An R-STO photocatalyst, its preparation method and application

Abstract

This invention relates to an R-STO photocatalyst, its preparation method, and its applications, belonging to the field of photocatalytic materials technology. This invention synthesizes cubic SrTiO3 nanoparticles using a high-temperature molten salt medium. Ascorbic acid is used to reduce graphene oxide attached to the SrTiO3 surface, yielding RGO / SrTiO3 nanoparticles. The final product, named the R-STO photocatalyst, is then obtained using photodeposition. It can be applied in the field of photocatalytic water splitting. Compared to existing photocatalysts, the R-STO photocatalyst of this invention exhibits good controllability and strong stability. Furthermore, the cubic SrTiO3 nanoparticles with their unique morphology effectively suppress photogenerated electron and hole recombination, further improving carrier separation efficiency and enabling simultaneous water splitting for hydrogen and oxygen production. This invention is environmentally friendly, simple in method, convenient to operate, and has low material preparation costs, aligning with the current advocacy of green environmental protection and possessing broad market prospects.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to an R-STO photocatalyst, its preparation method, and its application. Background Technology

[0002] Photocatalytic complete water splitting is an innovative approach aimed at converting solar energy into hydrogen fuel by efficiently splitting water molecules into hydrogen and oxygen. This process typically involves semiconductor materials capable of absorbing sunlight and facilitating the necessary chemical reactions. However, photocatalytic water splitting currently faces several key challenges: the overall efficiency of the photocatalytic process is generally low due to factors such as poor light absorption, carrier recombination, and insufficient reaction kinetics. Many photocatalysts degrade over time under operating conditions, reducing their effectiveness and lifetime. The transition from laboratory-scale systems to large-scale applications remains difficult because the process needs to be both economically feasible and efficient. Achieving high selectivity in hydrogen production can be challenging compared to other reactions, leading to unwanted byproducts. Addressing these issues requires ongoing research into new materials, innovative designs, and improved reaction conditions.

[0003] Strontium titanate, as an important perovskite semiconductor material, has significant application potential in the field of photocatalysis. It shows broad application prospects in photocatalytic water splitting for hydrogen and oxygen production. This invention utilizes a molten salt method to prepare strontium titanate with a distinct cubic phase crystal structure, reducing surface defects inherent in traditional strontium titanate preparations and facilitating the effective separation of photogenerated electron-hole pairs. An R-STO photocatalyst was obtained by surface-loading RGO / SrTiO3 nanoparticles obtained through simultaneous GO reduction, and then loading rhodium, chromium atoms, and cobalt oxide onto the surface of the RGO / SrTiO3 nanoparticles using photodeposition technology. This approach results in higher performance for the material system, and there are no previous reports on the application of R-STO photocatalyst preparation methods in photocatalytic water splitting. Summary of the Invention

[0004] To address the problems in the prior art, this invention provides an R-STO photocatalyst, its preparation method, and its application.

[0005] The technical solution adopted in this invention is as follows:

[0006] An R-STO photocatalyst, the preparation method of which includes the following steps:

[0007] 1) Strontium chloride and SrTiO3 powder were ground and then transferred to a muffle furnace for calcination. After natural cooling, they were washed three times with deionized water and dried to obtain cubic SrTiO3 nanoparticles.

[0008] 2) Add GO solution dropwise to deionized water and add SrTiO3 nanoparticles. After stirring magnetically until homogeneous, add ascorbic acid solution dropwise to the above solution and continue stirring for 0.5 h. Transfer the mixed solution to a hydrothermal reactor lined with polytetrafluoroethylene, place it in an oven for heating, and after natural cooling, wash and dry to obtain RGO / SrTiO3 nanoparticles.

[0009] 3) Disperse RGO / SrTiO3 nanoparticles in a beaker containing 20 mL of deionized water, add sodium hexachlororhodium solution, and deposit rhodium ions on the catalyst surface using photodeposition under simulated sunlight.

[0010] 4) Add chromium nitrate solution nonahydrate to the mixed solution obtained in step 3), and use photodeposition to deposit chromium ions on the catalyst surface under simulated sunlight.

[0011] 5) Add cobalt nitrate hexahydrate solution to the mixed solution obtained in step 4), and use photodeposition to deposit cobalt ions on the catalyst surface under simulated sunlight irradiation.

[0012] 6) The mixed solution obtained in step 5) is filtered, washed and dried to obtain the final product named R-STO photocatalyst.

[0013] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in step 1), the strontium chloride is strontium chloride hexahydrate with a mass of 14.5g, and the SrTiO3 powder is commercially available SrTiO3 with a mass of 1g.

[0014] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in step 1), the calcination temperature is 1100℃ and the time is 10h.

[0015] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in step 2), the concentration of the GO solution is 1 mg / mL, the volume is 100 μL, and the mass of the SrTiO3 nanoparticles is 0.1 g.

[0016] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in step 2), the concentration of the ascorbic acid solution is 3.33 g / L and the volume is 30 mL.

[0017] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in step 2), the heating temperature in the oven is 90°C and the time is 6 hours.

[0018] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in step 3), the mass of the RGO / SrTiO3 nanoparticles is 20 mg, the concentration of the sodium hexachlororhodium solution is 0.59 mg / mL, and the volume is 126 μL.

[0019] Furthermore, in step 4) of the above-mentioned method for preparing an R-STO photocatalyst, the concentration of the chromium nitrate nonahydrate solution is 7.7 mg / mL and the volume is 6 μL.

[0020] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in step 5), the concentration of the cobalt nitrate hexahydrate solution is 2 mg / mL and the volume is 20 μL.

[0021] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in steps 3), 4), and 5), the light source simulating sunlight is a xenon lamp with a power of 148mW ​​and a light intensity.

[0022] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in step 3), the photodeposition time is 10 min.

[0023] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in step 4), the photodeposition time is 5 minutes.

[0024] Furthermore, in the above-mentioned method for preparing an R-STO photocatalyst, in step 5), the photodeposition time is 5 minutes.

[0025] The application of any one of the above-mentioned R-STO photocatalysts in photocatalytic water splitting for hydrogen production and oxygen evolution.

[0026] Furthermore, the above application is carried out as follows: R-STO photocatalyst is uniformly dispersed in 20 mL of deionized water. Argon gas is continuously introduced into the reaction vessel at a rate of 40 mL / min for 10 min. The vessel is then sealed, and photocatalytic decomposition of water to produce hydrogen and oxygen is carried out under the condition of simulated sunlight irradiation by a 300 W xenon lamp light source.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. This invention utilizes the high-temperature molten salt method, hydrothermal synthesis, and photodeposition method to prepare R-STO photocatalysts, which can effectively suppress the recombination efficiency of photogenerated electrons and holes, achieve efficient separation of photogenerated carriers, and exhibit excellent photocatalytic water splitting and hydrogen production under simulated sunlight irradiation.

[0029] 2. The preparation method of the present invention is simple, convenient, low-cost, and mild, which is conducive to large-scale production.

[0030] 3. The R-STO photocatalyst prepared by this invention has good photocatalytic cycle stability. Attached Figure Description

[0031] Figure 1 X-ray diffraction patterns of the SrTiO3 catalyst prepared in Example 1 and the R-STO-2 photocatalyst prepared in Example 3.

[0032] Figure 2 Fourier transform infrared spectra of the SrTiO3 catalyst prepared in Example 1, the R-STO-2 photocatalyst prepared in Example 3, and the RGO nanosheets prepared in Example 4.

[0033] Figure 3 Scanning electron microscope (SEM) images of the SrTiO3 catalyst prepared in Example 1, the R-STO-2 photocatalyst prepared in Example 3, and the RGO nanosheets prepared in Example 4.

[0034] Figure 4 Photoluminescence spectra of the SrTiO3 catalyst prepared in Example 1, the R-STO-2 photocatalyst prepared in Example 3, and the R-STO-1 and R-STO-3 photocatalysts prepared in Example 5.

[0035] Figure 5 Photocatalytic water splitting activity diagrams for the SrTiO3 catalyst prepared in Example 1, the R-STO-2 photocatalyst prepared in Example 3, and the R-STO-1 and R-STO-3 photocatalysts prepared in Example 5. Detailed Implementation

[0036] Example 1

[0037] The preparation method of SrTiO3 nanoparticles is as follows:

[0038] 14.5g of strontium chloride hexahydrate and 1g of commercially available SrTiO3 powder were mixed and ground, then transferred to a muffle furnace and calcined at 1100℃ for 10h. After natural cooling, the mixture was washed three times with deionized water and dried to obtain SrTiO3 nanoparticles.

[0039] Example 2

[0040] The preparation method of GO solution is as follows:

[0041] At 1°C, 1 g of natural graphene was dispersed in 23 mL of H₂SO₄ and stirred for 50 min. Then, 6 g of KMnO₄ was added to the solution at a very slow rate (approximately 25 min). After stirring for 3 h, the mixture was transferred to a 45°C environment and stirred for 45 min to induce bubbling and exothermic reaction. Next, the mixture was placed at 80°C, and 60 mL of distilled water was slowly added dropwise (over 20 min). After stirring for 15 min, 60 mL of distilled water was added to dilute the mixture, and 5 wt% hydrogen peroxide was added. The solution was washed several times by centrifugation with distilled water until the pH of the supernatant was 6, yielding a GO solution. After measuring the concentration of the obtained GO solution, 1 mL of the GO solution was diluted to 1 mg / mL.

[0042] Example 3

[0043] The preparation method of R-STO catalyst is as follows:

[0044] 100 μL of the GO solution prepared in Example 2 (concentration of 1 mg / mL) was added dropwise to 30 mL of deionized water, and 0.1 g of the SrTiO3 nanoparticles prepared in Example 1 were added. After magnetic stirring until homogeneous, 30 mL of ascorbic acid solution (concentration of 3.33 g / L) was added dropwise to the above solution and stirring was continued for 0.5 h. The mixed solution was transferred to a hydrothermal reactor lined with polytetrafluoroethylene and heated in a 90 °C oven for 6 h. After natural cooling, the mixture was washed three times and dried to obtain RGO / SrTiO3 nanoparticles.

[0045] 20 mg of RGO / SrTiO3 nanoparticles were dispersed in a beaker containing 20 mL of deionized water. 126 μL of sodium hexachlororhodium solution (0.59 mg / mL) was added, and photodeposition was performed under a xenon lamp with an intensity of 148 mW for 10 min. Subsequently, 6 μL of chromium nitrate nonahydrate solution (7.7 mg / mL) was added, and photodeposition was performed for 5 min. Then, 20 μL of cobalt nitrate hexahydrate solution (2 mg / mL) was added, and photodeposition was performed for 5 min. Finally, the mixed solution was filtered, washed three times, and dried to obtain the final target product, named R-STO-2.

[0046] Example 4

[0047] 10 mL of the GO solution prepared in Example 2 (concentration 1 mg / mL) was added dropwise to 50 mL of ascorbic acid solution (concentration 200 g / L) and stirred for 0.5 h. The mixture was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and heated in a 90 °C oven for 6 h. After natural cooling, the mixture was washed three times and dried to obtain RGO nanosheets.

[0048] Example 5

[0049] The amount of GO solution used in Example 3 was changed to 50 μL and 150 μL, respectively, while all other operations remained unchanged. The final products were labeled as R-STO-1 and R-STO-3, respectively.

[0050] Figure 1 X-ray diffraction patterns of the SrTiO3 catalyst prepared in Example 1 and the R-STO-2 photocatalyst prepared in Example 3. Figure 1 In the XRD pattern, the characteristic peaks of SrTiO3 are located at 32.4°, 40.1°, 46.6°, 57.9°, 67.9°, and 77.5°, corresponding to the (110), (111), (200), (211), (220), and (310) crystal planes of cubic SrTiO3, respectively. This is completely consistent with the arrangement order of the standard card (PDF.84-0443) for cubic perovskite SrTiO3. No additional characteristic peaks were found in the XRD pattern of the R-STO-2 composite sample, which may be attributed to the fact that the RGO content in the composite sample is less than 1% and cannot be detected. However, in the Fourier transform infrared spectrum (… Figure 2 As can be seen from the image, the absorption peak of the R-STO-2 composite sample corresponds to that of the RGO nanosheets prepared in Example 4, indicating that the R-STO photocatalyst was successfully prepared. Scanning electron microscope (SEM) image (…) Figure 3 The morphology of SrTiO3 nanoparticles is mainly hexahedral, and the hexahedral structure of SrTiO3 can still be clearly seen in the SEM image of the R-STO-2 composite sample. However, upon closer observation, it appears that the surface of the sample is uniformly covered with a layer of RGO. (The photoluminescence spectrum...) Figure 4 As can be seen from the data, the emission peaks of all composite samples are lower than those of SrTiO3, indicating that there is good charge transfer at the interface between SrTiO3 and RGO.

[0051] Example 6

[0052] Application of photocatalysts in the catalytic splitting of water under light:

[0053] Under normal temperature and pressure conditions, 20 mg of the catalyst was placed in a reactor containing 20 mL of distilled water, and argon gas was introduced into the reactor at a rate of 40 mL / min for 10 min to purge air. Under simulated sunlight irradiation conditions using a 300 W xenon lamp light source, 1000 μL of gas was extracted from the reactor at 10 min, 20 min, 30 min, 60 min, 90 min, and 120 min, respectively, and the collected catalytic products were quantitatively analyzed using a gas chromatograph.

[0054] Figure 5The photocatalytic water splitting activity diagrams for the SrTiO3 catalyst prepared in Example 1, the R-STO-2 photocatalyst prepared in Example 3, and the R-STO-1 and R-STO-3 photocatalysts prepared in Example 5 are shown. The peak areas of the extracted gases were measured by gas chromatography, and then the amounts were calculated. Figure 5 As shown, after 1 h, the H2 yield of the SrTiO3 catalyst was 15.9 mmol / g, and the O2 yield was 7.4 mmol / g. The H2 and O2 yields of the composite samples R-STO-1, R-STO-2, and R-STO-3 photocatalysts were 35.8 mmol / g and 16.2 mmol / g, 43.0 mmol / g and 19.4 mmol / g, and 25.1 mmol / g and 9.9 mmol / g, respectively. Among them, the yield of R-STO-2 reached 2.7 times that of the original sample, and the hydrogen evolution and oxygen production rate was higher than that of other related catalysts studied to date.

Claims

1. An R-STO photocatalyst, characterized in that, Its preparation method includes the following steps: 1) Strontium chloride and SrTiO3 powder were ground and then transferred to a muffle furnace for calcination. After natural cooling, they were washed three times with deionized water and dried to obtain cubic SrTiO3 nanoparticles. 2) Add GO solution dropwise to deionized water and add SrTiO3 nanoparticles. After stirring magnetically until homogeneous, add ascorbic acid solution dropwise to the above solution and continue stirring for 0.5 h. Transfer the mixed solution to a hydrothermal reactor lined with polytetrafluoroethylene, place it in an oven for heating, and after natural cooling, wash and dry to obtain RGO / SrTiO3 nanoparticles. 3) Disperse RGO / SrTiO3 nanoparticles in a beaker containing 20 mL of deionized water, add sodium hexachlororhodium solution, and deposit rhodium ions on the catalyst surface using photodeposition under simulated sunlight. 4) Add chromium nitrate solution nonahydrate to the mixed solution obtained in step 3), and use photodeposition to deposit chromium ions on the catalyst surface under simulated sunlight. 5) Add cobalt nitrate hexahydrate solution to the mixed solution obtained in step 4), and use photodeposition to deposit cobalt ions on the catalyst surface under simulated sunlight irradiation. 6) The mixed solution obtained in step 5) is filtered, washed and dried to obtain the final product named R-STO photocatalyst.

2. The R-STO photocatalyst according to claim 1, characterized in that, In step 1), the strontium chloride is strontium chloride hexahydrate with a mass of 14.5g, and the SrTiO3 powder is commercially available SrTiO3 with a mass of 1g; in step 2), the concentration of the GO solution is 1mg / mL and the volume is 100μL, the mass of the SrTiO3 nanoparticles is 0.1g, and the concentration of the ascorbic acid solution is 3.33g / L and the volume is 30mL.

3. The R-STO photocatalyst according to claim 1, characterized in that, In step 1), the calcination temperature is 1100℃ and the time is 10h.

4. The R-STO photocatalyst according to claim 1, characterized in that, In step 2), the temperature in the oven is 90°C and the time is 6 hours.

5. The R-STO photocatalyst according to claim 1, characterized in that, In step 3), the mass of the RGO / SrTiO3 nanoparticles is 20 mg, the concentration of the sodium hexachlororhodium solution is 0.59 mg / mL, and the volume is 126 μL.

6. The R-STO photocatalyst according to claim 1, characterized in that, In step 4), the concentration of the chromium nitrate nonahydrate solution is 7.7 mg / mL and the volume is 6 μL.

7. The R-STO photocatalyst according to claim 1, characterized in that, In step 5), the concentration of the cobalt nitrate hexahydrate solution is 2 mg / mL and the volume is 20 μL.

8. The R-STO photocatalyst according to claim 1, characterized in that, In steps 3), 4), and 5), the light source simulating sunlight is a xenon lamp with a power of 148mW ​​and a light intensity; in step 3), the light deposition time is 10 minutes; in steps 4) and 5), the light deposition time is 5 minutes.

9. The application of an R-STO photocatalyst according to any one of claims 1-8 in photocatalytic water splitting for hydrogen production and oxygen evolution.

10. The application according to claim 9, characterized in that, The method is as follows: R-STO photocatalyst is uniformly dispersed in 20 mL of deionized water. Argon gas is continuously introduced into the reaction vessel at a rate of 40 mL / min for 10 min. The vessel is then sealed, and photocatalytic decomposition of water to produce hydrogen and oxygen is carried out under the condition of simulated sunlight irradiation by a xenon lamp source with a power of 300 W.

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