Round-corner polyhedral strontium titanate single crystal particle, strontium titanate catalyst and preparation method thereof

Abstract

The invention provides a rounded-corner polyhedral strontium titanate single-crystal particle, a strontium titanate catalyst and a preparation method of the rounded-corner polyhedral strontium titanate single-crystal particle. The preparation method of the single crystal particles comprises the following steps: mixing strontium titanate, an aluminum source, a cerium source and a fluxing agent to obtain a mixed material; the mixed material is subjected to melting treatment and then sequentially subjected to cooling, washing and drying, and the rounded-corner polyhedral strontium titanate single crystal particles are obtained. The strontium titanate single crystal particle provided by the invention is of a twenty-six-surface body structure with a fillet, and has a (100), (110) and (112) fused fillet crystal face; the rounded corner of the particle is easier to load a cocatalyst, so that the catalytic particle has higher photocatalytic performance; the strontium titanate catalyst has excellent water photolysis hydrogen production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation, and relates to a strontium titanate single crystal particle, specifically a rounded polyhedral strontium titanate single crystal particle, a strontium titanate catalyst, and a preparation method thereof. Background Technology

[0002] Hydrogen, as a green, zero-pollution, and highly efficient energy source, is an ideal new energy choice for the future. After years of development and long-term efforts, extensive research and practice have been conducted in the fields of hydrogen production, storage, transportation, and end-use applications. Photocatalytic water splitting for hydrogen production is an emerging, environmentally friendly, and low-carbon pure green hydrogen production technology. Compared with water electrolysis, it features a simpler process, higher energy conversion rate, and lower cost. Among commonly used photocatalysts for water splitting, titanium dioxide is a key component. The research results on photocatalytic water splitting using TiO2 electrodes in 1972 opened the door to the world of photocatalysis. Since then, researchers in chemistry, physics, materials science, and other fields have conducted extensive research on semiconductor materials and special crystal materials in areas such as solar energy conversion and storage, photochemical synthesis, photocatalytic water splitting for hydrogen production, and photocatalytic degradation. However, titanium dioxide suffers from low photocatalytic efficiency and structural instability.

[0003] Strontium titanate (SrTiO3) is an excellent photocatalytic material with high temperature resistance and high ultraviolet light absorption efficiency. It possesses a suitable band gap and hydrogen evolution and oxygen evolution potentials, with a band gap of 3.2 eV. Therefore, SrTiO3 is an ideal material for photocatalytic water splitting to produce hydrogen. Strontium titanate also has a high refractive index (n=2.409) and strong dispersion (0.190), and is often used as a diamond analog in precision optical devices. Furthermore, it is widely used in the field of high-temperature superconducting substrates due to its high lattice matching.

[0004] Polyhedral SrTiO3, when applied to photocatalysis, can significantly improve the photocatalytic efficiency of the system, especially in the field of photocatalytic water splitting for hydrogen production, where its high catalytic performance has been verified. Studies show that different crystal faces of SrTiO3 correspond to different photocatalytic performances; that is, exposing more crystal faces can induce anisotropic migration of charge carriers, thereby improving the carrier separation efficiency and enhancing the photocatalytic performance of SrTiO3. Although many polyhedral morphologies have been developed, including hexahedrons, octahedra, and icosahedrons, the icosahedron exposes the most crystal faces, with (100), (110), and (111) crystal faces exposed. Currently, no SrTiO3 crystal particles with more exposed crystal faces have been prepared or reported. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide rounded-corner polyhedral strontium titanate single crystal particles, a strontium titanate catalyst, and a method for its preparation. The strontium titanate catalyst provided by this invention achieves a photocatalytic hydrogen production efficiency of over 12 mmol / h·g under simulated sunlight irradiation conditions using a 300W full-band xenon lamp. The preparation method is based on a clear principle, is simple in process, uses readily available raw materials, provides stable particle morphology control, and is suitable for high-density illumination and long-term use scenarios.

[0006] To achieve this objective, the present invention employs the following technical solution:

[0007] This invention provides a method for preparing rounded-corner polyhedral strontium titanate single crystal particles, the method comprising: mixing strontium titanate, an aluminum source, a cerium source and a flux to obtain a mixture;

[0008] After the mixture is melted, it is cooled, washed and dried in sequence to obtain the rounded polyhedral strontium titanate single crystal particles.

[0009] This invention prepares rounded polyhedral strontium titanate single crystal particles by a melting method. The preparation principle is clear, the process is simple, the raw materials are readily available, and the particle morphology is stably controlled, making it suitable for industrial applications.

[0010] As a preferred embodiment of the present invention, the purity of the strontium titanate is 99~99.99%, for example, it can be 99%, 99.3%, 99.6%, 99.9%, 99.93%, 99.96% or 99.99%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0011] Preferably, the average particle size of the strontium titanate is 100~5000nm, for example, it can be 100nm, 500nm, 1000nm, 2000nm, 3000nm, 4000nm or 5000nm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0012] Preferably, the aluminum source includes aluminum oxide and / or aluminum hydroxide.

[0013] Preferably, the average particle size of the aluminum source is 10~500nm, for example, it can be 10nm, 100nm, 200nm, 300nm, 400nm or 500nm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] Preferably, the cerium source includes cerium oxide and / or cerium chloride.

[0015] Preferably, the flux includes strontium chloride.

[0016] As a preferred embodiment of the present invention, the molar ratio of strontium titanate to flux is 1:3 to 8, for example, it can be 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] In this invention, the amount of strontium titanate used in the preparation process will affect the radius of the rounded corners of the strontium titanate single crystal particles, thereby affecting the area of ​​the (112) crystal plane and lattice defects. If the amount of strontium titanate is too high, it will lead to a reduction in the (112) crystal plane and a large number of lattice defects. If it is too low, it will lead to a reduction in the (112) crystal plane and surface protrusions.

[0018] Preferably, the aluminum source content in the mixture is 0.1~0.5wt%, for example, it can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt% or 0.5wt%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] In this invention, the aluminum source is used to control the morphology of the strontium titanate single crystal particles and to supplement the crystal lattice; if the amount of aluminum source is too high, it will cause the particle surface to bulge, and if it is too low, the crystal lattice defects will be impossible to compensate for.

[0020] Preferably, the content of cerium source in the mixture is 0.1~1wt%, for example, it can be 0.1wt%, 0.2wt%, 0.4wt%, 0.6wt%, 0.8wt% or 1wt%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] In this invention, the cerium source is used to adjust the radius of the rounded corner crystal surface; if the amount of the cerium source is too high, the radius of the rounded corner will decrease, and if it is too low, the radius of the rounded corner will be too large.

[0022] As a preferred embodiment of the present invention, the melting temperature is 900~1100℃, for example, it can be 900℃, 940℃, 980℃, 1020℃, 1060℃ or 1100℃, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0023] Preferably, the holding time for the melting treatment is 5 to 10 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] This invention uses a melting method to prepare rounded polyhedral strontium titanate single crystal particles. The melting temperature affects the rounded radius of the single crystal particles. If the melting temperature is too high or too low, the rounded radius will decrease.

[0025] In a second aspect, the present invention provides a rounded polyhedral strontium titanate single crystal particle, wherein the rounded polyhedral strontium titanate single crystal particle is obtained by the preparation method described in any one of claims 1-4.

[0026] Preferably, the average particle size of the rounded polyhedral strontium titanate single crystal particles is 100~1000nm, for example, it can be 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the exposed crystal faces of the rounded polyhedral strontium titanate single crystal particles include (100) crystal face, (110) crystal face, and (112) crystal face.

[0028] The rounded-corner polyhedral strontium titanate single crystal particles of this invention have a 26-hexahedron structure. Unlike other polyhedral particles, the (110) and (111) faces of the rounded-corner polyhedron do not have a clear boundary. This boundary exhibits the characteristics of a new crystal face (i.e., the (112) crystal face). The crystal face of the rounded-corner polyhedral strontium titanate single crystal particles of this invention can be regarded as a fusion of (100), (110), and (112) rounded-corner crystal faces. The rounded corners of these particles are more likely to support co-catalysts, and test data proves that these catalytic particles have higher photocatalytic performance.

[0029] Thirdly, the present invention provides a strontium titanate catalyst, the strontium titanate catalyst comprising the rounded polyhedral strontium titanate single crystal particles provided in the second aspect, and a co-catalyst deposited on the surface of the rounded polyhedral strontium titanate single crystal particles;

[0030] The co-catalysts include Rh, Cr, and Co.

[0031] As a preferred embodiment of the present invention, the method for preparing the strontium titanate catalyst includes:

[0032] The strontium titanate single crystal particles with rounded corners were photo-deposited with h atoms, Cr atoms and Co atoms in a single photodeposition using Rh source, Cr source and Co source to complete the deposition of the co-catalyst; after water bath drying, they were calcined to obtain the strontium titanate catalyst.

[0033] As a preferred embodiment of the present invention, the concentrations of the Rh source, Cr source and Co source are all 2~4 mg / mL, for example, 2 mg / mL, 2.4 mg / mL, 2.8 mg / mL, 3.2 mg / mL, 3.6 mg / mL or 4 mg / mL, etc., but are not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0034] Preferably, the solid-liquid ratio of the rounded-corner polyhedral strontium titanate single crystal particles and the Rh source is 1g:100~500μL, for example, it can be 1g:100μL, 1g:200μL, 1g:300μL, 1g:400μL or 1g:500μL, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the Rh source includes RhCl3.

[0036] Preferably, the solid-liquid ratio of the rounded-corner polyhedral strontium titanate single crystal particles and the Cr source is 1g:100~200μL, for example, it can be 1g:100μL, 1g:120μL, 1g:140μL, 1g:160μL, 1g:180μL or 1g:200μL, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the Cr source includes K2CrO4.

[0038] Preferably, the solid-liquid ratio of the rounded-corner polyhedral strontium titanate single crystal particles and the Co source is 1g:100~200μL, for example, it can be 1g:100μL, 1g:120μL, 1g:140μL, 1g:160μL, 1g:180μL or 1g:200μL, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, the Co source includes Co(NO3)2.

[0040] Preferably, the power of the xenon lamp used for photodeposition is 280~320W, for example, it can be 280W, 290W, 300W, 310W or 320W, but is not limited to the listed values. Other values ​​not listed within the value range are also applicable.

[0041] Preferably, the photodeposition time for each time is 5 to 10 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, the calcination temperature is 350~550℃, for example, it can be 350℃, 390℃, 430℃, 470℃, 510℃ or 550℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Preferably, the calcination time is 1 to 2 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours or 2 hours, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The strontium titanate single crystal particles provided by the present invention are icosahedral structures with rounded corners, having (100), (110) and (112) fused rounded corner crystal faces; the rounded corners of the particles are more likely to be loaded with co-catalysts, so that the catalytic particles have higher photocatalytic performance;

[0047] (2) The strontium titanate catalyst provided by the present invention can achieve a photocatalytic hydrogen production efficiency of more than 12 mmol / hg under the simulated sunlight irradiation condition of a 300W full-band xenon lamp;

[0048] (3) The preparation method of the strontium titanate catalyst provided by the present invention has a clear principle, a simple process, readily available raw materials, stable particle morphology control, and is applicable to high-density light irradiation and long-term use scenarios. Attached Figure Description

[0049] Figure 1 Electron microscope image of the rounded polyhedral strontium titanate single crystal particles provided in Embodiment 1 of the present invention, with a scale bar of 1 μm;

[0050] Figure 2 Electron microscope image of the rounded polyhedral strontium titanate single crystal particles provided in Embodiment 1 of the present invention, with a scale bar of 500 nm;

[0051] Figure 3 This is a schematic diagram of the crystal plane distribution of the rounded polyhedral strontium titanate single crystal particles provided in Embodiment 1 of the present invention. Detailed Implementation

[0052] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0053] The raw materials used in the following examples and comparative examples are all commercially available products.

[0054] Example 1

[0055] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle, the scanning electron microscope image of which is shown below. Figure 1 and Figure 2 As shown in the diagram, the crystal plane distribution is as follows: Figure 3 As shown in the figure, the rounded polyhedral strontium titanate single crystal provided in this embodiment has (100) crystal plane, (110) crystal plane and (112) crystal plane morphology, and its average particle size is 100 nm.

[0056] The preparation method of the rounded-corner polyhedral strontium titanate single crystal particles includes the following steps:

[0057] S1. Strontium titanate, aluminum source (alumina), cerium source (cerium oxide) and flux (strontium chloride) are mixed to obtain a mixture.

[0058] The strontium titanate has a purity of 99.5% and an average particle size of 100 nm; the aluminum source has an average particle size of 100 nm.

[0059] The molar ratio of strontium titanate to flux is 1:4; the content of aluminum source in the mixture is 0.3 wt%, and the content of cerium source is 0.5 wt%.

[0060] S2. After melting the mixture, it is sequentially cooled, washed and dried to obtain the rounded polyhedral strontium titanate single crystal particles.

[0061] The melting treatment temperature is 1000℃, and the holding time is 8h.

[0062] This embodiment also provides a strontium titanate catalyst, which comprises the above-mentioned rounded polyhedral strontium titanate single crystal particles and a co-catalyst deposited on the surface of the rounded polyhedral strontium titanate single crystal particles;

[0063] The preparation method of the strontium titanate catalyst includes:

[0064] (1) Disperse 0.1g of the above strontium titanate single crystal particles in 100mL of distilled water, and after ultrasonic dispersion, add 30μL of RuCl3 solution with a concentration of 3mg / mL, and then irradiate with a 300W xenon lamp for 8min (with magnetic stirring).

[0065] Add 15 μL of K2CrO4 solution with a concentration of 2 mg / mL, and then irradiate with a 280 W xenon lamp in full arc for 10 min (with magnetic stirring).

[0066] Add 15 μL of a 4 mg / mL Co(NO3)2 solution, and then irradiate with a 320 W xenon lamp in full arc for 5 min (with magnetic stirring).

[0067] Heat in a water bath until the mixture is dry;

[0068] (2) The catalyst was calcined in air at 450°C for 1.5 h to obtain the strontium titanate catalyst.

[0069] Example 2

[0070] This embodiment provides a rounded polyhedral strontium titanate single crystal particle, which has (100) crystal plane, (110) crystal plane and (112) crystal plane morphology, and its average particle size is 500 nm.

[0071] The preparation method of the rounded-corner polyhedral strontium titanate single crystal particles includes the following steps:

[0072] S1. Strontium titanate, aluminum source (aluminum hydroxide), cerium source (cerium chloride) and flux (strontium chloride) are mixed to obtain a mixture.

[0073] The strontium titanate has a purity of 99.99% and an average particle size of 500 nm; the aluminum source has an average particle size of 100 nm.

[0074] The molar ratio of strontium titanate to flux is 1:3; the content of aluminum source in the mixture is 0.1 wt%, and the content of cerium source is 1 wt%.

[0075] S2. After melting the mixture, it is sequentially cooled, washed and dried to obtain the rounded polyhedral strontium titanate single crystal particles.

[0076] The melting treatment temperature is 900℃, and the holding time is 10h.

[0077] This embodiment also provides a strontium titanate catalyst, which comprises the above-mentioned rounded polyhedral strontium titanate single crystal particles and a co-catalyst deposited on the surface of the rounded polyhedral strontium titanate single crystal particles;

[0078] The preparation method of the strontium titanate catalyst includes:

[0079] (1) Disperse 0.1g of the above strontium titanate single crystal particles in 100mL of distilled water, and after ultrasonic dispersion, add 50μL of RuCl3 solution with a concentration of 2mg / mL, and then irradiate with a 280W xenon lamp for 10min (with magnetic stirring).

[0080] Add 10 μL of K2CrO4 solution with a concentration of 4 mg / mL, and then irradiate with a 290 W xenon lamp in full arc for 6 min (with magnetic stirring).

[0081] Add 10 μL of a 2 mg / mL Co(NO3)2 solution, and then irradiate with a 320 W xenon lamp in full arc for 10 min (with magnetic stirring).

[0082] Heat in a water bath until the mixture is dry;

[0083] (2) The catalyst was calcined in air at 350°C for 2 hours to obtain the strontium titanate catalyst.

[0084] Example 3

[0085] This embodiment provides a rounded polyhedral strontium titanate single crystal particle, which simultaneously has (100) crystal plane, (110) crystal plane and (112) crystal plane morphology, and its average particle size is 1000 nm.

[0086] The preparation method of the rounded-corner polyhedral strontium titanate single crystal particles includes the following steps:

[0087] S1. Strontium titanate, aluminum source, cerium source and flux are mixed to obtain a mixture;

[0088] The strontium titanate has a purity of 99% and an average particle size of 2000 nm; the aluminum source has an average particle size of 100 nm.

[0089] The molar ratio of strontium titanate to flux is 1:8; the content of aluminum source in the mixture is 0.5 wt%, and the content of cerium source is 0.1 wt%.

[0090] S2. After melting the mixture, it is sequentially cooled, washed and dried to obtain the rounded polyhedral strontium titanate single crystal particles.

[0091] The melting treatment temperature is 1100℃, and the holding time is 5h.

[0092] This embodiment also provides a strontium titanate catalyst, which comprises the above-mentioned rounded polyhedral strontium titanate single crystal particles and a co-catalyst deposited on the surface of the rounded polyhedral strontium titanate single crystal particles;

[0093] The preparation method of the strontium titanate catalyst includes:

[0094] (1) Disperse 0.1g of the above strontium titanate single crystal particles in 100mL of distilled water, and after ultrasonic dispersion, add 50μL of RuCl3 solution with a concentration of 2mg / mL, and then irradiate with a 300W xenon lamp for 10min (with magnetic stirring).

[0095] Add 20 μL of K2CrO4 solution with a concentration of 2 mg / mL, and then irradiate with a 290 W xenon lamp in full arc for 9 min (with magnetic stirring).

[0096] Add 20 μL of a 2 mg / mL Co(NO3)2 solution, and then irradiate with a 310 W xenon lamp in full arc for 7 min (with magnetic stirring).

[0097] Heat in a water bath until the mixture is dry;

[0098] (2) The catalyst was calcined in air at 550°C for 1 hour to obtain the strontium titanate catalyst.

[0099] Example 4

[0100] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0101] In this embodiment, the average particle size of the strontium titanate is adjusted to 50 nm.

[0102] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0103] Example 5

[0104] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0105] In this embodiment, the average particle size of the strontium titanate is adjusted to 10 μm.

[0106] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0107] Example 6

[0108] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0109] In this embodiment, the molar ratio of strontium titanate to flux is adjusted to 1:10.

[0110] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0111] Example 7

[0112] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0113] In this embodiment, the molar ratio of strontium titanate to flux is adjusted to 1:1.

[0114] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0115] Example 8

[0116] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0117] In this embodiment, the aluminum source content in the mixture is adjusted to 0.8 wt%.

[0118] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0119] Example 9

[0120] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0121] In this embodiment, the aluminum source content in the mixture is adjusted to 0.05 wt%.

[0122] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0123] Example 10

[0124] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0125] In this embodiment, the average particle size of the aluminum source in the mixture is adjusted to 5 nm.

[0126] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0127] Example 11

[0128] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0129] In this embodiment, the average particle size of the aluminum source in the mixture is adjusted to 1000 nm.

[0130] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0131] Example 12

[0132] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0133] In this embodiment, the temperature of the melting process is adjusted to 800°C.

[0134] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0135] Example 13

[0136] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0137] In this embodiment, the temperature of the melting process is adjusted to 1150°C.

[0138] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0139] Example 14

[0140] This embodiment provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:

[0141] In this embodiment, strontium chloride is replaced with an equal amount of sodium chloride.

[0142] The preparation method of the strontium titanate catalyst is the same as that in Example 1.

[0143] Comparative Example 1

[0144] This comparative example provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Example 1 only in that:

[0145] The mixing of the cerium source is omitted in this comparative example.

[0146] Comparative Example 2

[0147] This comparative example provides a rounded-corner polyhedral strontium titanate single crystal particle. The preparation method of the rounded-corner polyhedral strontium titanate single crystal particle differs from that of Example 1 only in that:

[0148] The mixing of the aluminum source is omitted in this comparative example.

[0149] 0.1 g of strontium titanate catalyst prepared in the above examples and comparative examples was added to 70 mL of deionized water. The reactor was stirred at 120 r / min and evacuated to a vacuum. It was then irradiated with a xenon lamp (300 W, full arc). 1 mL of gas was extracted every half hour, and the hydrogen content was detected using a gas chromatograph. The hydrogen generation rate was tested under illumination, and the results are shown in Table 1.

[0150] Table 1

[0151]

[0152] According to Table 1, the following points can be observed:

[0153] (1) Comprehensive analysis of Examples 1-3 shows that the strontium titanate single crystal particles provided by the present invention have an obvious rounded corner icosahedral structure and a large rounded corner radius, which is more conducive to the deposition of different co-catalysts and has a stronger anisotropic effect on photoelectrons.

[0154] (2) Comprehensive analysis of Examples 1 and 4-7 shows that the selection of strontium titanate during the preparation of the rounded polyhedral strontium titanate single crystal particles will affect the radius of the rounded corners of the single crystal particles;

[0155] If the amount of strontium titanate is too high, it will lead to a decrease in the radius of the fillet, a smaller area (112) and lattice defects. If the amount is too low, it will lead to a decrease in the radius of the fillet, a smaller crystal plane (112) and surface protrusions.

[0156] If the average particle size of the strontium titanate is too low or too high, it will lead to a decrease in the radius of the rounded corners and a decrease in the crystal plane (112).

[0157] (3) Comprehensive analysis of Examples 1 and 8-11 shows that the selection of aluminum source during the preparation of the rounded polyhedral strontium titanate single crystal particles will affect the morphology of the single crystal particles and thus affect the catalytic effect of the catalyst.

[0158] If the amount of aluminum source used is too high, it will cause the particle surface to bulge; if the amount used is too low, it will cause the lattice defects to be uncompensated.

[0159] If the average particle size of the aluminum source is too low, the (112) crystal plane will be slightly reduced; if the average particle size is too high, the lattice defects of strontium titanate cannot be completely compensated.

[0160] (4) Comprehensive analysis of Examples 1 and 12-13 shows that the melting temperature during the preparation of the rounded polyhedral strontium titanate single crystal particles will affect the radius of the rounded corners of the single crystal particles; if the temperature is too high, the rounded corner morphology will be irregular, and if the temperature is too low, the crystallization will not be effective and lattice defects will appear on the surface.

[0161] (5) A comprehensive analysis of Examples 1 and 14 shows that, compared with strontium chloride, using sodium chloride as a flux leads to more lattice defects;

[0162] (6) A comprehensive analysis of Example 1 and Comparative Example 1 shows that omitting the cerium source will result in a reduction in the radius of the rounded corners, and (112) the area will be significantly reduced;

[0163] (7) Comprehensive analysis of Example 1 and Comparative Example 2 shows that omitting the aluminum source will result in irregular (112) crystal planes and too many lattice defects.

[0164] In summary, by adjusting the process parameters such as the particle size and dosage of aluminum source and strontium titanate, and coordinating the melting temperature, the resulting single crystal particles have a larger radius of rounded corners. By controlling the dosage of aluminum source and cerium source to control the area of ​​the rounded corner (112) crystal face, the exposed crystal face is further increased, so that the strontium titanate catalyst has a more excellent photocatalytic water splitting hydrogen production efficiency.

[0165] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing rounded-corner polyhedral strontium titanate single crystal particles, characterized in that, The preparation method includes: mixing strontium titanate, aluminum source, cerium source and flux to obtain a mixture; After the mixture is melted, it is cooled, washed and dried in sequence to obtain the rounded polyhedral strontium titanate single crystal particles.

2. The preparation method according to claim 1, characterized in that, The purity of the strontium titanate is 99~99.99%; Preferably, the average particle size of the strontium titanate is 100~5000 nm; Preferably, the aluminum source includes aluminum oxide and / or aluminum hydroxide; Preferably, the average particle size of the aluminum source is 10~500 nm; Preferably, the cerium source includes cerium oxide and / or cerium chloride; Preferably, the flux includes strontium chloride.

3. The preparation method according to claim 2, characterized in that, The molar ratio of strontium titanate to flux is 1:3~8; Preferably, the aluminum source content in the mixture is 0.1~0.5 wt%; Preferably, the content of cerium source in the mixture is 0.1~1wt%.

4. The preparation method according to any one of claims 1-3, characterized in that, The melting treatment temperature is 900~1100℃; Preferably, the holding time for the melting treatment is 5 to 10 hours.

5. A rounded-corner polyhedral strontium titanate single crystal particle, characterized in that, The rounded polyhedral strontium titanate single crystal particles are obtained by the preparation method described in any one of claims 1-4.

6. The rounded-corner polyhedral strontium titanate single crystal particles according to claim 5, characterized in that, The average particle size of the rounded polyhedral strontium titanate single crystal particles is 100~1000 nm; Preferably, the exposed crystal faces of the rounded polyhedral strontium titanate single crystal particles include (100) crystal face, (110) crystal face, and (112) crystal face.

7. A strontium titanate catalyst, characterized in that, The strontium titanate catalyst includes the rounded polyhedral strontium titanate single crystal particles as described in claim 5 or 6, and a co-catalyst deposited on the surface of the rounded polyhedral strontium titanate single crystal particles. The co-catalysts include Rh, Cr, and Co.

8. The strontium titanate catalyst according to claim 7, characterized in that, The preparation method of the strontium titanate catalyst includes: The strontium titanate single crystal particles with rounded corners were photo-deposited with h atoms, Cr atoms and Co atoms in a single photodeposition using Rh source, Cr source and Co source to complete the deposition of the co-catalyst; after water bath drying, they were calcined to obtain the strontium titanate catalyst.

9. The strontium titanate catalyst according to claim 8, characterized in that, The concentrations of the Rh source, Cr source, and Co source were all 2-4 mg / mL; Preferably, the solid-liquid ratio of the rounded-corner polyhedral strontium titanate single crystal particles to the Rh source is 1g:100~500μL; Preferably, the solid-liquid ratio of the rounded-corner polyhedral strontium titanate single crystal particles and the Cr source is 1g:100~200μL; Preferably, the solid-liquid ratio of the rounded-corner polyhedral strontium titanate single crystal particles to the Co source is 1g:100~200μL; Preferably, the power of the xenon lamp used for photodeposition is 280~320W; Preferably, the photodeposition time for each step is 5 to 10 minutes.

10. The strontium titanate catalyst according to claim 8, characterized in that, The calcination temperature is 350~550℃; Preferably, the calcination time is 1 to 2 hours.

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