Method for constructing a hydrophilic network modified strontium titanate photocatalyst and application thereof

Abstract

The application relates to a method for constructing a hydrophilic network modified strontium titanate photocatalyst, which adopts nanoscale SrTiO3 powder as a base material, adopts phytic acid with a volume concentration of 50% to 90% as a surface hydrophilic modification solution, immerses the nanoscale SrTiO3 powder in the phytic acid solution, immerses for 2 to 48 hours at room temperature, then adds one or more nitrate solutions as coordination metal ions, immerses for 2 to 48 hours at room temperature, and the surface hydrophilic network modified SrTiO3 photocatalyst is obtained after filtration, washing and drying. Meanwhile, the application also discloses application of the surface hydrophilic network modified SrTiO3 photocatalyst in a photocatalytic overall water reaction. The application has the advantages of simple operation and low cost, and the obtained SrTiO3 photocatalyst can realize efficient H2 and O2 output and good cycle stability in a photocatalytic overall water reaction.

Description

Technical Field

[0001] This invention relates to the field of inorganic nanomaterial preparation technology, and in particular to a method for constructing a hydrophilic network modified strontium titanate (SrTiO3) photocatalyst and its application. Background Technology

[0002] Hydrogen energy is hailed as an ideal energy form that combines cleanliness, efficiency, safety, and sustainability. Among various hydrogen production technologies, solar-driven water splitting based on particulate photocatalysts is considered the most promising approach due to its economic viability. In recent years, strontium titanate (SrTiO3) has become a research hotspot in this field due to its unique structure and excellent physicochemical properties. Research on SrTiO3 has gradually focused on utilizing its chemical tailoring flexibility to conduct defect engineering design, thereby improving its photocatalytic water splitting performance.

[0003] The core of photocatalytic water splitting lies in the reaction efficiency at the solid-liquid interface, and the surface hydrophilicity of the catalyst directly determines the accessibility of water molecules to active sites and the interfacial reaction kinetics. For SrTiO3, a typical wide-bandgap photocatalyst, its intrinsic surface hydrophilicity is limited, making it prone to particle aggregation in aqueous reaction systems due to hydrophobic interactions. This leads to a reduction in effective active area and light scattering loss, severely restricting its photocatalytic performance. Constructing a hydrophilic surface layer can significantly improve the catalyst's dispersion stability in water, ensuring each particle is fully dispersed and exposed to the reaction solution, maximizing the utilization of the catalyst's specific surface area and light absorption capacity. Furthermore, the hydrophilic surface environment facilitates the adsorption and activation of water molecules at active sites, promoting the rapid migration of photogenerated holes to the surface and their participation in water oxidation, thereby inhibiting bulk charge recombination and enhancing photocatalytic activity. Therefore, without altering the intrinsic band structure of SrTiO3, optimizing the solid-liquid interface microenvironment through surface hydrophilic modification is an effective way to unlock its potential for photocatalytic water splitting.

[0004] Traditional SrTiO3 modification strategies mainly focus on elemental doping, such as cobalt doping (CN121911421A), scandium doping (CN121911391A), nickel-cobalt bimetallic co-doping (CN118904346A), and tantalum-aluminum bimetallic co-doping (CN117401970A). Although these methods can expand the photoresponse range or promote charge separation to some extent, they generally have limitations such as complicated operation steps, high-temperature heat treatment, high equipment requirements, and high cost of precious metals. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a simple and low-cost method for constructing a hydrophilic network modified strontium titanate photocatalyst.

[0006] Another technical problem to be solved by the present invention is to provide the application of the hydrophilic network modified strontium titanate photocatalyst.

[0007] To address the aforementioned problems, the present invention provides a method for constructing a hydrophilic network modified strontium titanate photocatalyst, characterized in that: nano-sized SrTiO3 powder is used as the substrate material, and phytic acid with a volume concentration of 50%~90% is used as the surface hydrophilic modification solution. The nano-sized SrTiO3 powder is impregnated in the phytic acid solution at room temperature for 2~48 hours; then one or more nitrate solutions are added as coordinating metal ions, and the mixture is impregnated again at room temperature for 2~48 hours. After filtration, washing, and drying, the surface hydrophilic network modified SrTiO3 photocatalyst is obtained.

[0008] The volume concentrations of the phytic acid solutions were 50%, 70%, and 90%, respectively.

[0009] The solid-liquid mass ratio of the nano-sized SrTiO3 powder to the phytic acid solution is 1:1 to 1:10.

[0010] The nitrate solution refers to one or more of the following: nickel nitrate aqueous solution, cobalt nitrate aqueous solution, or ferric nitrate aqueous solution.

[0011] The molar percentage of the nitrate solution to the phytic acid solution is 25% to 100%.

[0012] The molar percentages of the nitrate solution and the phytic acid solution are 25%, 50%, 75%, and 100%.

[0013] The drying conditions refer to a temperature of 40~60℃ and a time of 6~24h.

[0014] A surface hydrophilic network modified SrTiO3 photocatalyst was constructed using the method described above.

[0015] The application of a surface hydrophilic network modified SrTiO3 photocatalyst as described above in photocatalytic all-water reaction.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention utilizes the bonding between phytic acid phosphonate groups and hydroxyl groups on the surface of SrTiO3, as well as the coordination crosslinking reaction between phytic acid and metal ions, to construct a three-dimensional hydrophilic network structure in situ on the surface of SrTiO3. Compared with traditional methods that require high temperatures for noble metal loading or doping modification, this invention is simple to operate and operates under mild conditions, involving only room temperature liquid phase impregnation and coordination self-assembly, and modification can be achieved at room temperature.

[0017] 2. The impregnation modification process of this invention does not require complex equipment or harsh reaction conditions, is low in cost, and is suitable for large-scale production.

[0018] 3. The modification route of this invention significantly improves the hydrophilicity of SrTiO3 photocatalyst by adjusting parameters such as phytic acid concentration, solid-liquid ratio, type and ratio of coordinating ions, impregnation time and drying temperature, thereby achieving efficient H2 and O2 production and good cycle stability in the photocatalytic water splitting process.

[0019] 4. Compared with the traditional photocatalytic water splitting process that requires a supported catalyst, the modification strategy of this invention can achieve efficient photocatalytic water splitting without a supported catalyst.

[0020] 5. The modification strategy of this invention does not change the intrinsic crystal phase structure and light absorption characteristics of SrTiO3, but improves the interfacial properties of the material through physicochemical surface engineering. Therefore, it can be used in conjunction with bulk phase modification methods such as doping, providing a more flexible control space for the performance optimization of photocatalysts. Attached Figure Description

[0021] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0022] Figure 1 The XRD patterns are of the SrTiO3 photocatalysts obtained in Comparative Example 1, Example 1 and Example 2 of this invention.

[0023] Figure 2 The graph shows the photocatalytic hydrogen production at different time points for Comparative Example 1, Example 1, and Example 2 of the present invention.

[0024] Figure 3 The graph shows the photocatalytic hydrogen production rate of Comparative Example 1, Example 1, and Example 2 of this invention.

[0025] Figure 4 This is a cycle stability diagram of the photocatalytic hydrogen production rate in Example 2 of the present invention. Detailed Implementation

[0026] A method for constructing a hydrophilic network modified strontium titanate photocatalyst: Nanoscale SrTiO3 powder is used as the substrate material, which is untreated. Phytic acid with a volume concentration of 50% to 90% is used as the surface hydrophilic modification solution, and the volume concentration of the phytic acid solution is preferably 50%, 70%, and 90%.

[0027] Nanoscale SrTiO3 powder is impregnated in phytic acid solution at a solid-liquid mass ratio (g / g) of 1:1 to 1:10. Impregnation is carried out at room temperature for 2–48 h, allowing a layer of hydrophilic hydroxyl groups to adsorb onto the SrTiO3 surface. Then, one or more nitrate solutions are added as coordinating metal ions, with the molar percentage of nitrate solution to phytic acid solution being 25%–100%, preferably 25%, 50%, 75%, and 100%. The nitrate solution refers to one or more of nickel nitrate aqueous solution, cobalt nitrate aqueous solution, or ferric nitrate aqueous solution. Impregnation is then continued at room temperature for 2–48 h. Through the coordination self-assembly of phytic acid and metal ions, a three-dimensional hydrophilic network structure is further constructed on the SrTiO3 surface. After filtration and washing with anhydrous ethanol, the surface is dried at 40–60 °C for 6–24 h to obtain the surface-modified hydrophilic network SrTiO3 photocatalyst.

[0028] The above-mentioned surface hydrophilic network modified SrTiO3 photocatalyst can be applied in photocatalytic all-water reactions.

[0029] Take Ni 2+ Taking metal ligand ions as an example, the principle of successful modification in this invention will be briefly described.

[0030] Because SrTiO3 has a certain number of hydroxyl groups (-OH), and the phosphate groups (-PO4) in phytic acid molecules contain a large number of -OH and oxygen atoms, they can form hydrogen bonds or coordinate bonds with the -OH or metal atoms (Sr or Ti) on the SrTiO3 surface. Through this chemical interaction, phytic acid molecules are firmly anchored to the SrTiO3 surface. When the SrTiO3 anchored with phytic acid molecules reacts with metal ions (such as Fe), 3 + Co 2+ Ni 2+ After mixing with the solution, the phytic acid molecules, containing six phosphate groups with strong chelating ability, firmly bind to the metal ions, initiating in-situ coordination self-assembly on the material surface, ultimately constructing a stable, robust, and highly hydrophilic three-dimensional network structure. By constructing a hydrophilic network, it is possible to effectively ensure that water molecules can diffuse rapidly and fully to the active sites on the catalyst surface, increasing the contact frequency between the reactants (water molecules) and the catalyst, thereby enhancing the overall total water splitting rate.

[0031] Example 1 Using 5g of 50% phytic acid solution as the modification solution, 1g of nano-sized SrTiO3 powder was added to the phytic acid solution and impregnated at room temperature for 24 h. After filtration, it was washed three times with anhydrous ethanol solution and dried at 40℃ for 12 h to obtain the surface-modified hydrophilic SrTiO3 photocatalyst.

[0032] Example 2 Compared with Example 1, this embodiment adds metal coordination ions.

[0033] Using 5g of 50% phytic acid solution as the modification solution, 1g of nano-sized SrTiO3 powder was added to the phytic acid solution and impregnated at room temperature for 24 h. Then, nickel nitrate solution was added, and the molar percentage of nickel nitrate solution to phytic acid solution was 50%. The mixture was then impregnated at room temperature for another 24 h. After filtration, the mixture was washed three times with anhydrous ethanol solution and dried at 40℃ for 12 h to obtain the surface hydrophilic network modified SrTiO3 photocatalyst.

[0034] Example 3 Using 1g of 70% phytic acid solution as the modification solution, 1g of nano-sized SrTiO3 powder was added to the phytic acid solution and impregnated at room temperature for 2 h. Then, cobalt nitrate solution was added, and the molar percentage of cobalt nitrate solution to phytic acid solution was 25%. The mixture was then impregnated at room temperature for another 2 h. After filtration, the mixture was washed three times with anhydrous ethanol solution and dried at 60℃ for 6 h to obtain the surface hydrophilic network modified SrTiO3 photocatalyst.

[0035] Example 4 Using 10g of 50% phytic acid solution as the modification solution, 1g of nano-sized SrTiO3 powder was added to the phytic acid solution and impregnated at room temperature for 48 h. Then, ferric nitrate solution was added, and the molar percentage of ferric nitrate solution to phytic acid solution was 75%. The mixture was then impregnated at room temperature for another 48 h. After filtration, the mixture was washed three times with anhydrous ethanol solution and dried at 50℃ for 24 h to obtain the surface hydrophilic network modified SrTiO3 photocatalyst.

[0036] Example 5 Using 10g of a 50% (v / v) phytic acid solution as the modification solution, 1g of nano-sized SrTiO3 powder was added to the phytic acid solution and impregnated at room temperature for 48 h. Then, a mixed nitrate solution was added, ensuring that the molar percentage of the mixed nitrate solution to the phytic acid solution was 100%. The mixed nitrate solution was a mixture of nickel nitrate solution and ferric nitrate solution in a molar ratio of 1:1. Impregnation was continued at room temperature for another 48 h. After filtration, the sample was washed three times with anhydrous ethanol solution and dried at 40℃ for 12 h to obtain the surface hydrophilic network modified SrTiO3 photocatalyst.

[0037] Comparative Example 1 It is an untreated nanoscale SrTiO3 powder molecular sieve.

[0038] Characterization and Performance Testing XRD tests were performed on the SrTiO3 photocatalysts obtained in Comparative Example 1, Example 1, and Example 2, respectively. The results are as follows: Figure 1As shown in the figure, the characteristic diffraction peaks at 22.78°, 32.42°, 39.98°, 46.48°, 57.79°, and 67.80° correspond to the (100), (110), (111), (200), (211), and (220) crystal planes of cubic SrTiO3 (PDF#84-0443). It can be seen from the figure that all XRD patterns exhibit very similar characteristics, which means that the surface hydrophilic modification did not change the structure of SrTiO3.

[0039] The photocatalytic performance of the SrTiO3 photocatalysts obtained in Comparative Example 1, Example 1, and Example 2 was tested: 100 mg of SrTiO3 photocatalyst powder obtained in Comparative Example 1, Example 1, and Example 2 were weighed, added to 100 mL of deionized water, placed in a quartz glass bottle, and ultrasonically dispersed evenly. After purging with argon gas for 20 min, the mixture was continuously stirred on a magnetic stirrer and a xenon lamp light source (with light intensity controlled at 100 mW / cm²) was used. 2 Irradiation was performed, and 0.5 mL of gas was extracted using a syringe every 30 minutes. The H2 and O2 yields in the glass vial were measured using gas chromatography. The results are as follows: Figures 2-3 As shown.

[0040] Figure 2 The trends of hydrogen production over time are shown in Comparative Example 1, Example 1, and Example 2. The results show that the hydrogen production is improved to a certain extent after hydrophilic modification of the phytic acid surface. On this basis, the addition of metal ions to coordinate with phytic acid significantly increases the hydrogen production, approximately 8.6 times the previous amount. This indicates that the hydrophilic network formed by the coordination of phytic acid and metal ions can further enhance the hydrophilicity of SrTiO3, which is beneficial to the adsorption and activation of water molecules at the active sites. Figure 3 The hydrogen production rates of Comparative Example 1, Example 1 and Example 2 are shown. It can be seen that the hydrogen production rates of H2 and O2 are close to 2:1, which falls within the category of photocatalytic water splitting. It can also be seen from the hydrogen production rate that the formation of a hydrophilic network by metal ions and phytic acid can significantly improve the performance of photocatalytic water splitting.

[0041] Photocatalytic stability testing was conducted on Example 2. After one round of performance testing, argon gas was purged for 20 min, and stirring continued on a magnetic stirrer while maintaining constant light intensity, stirring rate, and sampling time. The yields of H2 and O2 in the glass vial were measured using gas chromatography. Subsequent stability tests were performed using the same procedure, and the results are as follows. Figure 4 As shown in the figure, the hydrophilically modified SrTiO3 exhibits good cycling stability, with no significant decrease in adsorption performance after five cycles.

[0042] In summary, surface hydrophilic network modification offers advantages over traditional doping modification methods in terms of ease of operation and wide applicability. Phytic acid and its hydrophilic network significantly enhance its hydrophilicity, thereby improving the photocatalytic water splitting performance. Furthermore, this process does not rely on precious metal catalysts, effectively reducing the cost of photocatalytic water splitting.

[0043] Although the present invention has been described herein with reference to illustrative embodiments, the above embodiments are merely preferred embodiments of the present invention, and the implementation of the present invention is not limited to the above embodiments. It should be understood that those skilled in the art can devise many other modifications and implementations, which will fall within the scope and spirit of the principles disclosed in this application.

Claims

1. A method for constructing a hydrophilic network modified strontium titanate photocatalyst, characterized in that: Nanoscale SrTiO3 powder was used as the substrate material, and phytic acid with a volume concentration of 50%~90% was used as the surface hydrophilic modification solution. The nanoscale SrTiO3 powder was impregnated in the phytic acid solution at room temperature for 2~48h. Then, one or more nitrate solutions were added as coordinating metal ions, and the powder was impregnated at room temperature for another 2~48h. After filtration, washing and drying, the surface hydrophilic network modified SrTiO3 photocatalyst was obtained.

2. The method for constructing a hydrophilic network modified strontium titanate photocatalyst as described in claim 1, characterized in that: The volume concentrations of the phytic acid solutions were 50%, 70%, and 90%, respectively.

3. The method for constructing a hydrophilic network modified strontium titanate photocatalyst as described in claim 1, characterized in that: The solid-liquid mass ratio of the nano-sized SrTiO3 powder to the phytic acid solution is 1:1 to 1:

10.

4. The method for constructing a hydrophilic network modified strontium titanate photocatalyst as described in claim 1, characterized in that: The nitrate solution refers to one or more of the following: nickel nitrate aqueous solution, cobalt nitrate aqueous solution, or ferric nitrate aqueous solution.

5. The method for constructing a hydrophilic network modified strontium titanate photocatalyst as described in claim 1, characterized in that: The molar percentage of the nitrate solution to the phytic acid solution is 25% to 100%.

6. The method for constructing a hydrophilic network modified strontium titanate photocatalyst as described in claim 5, characterized in that: The molar percentages of the nitrate solution and the phytic acid solution are 25%, 50%, 75%, and 100%.

7. The method for constructing a hydrophilic network modified strontium titanate photocatalyst as described in claim 1, characterized in that: The drying conditions refer to a temperature of 40~60℃ and a time of 6~24h.

8. A surface hydrophilic network modified SrTiO3 photocatalyst constructed by the method of any one of claims 1 to 7.

9. The application of the surface hydrophilic network modified SrTiO3 photocatalyst as described in claim 8 in photocatalytic all-water reaction.

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