detected near 132.86 eV and 134.60 eV. 5 / 2 Orbits and Sr 3d 3 / 2 Spectral peaks of the orbit. Figure 4 (c) shows the broad spectrum of Ti, with Ti 2p detected near 458.21 eV, 463.95 eV, and 471.31 eV. 3 / 2 Ti 3d1 / 2 Spectral peaks of orbits and satellites. Figure 4 The characteristic peak of O1s at 529.97 eV in (d) represents lattice oxygen, which is related to the Ti-O bond, while another peak centered at 532.55 eV is thought to be related to adsorbed oxygen such as carbonates and hydroxyl oxides.

[0052] Figure 5 The results show the photoelectrochemical performance of the SrTiO3 / FTO prepared in Example 1 as a photoanode. The SrTiO3 / FTO had 20 spin-coated layers and was calcined at 600℃. Figure 5 Linear sweep voltammetry curves of the SrTiO3 photoanode are shown. Under different light intensities, the prepared SrTiO3 / FTO photoanode exhibits photoresponsive activity.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a strontium titanate photoanode film, characterized in that: Includes the following steps: After cleaning and drying the conductive glass, it is calcined with the conductive side facing up. Tetrabutyl titanate was chelated with acetylacetone, then added to a strontium acetate solution, diluted with ethylene glycol methyl ether, stirred, and then acetonitrile was added. After stirring for a set time and aging for 6-10 hours, a precursor solution was obtained. In the precursor solution, the concentrations of acetonitrile, strontium acetate, tetrabutyl titanate, and acetylacetone are 0.1-0.2 mol / L, 0.2-0.4 mol / L, 0.2-0.4 mol / L, and 0.1-0.2 mol / L, respectively. The molar ratio of strontium in the strontium acetate to that in the tetrabutyl titanate is 1:

1. The strontium acetate solution is obtained by dissolving strontium acetate in acetic acid. The conductive surface of the calcined conductive glass is covered with tape to cover the reserved area. Then, the precursor solution is coated layer by layer onto the conductive surface. After each layer is coated, the conductive glass is calcined at 550-650℃ for 5-15 minutes. After coating is completed, the conductive glass is calcined at 600-650℃ for 0.8-1.2 hours. After cooling, the strontium titanate photoanode film is obtained.

2. The method for preparing the strontium titanate photoanode film according to claim 1, characterized in that: The cleaning method for conductive glass is as follows: immerse the conductive glass in an aqueous solution of glass cleaner, ultrasonically clean it, rinse off the residual glass cleaner on the surface with water, and then immerse it in ethanol for ultrasonic cleaning.

3. The method for preparing the strontium titanate photoanode film according to claim 2, characterized in that: The concentration of the aqueous solution of the glass cleaner is 0.3-0.7 v / v.

4. The method for preparing the strontium titanate photoanode film according to claim 1, characterized in that: The calcination temperature of the conductive glass is 400-500℃, and the calcination time is 2-4 hours.

5. The method for preparing the strontium titanate photoanode film according to claim 1, characterized in that: After adding acetonitrile, continue stirring for 0.8-1.2 hours.

6. A strontium titanate photoanode film, characterized in that: It is prepared by any one of the preparation methods described in claims 1-5.

7. The application of the strontium titanate photoanode membrane according to claim 6 in photoelectrocatalytic water splitting to produce oxygen.

Images