A strontium titanate thin film composite catalyst for photocatalytic water splitting to produce hydrogen, and its preparation method and application

Abstract

The present invention provides a strontium titanate thin film composite catalyst for photocatalytic water decomposition to produce hydrogen, and its preparation method and application. The preparation method comprises: (1) mixing strontium titanate, aluminum oxide, and strontium oxide in a reaction vessel, and then calcining and washing to obtain SrTiO3:Al; (2) dispersing the SrTiO3:Al obtained in step (1) in water, adding a heavy metal ion solution, drying and calcining after a photodeposition reaction to obtain catalyst powder; (3) mixing micro-nano particles and catalyst powder in water, ultrasonically dispersing, and then mixing an auxiliary agent and a surfactant to obtain a suspension; (4) forming a film of the suspension obtained in step (3) on a mesoporous silica substrate, and calcining to obtain the composite catalyst. The present invention prepares the strontium titanate photocatalyst into a thin film, immerses it in water, and produces hydrogen under light. The hydrogen production effect is good, it is easy to recycle, and can avoid secondary pollution to the environment.

Description

Technical Field

[0001] The present invention belongs to the field of catalyst preparation and relates to a photocatalyst, in particular to a strontium titanate thin film composite catalyst for photolysis of water to produce hydrogen, and a preparation method and application thereof. Background Art

[0002] Hydrogen is known as the most promising green and environmentally friendly clean fuel because its combustion product is water.

[0003] Currently, the hydrogen production industry has three main, relatively mature technological routes: fossil fuel hydrogen production, represented by coal and natural gas; industrial by-product gas hydrogen production, represented by coke oven gas, chlor-alkali tail gas, and propane dehydrogenation; and water electrolysis hydrogen production. Currently, the primary hydrogen production method in my country is fossil fuel hydrogen production, but this method is unsustainable, fails to resolve the fundamental contradiction between energy and the environment, and has high carbon emissions, making it a suboptimal hydrogen production method. Solar energy is an inexhaustible, clean, and pollution-free energy source. Using semiconductor-based photocatalysis to convert solar energy into chemical energy is one of the most promising approaches to addressing future energy challenges. Therefore, photocatalytic water splitting technology, which utilizes solar energy to produce hydrogen, is one of the most promising approaches to addressing sustainable energy and environmental challenges.

[0004] Strontium titanate (STiO) has a typical ABO₃ perovskite structure and features a wide bandgap (~3.2 eV), stable physicochemical properties, high photocatalytic activity, high dielectric constant and low loss, and excellent thermal stability. This makes it ideal for photocatalytic water splitting to produce hydrogen. In recent years, the use of STiO composite photocatalysts for hydrogen production has attracted considerable research. Research and application of STiO photocatalysts have revealed that numerous factors influence its catalytic activity, including the efficiency of light energy utilization, the efficiency of photogenerated carrier separation, and the number of active sites on the catalyst surface. Low photocatalytic efficiency severely limits the large-scale application of STiO. Consequently, experts and researchers in the field have conducted a series of research efforts to address this limitation, and new approaches have been reported to enhance the photocatalytic performance of STiO. For example, researchers have manipulated the energy bands of STiO semiconductor catalysts, reduced the dimensionality and nanoscale size of catalyst particles, and implemented metal deposition, element doping, and composites with other semiconductors to achieve more efficient and economical photocatalysis.

[0005] Tsuyoshi et al. (Nature, 2020, 581(7809): 411-414) selectively loaded highly active hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) co-catalysts on SrTiO3:Al particles by step-by-step photodeposition, achieving complete photocatalytic water splitting, and its external quantum efficiency (EQE) can reach 95.9% under ultraviolet light conditions (350nm–360nm). Niishiro et al. (Applied Catalysis B Environmental, 2014, 151: 187-196) and Furuhashi et al. (Journal of Physical Chemistry C, 2013, 117: 19101-19106) reported that the visible light absorption of SrTiO3 can be significantly enhanced by doping it with Rh. When only Rh is doped, the Rh in SrTiO3 is mainly in the form of Rh. 4+ ions, and Rh and Sb co-doping will partially convert Rh 4+ Transformed to Rh 3+ , thereby improving the efficiency of photocatalytic hydrogen production. Ishii et al. (Journal of Photochemistry and Photobiology A: Chemistry, 2004, 163(1-2):181-186) reported the effects of Cr and Ta doping on the hydrogen evolution efficiency of SrTiO3. When Ta is co-doped with Cr, it can convert the valence of Cr from +6 to +3, increasing the H2 evolution rate by sixfold.

[0006] As research continues to deepen, it has been discovered that using two or more semiconductors to construct composite materials can promote the effective separation of photogenerated charges and enhance photocatalytic performance. Jiao et al. (Scientific Reports, 2013, 3:1-6) studied a simple hydrothermal method for preparing visible-light-responsive Cr-doped SrTiO3 / TiO2 nanotube arrays. After a short hydrothermal treatment of the Cr-doped SrTiO3 and TiO2 nanotubes, the TiO2 nanotube arrays were uniformly and thinly coated on the surface of the Cr-doped SrTiO3, significantly improving the utilization of sunlight. Chang et al. (Applied Catalysis B: Environmental, 2017, 215:74-84) prepared a three-dimensional ordered microporous SrTiO3 ternary composite (CdS / Au / SrTiO3) for visible-light-induced photocatalytic water splitting. Han et al. (Applied Surface Science, 2019, 467–468: 1033–1039) prepared SrTiO3 / CdSe nanocomposites that can effectively capture sunlight and decompose water, and have high photocatalytic activity for hydrogen production. Tan et al. (ACS Applied Materials & Interfaces, 2014, 6(21): 19184–19190) prepared SrTiO3 containing oxygen vacancy defects by controlling the solid-phase reaction of NaBH4 with SrTiO3. By adjusting the reaction time and temperature during the synthesis process to control the concentration of oxygen vacancies, the photocatalytic hydrogen production activity reached 2.2 mmol h - 1 g -1 , which is about 2.3 times that of the original SrTiO3. Wang et al. (Nature Materials, 2016.15(6):611-615) formed a heterojunction of La and Rh co-doped SrTiO3 and Au-loaded Mo-doped BiVO4, loaded with co-catalysts Ru and RuOx, and achieved photocatalytic decomposition of pure water. Its solar energy conversion efficiency reached 1.1%, and the apparent quantum efficiency at 419nm exceeded 30%. Chiang et al. (ACS Catalysis, 2018,8(4):2782-2788) found that after the SrTiO3:Al photocatalyst was loaded with co-catalyst RhCrOx, it could achieve photocatalytic complete water decomposition under 365nm ultraviolet light excitation, and its apparent quantum yield reached 56%.

[0007] Current research focuses on dispersing photocatalyst powder directly in water and producing hydrogen under light, without considering the problem of secondary pollution to the water body caused by the inability to remove or recover the strontium titanate photocatalyst from the water in a timely manner after deactivation. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention provides a strontium titanate thin film composite catalyst, its preparation method, and its application. This invention prepares the strontium titanate photocatalyst into a thin film, immerses it in water, and produces hydrogen under light. The resulting hydrogen production is efficient, easily recyclable, and avoids secondary environmental pollution.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a method for preparing a strontium titanate thin film composite catalyst for photocatalytic water decomposition to produce hydrogen, the preparation method comprising the following steps:

[0011] (1) SrTiO3:Al is obtained by mixing strontium titanate, aluminum oxide, and strontium oxide in a reaction vessel, and then calcining and washing them in sequence;

[0012] (2) dispersing the SrTiO3:Al obtained in step (1) in water, adding a heavy metal ion solution, and drying and calcining the solution after photodeposition reaction to obtain a catalyst powder;

[0013] (3) mixing the micro-nano particles and the catalyst powder obtained in step (2) in water, and then ultrasonically dispersing and mixing with an auxiliary agent and a surfactant to obtain a suspension;

[0014] (4) The suspension obtained in step (3) is prepared into a film on a mesoporous silica substrate, and the film is calcined to obtain the strontium titanate thin film composite catalyst for photocatalytic water decomposition to produce hydrogen.

[0015] The preparation method provided by the present invention prepares the catalyst into a thin film, immerses it in water, and produces hydrogen under light. The hydrogen production effect is good, and it is easy to recycle and reuse, which can avoid secondary pollution to the environment.

[0016] In step (2) of the present invention, heavy metal ions are deposited on SrTiO3:Al by means of a photodeposition reaction. The heavy metal ions act as hydrogen evolution co-catalysts to promote the interaction between the charges generated by solar energy and the reacting water molecules, thereby increasing the hydrogen production rate.

[0017] As a preferred technical solution of the present invention, the molar ratio of strontium titanate, aluminum oxide and strontium oxide in step (1) is 1:(0.01-0.1):(5-12), for example, it can be 1:0.01:5, 1:0.1:5, 1:0.01:12, 1:0.1:12, 1:0.05:8 or 1:0.05:8, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0018] The molar ratio of strontium titanate, aluminum oxide and strontium oxide in the present invention is 1:(0.01-0.1):(5-12), wherein too high alumina content will cause excessive Al in strontium titanate, while too low alumina content will cause strontium titanate defects, affecting photocatalytic performance.

[0019] Preferably, the calcination temperature in step (1) is 1000°C to 1300°C, for example, 1000°C, 1100°C, 1200°C or 1300°C, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0020] Preferably, the calcination time in step (1) is 8 h to 12 h, for example, 5 h, 9 h, 10 h, 11 h or 12 h, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0021] In the calcination process of the present invention, if the calcination temperature is too high, defects of strontium titanate will be caused, while if the calcination temperature is too low, incomplete reaction of Al and strontium titanate will be caused.

[0022] Preferably, the washing liquid used in step (1) comprises deionized water.

[0023] Preferably, the number of washings in step (1) is 2 to 5 times, for example, 2 times, 3 times, 4 times or 5 times.

[0024] The purpose of the washing in the present invention is to wash away unreacted strontium titanate, aluminum oxide and strontium oxide.

[0025] Preferably, the reaction vessel in step (1) comprises a crucible.

[0026] Preferably, the crucible comprises an alumina crucible.

[0027] The crucible of the present invention adopts an alumina crucible, which acts as a dopant source during the calcination process, providing sufficient Al, which is conducive to the realization of Ti in the strontium titanate lattice. 3+ regulation.

[0028] Preferably, the heavy metal ion solution in step (2) comprises any one or a combination of at least two of a rhodium source solution, a chromium source solution or a cobalt source solution. Typical limiting combinations include a combination of a rhodium source solution and a chromium source solution, a combination of a rhodium source solution and a cobalt source solution, a combination of a chromium source solution and a cobalt source solution, or a combination of a rhodium source solution, a chromium source solution and a cobalt source solution.

[0029] Preferably, the rhodium source solution comprises rhodium trichloride hydrate and / or sodium hexachlororhodate.

[0030] Preferably, the chromium source solution comprises chromium nitrate and / or potassium chromate.

[0031] Preferably, the cobalt source solution comprises cobalt chloride and / or cobalt nitrate.

[0032] Preferably, the light source used in the photodeposition in step (2) comprises a xenon lamp.

[0033] Preferably, the optical power in the optical deposition in step (2) is 200W to 500W, for example, 200W, 300W, 400W or 500W, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0034] Preferably, the time of the photodeposition in step (2) is 2 min to 40 min, for example, 2 min, 4 min, 6 min, 20 min, 30 min or 40 min, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0035] As a preferred technical solution of the present invention, the photodeposition described in the present invention specifically includes first adding a rhodium source solution and irradiating with a 200W to 500W xenon lamp for 5 minutes to 20 minutes; then adding a chromium source solution and irradiating with a 200W to 500W xenon lamp for 2 minutes to 10 minutes; finally, adding a cobalt source solution and irradiating with a 200W to 500W xenon lamp for 2 minutes to 10 minutes.

[0036] The purpose of depositing the rhodium source, chromium source and cobalt source in this order is to form a core-shell structure of rhodium and chromium, generate more active sites and improve the catalytic performance of the photocatalyst.

[0037] The present invention uniformly loads heavy metal ions on SrTiO3:Al through photodeposition technology. If the light power is too high during the photodeposition process, the metal ion deposition amount will be too large, covering other active sites. If the light power is too low, the metal ion deposition amount will be insufficient, and there will be fewer active sites, which will reduce the photocatalytic performance.

[0038] Preferably, the drying temperature in step (2) is 50°C to 100°C, for example, it can be 50°C, 60°C, 70°C, 80°C, 90°C or 100°C, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0039] Preferably, the calcination temperature in step (2) is 300°C to 500°C, for example, 300°C, 350°C, 400°C, 450°C or 500°C, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0040] Preferably, the calcination time in step (2) is 1 h to 5 h, for example, 1 h, 2 h, 3 h, 4 h or 5 h, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0041] The present invention obtains catalyst powder by calcination. If the calcination temperature is too high, it will cause strontium titanate lattice defects, while if the calcination temperature is too low, it will not have an activation effect and affect the catalyst activity.

[0042] Preferably, the rhodium loading in the catalyst powder in step (2) is 0.01 wt% to 0.3 wt%, for example, it can be 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt% or 0.3 wt%, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0043] Preferably, the chromium loading in the catalyst powder in step (2) is 0.01 wt% to 0.3 wt%, for example, 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt% or 0.3 wt%, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0044] Preferably, the cobalt loading in the catalyst powder in step (2) is 0.01 wt% to 0.3 wt%, for example, it can be 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt% or 0.3 wt%, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0045] Preferably, the mass ratio of the micro-nanoparticles to the catalyst powder in step (3) is 5:(1-10), for example, it can be 5:1, 5:2, 5:4, 5:6, 5:8 or 5:10, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0046] The purpose of mixing micro-nanoparticles into the catalyst powder is to increase the interstices between the photocatalyst particles, providing space for water transfer and gas evolution. Too high a content of these micro-nanoparticles will reduce the photocatalyst particle content, while too low a content will not provide sufficient space for water transfer and gas evolution, affecting the photocatalytic effect.

[0047] Preferably, the average particle size of the micro-nanoparticles in step (3) is 0.5 to 5 μm, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0048] Preferably, the ultrasonic dispersion time in step (3) is 2 to 10 minutes, for example, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes or 9 minutes, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0049] Preferably, the auxiliary agent in step (3) includes acetylacetone.

[0050] Preferably, the surfactant in step (3) includes any one or a combination of at least two of sodium lauryl sulfate, isopropyl alcohol or polyvinyl alcohol. Typical but non-limiting combinations include a combination of sodium lauryl sulfate and isopropyl alcohol, a combination of sodium lauryl sulfate and polyvinyl alcohol, a combination of isopropyl alcohol and polyvinyl alcohol, or a combination of sodium lauryl sulfate, isopropyl alcohol and polyvinyl alcohol.

[0051] Preferably, the film forming method in step (4) includes any one of a scraping method, a spin coating method or a dripping method.

[0052] Preferably, the scraping method comprises: repeatedly dripping the suspension obtained in step (3) onto the mesoporous silica substrate, scraping it flat, and then drying it.

[0053] The present invention adopts a scraping film method to prepare a strontium titanate thin film composite catalyst. The film layer prepared by the scraping film method is thicker and forms a porous structure, which is beneficial to photocatalysis.

[0054] Preferably, the pore size of the mesoporous silica substrate is 2 to 50 nm, for example, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm or 45 nm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0055] Preferably, the number of repetitions is 5 to 10 times, for example, 5 times, 6 times, 7 times, 8 times, 9 times or 10 times.

[0056] Preferably, the drying temperature is 50°C to 90°C, for example, 50°C, 60°C, 70°C, 80°C or 90°C, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0057] Preferably, the calcination temperature in step (4) is 300°C to 500°C, for example, 300°C, 350°C, 400°C, 450°C or 500°C, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0058] Preferably, the calcination time in step (4) is 1 h to 5 h, for example, 1 h, 2 h, 3 h, 4 h or 5 h, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0059] The present invention obtains a strontium titanate thin film composite catalyst for photolysis of water to produce hydrogen by calcination. If the calcination temperature is too high, the film surface active material may crack, while if the calcination temperature is too low, the film surface active material may have insufficient mechanical strength and may easily fall off.

[0060] As a preferred technical solution of the present invention, the preparation method of the strontium titanate thin film composite catalyst for photocatalytic water decomposition to produce hydrogen provided in the first aspect of the present invention comprises the following steps:

[0061] (1) SrTiO3:Al is obtained by mixing strontium titanate, aluminum oxide, and strontium oxide in an alumina crucible at a molar ratio of 1:(0.01-0.1):(5-12), calcining the mixture at 1000°C-1300°C for 8-12 hours, and then washing the mixture with deionized water for 2-5 times.

[0062] (2) dispersing the SrTiO3:Al obtained in step (1) in water, adding a heavy metal ion solution, performing a photodeposition reaction, drying at 50°C to 100°C, and calcining at 300°C to 500°C for 1h to 5h to obtain a catalyst powder;

[0063] In the catalyst powder, the loading amounts of rhodium, chromium and cobalt are all 0.01wt% to 0.3wt%;

[0064] (3) mixing micro-nanoparticles with an average particle size of 0.5 to 5 μm and the catalyst powder obtained in step (2) in water at a mass ratio of 5:(1 to 10), and mixing with acetylacetone and a surfactant after ultrasonic dispersion to obtain a suspension;

[0065] (4) Repeat the process of dripping the suspension obtained in step (3) onto a mesoporous silica substrate, flattening it, and then drying it at 50°C to 90°C. After repeating this process 5 to 10 times, the suspension is calcined at 300°C to 500°C for 1 hour to 5 hours to obtain the strontium titanate thin film composite catalyst for photocatalytic water splitting to produce hydrogen.

[0066] In a second aspect, the present invention provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water, wherein the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water is obtained by the preparation method provided in the first aspect.

[0067] Preferably, the thickness of the strontium titanate thin film composite catalyst for photolysis of water to hydrogen is 0.5 mm to 3 mm, for example, it can be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm or 3 mm, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0068] In a third aspect, the present invention provides an application of a strontium titanate thin film composite catalyst for producing hydrogen from photocatalytic water splitting obtained by the preparation method provided in the first aspect, wherein the strontium titanate thin film composite catalyst for producing hydrogen from photocatalytic water splitting is used for producing hydrogen;

[0069] The hydrogen production comprises: immersing the strontium titanate thin film composite catalyst in water to generate hydrogen under light;

[0070] The hydrogen production rate in the hydrogen production process is 1 mmol / gh to 20 mmol / gh, for example, 5 mmol / gh, 9 mmol / gh, 13 mmol / gh, 17 mmol / gh or 20 mmol / gh, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0071] In the hydrogen production process of the present invention, the strontium titanate thin film composite catalyst and the mesoporous silica substrate are immersed in water at the same time. When the catalyst is deactivated, it can be removed from the water or recovered in time.

[0072] The numerical range described in the present invention includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0073] Compared with the prior art, the present invention has the following beneficial effects:

[0074] (1) The strontium titanate thin film composite catalyst provided by the present invention has high catalytic activity, good hydrogen production effect, and is easy to recycle without causing secondary pollution to the environment;

[0075] (2) The preparation method of the strontium titanate thin film composite catalyst provided by the present invention is simple, does not cause secondary pollution to the environment, and is conducive to large-scale production;

[0076] (3) The present invention adopts a scraping film method to prepare a strontium titanate thin film composite catalyst. The film layer prepared by the scraping film method is thicker and forms a porous structure, which is beneficial to photocatalysis. DETAILED DESCRIPTION

[0077] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0078] Example 1

[0079] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water comprises the following steps:

[0080] (1) SrTiO3:Al was obtained by mixing strontium titanate, aluminum oxide, and strontium oxide in a molar ratio of 1:0.05:8.5 in an alumina crucible, calcining at 1150°C for 10 h, and then washing with deionized water three times.

[0081] (2) dispersing the SrTiO3:Al obtained in step (1) in water, adding a rhodium source solution, a chromium source solution, and a cobalt source solution, performing a photodeposition reaction, drying at 80°C, and calcining at 400°C for 3h to obtain a catalyst powder;

[0082] The catalyst powder has a rhodium loading of 0.2 wt%, a chromium loading of 0.2 wt%, and a cobalt loading of 0.2 wt%;

[0083] (3) mixing aluminum oxide particles with an average particle size of 3 μm and the catalyst powder obtained in step (2) in a mass ratio of 5:5 in water, and mixing with acetylacetone and a surfactant after ultrasonic dispersion to obtain a suspension;

[0084] (4) Repeat the process of dripping the suspension obtained in step (3) onto a mesoporous silica substrate, scraping it flat, and then drying it at 70° C. This was repeated 8 times, and then calcined at 400° C. for 3 h to obtain the strontium titanate thin film composite catalyst for photocatalytic water splitting to produce hydrogen.

[0085] The thickness of the catalyst in this embodiment is 1.5 mm.

[0086] Example 2

[0087] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water comprises the following steps:

[0088] (1) SrTiO3:Al was obtained by mixing strontium titanate, aluminum oxide, and strontium oxide in an alumina crucible at a molar ratio of 1:0.01:5, calcining the mixture at 1000°C for 12 hours, and then washing the mixture twice with deionized water.

[0089] (2) dispersing the SrTiO3:Al obtained in step (1) in water, adding a rhodium source solution, a chromium source solution, and a cobalt source solution, performing a photodeposition reaction, drying at 50°C, and calcining at 300°C for 5h to obtain a catalyst powder;

[0090] The catalyst powder has a rhodium loading of 0.01 wt%, a chromium loading of 0.01 wt%, and a cobalt loading of 0.01 wt%;

[0091] (3) mixing zirconium oxide particles with an average particle size of 5 μm and the catalyst powder obtained in step (2) in water at a mass ratio of 5:1, and mixing with acetylacetone and a surfactant after ultrasonic dispersion to obtain a suspension;

[0092] (4) Repeat the process of dripping the suspension obtained in step (3) onto a mesoporous silica substrate, scraping it flat, and then drying it at 50° C. After repeating this process 10 times, the substrate was calcined at 300° C. for 5 h to obtain the strontium titanate thin film composite catalyst for photocatalytic water splitting to produce hydrogen.

[0093] The thickness of the catalyst in this embodiment is 2 mm.

[0094] Example 3

[0095] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water comprises the following steps:

[0096] (1) SrTiO3:Al was obtained by mixing strontium titanate, aluminum oxide, and strontium oxide in a molar ratio of 1:0.1:12 in an alumina crucible, calcining the mixture at 1300°C for 8 hours, and then washing the mixture with deionized water five times.

[0097] (2) dispersing the SrTiO3:Al obtained in step (1) in water, adding a heavy metal ion solution, performing a photodeposition reaction, drying at 100°C, and calcining at 500°C for 1h to obtain a catalyst powder;

[0098] The catalyst powder has a rhodium loading of 0.3 wt%, a chromium loading of 0.3 wt%, and a cobalt loading of 0.3 wt%;

[0099] (3) mixing tungsten oxide particles with an average particle size of 0.5 μm and the catalyst powder obtained in step (2) in water at a mass ratio of 5:10, and mixing with acetylacetone and a surfactant after ultrasonic dispersion to obtain a suspension;

[0100] (4) Repeat the process of dripping the suspension obtained in step (3) onto a mesoporous silica substrate, scraping it flat, and then drying it at 90° C. After repeating this process 5 times, the substrate was calcined at 500° C. for 1 h to obtain the strontium titanate thin film composite catalyst for photocatalytic water splitting to produce hydrogen.

[0101] The thickness of the catalyst in this embodiment is 1 mm.

[0102] Example 4

[0103] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water differs from that of Example 1 only in that:

[0104] In this embodiment, the heavy metal solution in step (2) is changed to a rhodium source solution and a chromium source solution. The loading amount of rhodium in the catalyst powder in step (2) is 0.3 wt%, and the loading amount of chromium is 0.3 wt%.

[0105] Example 5

[0106] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water differs from that of Example 1 only in that:

[0107] In this embodiment, the heavy metal solution in step (2) is changed to a rhodium source solution; the rhodium loading in the catalyst powder in step (2) is 0.6 wt%.

[0108] Example 6

[0109] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water differs from that of Example 1 only in that:

[0110] In this embodiment, the heavy metal solution in step (2) is changed to a chromium source solution; the chromium loading in the catalyst powder in step (2) is 0.6 wt%.

[0111] Example 7

[0112] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water differs from that of Example 1 only in that:

[0113] In this embodiment, the heavy metal solution in step (2) is replaced with a cobalt source solution; the cobalt loading in the catalyst powder in step (2) is 0.6 wt%.

[0114] Example 8

[0115] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water differs from that of Example 1 only in that:

[0116] In this embodiment, the molar ratio of strontium titanate, aluminum oxide, and strontium oxide in step (1) is changed to 1:0.5:8.5.

[0117] Example 9

[0118] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water differs from that of Example 1 only in that:

[0119] In this embodiment, the molar ratio of strontium titanate, aluminum oxide, and strontium oxide in step (1) is changed to 1:0.05:15.

[0120] Example 10

[0121] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water differs from that of Example 1 only in that:

[0122] In this embodiment, the calcination temperature in step (4) is changed to 250°C.

[0123] Example 11

[0124] This embodiment provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water differs from that of Example 1 only in that:

[0125] In this embodiment, the calcination temperature in step (4) is changed to 550°C.

[0126] Comparative Example 1

[0127] This comparative example provides a strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen by photolysis of water differs from that of Example 1 only in that:

[0128] In this comparative example, the micro-nanoparticles described in step (3) were omitted.

[0129] Comparative Example 2

[0130] This comparative example provides a strontium titanate composite catalyst for producing hydrogen from water by photolysis. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen from water by photolysis differs from that of Example 1 only in that:

[0131] In this comparative example, the film forming process described in step (4) was omitted and replaced with the following steps: drying the suspension described in step (3) at 80° C. and then calcining at 400° C. for 3 h to obtain catalyst powder.

[0132] Comparative Example 3

[0133] This comparative example provides a strontium titanate composite catalyst for producing hydrogen from water by photolysis. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen from water by photolysis differs from that of Example 1 only in that:

[0134] In this comparative example, the mesoporous silica substrate described in step (4) is modified into a frosted glass panel.

[0135] Comparative Example 4

[0136] This comparative example provides a strontium titanate composite catalyst for producing hydrogen from water by photolysis. The preparation method of the strontium titanate thin film composite catalyst for producing hydrogen from water by photolysis differs from that of Example 1 only in that:

[0137] In this comparative example, the micro-nano particles described in step (3) were modified to silica particles of the same mass.

[0138] The composite catalysts provided in Examples 1-11 and Comparative Examples 1-3 were used to produce hydrogen by hydrolysis. The catalysts were immersed in water and irradiated with a 350W xenon lamp to produce hydrogen. The hydrogen production rates are shown in Table 1.

[0139] Table 1

[0140]

[0141]

[0142] It can be seen from Table 1 that, from the analysis of Examples 1-5, it can be seen that the heavy metal content will further affect the hydrogen production efficiency of the composite catalyst; from the analysis of Example 1 and Comparative Example 2, it can be seen that when the catalyst is dispersed in water in powder form, its hydrogen production rate is slightly increased. The reason is that the powdered catalyst has a higher light utilization rate, but the powdered catalyst cannot be recycled for a second time, which in turn causes secondary pollution to the environment; from the analysis of Example 1 and Comparative Example 3, it can be seen that the hydrogen production rate of using a mesoporous silica plate as a substrate is higher than that of a frosted glass plate as a substrate. The reason is that there are a large number of pores in the mesoporous silica substrate, which can better adsorb the catalyst; from the analysis of Example 1 and Comparative Example 4, it can be seen that the hydrogen production rates of micro-nano particles and silica particles are similar. Both mainly serve to increase the voids in the photocatalyst particle layer and provide space for water transfer and gas precipitation, but the uniformity of micro-nano particles is easier to control and more stable, and the regulation of the void space is more precise.

[0143] In summary, the strontium titanate thin film composite catalyst provided by the present invention has high photocatalytic activity and good hydrogen production effect; in addition, the strontium titanate thin film composite catalyst of the present invention is easy to recycle and will not cause secondary pollution to the environment. It is a feasible means of photocatalytic water hydrogen production that can be produced on a large scale.

[0144] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a strontium titanate thin film composite catalyst for photocatalytic water decomposition to produce hydrogen, characterized in that: The preparation method comprises the following steps: (1) SrTiO3:Al is obtained by mixing strontium titanate, aluminum oxide, and strontium oxide in a reaction vessel, and then calcining and washing them in sequence; (2) dispersing the SrTiO3:Al obtained in step (1) in water, adding a metal ion solution, and drying and calcining the solution after photodeposition reaction to obtain a catalyst powder; The metal ion solution includes any one of a rhodium source solution, a chromium source solution or a cobalt source solution, or a combination of at least two thereof; (3) mixing the micro-nano particles and the catalyst powder obtained in step (2) in water, and then ultrasonically dispersing the mixture and mixing it with an auxiliary agent and a surfactant to obtain a suspension; The mass ratio of the micro-nano particles to the catalyst powder is 5:(1-10); the micro-nano particles include any one of aluminum oxide, zirconium oxide, or tungsten oxide, or a combination of at least two thereof; the average particle size of the micro-nano particles is 0.5-5 μm; (4) The suspension obtained in step (3) is prepared into a film on a mesoporous silica substrate, and the film is calcined to obtain the strontium titanate thin film composite catalyst for photocatalytic water splitting and hydrogen production.

2. The preparation method according to claim 1, characterized in that The molar ratio of strontium titanate, aluminum oxide and strontium oxide in step (1) is 1:(0.01-0.1):(5-12).

3. The preparation method according to claim 1, characterized in that The calcination temperature in step (1) is 1000°C to 1300°C.

4. The preparation method according to claim 1, characterized in that The calcination time in step (1) is 8 h to 12 h.

5. The preparation method according to claim 1, characterized in that The washing liquid used in step (1) includes deionized water.

6. The preparation method according to claim 1, characterized in that The number of washing steps (1) is 2 to 5 times.

7. The preparation method according to claim 1, characterized in that The reaction vessel in step (1) includes a crucible.

8. The preparation method according to claim 7, characterized in that The crucible includes an alumina crucible.

9. The preparation method according to claim 1, characterized in that The rhodium source solution includes rhodium trichloride hydrate and / or sodium hexachlororhodate.

10. The preparation method according to claim 1, characterized in that The chromium source solution includes chromium nitrate and / or potassium chromate.

11. The preparation method according to claim 1, characterized in that The cobalt source solution includes cobalt chloride and / or cobalt nitrate.

12. The preparation method according to claim 1, characterized in that The light source used in the photodeposition in step (2) includes a xenon lamp.

13. The preparation method according to claim 1, characterized in that The optical power in the optical deposition in step (2) is 200W to 500W.

14. The preparation method according to claim 1, characterized in that The photodeposition time in step (2) is 2 min to 40 min.

15. The preparation method according to claim 1, characterized in that The drying temperature in step (2) is 50°C to 100°C.

16. The preparation method according to claim 1, characterized in that The calcination temperature in step (2) is 300°C to 500°C.

17. The preparation method according to claim 1, characterized in that The calcination time in step (2) is 1 h to 5 h.

18. The preparation method according to claim 1, characterized in that The rhodium loading in the catalyst powder in step (2) is 0.01 wt% to 0.3 wt%.

19. The preparation method according to claim 1, characterized in that The chromium loading in the catalyst powder in step (2) is 0.01 wt% to 0.3 wt%.

20. The preparation method according to claim 1, characterized in that The cobalt loading in the catalyst powder in step (2) is 0.01 wt% to 0.3 wt%.

21. The preparation method according to claim 1, characterized in that The ultrasonic dispersion time in step (3) is 2 to 10 minutes.

22. The preparation method according to claim 1, characterized in that The auxiliary agent in step (3) includes acetylacetone.

23. The preparation method according to claim 1, characterized in that The surfactant in step (3) includes any one of sodium lauryl sulfate, isopropyl alcohol or polyvinyl alcohol, or a combination of at least two of them.

24. The preparation method according to claim 1, characterized in that The film forming method in step (4) includes any one of a scraping method, a spin coating method or a dripping method.

25. The preparation method according to claim 24, characterized in that The scraping method comprises the following steps: repeatedly dripping the suspension obtained in step (3) onto the mesoporous silica substrate, scraping it flat, and then drying it.

26. The preparation method according to claim 25, characterized in that The pore size of the mesoporous silica substrate is 2-50 nm.

27. The preparation method according to claim 25, characterized in that The number of repetitions is 5 to 10 times.

28. The preparation method according to claim 25, characterized in that The drying temperature is 50°C to 90°C.

29. The preparation method according to claim 1, characterized in that The calcination temperature in step (4) is 300°C to 500°C.

30. The preparation method according to claim 1, characterized in that The calcination time in step (4) is 1 h to 5 h.

31. The preparation method according to claim 1, characterized in that The preparation method comprises the following steps: (1) SrTiO3:Al was obtained by mixing strontium titanate, alumina and strontium oxide in an alumina crucible at a molar ratio of 1:(0.01-0.1):(5-12), calcining at 1000-1300°C for 8-12 h, and then washing with deionized water 2-5 times. (2) The SrTiO3:Al obtained in step (1) is dispersed in water, a metal ion solution is added, and after a photodeposition reaction, the catalyst is dried at 50°C to 100°C, and then calcined at 300°C to 500°C for 1 h to 5 h to obtain a catalyst powder; In the catalyst powder, the loading amounts of rhodium, chromium and cobalt are all 0.01 wt% to 0.3 wt%; (3) mixing micro-nano particles with an average particle size of 0.5-5 μm and the catalyst powder obtained in step (2) in water at a mass ratio of 5:(1-10), and mixing with acetylacetone and a surfactant after ultrasonic dispersion to obtain a suspension; (4) Repeat the process of dripping the suspension obtained in step (3) onto a mesoporous silica substrate, scraping it flat, and then drying it at 50°C to 90°C. After repeating this process 5 to 10 times, the substrate is calcined at 300°C to 500°C for 1 h to 5 h to obtain the strontium titanate thin film composite catalyst for photocatalytic water splitting to produce hydrogen.

32. A strontium titanate thin film composite catalyst for photolysis of water to produce hydrogen, characterized in that: The strontium titanate thin film composite catalyst for photolysis of water to produce hydrogen is prepared by the preparation method described in any one of claims 1 to 31.

33. The strontium titanate thin film composite catalyst for photocatalytic water decomposition to produce hydrogen according to claim 32, characterized in that: The thickness of the strontium titanate thin film composite catalyst for photolysis of water to produce hydrogen is 0.5 mm to 3 mm.

34. An application of the strontium titanate thin film composite catalyst for photocatalytic water decomposition to produce hydrogen as claimed in claim 32 or 33, characterized in that: The strontium titanate thin film composite catalyst for photolysis of water to produce hydrogen is used for producing hydrogen; The hydrogen production comprises: immersing the strontium titanate thin film composite catalyst in water to generate hydrogen under light; The hydrogen production rate in the hydrogen production process is 1 mmol / g·h to 20 mmol / g·h.

Images