Co-catalyst-loaded Fe and Al co-doped SrTiO3 photocatalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of photocatalytic materials, and particularly relates to a cocatalyst-loaded Fe and Al co-doped SrTiO3 photocatalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: grinding ferric chloride hexahydrate, adding the ground ferric chloride hexahydrate into an Al-SrTiO3 precursor, changing the molar ratio of an Fe source to obtain Al-SrTiO3-x% Fe with different molar ratios, then adding an Rh precursor solution, a Cr precursor solution and a Co precursor solution, and irradiating under a 300W xenon lamp to obtain the Fe and Al co-doped SrTiO3 photocatalyst loaded with the cocatalyst. The photocatalyst can be applied to the field of photocatalytic full water splitting. Compared with an existing photocatalyst, the photocatalyst disclosed by the invention is good in controllability, the separation efficiency of current carriers is further improved, and the composite material is relatively high in hydrogen yield and relatively good in stability when being used for photocatalytic full water splitting. The preparation method is green, environment-friendly, simple, convenient to operate and low in material preparation cost, and has a wide application market prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalytic materials, and particularly relates to a preparation method and application of a Fe, Al co-doped SrTiO photocatalyst loaded with a cocatalyst for overall water splitting. 3 Background Art

[0002] Hydrogen is a promising primary energy carrier due to its abundance and high energy density. Photocatalytic water splitting for hydrogen production using abundant solar energy has attracted extensive attention.

[0003] SrTiO 3 has received extensive attention and applications due to its significant advantages of simple synthesis, environmental friendliness, good stability, and suitable band structure. However, the photocatalytic efficiency of pure SrTiO 3 photocatalyst is usually limited, mainly due to its significantly lower exploitation efficiency of sunlight and the substantial recombination of photo-generated charges. Therefore, various modification techniques have been designed to improve the photocatalytic efficiency of SrTiO 3 for overall water splitting. However, there has been no relevant report on Fe, Al co-doped SrTiO 3 as a photocatalyst for overall water splitting. Summary of the Invention

[0004] To solve the problems existing in the prior art, the present invention provides a preparation method and application of a Fe, Al co-doped SrTiO 3 photocatalyst for overall water splitting.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A Fe, Al co-doped SrTiO 3 photocatalyst loaded with a cocatalyst, wherein the doping amount of Fe is 0.05 - 0.15% of Al-SrTiO 3 in terms of molar percentage.

[0007] The preparation method of the above-mentioned Fe, Al co-doped SrTiO 3 photocatalyst loaded with a cocatalyst comprises the following steps:

[0008] 1) Add SrTiO 3 , Al 2 O 3 and SrCl 2 ·6H 2 O into a mortar and grind to form a uniform precursor powder; Add FeCl 3 ·6H 2 ​O is added to the precursor powder. After continuous grinding to uniformity, it is transferred to a high-temperature muffle furnace for calcination reaction. After the reaction ends, it is cooled to room temperature to obtain Fe, Al-SrTiO 3 photocatalyst;

[0009] 2) Fe, Al-SrTiO 3 is ultrasonically soaked in deionized water for 10 - 20 min, then Rh precursor solution and Cr precursor solution are added. After irradiation under a 300 W xenon lamp for 1 - 2 h, Co precursor solution is added, and irradiation continues under a 300 W xenon lamp for 0.5 h. After each addition of the precursor solution, argon is introduced at a constant flow rate to prevent the liquid from contacting air and exclude the interference of air on the solution. After the reaction ends, it is cooled to room temperature, filtered by suction, and dried in vacuum to obtain Fe, Al co-doped SrTiO loaded with co-catalyst 3 photocatalyst.

[0010] Furthermore, in the above preparation method, in step 1), by molar ratio, SrTiO 3 :Al 2 O 3 :SrCl 2 ·6H 2 O = 1:0.01:10.

[0011] Furthermore, in the above preparation method, in step 1), the calcination is carried out at a heating rate of 5 °C / min at 1000 °C for 10 h.

[0012] Furthermore, in the above preparation method, in step 2), the Rh precursor solution is: Dissolve Na 3 RhCl 6 ·12H 2 O in deionized water, with a mass percentage concentration of 0.1%.

[0013] Furthermore, in the above preparation method, in step 2), the Cr precursor solution is: Dissolve Cr(NO 3 )·9H 2 O in deionized water, with a mass percentage concentration of 0.05%.

[0014] Furthermore, in the above preparation method, in step 2), the Co precursor solution is: Dissolve CoCl 2 ·6H 2 O in deionized water, with a mass percentage concentration of 0.05%.

[0015] Furthermore, in the above preparation method, in step 2), by solid-liquid ratio, Fe, Al-SrTiO 3Deionized water: Rh precursor solution: Cr precursor solution: Co precursor solution = 20 mg: 20 mL: 126 μL: 10 μL: 21 μL.

[0016] The above-mentioned Fe and Al co-doped SrTiO supported with a cocatalyst 3 Application in photocatalytic overall water splitting under visible light irradiation.

[0017] Furthermore, for the above application, the method is as follows: The Fe and Al co-doped SrTiO 3 photocatalyst supported with a cocatalyst is uniformly dispersed in a reaction cell filled with deionized water. Before the reaction, the system is evacuated to remove the air in the system, and then irradiated under a 300 W xenon lamp.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The present invention uses the calcination method to prepare the Fe and Al co-doped SrTiO 3 photocatalyst. After being modified by Fe and Al co-doping, it can effectively reduce the recombination of photogenerated electrons and holes, improve the separation efficiency of carriers, thereby significantly enhancing the visible light response of the catalyst and enhancing the photocatalytic activity.

[0020] 2. The Fe and Al co-doped SrTiO 3 photocatalyst prepared by the present invention has a larger photocurrent response, a more effective separation ability of photogenerated electrons and holes, and a stronger photocatalytic reduction ability, and participates in the catalytic reaction, which is an effective way to improve the visible light catalytic activity.

[0021] 3. The Fe and Al co-doped SrTiO 3 photocatalyst prepared by the present invention has good photocatalytic overall water splitting performance, and this method is simple, efficient, environmentally friendly, clean and conducive to large-scale production. Description of the Drawings

[0022] Figure 1 X-ray diffraction patterns of the Al-SrTiO 3 , Fe / Al-SrTiO 3 -1, Fe / Al-SrTiO 3 -2 and Fe / Al-SrTiO 3 -3 photocatalysts prepared in Example 1.

[0023] Figure 2 Hydrogen and oxygen evolution rate diagrams of the Fe / Al-SrTiO 3 -2 photocatalyst prepared in Example 1.

[0024] Figure 3 X-ray diffraction patterns of the Al-SrTiO prepared in Example 13 and Fe / Al-SrTiO 3 -1.Fe / Al-SrTiO 3 -2 and Fe / Al-SrTiO 3 -3 Comparison of the activity of photocatalysts for water decomposition and hydrogen evolution. DETAILED DESCRIPTION

[0025] Example 1 Fe and Al co-doped SrTiO loaded with promoters 3 Photocatalyst (I) Al-SrTiO 3 Preparation

[0026] 1 mmol SrCO 3 、0.01mmol Al 2 O 3 and 10mmol SrCl 2 6H 2 O was put into a mortar and mixed evenly to form a precursor powder, which was then put into a porcelain boat and reacted at 1000°C in a high-temperature muffle furnace at a heating rate of 5°C / min for 10 h, and then naturally cooled to room temperature to obtain Al-SrTiO 3 .

[0027] (ii) Al-SrTiO with Fe doping of 0.05% loaded with co-catalyst 3 Preparation of photocatalyst

[0028] 1) 1mmol SrCO 3 、0.01mmol Al 2 O 3 and 10mmol SrCl 2 6H 2 O was put into a mortar and mixed evenly to form a precursor powder. Then 0.0005 mmol FeCl 3 6H 2 O, and then continue to grind for 30 minutes after mixing evenly. After fully grinding, transfer to a porcelain boat and react at 1000℃ in a high-temperature muffle furnace at a heating rate of 5℃ / min for 10 hours. After the reaction is completed, naturally cool to room temperature to obtain Al-SrTiO with a Fe doping amount of 0.05%. 3 Photocatalyst, labeled as Al-SrTiO 3 -0.05%Fe.

[0029] 2) Put Na 3 RhCl 6 12H 2 O was dissolved in deionized water to prepare a Rh precursor solution with a mass percentage concentration of 0.1%. 3 )·9H2 O is dissolved in deionized water to prepare a Cr precursor solution with a mass percentage concentration of 0.05%. CoCl 2 ·6H 2 O is dissolved in deionized water to prepare a Co precursor solution with a mass percentage concentration of 0.05%.

[0030] 3) 20 mg of Al-SrTiO 3 -0.05% Fe is ultrasonically soaked in 20 mL of deionized water for 10 min, then 126 μL of Rh precursor solution and 10 μL of Cr precursor solution are added. After irradiation under a 300 W xenon lamp for 2 h, 21 μL of Co precursor solution is added, and irradiation continues under a 300 W xenon lamp for 0.5 h. Argon is introduced at a constant flow rate after each addition of the precursor solution to prevent the liquid from contacting air and exclude the interference of air on the solution. After the reaction, it is cooled to room temperature, filtered by suction, and dried in vacuum to obtain Al-SrTiO 3 -0.05% Fe, abbreviated as Fe / Al-SrTiO 3 -1.

[0031] (III) Preparation of the photocatalyst of Al-SrTiO 3 with 0.1% Fe doping of the co-catalyst

[0032] 1) 1 mmol of SrCO 3 , 0.01 mmol of Al 2 O 3 and 10 mmol of SrCl 2 ·6H 2 O are put into a mortar, mixed evenly to form a precursor powder, then 0.001 mmol of FeCl 3 ·6H 2 O is added. After mixing evenly, it is ground for another 30 min. After being fully ground evenly, it is transferred to a porcelain boat and reacted in a high-temperature muffle furnace at a heating rate of 5 °C / min at 1000 °C for 10 h. After the reaction, it is naturally cooled to room temperature to obtain the photocatalyst of Al-SrTiO 3 with 0.1% Fe doping, marked as Al-SrTiO 3 -0.1% Fe.

[0033] 2) Na 3 RhCl 6 ·12H 2 O is dissolved in deionized water to prepare a Rh precursor solution with a mass percentage concentration of 0.1%. Cr(NO 3 )·9H 2 O is dissolved in deionized water to prepare a Cr precursor solution with a mass percentage concentration of 0.05%. CoCl2 ·6H 2 Dissolve CoCl₂·6H₂O in deionized water to prepare a Co precursor solution with a mass percentage concentration of 0.05%.

[0034] 3) Ultrasonically soak 20 mg of Al-SrTiO₃-0.1% Fe in 20 mL of deionized water for 10 min, then add 126 μL of Rh precursor solution and 10 μL of Cr precursor solution. After irradiating under a 300 W xenon lamp for 2 h, add 21 μL of Co precursor solution and continue irradiating under a 300 W xenon lamp for 0.5 h. Each time a precursor solution is added, argon is introduced at a constant flow rate to prevent the liquid from contacting air and exclude the interference of air on the solution. After the reaction, cool to room temperature, filter by suction, and dry in vacuum to obtain Al-SrTiO₃-0.1% Fe loaded with a cocatalyst, abbreviated as Fe / Al-SrTiO₃-2. 3 3 -0.1% Fe, abbreviated as Fe / Al-SrTiO₃ 3 -2.

[0035] (IV) Preparation of the photocatalyst of Al-SrTiO₃ with a Fe doping amount of 0.15% loaded with a cocatalyst 3

[0036] 1) Put 1 mmol of SrCO₃, 0.01 mmol of Al₂O₃, and 10 mmol of SrCl₂·6H₂O into a mortar, mix evenly to form a precursor powder, then add 0.0015 mmol of FeCl₃·6H₂O, continue to grind for 30 min after mixing evenly. After fully grinding evenly, transfer to a porcelain boat and react in a high-temperature muffle furnace at a heating rate of 5 °C / min at 1000 °C for 10 h. After the reaction, naturally cool to room temperature to obtain a photocatalyst of Al-SrTiO₃ with a Fe doping amount of 0.15%, marked as Al-SrTiO₃-0.15% Fe. 3 、0.01 mmol Al 2 O 3 and 10 mmol SrCl 2 ·6H 2 O into a mortar, mix evenly to form a precursor powder, then add 0.0015 mmol FeCl 3 ·6H 2 O, mix evenly and continue grinding for 30 min. After fully grinding evenly, transfer to a porcelain boat and react in a high-temperature muffle furnace at a heating rate of 5 °C / min at 1000 °C for 10 h. After the reaction, naturally cool to room temperature to obtain an Al-SrTiO₃ photocatalyst with a Fe doping amount of 0.15%, marked as Al-SrTiO₃ 3 photocatalyst, labeled as Al-SrTiO₃ 3 -0.15% Fe.

[0037] 2) Dissolve Na₃RhCl₆·12H₂O in deionized water to prepare a Rh precursor solution with a mass percentage concentration of 0.1%. Dissolve Cr(NO₃)₃·9H₂O in deionized water to prepare a Cr precursor solution with a mass percentage concentration of 0.05%. Dissolve CoCl₂·6H₂O in deionized water to prepare a Co precursor solution with a mass percentage concentration of 0.05%. 3 RhCl 6 ·12H 2 O in deionized water to prepare a Rh precursor solution with a mass percentage concentration of 0.1%. Dissolve Cr(NO 3 )·9H 2 O in deionized water to prepare a Cr precursor solution with a mass percentage concentration of 0.05%. Dissolve CoCl 2 ·6H 2 ​​O was dissolved in deionized water to prepare a Co precursor solution with a mass percentage concentration of 0.05%.

[0038] 3) 20 mg of Al-SrTiO 3 -0.15% Fe was ultrasonically soaked in 20 mL of deionized water for 10 min, then 126 μL of Rh precursor solution and 10 μL of Cr precursor solution were added. After irradiation under a 300 W xenon lamp for 2 h, 21 μL of Co precursor solution was added, and irradiation was continued under a 300 W xenon lamp for 0.5 h. Argon was introduced at a constant flow rate after each addition of the precursor solution to prevent the liquid from contacting air and to exclude the interference of air on the solution. After the reaction, it was cooled to room temperature, filtered by suction, and dried in vacuum to obtain Al-SrTiO 3 -0.15% Fe, abbreviated as Fe / Al-SrTiO 3 -3.

[0039] (V) Detection

[0040] Figure 1 The X-ray diffraction patterns of the Al-SrTiO 3 , Fe / Al-SrTiO 3 -1, Fe / Al-SrTiO 3 -2 and Fe / Al-SrTiO 3 -3 photocatalysts prepared in Example 1. Figure 1 Among them, seven significant characteristic diffraction peaks at 2θ = 22.7°, 32.4°, 39.9°, 46.5°, 52.3°, 57.9° and 67.9° correspond to the (100), (110), (111), (200), (210), (211) and (220) crystal planes of Al-SrTiO 3 (standard card PDF#35-0734). No characteristic peaks of other impurities were observed in Figure 1 , indicating that the original structure of SrTiO 3 was still retained after co-doping with Fe and Al. 3

[0041] Application of the Fe and Al co-doped SrTiO 3 photocatalyst loaded with co-catalyst in photocatalytic overall water splitting

[0042] The method is as follows: At normal temperature and pressure, deionized water was added to the reaction cell, and then 20 mg of the Al-SrTiO 3 , Fe / Al-SrTiO 3 -1, Fe / Al-SrTiO 3 -2 and Fe / Al-SrTiO prepared in Example 1 were added respectively.3 After adding -3 photocatalyst, ultrasonicate for 10 min to obtain a dispersed solution. Seal the container. Before the reaction, evacuate the system to remove the air in the system and keep the container in a vacuum state at all times. Under visible light (300W xenon lamp) irradiation, extract the gaseous products through the on-line sampling loop system every 30 min, and detect the components of the sample gas by gas chromatography separation technology to determine the hydrogen evolution and oxygen evolution concentrations.

[0043] Figure 2 For the Fe / Al-SrTiO prepared in Example 1 3 -2 photocatalyst hydrogen and oxygen evolution rate diagram. The results show that within 2.5 h, the highest hydrogen evolution rate of Fe / Al-SrTiO 3 -2 is 5.58 mmol·g -1 ·h -1 , and the highest oxygen evolution rate is 2.8 mmol·g -1 ·h -1 , and the rate ratio of hydrogen to oxygen is about 2:1, which is 3.68 times that of pure Al-SrTiO 3 (1.22 mmol·g -1 ·h -1 ). This shows that doping with Fe improves the separation efficiency of semiconductor photo-generated carriers and is beneficial to improving the photocatalytic overall water splitting activity.

[0044] Figure 3 For the Al-SrTiO, Fe / Al-SrTiO 3 prepared in Example 1, 3 -1, Fe / Al-SrTiO 3 -2 and Fe / Al-SrTiO 3 -3 catalyst water splitting hydrogen evolution activity comparison diagram. As Figure 3 can be seen, after 60 min of light irradiation reaction, the hydrogen production of Al-SrTiO 3 is 1.22 mmol·g -1 ·h -1 , the H 3 production of Fe / Al-SrTiO 2 -1 is 2.99 mmol·g -1 ·h -1 , the H 3 production of Fe / Al-SrTiO 2 -2 is 5.58 mmol·g -1 ·h -1 , the H 3 production of Fe / Al-SrTiO 2 -3 is 2.5 mmol·g -1 ·h -1。The hydrogen production performance of the photocatalyst doped with Fe in the supported cocatalyst Al-SrTiO 3 is much improved compared with that of pure Al-SrTiO 3 . It shows that after Fe is doped into Al-SrTiO 3 with the supported cocatalyst, the ability of photogenerated electron transfer is strong, and the electron-hole has strong redox ability.

Claims

1. A Fe and Al co-doped SrTiO3 photocatalyst loaded with a promoter, characterized in that: In terms of molar percentage, the doping amount of Fe is 0.05-0.15% of Al-SrTiO3.

2. The method for preparing a Fe and Al co-doped SrTiO3 photocatalyst loaded with a promoter according to claim 1, characterized in that: The steps include: 1) SrTiO3, Al2O3 and SrCl2·6H2O are added into a mortar and ground into a uniform precursor powder; FeCl3·6H2O is added into the precursor powder, and after grinding evenly, the powder is transferred into a high-temperature muffle furnace for calcination reaction, and after the reaction is completed, the powder is cooled to room temperature to obtain Fe, Al-SrTiO3 photocatalyst; 2) Fe and Al-SrTiO3 were ultrasonically soaked in deionized water for 10-20 minutes, and then Rh precursor solution and Cr precursor solution were added. After irradiation under a 300W xenon lamp for 1-2 hours, Co precursor solution was added and irradiation under a 300W xenon lamp was continued for 0.5 hours. After each addition of the precursor solution, argon gas was introduced at a constant flow rate to prevent the liquid from contacting with the air and eliminate the interference of air on the solution. After the reaction was completed, it was cooled to room temperature, filtered, and vacuum dried to obtain Fe, Al co-doped SrTiO3 photocatalyst loaded with a co-catalyst.

3. The preparation method according to claim 2, characterized in that: In step 1), the molar ratio is SrTiO3:Al2O3:SrCl2·6H2O=1:0.01:

10.

4. The preparation method according to claim 2, characterized in that: In step 1), the calcination is carried out at 1000° C. for 10 h at a heating rate of 5° C. / min.

5. The preparation method according to claim 2, characterized in that: In step 2), the Rh precursor solution is: Na3RhCl6·12H2O is dissolved in deionized water, and the mass percentage concentration is 0.1%.

6. The preparation method according to claim 2, characterized in that: In step 2), the Cr precursor solution is: Cr(NO3)·9H2O is dissolved in deionized water, and the mass percentage concentration is 0.05%.

7. The preparation method according to claim 2, characterized in that: In step 2), the Co precursor solution is: CoCl2·6H2O is dissolved in deionized water, and the mass percentage concentration is 0.05%.

8. The preparation method according to claim 2, characterized in that: In step 2), according to the solid-liquid ratio, Fe, Al-SrTiO3: deionized water: Rh precursor solution: Cr precursor solution: Co precursor solution = 20 mg: 20 mL: 126 μL: 10 μL: 21 μL.

9. Use of the Fe and Al co-doped SrTiO3 photocatalyst loaded with a promoter as claimed in claim 1 in catalytic overall water splitting under visible light irradiation.

10. The use according to claim 9, characterized in that: The method is as follows: the Fe and Al co-doped SrTiO3 photocatalyst loaded with the co-catalyst is uniformly dispersed in a reaction tank filled with deionized water, the system is evacuated to remove the air in the system before the reaction, and irradiated under a 300W xenon lamp.

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