Application of piezoelectric-photocatalytic composite material in spiral-flow type hydrogen production device

Abstract

The invention discloses application of a piezoelectric-photocatalytic composite material in a spiral-flow type hydrogen production device, and belongs to the technical field of energy environments and materials. The preparation method comprises the following steps: growing a ZnO nanorod array on the surface of a designed porous material in situ through a hydrothermal method, and carrying out annealing treatment to obtain a composite structure with remarkable piezoelectric property; then the composite material is placed in a spiral-flow type hydrogen production device matched with the composite material, the piezoelectric effect of the piezoelectric-photocatalytic composite material can be improved under excitation of a high-speed rotating turbulent flow field, and meanwhile efficient gathering and separation of hydrogen are achieved through a central negative pressure area. Experimental verification shows that ZnO / NF particles show higher hydrogen evolution efficiency and stability under the action of dynamic shear force after the designed piezoelectric-photocatalytic composite material loaded ZnO particles are put into a cyclone. The test verifies that the piezoelectric-photocatalytic composite material prepared by the invention has the optimal hydrogen evolution rate at the rotating speed of 1000rpm.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy environment and materials, and particularly relates to application of a piezoelectric-photocatalysis composite material in a rotational flow type hydrogen production device. BACKGROUND

[0002] With the rapid development of industrialization, environmental pollution and energy crisis problems are increasingly prominent. The continuous advancement of global industrialization and urbanization has led to a continuous increase in energy demand, and the overuse of traditional fossil energy has resulted in pollution of the atmosphere, water bodies and soil and other multi-medium environments. Under this background, the development of a clean energy system has become a global strategic issue. Hydrogen energy, as an energy carrier with high energy density, zero carbon emissions and renewable characteristics, is becoming the most promising solution in the future energy system. In particular, although the technology of photocatalytic decomposition of water driven by solar energy to produce hydrogen has made significant progress, there are still many technical bottlenecks that need to be broken through. For example, piezoelectric photocatalytic materials driven by mechanical energy and solar energy to drive catalytic reactions can improve the efficiency of water decomposition to produce hydrogen, and are one of the keys to realizing large-scale application of hydrogen energy. How to make piezoelectric-photocatalytic materials and water decomposition to produce hydrogen with maximum efficiency to improve hydrogen production efficiency and promote resource recycling has become the core research direction in the field of energy conversion. SUMMARY

[0003] The purpose of the present application is to provide a piezoelectric-photocatalysis composite material in a rotational flow type hydrogen production device, which can produce hydrogen efficiently by precisely designing the pore structure of the porous nickel foam carrier and loading ZnO nanorod arrays to obtain a piezoelectric-photocatalysis composite material, and placing it in a rotational flow type hydrogen production device with a rotational turbulent flow field of 1000 rpm.

[0004] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0005] The application of a piezoelectric-photocatalysis composite material in a rotational flow type hydrogen production device includes the following steps:

[0006] a. Wire cutting to obtain foam nickel particles with different pore densities, and pretreating the same;

[0007] b. Immersing the pretreated foam nickel particles in a zinc acetate ethanol solution, drying and then annealing to obtain a ZnO seed layer;

[0008] c. Placing the ZnO seed layer in a hydrothermal reaction solution containing zinc nitrate hexahydrate and hexamethylenetetramine to grow ZnO nanorod arrays, and then washing and drying the obtained product to obtain a piezoelectric-photocatalysis composite material with a ZnO / NF structure; the porosity of the piezoelectric-photocatalysis composite material is 40 PPI;

[0009] d. Placing the piezoelectric-photocatalytic composite material in a water solution containing a sacrificial agent, and performing a reaction under the condition of a rotating turbulent flow field provided by a rotating flow hydrogen production device at 1000 rpm and light irradiation, to excite piezoelectric polarization of the piezoelectric-photocatalytic composite material and promote photocatalytic hydrogen evolution.

[0010] In the application of the piezoelectric-photocatalytic composite material in the rotating flow hydrogen production device, in step a, the diameter of the nickel foam particles is 5 mm, and the thickness is 5 mm; the pore density of the nickel foam particles is 20-60 PPI; the pretreatment of the nickel foam particles includes pickling, alcohol washing, water washing, and drying treatment.

[0011] In the application of the piezoelectric-photocatalytic composite material in the rotating flow hydrogen production device, in step b, the concentration of the zinc acetate ethanol solution is 50-70 mM; the immersion time is 50-70 s, the drying temperature is 70-90 °C, the annealing heating rate is 0.5-1.5 °C / min, and the annealing temperature is 300-400 °C.

[0012] In the application of the piezoelectric-photocatalytic composite material in the rotating flow hydrogen production device, in step c, the concentration ratio of zinc nitrate hexahydrate to hexamethylenetetramine is 1:1, the reaction temperature is 90-100 °C, and the reaction time is 5-7 h; the drying temperature is 50-70 °C.

[0013] In the application of the piezoelectric-photocatalytic composite material in the rotating flow hydrogen production device, in step d, the water solution of the sacrificial agent is a mixed solution of 5 mM Na2S and 5 mM Na2SO3, and the light irradiation condition is a 300 W xenon lamp with λ < 400 nm.

[0014] In the application of the piezoelectric-photocatalytic composite material in the rotating flow hydrogen production device, in step d, the rotating flow hydrogen production device includes a hydrocyclone reactor for generating a high-speed rotating flow field, a central negative pressure area for hydrogen bubble convergence and discharge, a light source irradiation system for providing ultraviolet light irradiation, a catalyst recovery port, and a reaction liquid circulation channel.

[0015] In the application of the piezoelectric-photocatalytic composite material in the rotating flow hydrogen production device, the hydrocyclone reactor is designed with adjustable rotating speed.

[0016] In the application of the piezoelectric-photocatalytic composite material in the rotating flow hydrogen production device, the hydrocyclone reactor includes a feed port, a cyclone cavity, and an overflow port, and a hydrocyclone member for generating a high-speed rotating flow field is arranged in the cyclone cavity.

[0017] The application of the piezoelectric-photocatalytic composite material in a rotating flow type hydrogen production device, wherein the ZnO nanorods are vertically distributed on the surface of the foam nickel, and the average diameter is 100 nm and the length is 1.5 microns.

[0018] The mechanism of the application is as follows:

[0019] By designing the foam nickel carrier with a specific porosity (PPI), the ZnO nanorod array is assembled on the surface of the pretreated foam nickel to obtain the piezoelectric-photocatalytic composite material ZnO / NF, and the piezoelectric-photocatalytic hydrogen evolution performance of the material in the rotating flow type hydrogen production device is investigated. The competitive influence law of the porosity (PPI) of the foam nickel on the piezoelectric polarization efficiency and the light absorption area in the rotating flow field is revealed. By adjusting the pore structure, the optimal balance between the piezoelectric excitation and the light capture can be achieved. In the rotating turbulent flow field (1000 rpm), the ZnO / NF-40PPI maximizes the separation of the photo-generated carriers and promotes the surface reduction reaction, and the hydrogen production rate reaches the peak value of 1.02 mmol·g -1 ·h-1. The application proves that the design of the pore structure matching the rotating flow type hydrogen production device is the key to improving the piezoelectric-photocatalytic hydrogen production efficiency.

[0020] Compared with the prior art, the application has the following beneficial technical effects:

[0021] (1) The nickel-based material used in the application has a lower price than the traditional catalytic hydrogen production catalyst, is widely available, and can be mass-produced.

[0022] (2) By testing, it can be obtained that the hydrogen evolution rate of ZnO / NF-p is 3.1 times that of ZnO / NF-s (0.35 mmol·g -1 ·h -1 ) and 7.3 times that of ZnO / FTO (0.14 mmol·g -1 ·h -1 ) at a stirring rate of 1000 rpm, which is more efficient. BRIEF DESCRIPTION OF DRAWINGS

[0023] The application will be further described below in combination with the drawings:

[0024] Figure 1 The X-ray diffraction pattern and the crystal lattice structure diagram of the piezoelectric-photocatalytic composite material (ZnO / NF) prepared by the application.

[0025] Figure 2 The Raman spectrum diagram of ZnO and ZnO / NF-20PPI samples;

[0026] Figure 3Fig. 1 is a scanning electron microscope image of the piezophotocatalytic composite material (ZnO / NF) prepared in the application, Fig. 2 is a high-resolution transmission electron microscope (HR-TEM) image of the ZnO nanorod, Figs. 3 and 4 are micro-morphology and three-dimensional morphology of the ZnO nanorod and corresponding amplitude and phase images under an applied alternating voltage, and Fig. 5 is an amplitude-voltage curve of the ZnO obtained under an alternating bias field of ±10V.

[0027] Figure 4 Fig. 6 is a performance test diagram of the piezophotocatalytic composite material (ZnO / NF) at different PPI, and Fig. 7 is a diagram of hydrogen evolution rate per unit time and per unit mass at different PPI;

[0028] Figure 5 Fig. 8 is a performance comparison of a traditional stirrer and a hydrocyclone at 1000 rpm, and Fig. 9 is a comparison diagram of hydrogen evolution rates of the two;

[0029] Figure 6 Fig. 10 is a performance comparison of a traditional sheet nickel and a porous foam nickel at 1000 rpm, and Fig. 11 is a comparison diagram of hydrogen evolution rates of the two;

[0030] Figure 7 Fig. 12 is a piezophotocatalytic stability test diagram of the piezophotocatalytic composite material (ZnO / NF) particles (40PPI);

[0031] Figure 8 Fig. 13 is a structural schematic diagram of the cyclone type hydrogen production device. DETAILED DESCRIPTION

[0032] The application proposes an application of a piezophotocatalytic composite material in a cyclone type hydrogen production device, and the application will be further described below in combination with specific embodiments.

[0033] The raw materials described in the application can be purchased through a commercial channel.

[0034] Example 1

[0035] The application is a specific preparation method of the ZnO / NF-20 piezophotocatalytic composite material, and the preparation method comprises the following steps:

[0036] Step 1, foam nickel substrate pretreatment: 20PPI foam nickel particles (diameter 5mm, thickness 5mm) are prepared by wire cutting technology; the foam nickel particles are sequentially placed in 3M dilute hydrochloric acid for ultrasonic cleaning for 10 minutes, and then ultrasonic cleaning is performed with anhydrous ethanol and deionized water for 15 minutes each time; after cleaning, the foam nickel particles are dried in a vacuum drying oven at 110℃ for 2 hours.

[0037] Step 2, ZnO seed layer deposition: Immerse the dried nickel foam particles in a 60mM zinc acetate ethanol solution for 60 seconds, dry at 80℃ for 5 minutes, and repeat the immersion-drying step three times; anneal at 350℃ for 1 hour with the temperature increased at 1℃ / min to form a ZnO seed layer.

[0038] Step 3, hydrothermal growth of ZnO nanorod array: Prepare hydrothermal reaction solution: Dissolve 60 mM Zn(NO3)2·6H2O and 60 mM MMTA in deionized water; Place seeded nickel foam particles in a 100 mL polytetrafluoroethylene reactor and hydrothermally react at 95 °C for 6 hours; After removal, rinse three times with deionized water and dry at 60 °C for 12 hours to obtain ZnO / NF-20 piezoelectric-photocatalytic composite material.

[0039] XRD and Raman analyses revealed characteristic peaks in the ZnO wurtzite structure (JCPDS No. 36-1451) and the nickel foam matrix (JCPDS No. 04-0850), such as... Figure 1 and Figure 2 As shown.

[0040] The piezoelectric-photocatalytic composite material prepared above can be applied to, for example... Figure 8 In the cyclone hydrogen production device shown, such as Figure 8 As shown, the cyclone hydrogen production device includes a hydrocyclone reactor for generating a high-speed rotating flow field, a central negative pressure zone for hydrogen bubble convergence and discharge, a light source irradiation system for providing ultraviolet light irradiation, a catalyst recovery port, and a reaction liquid circulation channel. The hydrocyclone reactor is designed with adjustable rotation speed. The hydrocyclone reactor includes a feed inlet, a cyclone chamber, and an overflow port. A hydrocyclone circulation element for generating a high-speed rotating flow field is provided in the cyclone chamber. The operation method of the cyclone hydrogen production device can be implemented by those skilled in the art with reference to existing technology. The piezoelectric-photocatalytic composite material prepared in the above embodiment was applied to the cyclone hydrogen production device for performance testing: 1g of ZnO / NF-20 was loaded into the hydrocyclone reactor, 60mL of a solution containing 5mM Na2S and 5mM Na2SO3 was added, a 300W xenon lamp (λ<400nm) and a hydrocyclone (rotation speed 1000rpm) were turned on, and continuous operation was carried out at 25℃. The hydrogen evolution rate was 0.24mmol·g. -1 ·h-1, such as Figure 4 As shown, Figure 4 (a) shows the performance test graph of the piezoelectric-photocatalytic composite material (ZnO / NF) at different PPIs, and (b) shows the hydrogen evolution rate per unit time and per unit mass at different PPIs.

[0041] Example 2:

[0042] The application discloses a preparation method of a ZnO / NF-30PPI composite material, and specifically comprises the following steps.

[0043] Step one, foam nickel substrate pretreatment: 30PPI foam nickel particles (diameter 5mm, thickness 5mm) are prepared by wire cutting technology; the foam nickel particles are sequentially placed in 3M dilute hydrochloric acid for ultrasonic cleaning for 10 minutes, and then ultrasonic cleaning is performed with anhydrous ethanol and deionized water for 15 minutes; after cleaning, drying is performed in a vacuum drying box at 110 DEG C for 2 hours.

[0044] Step two, ZnO seed layer deposition: the dried foam nickel particles are immersed in a 60mM zinc acetate ethanol solution for 60 seconds, dried at 80 DEG C for 5 minutes, and the immersion-drying step is repeated for three times; annealing is performed at 1 DEG C / min to 350 DEG C for 1 hour to form a ZnO seed layer.

[0045] Step three, hydrothermal growth of ZnO nanorod array: a hydrothermal reaction solution is prepared by dissolving 60mM Zn(NO3)2.6H2O and 60mM HMTA in deionized water; the foam nickel particles loaded with the seed are placed in a 100mL polytetrafluoroethylene reaction kettle, and hydrothermal reaction is performed at 95 DEG C for 6 hours; after being taken out, the foam nickel particles are washed with deionized water for three times, and drying is performed at 60 DEG C for 12 hours to obtain a ZnO / NF-30 composite material.

[0046] The cyclone performance test is performed, 1g ZnO / NF-30 is loaded into a hydrocyclone reactor, 60mL of a solution containing 5mM Na2S and 5mM Na2SO3 is added, a 300W xenon lamp (wavelength <400nm) and the cyclone (rotation speed 1000rpm) are started, and continuous operation is performed at 25 DEG C, and the hydrogen evolution rate is 0.71mmol.g -1 -1.h-1.

[0047] Example 3:

[0048] The application discloses a preparation method of a ZnO / NF-40PPI composite material, and specifically comprises the following steps:

[0049] Step one, foam nickel substrate pretreatment: 40PPI foam nickel particles (diameter 5mm, thickness 5mm) are prepared by wire cutting technology; the foam nickel particles are sequentially placed in 3M dilute hydrochloric acid for ultrasonic cleaning for 10 minutes, and then ultrasonic cleaning is performed with anhydrous ethanol and deionized water for 15 minutes; after cleaning, drying is performed in a vacuum drying box at 110 DEG C for 2 hours.

[0050] Step two, ZnO seed layer deposition: the dried foam nickel particles are immersed in a 60mM zinc acetate ethanol solution for 60 seconds, dried at 80 DEG C for 5 minutes, and the immersion-drying step is repeated for three times; annealing is performed at 1 DEG C / min to 350 DEG C for 1 hour to form a ZnO seed layer.

[0051] Step three, hydrothermal growth of ZnO nanorod arrays: prepare the hydrothermal reaction solution: 60 mM Zn(NO3)2·6H2O and 60 mM HMTA are dissolved in deionized water; the seed-loaded nickel foam particles are placed in a 100 mL polytetrafluoroethylene reactor, and hydrothermal reaction is carried out at 95℃ for 6 hours; after being taken out, it is washed with deionized water for three times, and dried at 60℃ for 12 hours to obtain the ZnO / NF-40 composite material.

[0052] The cyclone performance test is carried out, 1g of ZnO / NF-40 is loaded into the hydrocyclone reactor, 60mL of a solution containing 5mM Na2S and 5mM Na2SO3 is added, a 300W xenon lamp (λ<400nm) and the cyclone (rotation speed 1000rpm) are started, and continuous operation is carried out at 25℃, and the hydrogen evolution rate is 1.02mmol·g -1 ·h-1. In addition, the stability test is carried out, and the experiment shows that the activity remains 92% of the initial value after 15 hours, as shown in Figure 7 .

[0053] The SEM analysis of the ZnO / NF-40 PPI piezoelectric-photocatalytic composite material of the embodiment shows that the ZnO nanorods are vertically distributed on the surface of the nickel foam, with an average diameter of 100nm and a length of 1.5μm. The material has excellent piezoelectric properties, as shown in Figure 3 . Figure 3 Fig. a is a scanning electron microscope image of the piezoelectric-photocatalytic composite material (ZnO / NF) prepared by the application, Fig. b is a high-resolution transmission electron microscope (HR-TEM) image of the ZnO nanorod, Figs. c and d are micro-morphology and three-dimensional morphology of the ZnO nanorod, and the corresponding amplitude and phase images under an applied alternating voltage show clear contrast, and Fig. e is an amplitude-voltage curve of the ZnO obtained under an alternating bias field of ±10V.

[0054] Example 4:

[0055] The application discloses a preparation method of a ZnO / NF-50 PPI composite material, which specifically comprises the following steps:

[0056] Step one, pretreatment of the nickel foam substrate: 50PPI nickel foam particles (diameter 5mm, thickness 5mm) are prepared by wire cutting technology; the nickel foam particles are sequentially ultrasonically cleaned in 3M dilute hydrochloric acid for 10 minutes, and then ultrasonically cleaned with anhydrous ethanol and deionized water for 15 minutes each time; after cleaning, the particles are dried in a vacuum drying oven at 110℃ for 2 hours.

[0057] Step two, deposition of the ZnO seed layer: the dried nickel foam particles are immersed in a 60mM zinc acetate ethanol solution for 60 seconds, dried at 80℃ for 5 minutes, and the immersion-drying step is repeated three times; the temperature is increased to 350℃ at a rate of 1℃ / min, and annealing is performed for 1 hour to form a ZnO seed layer.

[0058] Step three, hydrothermal growth of ZnO nanorod arrays: prepare the hydrothermal reaction solution: 60mM Zn(NO3)2·6H2O and 60mM HMTA are dissolved in deionized water; put the seed-loaded nickel foam particles into a 100mL polytetrafluoroethylene reactor, and hydrothermal reaction at 95℃ for 6 hours; after taking out, rinse with deionized water for three times, and dry at 60℃ for 12 hours to obtain ZnO / NF-50 composite material.

[0059] Perform cyclone performance test, put 1g ZnO / NF-50 into the hydrocyclone reactor, add 60mL solution containing 5mM Na2S and 5mM Na2SO3, open 300W xenon lamp (λ<400nm) and cyclone (rotation speed 1000rpm), continuously run at 25℃, and the hydrogen evolution rate is 0.90mmol·g -1 ·h-1.

[0060] Example 5:

[0061] The application discloses a preparation method of ZnO / NF-60PPI composite material, which comprises the following steps:

[0062] Step one, pretreatment of nickel foam matrix: 60PPI nickel foam particles (diameter 5mm, thickness 5mm) are prepared by wire cutting technology; the nickel foam particles are sequentially ultrasonically cleaned in 3M dilute hydrochloric acid for 10 minutes, and then ultrasonically cleaned with anhydrous ethanol and deionized water for 15 minutes each time; after cleaning, the nickel foam particles are dried in a vacuum drying box at 110℃ for 2 hours.

[0063] Step two, deposition of ZnO seed layer: the dried nickel foam particles are immersed in 60mM zinc acetate ethanol solution for 60 seconds, dried at 80℃ for 5 minutes, and the immersion-drying step is repeated three times; annealing at 1℃ / min to 350℃ for 1 hour to form a ZnO seed layer.

[0064] Step three, hydrothermal growth of ZnO nanorod arrays: prepare the hydrothermal reaction solution: 60mM Zn(NO3)2·6H2O and 60mM HMTA are dissolved in deionized water; put the seed-loaded nickel foam particles into a 100mL polytetrafluoroethylene reactor, and hydrothermal reaction at 95℃ for 6 hours; after taking out, rinse with deionized water for three times, and dry at 60℃ for 12 hours to obtain ZnO / NF-60 composite material.

[0065] Perform cyclone performance test, put 1g ZnO / NF-60 into the hydrocyclone reactor, add 60mL solution containing 5mM Na2S and 5mM Na2SO3, open 300W xenon lamp (λ<400nm) and cyclone (rotation speed 1000rpm), continuously run at 25℃, and the hydrogen evolution rate is 0.65mmol·g -1 ·h-1.

[0066] Comparative Example 1:

[0067] The present comparative example compares a traditional stirring reactor (1000 rpm).

[0068] The piezoelectric-photocatalytic hydrogen evolution test was carried out, and the test method was as follows:

[0069] Step one, using ZnO / NF-40 material (40PPI porous nickel foam substrate loaded with ZnO nanorod array), sacrificial agent: 60 mL of aqueous solution containing 5 mM Na2S and 5 mM Na2SO3, argon gas was passed for 30 min to remove oxygen, 300 W xenon lamp (λ < 400 nm), the light intensity was calibrated to 100 mW / cm 2 , flow field control: hydrocyclone reactor: 1000 rpm, central negative pressure area (-5.2 kPa); traditional stirring reactor: 1000 rpm magnetic stirring.

[0070] Step two, hydrogen detection: sampling every 30 min, quantitative analysis of H2 production by gas chromatography (GC 9790II, TCD detector), Ar as carrier gas. Finally, the hydrogen evolution rate was determined according to the ratio of hydrogen production per unit time to catalyst mass (total mass of nickel foam particles).

[0071] The hydrogen evolution rate of the traditional stirring reactor (1000 rpm) of the present comparative example was 0.14 mmol·g -1 ·h-1,

[0072] While the hydrogen evolution rate of the hydrocyclone reactor (1000 rpm) of the present example was 1.02 mmol·g -1 ·h-1, the hydrogen evolution performance of the hydrocyclone reactor was better, as shown in Figure 5 , Figure 5 (a) is the performance comparison of the traditional stirrer and the hydrocyclone at 1000 rpm, and (b) is the comparison chart of the hydrogen evolution rates of the two.

[0073] Comparative Example 2:

[0074] The present comparative example uses traditional sheet nickel loaded with ZnO nanorods (ZnO / PSN) to explore the difference in hydrogen production effect between the present porous nickel foam loaded with ZnO nanorods (ZnO / NF) and the preparation method is as follows:

[0075] Step one, using traditional sheet nickel with a thickness of 0.1 mm and an area of 25 mm x 25 mm as the substrate.

[0076] Step two, the flaky nickel was sequentially cleaned by ultrasonic in 3M dilute hydrochloric acid (30 min), absolute ethanol (20 min), and deionized water (20 min) to remove surface oxides and organic contaminants. After cleaning, the flaky nickel substrate was dried in a vacuum oven at 110°C for 12h to obtain a clean flaky nickel substrate.

[0077] Step three, ZnO seed layer deposition, a 60mM zinc acetate (Zn(CH3COO)2·2H2O) ethanol solution was prepared, and the clean flaky nickel substrate was immersed in the zinc acetate ethanol solution for 60s, followed by drying at 80°C for 10min. The immersion-drying process was repeated 3 times to ensure that Zn 2+ was uniformly adsorbed on the surface of the flaky nickel substrate. The Zn 2+ loaded flaky nickel was placed in a muffle furnace and heated to 350°C at a rate of 1°C / min, and held for 2h to decompose Zn 2+ into ZnO seeds. Natural cooling to room temperature obtained a uniform distribution of ZnO seed layer.

[0078] Step four, ZnO nanorod array hydrothermal growth, 60mM zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and 60mM hexamethylenetetramine (HMTA) were weighed respectively and dissolved in 80mL deionized water, and magnetically stirred for 30min until completely dissolved.

[0079] Step five, the ZnO seed loaded flaky nickel was vertically placed in a 100mL polytetrafluoroethylene reaction kettle liner, and the above reaction solution was poured into it. After sealing, it was placed in a 95°C oven for 6h.

[0080] Step six, post-processing, after the reaction was completed, the flaky nickel was removed and washed with deionized water 3 times to remove loose surface attachments. Drying in a 60°C oven for 12h obtained traditional flaky nickel loaded ZnO nanorods (ZnO / PSN).

[0081] The ZnO / PSN prepared in this comparative example was tested for piezoelectric-photocatalytic hydrogen evolution, and the test method was consistent with Comparative Example 1. The results showed that under 1000rpm stirring and light, the hydrogen evolution rate of ZnO / PSN was 0.35mmol·g -1 ·h-1, which was lower than the 1.02mmol·g -1 ·h-1 of the ZnO / NF-40 sample of the present application.

[0082] This shows that the traditional flaky nickel substrate lacks a porous structure and cannot provide sufficient active sites and effective piezoelectric polarization fields, resulting in a hydrogen evolution efficiency much lower than that of the composite material of the porous nickel foam substrate loaded with ZnO nanorods of the present application.

[0083] To sum up, the application precisely designs the pore structure of the porous foam nickel carrier and loads the preparation method and application of the piezoelectric-photocatalytic composite material ZnO / NF of the ZnO nanorod array. -1 The ZnO / NF-40PPI composite material prepared by the application has the optimal hydrogen evolution rate (1.02 mmol·g Figure 6 -1) at a rotation speed of 1000 rpm, as shown in Figure 6 (a) is the performance comparison of the traditional sheet nickel and the porous foam nickel at 1000 rpm, and (b) is a hydrogen evolution rate comparison diagram of the two.

[0084] The parts not described in the application can be realized by referring to the prior art.

[0085] Those skilled in the art should recognize that the above embodiments are only used to illustrate the application, and are not used as a limitation on the application, and any appropriate changes and variations to the above embodiments within the spirit and principles of the application fall within the scope of the application.

Claims

1. The use of a piezophotocatalytic composite material in a hydrogen production device of the cyclone type, characterized in that, The application comprises the following steps: a. wire cutting nickel foam particles with different pore densities and pretreating the same; b. immersing the pretreated nickel foam particles in a zinc acetate ethanol solution, drying and annealing to obtain a ZnO seed layer; c. growing ZnO nanorod arrays by placing the ZnO seed layer in a hydrothermal reaction solution containing zinc nitrate hexahydrate and hexamethylenetetramine, and then washing and drying the obtained product to obtain a piezoelectric-photocatalytic composite material with ZnO / NF structure; the porosity of the piezoelectric-photocatalytic composite material is 40 PPI; d. placing the piezoelectric-photocatalytic composite material in an aqueous solution containing a sacrificial agent, and performing a reaction under the conditions of a rotational turbulent flow field provided by a rotational flow hydrogen production device at 1000 rpm and light irradiation, to excite piezoelectric polarization of the piezoelectric-photocatalytic composite material and promote photocatalytic hydrogen evolution.

2. The piezoelectric-photocatalytic composite material according to claim 1, wherein the piezoelectric-photocatalytic composite material is used in a hydrogen production device of a cyclone type. In step a, the diameter of the nickel foam particles is 5 mm, and the thickness is 5 mm; the pore density of the nickel foam particles is 20-60 PPI; the pretreatment of the nickel foam particles comprises acid pickling, alcohol washing, water washing and drying.

3. The piezoelectric-photocatalytic composite material according to claim 1, wherein the piezoelectric-photocatalytic composite material is used in a hydrogen production device of a cyclone type. In step b, the concentration of the zinc acetate ethanol solution is 50-70 mM; the immersion time is 50-70 s, the drying temperature is 70-90℃, the annealing heating rate is 0.5-1.5℃ / min, and the annealing temperature is 300-400℃.

4. The piezoelectric-photocatalytic composite material according to claim 1, wherein the piezoelectric-photocatalytic composite material is used in a hydrogen production device of a cyclone type. In step c, the concentration ratio of zinc nitrate hexahydrate to hexamethylenetetramine is 1:1, the reaction temperature is 90-100℃, and the reaction time is 5-7 h; the drying temperature is 50-70℃.

5. The piezoelectric-photocatalytic composite material according to claim 1, wherein the piezoelectric-photocatalytic composite material is used in a hydrogen production device of a cyclone type. In step d, the aqueous solution of the sacrificial agent is a mixed solution of 5mM Na2S and 5mM Na2SO3, and the light irradiation condition is 300W xenon lamp with λ<400nm.

6. The piezoelectric-photocatalytic composite material according to claim 1, wherein the piezoelectric-photocatalytic composite material is used in a hydrogen production device of a cyclone type. In step d, the rotational flow hydrogen production device comprises a hydrocyclone reactor for generating a high-speed rotational flow field, a central negative pressure zone for hydrogen bubble aggregation and discharge, a light source irradiation system for providing ultraviolet light irradiation, a catalyst recovery port and a reaction liquid circulation channel.

7. The piezoelectric-photocatalytic composite material according to claim 6, wherein the piezoelectric-photocatalytic composite material is used in a hydrogen production device of a cyclone type. The hydrocyclone reactor is designed with adjustable rotational speed.

8. The piezoelectric-photocatalytic composite material according to claim 6, wherein the piezoelectric-photocatalytic composite material is used in a hydrogen production device of a cyclone type. The hydrocyclone reactor comprises a feed inlet, a rotational flow cavity, an overflow port, and a hydrocyclone member for generating a high-speed rotational flow field arranged in the rotational flow cavity.

9. The piezoelectric-photocatalytic composite material according to claim 1, wherein the piezoelectric-photocatalytic composite material is used in a hydrogen production device of a cyclone type. In the piezoelectric-photocatalytic composite material, the ZnO nanorods are vertically distributed on the surface of the nickel foam, with an average diameter of 100 nm and a length of 1.5μm.

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