RGO-caTiO3 composite material for photocatalytic overall water splitting and preparation method and application thereof
By growing RGO in situ on the surface of calcium titanate, an RGO-CaTiO3 composite material was prepared, which solved the problem of reverse reaction in photocatalytic water splitting, improved the separation efficiency of photogenerated carriers, and achieved efficient hydrogen evolution and oxygen production. It has good photocatalytic stability and low cost advantages.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LIAONING UNIVERSITY
- Filing Date
- 2026-02-06
- Publication Date
- 2026-06-02
Smart Images
Figure CN122124770A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to an RGO-CaTiO3 composite material for photocatalytic water splitting, its preparation method, and its application. Background Technology
[0002] High-efficiency complete water splitting is currently a hot research topic in the field of photocatalysis. However, the existence of reverse reactions in the photocatalytic water splitting process has always been one of the challenges hindering the efficient hydrogen evolution and oxygen production. Photocatalytic materials with spatially separated redox sites enable photogenerated electrons and holes to undergo hydrogen evolution reaction (HER) or oxygen evolution reaction (OER) on different crystal planes, effectively preventing the recombination of photogenerated electrons and holes. This is one of the solutions to the problem of reverse reactions in photocatalysis.
[0003] Calcium titanate, as a perovskite material, has certain application potential in the field of photocatalysis. This invention utilizes a high-temperature molten salt method to prepare calcium titanate with a distinct cubic phase crystal structure. This unique structure possesses spatially separated oxidation and reduction sites, effectively suppressing the reverse reaction in photocatalysis. Despite these advancements, the poor charge transport efficiency of calcium titanate remains a problem to be solved. Therefore, a method was chosen to simultaneously reduce GO onto the surface of calcium titanate to grow highly charged reactive oxygen species (RGO). This approach results in higher performance for the material system, and there are no previous reports on the application of R / ACTO photocatalyst preparation methods in photocatalytic water splitting. Summary of the Invention
[0004] To address the problems of existing technologies, this invention provides an RGO-CaTiO3 composite material for photocatalytic water splitting, its preparation method, and its application. The RGO-CaTiO3 composite material for photocatalytic water splitting is referred to as R / ACTO photocatalyst.
[0005] The technical solution adopted in this invention is as follows:
[0006] An R / ACTO photocatalyst, the preparation method of which includes the following steps:
[0007] Step 1: Disperse anhydrous calcium chloride in anhydrous ethanol and stir continuously, denoted as solution A. Add tetrabutyl titanate dropwise to solution A and stir continuously, then add KOH powder. Continue stirring and sonication, then 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 CTO white precursor powder;
[0008] Step 2: Mix the above CTO with anhydrous calcium chloride and grind it thoroughly. Then transfer it to a high-temperature muffle furnace for continuous calcination. After natural cooling, wash and dry to obtain the final product, named ACTO nanoparticles.
[0009] Step 3: Disperse the above-mentioned ACTO nanoparticles in distilled water and stir continuously, denoted as solution B. Add GO aqueous solution dropwise to solution B and stir continuously. Add ascorbic acid solution. After continuing to stir, 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 R / ACTO nanoparticles;
[0010] Furthermore, in the above-mentioned method for preparing an R / ACTO photocatalyst, in step 1, the molar ratio of anhydrous calcium chloride: tetrabutyl titanate: KOH is 1:1:2, and in step 2, the molar ratio of CTO nanoparticles: anhydrous calcium chloride is 1:10.
[0011] Furthermore, in the above-mentioned method for preparing an R / ACTO photocatalyst, in step 1, the temperature of the oven is 160°C and the time is 18-24 h.
[0012] Furthermore, in the above-mentioned method for preparing an R / ACTO photocatalyst, step 2 involves a calcination temperature of 1150°C and a calcination time of 10 h.
[0013] Furthermore, in the above-mentioned method for preparing an R / ACTO photocatalyst, in step 3, the mass ratio of CTO nanoparticles, GO, and ascorbic acid is 200:1:2000.
[0014] Furthermore, in the above-mentioned method for preparing an R / ACTO photocatalyst, in step 3, the temperature of the oven is 90°C and the time is 6 hours.
[0015] The application of any one of the above-mentioned R / ACTO photocatalysts in photocatalytic water splitting for hydrogen production and oxygen evolution.
[0016] Further, the above application is carried out as follows: 20 mg of the R / ACTO photocatalyst is uniformly dispersed in a reactor containing 20 mL of distilled water. Under simulated sunlight irradiation, Rh, Cr, and Co are photodeposited onto the surface of the photocatalyst as co-catalysts. Specifically, during stirring, 256 μL of a 0.59 mg / mL sodium hexachlororhodium solution is first added, and deposition is carried out for 10 min to deposit rhodium ions onto the catalyst surface; then 10 μL of a 7.7 mg / mL chromium nitrate nonahydrate solution is added, and deposition is carried out for 5 min to deposit chromium ions onto the catalyst surface; finally, 21 μL of a 2 mg / mL cobalt nitrate hexahydrate solution is added, and deposition is carried out for 5 min to deposit cobalt ions onto the catalyst surface.
[0017] Argon gas was continuously introduced into the reaction vessel of the photodeposited R / ACTO photocatalyst at a rate of 40 mL / min for 20 min. The vessel was then sealed, and photocatalytic decomposition of water to produce hydrogen and oxygen was carried out under simulated sunlight irradiation conditions.
[0018] This invention synthesizes cubic CaTiO3 (CTO) nanoparticles using a high-temperature molten salt medium. RGO is then grown in situ on the CTO surface via hydrothermal methods to obtain R / ACTO nanoparticles, which can be applied in the field of photocatalytic water splitting. Compared to existing photocatalysts, the R / ACTO photocatalyst of this invention exhibits good controllability and strong stability. Furthermore, the unique morphology of the cubic CTO nanoparticles provides spatially separated redox sites, and the high conductivity of RGO further enhances its advantages. 2 Carbon frameworks, acting as electron storage and rapid charge transport channels, significantly accelerate surface reduction reactions, effectively suppress reverse reactions in photocatalytic processes, reduce the recombination rate of photogenerated electrons and holes, and further improve carrier separation efficiency, enabling simultaneous water splitting for hydrogen production and oxygen generation. This invention is environmentally friendly, simple in method, convenient to operate, and inexpensive in material preparation, aligning with current green and environmentally friendly principles and possessing broad market prospects.
[0019] The beneficial effects of this invention are as follows:
[0020] 1. This invention utilizes hydrothermal synthesis and high-temperature molten salt methods to prepare R / ACTO photocatalysts, which can effectively suppress the recombination efficiency of photogenerated electrons and holes, achieve efficient separation of photogenerated charge carriers, and exhibit excellent photocatalytic water splitting and hydrogen evolution to oxygen production performance under simulated sunlight irradiation.
[0021] 2. The preparation method of the present invention is simple, convenient, low-cost, and mild, which is conducive to large-scale production.
[0022] 3. The R / ACTO photocatalyst prepared by this invention has good photocatalytic cycle stability. Attached Figure Description
[0023] Figure 1 shows the X-ray diffraction patterns of the CTO catalyst prepared in Example 1 and the R / ACTO-2 photocatalyst prepared in Example 3.
[0024] Figure 2 Fourier transform infrared spectra of the ACTO catalyst prepared in Example 1, the R / ACTO-2 photocatalyst prepared in Example 3, and the RGO nanosheets prepared in Example 4.
[0025] Figure 3 Images of the ACTO catalyst prepared in Example 1, the R / ACTO-2 photocatalyst prepared in Example 3, and the RGO nanosheets prepared in Example 4, including scanning electron microscope (SEM) images of GO and EDS energy dispersive spectra of R / ACTO-2.
[0026] Figure 4 Photoluminescence spectra of the CTO catalyst prepared in Example 1, the R / ACTO-2 photocatalyst prepared in Example 3, and the R / ACTO-1 and R / ACTO-3 photocatalysts prepared in Example 5.
[0027] Figure 5 shows the photocatalytic water splitting activity of the CTO catalyst prepared in Example 1, the R / ACTO-2 photocatalyst prepared in Example 3, and the R / ACTO-1 and R / ACTO-3 photocatalysts prepared in Example 5, where (a) is the photocatalytic hydrogen evolution performance of water splitting and (b) is the photocatalytic oxygen evolution performance of water splitting. Detailed Implementation
[0028] Example 1
[0029] The preparation method of CTO nanoparticles is as follows:
[0030] 1.1 g of anhydrous calcium chloride was dispersed in 30 mL of anhydrous ethanol and stirred continuously for 10 min, denoted as solution A. 3.01 mL of tetrabutyl titanate was added dropwise to solution A and stirred continuously for 10 min, followed by the addition of 1.122 g of KOH powder. The mixture was stirred for another 30 min and then sonicated for 30 min. The resulting solution was then transferred to a polytetrafluoroethylene-lined hydrothermal reactor and heated in a 160 ℃ oven for 18–24 h. After natural cooling, the solution was washed and dried to obtain a white CaTiO3 powder, denoted as CTO.
[0031] 1 g of CTO white powder was mixed with 7.77 g of anhydrous calcium chloride and ground thoroughly. The mixture was then transferred to a high-temperature muffle furnace and calcined at 1150 °C for 10 h. After natural cooling, the mixture was washed and dried to obtain the final product, which was named ACTO nanoparticles.
[0032] Example 2
[0033] The preparation method of GO solution is as follows:
[0034] 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 45°C 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. The concentration of the obtained GO solution was measured, and 1 mL of the GO solution was diluted to 1 mg / mL.
[0035] Example 3
[0036] 100 mg of ACTO nanoparticles from Example 1 were dispersed in 30 mL of distilled water and stirred continuously for 30 min, denoted as solution B. 500 μL of a 1 mg / mL GO aqueous solution was added dropwise to solution B and stirred continuously for 10 min. Then, 30 mL of ascorbic acid solution (concentration 0.033 g / mL) was added. After stirring for another 30 min, the mixture was transferred to a polytetrafluoroethylene-lined hydrothermal reactor and placed in an oven at 90 °C for 6 h. After natural cooling, the nanoparticles were washed and dried to obtain R / ACTO-2 nanoparticles.
[0037] Example 4
[0038] 10 mL of the GO solution prepared in Example 2 (concentration of 1 mg / mL) was added dropwise to 50 mL of ascorbic acid solution (concentration of 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.
[0039] Example 5
[0040] The volume of GO solution used in Example 3 was changed to 250 μL and 750 μL, respectively, corresponding to ascorbic acid concentrations of 8.33 g / L and 25 g / L, respectively. Other methods were the same as in Example 3, and the final products were labeled as R / ACTO-1 and R / ACTO-3, respectively.
[0041] Figure 1 shows the X-ray diffraction patterns of the ACTO catalyst prepared in Example 1 and the R / ACTO-2 photocatalyst prepared in Example 3. In Figure 1, the characteristic peaks of ACTO are located at 23.2°, 33.1°, 47.5°, 59.3°, and 69.5°, corresponding to the (101), (121), (040), (042), and (242) crystal planes of cubic ACTO, respectively. This is completely consistent with the arrangement order of the standard card (PDF#22-0153) for perovskite phase CTO. Since the loading of RGO is less than 1%, no additional characteristic peaks were found in the composite sample. However, it can be seen from the Fourier transform infrared spectrum (Figure 2) that the absorption peaks of the composite sample correspond to those of the RGO nanosheets prepared in Example 4, indicating that the R / ACTO photocatalyst was successfully prepared. Scanning electron microscopy (SEM) images (Figure 3) show that the morphology of CTO nanoparticles is mainly hexahedral, and the hexahedral structure of CTO can still be clearly seen in the SEM images of the R / ACTO-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 spectra (Figure 4) show that the emission peaks of all composite samples are lower than the ACTO emission peak, indicating good charge transfer at the ACTO-RGO interface.
[0042] Example 6
[0043] Application of photocatalysts in the catalytic splitting of water under light:
[0044] The 20 mg R / ACTO-2 photocatalyst from Example 3 was dispersed in a reactor containing 20 mL of distilled water. Rh, Cr, and Co were photodeposited onto the photocatalyst surface as co-catalysts under simulated sunlight irradiation. Specifically, 256 μL of a 0.59 mg / mL sodium hexachlororhodium solution was added during stirring, and deposition was allowed for 10 min to deposit rhodium ions onto the catalyst surface. Then, 10 μL of a 7.7 mg / mL chromium nitrate nonahydrate solution was added, and deposition was allowed for 5 min to deposit chromium ions onto the catalyst surface. Finally, 21 μL of a 2 mg / mL cobalt nitrate hexahydrate solution was added, and deposition was allowed for 5 min to deposit cobalt ions onto the catalyst surface.
[0045] Argon gas was continuously introduced into the reaction vessel containing the photodeposited R / ACTO-2 photocatalyst at a rate of 40 mL / min for 20 min to purge air. The vessel was then sealed, and photocatalytic decomposition of water to produce hydrogen and oxygen was carried out under simulated sunlight irradiation conditions. 1000 μL of gas was extracted from the reactor at 30 min, 60 min, 90 min, and 120 min, and the collected catalytic products were quantitatively analyzed using gas chromatography.
[0046] Figure 5 shows the photocatalytic water splitting activity of the CTO catalyst prepared in Example 1, the R / ACTO-2 photocatalyst prepared in Example 3, and the R / ACTO-1 and R / ACTO-3 photocatalysts prepared in Example 5. The peak area of the extracted gas was measured by gas chromatography, and then the amount of substance was calculated. As shown in Figure 5, after 1 h, the H2 yield of the R / ACTO-2 catalyst was 18.7 mmol / g, and the O2 yield was 8.7 mmol / g, which was 2.7 times that of the original CTO sample. The hydrogen evolution and oxygen production rate was higher than that of other CTO-related catalysts studied so far.
Claims
1. An R / ACTO photocatalyst, characterized in that, Its preparation method includes the following steps: Step 1: Disperse anhydrous calcium chloride in anhydrous ethanol and stir continuously, denoted as solution A. Add tetrabutyl titanate dropwise to solution A and stir continuously. Then add KOH powder, continue stirring and sonicating. 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 CaTiO3 white powder, denoted as CTO. Step 2: Mix the above white powder with anhydrous calcium chloride and grind it thoroughly. Then transfer it to a high-temperature muffle furnace for continuous calcination. After natural cooling, wash and dry the product to obtain ACTO nanoparticles. Step 3: Disperse the above ACTO nanoparticles in distilled water and stir continuously, denoted as solution B. Add GO aqueous solution dropwise to solution B and stir continuously. Add ascorbic acid solution and continue stirring. 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 R / ACTO nanoparticles.
2. The R / ACTO photocatalyst according to claim 1, characterized in that, In step 1, the molar ratio of anhydrous calcium chloride: tetrabutyl titanate: KOH is 1:1:
2. In step 2, the molar ratio of CTO nanoparticles: anhydrous calcium chloride is 1:
10.
3. The R / ACTO photocatalyst according to claim 1, characterized in that, In step 1, the heating temperature is 160℃ and the time is 18-24 h.
4. The R / ACTO photocatalyst according to claim 1, characterized in that, In step 2, the calcination temperature is 1150℃ and the time is 10 h.
5. The R / ACTO photocatalyst according to claim 1, characterized in that, In step 3, the mass ratio of ACTO nanoparticles, GO, and ascorbic acid is 200:1:2000.
6. The R / ACTO photocatalyst according to claim 1, characterized in that, In step 3, the heating temperature is 90°C and the heating time is 6 hours.
7. The application of the R / ACTO photocatalyst according to any one of claims 1-6 in photocatalytic water splitting for hydrogen production and oxygen evolution.
8. The application according to claim 7, characterized in that, Rh, Cr, and Co were photodeposited onto the surface of an R / ACTO photocatalyst under simulated sunlight irradiation. Argon gas was continuously introduced into the R / ACTO photocatalyst after photodeposition of the co-catalyst, and the container was sealed. Photocatalytic decomposition of water to produce hydrogen and oxygen was carried out under simulated sunlight irradiation conditions using a xenon lamp.
9. The application according to claim 8, characterized in that, The method for photodepositing Rh, Cr, and Co as co-catalysts onto the surface of R / ACTO photocatalyst is as follows: R / ACTO photocatalyst is dispersed in a reactor containing distilled water. During stirring, sodium hexachlororhodium solution is added first for photodeposition, depositing rhodium ions onto the catalyst surface; then chromium nitrate nonahydrate solution is added for photodeposition, depositing chromium ions onto the catalyst surface; finally, cobalt nitrate hexahydrate solution is added for photodeposition, depositing cobalt ions onto the catalyst surface.