CN114314506A - Method for water piezoelectric catalytic cracking by Zn-CoNG nano-foam catalyst - Google Patents

Abstract

The invention discloses a method for water piezoelectric catalytic cracking by using a Zn-CoNG nano foam catalyst, which comprises the following steps: 1) dispersing water and Zn-CoNG nano foam to form turbid liquid, and then adjusting the system atmosphere to a protective gas atmosphere; 2) applying mechanical energy to the system to carry out water decomposition reaction under the condition of keeping out of the sun; the Zn-CoNG nano foam is formed by stacking and assembling two-dimensional Zn, Co and N Co-doped graphene nano sheets. The method can catalyze the water decomposition to prepare the hydrogen with high efficiency and environmental protection.

Description

A method for piezoelectric catalytic water splitting of Zn-CoNG nanofoam catalyst

technical field

The invention relates to the field of catalytic water splitting, in particular to a method for piezoelectric catalytic water splitting of a Zn-CoNG nanofoam catalyst.

Background technique

Energy shortage and environmental pollution are becoming increasingly severe, which have become two major problems restricting the survival and development of human society. Traditional fossil energy reserves are limited, and combustion products are not friendly enough to the environment to meet the needs of sustainable development of human society. Therefore, the need to develop and utilize clean energy is imminent.

Hydrogen energy is recognized as one of the most potential energy carriers in the future because of its high efficiency and cleanliness. Hydrogen generation through the reaction of splitting water is an extremely important technological path in the field of hydrogen production. Among them, the use of abundant renewable energy in nature to directly drive the water splitting reaction with the assistance of energy conversion materials, that is, to convert low-density energy in various environments into high-density hydrogen energy based on the physical or chemical effects of the material itself, In line with the sustainable development requirements of the economy and society, it has bright application prospects and attracts more and more research interests.

As we all know, mechanical energy is ubiquitous in the human living environment, and compared with solar energy, thermal energy and electrical energy, mechanical energy is a more abundant and stable energy source. From natural movements (such as wind, currents, waves, raindrops, etc.) to body movements (such as heart beating, muscle contractions, etc.), to sounds that are widely present in densely populated cities. Among them, sound, as a form of vibrational energy, includes various sounds brought by human activities such as factory production, vehicle travel, construction site operations, and casino activities. And these sounds usually become a kind of environmental pollution (noise pollution). At present, it is difficult for catalysts for water splitting to utilize mechanical energy for water splitting to produce hydrogen.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for piezoelectric catalytic water splitting of Zn-CoNG nanofoam catalyst, which can catalyze water splitting to produce hydrogen efficiently and environmentally.

In order to achieve the above object, the present invention provides a method for piezoelectric catalytic water splitting of a Zn-CoNG nanofoam catalyst, the method comprising:

1) Disperse water and Zn-CoNG nanofoam to form a suspension, then adjust the system atmosphere to a protective gas atmosphere;

2) Under the condition of avoiding light, apply mechanical energy to the system to carry out water splitting reaction;

Wherein, the Zn-CoNG nanofoam is assembled by stacking two-dimensional Zn, Co, N co-doped graphene nanosheets.

Generally speaking, an efficient piezoelectric catalytic material needs to have a high piezoelectric coefficient, a large cross-sectional area for mechanical energy capture, easy deformation, and abundant and efficient catalytic active sites. The 2D materials that are currently attracting attention are, on the one hand, as a low-dimensional material, 2D materials are easily deformable, and the large plane size enables them to have a large mechanical energy capture cross section; on the other hand, the high surface atomic ratio of the 2D structure also It can ensure a sufficiently large specific surface and sufficient catalytic active sites. And this unique structure has also begun to attract researchers' attention in the field of mechanocatalysis.

In addition, the inventors have also found that some bulk materials that do not originally have a non-centrosymmetric structure, when their thickness is reduced to a few atomic layers, and some 2D structures that are originally non-piezoelectric (such as graphene) through heterogeneity For the introduction of elements or defects, the present invention, by introducing N, Zn and Co, breaks the original centrosymmetric structure and exhibits a non-centrosymmetric structure, thereby possessing certain piezoelectric properties. It can be seen that the construction of 2D structure can not only realize the modulation of piezoelectric properties of materials, but also broaden the selection range of mechanocatalytic materials. In general, the 2D structure piezoelectric body can well meet the above requirements and may become a very potential piezoelectric catalyst. The present invention can collect and convert such mechanical energy into hydrogen energy with high energy density, turning waste into treasure, and its significance is self-evident. Based on the above, the present invention adopts Zn-CoNG nanofoam as piezoelectric material, which has piezoelectric properties due to the introduction of Zn-N and Co-N dipole structures. Based on the piezoelectric effect of the material, under the action of mechanical stress, the Zn-CoNG nanofoam deforms and generates separated positive and negative charge regions in different regions of the surface, thereby catalyzing water splitting to generate hydrogen. The catalytic water splitting method not only has an excellent water splitting rate, but also can recycle mechanical energy such as noise, which broadens ideas for environmental protection.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, and together with the following specific embodiments, are used to explain the present invention, but do not constitute a limitation to the present invention. In the attached image:

Fig. 1 is the XRD characterization diagram of the Zn-CoNG nanofoam prepared for Preparation Example 1;

Fig. 2 is the SEM characterization diagram of the Zn-CoNG nanofoam prepared for Preparation Example 1;

Figure 3 is a TEM characterization diagram of the Zn-CoNG nanofoam prepared in Preparation Example 1;

Fig. 4 is the HRTEM characterization diagram of the Zn-CoNG nanofoam prepared in Preparation Example 1;

Fig. 5 is the elemental surface scanning characterization diagram of the Zn-CoNG nanofoam obtained in Preparation Example 1;

FIG. 6 is a bar graph of hydrogen production rates for Examples and Comparative Examples.

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

The invention provides a method for piezoelectric catalytic water splitting of a Zn-CoNG nanofoam catalyst, the method comprising:

1) Disperse water and Zn-CoNG nanofoam to form a suspension, then adjust the system atmosphere to a protective gas atmosphere;

2) Under the condition of avoiding light, apply mechanical energy to the system to carry out hydrolysis reaction;

Wherein, the Zn-CoNG nanofoam is assembled by stacking two-dimensional Zn, Co, N co-doped graphene nanosheets.

In the present invention, the specific structure of the Zn-CoNG nanofoam can be selected in a wide range, but in order to further improve the water splitting rate of the method, preferably, the Zn-CoNG nanofoam has a sponge-like pore structure, The pore size distribution ranges from 2 to 100 nm.

In the above Zn-CoNG nanofoam, in order to further improve the catalytic effect of the Zn-CoNG nanofoam, preferably, the Zn-CoNG nanofoam is prepared by the following method: first, disperse the zinc source and the cobalt source in In an organic solvent, a first solution is formed; then, 2-methylimidazole is dispersed in an organic solvent to form a second solution; then, the first solution and the second solution are mixed and subjected to a contact reaction and post-treatment to A light purple powder was obtained; finally, the light purple powder was heat-treated under protective gas.

In the above-mentioned preparation method of Zn-CoNG nanofoam, the dosage of each material can be selected in a wide range, but in order to make the catalytic effect of Zn-CoNG nanofoam more excellent, preferably, the zinc source, cobalt source, 2 - The molar ratio of methylimidazole is 19:1:40-60.

In the preparation method of the above-mentioned Zn-CoNG nanofoam, the conditions of the contact reaction can be selected in a wide range, but in order to make the catalytic effect of the Zn-CoNG nanofoam more excellent, preferably, the contact reaction at least satisfies the following conditions: The reaction temperature is 15-35°C, and the reaction time is 20-30h.

In the above-mentioned preparation method of Zn-CoNG nanofoam, the conditions of the heat treatment can be selected in a wide range, but in order to make the catalytic effect of the Zn-CoNG nanofoam more excellent, preferably, the heat treatment at least satisfies the following conditions: The temperature is 900-950 ° C, the time is 1-3 h, and the heating rate is 5 ° C/min; preferably, in the first solution, the dosage ratio of the zinc source and the organic solvent is 19 mmol: 70-100 mL; In the second solution, the dosage ratio of the 2-methylimidazole and the organic solvent is 48 mmol: 70-100 mL.

In the above-mentioned preparation method of Zn-CoNG nanofoam, the conditions of the post-treatment can be selected in a wide range, but in order to make the catalytic effect of the Zn-CoNG nano-foam more excellent, preferably, the post-treatment sequentially includes: Centrifuge, wash with ethanol 2-3 times, and vacuum dry at 60°C for 12-24h.

In the above-mentioned preparation method of Zn-CoNG nanofoam, the shape of the protective gas can be selected in a wide range, but in order to make the catalytic effect of the Zn-CoNG nanofoam more excellent, preferably, the protective gas is in a flowing state , the flow rate is 40-60sccm.

In the above-mentioned preparation method of Zn-CoNG nanofoam, the type of the zinc source can be selected in a wide range, but in order to make the catalytic effect of Zn-CoNG nanofoam

In the above method, the amount of the Zn-CoNG nanofoam can be selected in a wide range, but in order to further improve the efficiency of water splitting, preferably, in step 1), the Zn-CoNG nanofoam in the suspension The mass concentration of the foam is 0.01-0.1 mg/mL.

In the above method, in order to further improve the efficiency of water splitting, preferably, in the dispersion, a sacrificial agent is also added, and the sacrificial agent is selected from at least one of methanol, ethanol, triethanolamine and lactic acid; wherein, the The sacrificial agent can also be selected in a wide range, but in order to further improve the efficiency of water splitting, more preferably, the volume ratio of the water to the sacrificial agent is (10-500):5.

In the above method, the conditions of the water splitting reaction can be selected in a wide range, but in order to further improve the efficiency of water splitting, preferably, in step 2), the water splitting reaction at least satisfies the following conditions: water splitting The temperature is 2-80℃, and the water decomposition time is 0.5-20h.

In the present invention, the application method of the mechanical energy is not specifically limited, but in order to improve the practical scope of the method, preferably, the application method of the mechanical energy adopts at least one of grinding, stirring, sound wave irradiation, airflow disturbance, and liquid flow. A sort of.

In the above embodiment, in order to improve the water splitting rate, preferably, the application mode of the mechanical energy is ultrasonic irradiation, and the ultrasonic irradiation satisfies at least the following conditions: the frequency of the ultrasonic wave is 21-100 kHz, and the power of the ultrasonic generator is 10-300W.

Of course, the application method of the mechanical energy can be ultrasonic irradiation, or other methods. In order to simplify the operating conditions, preferably, the application method of the mechanical energy is stirring, and the stirring rate of the stirring is 500-3000 rpm/ minute.

It is more excellent to obtain light purple powder after the first solution is mixed with the second solution, preferably, the zinc source is selected from at least one of zinc nitrate, zinc sulfate and zinc chloride, and the cobalt source is selected from cobalt nitrate, sulfuric acid At least one of cobalt and cobalt chloride.

In the above-mentioned preparation method of Zn-CoNG nanofoam, the type of the organic solvent can be selected in a wide range, but in order to make the catalytic effect of the Zn-CoNG nanofoam more excellent, preferably, the organic solvent is selected from methanol , at least one of ethanol and n-propanol, preferably a mixed solution of methanol and ethanol with a volume ratio of 1:1-1.5. In addition, in the present invention, in order to make the dispersion of the suspension more uniform, preferably, in step 1), the dispersion is carried out by ultrasonic, and the ultrasonic at least meets the following conditions: the ultrasonic time is 0.5-20min, The frequency of the ultrasonic wave is 21-100kHz, and the power of the ultrasonic generator is 10-300W.

In the present invention, there are various ways to adjust the system atmosphere, but in order to make the system completely in the protective atmosphere, preferably, in step 1), the system atmosphere adjustment includes: i) vacuuming the system for 1-2h; ii) ) filling the protective gas into the system for 1-5min; iii) evacuate the system for 15-25s; repeat steps ii) and iii) 5-7 times; more preferably, the protective gas is selected from nitrogen, argon and helium at least one of them.

Finally, in order to stabilize the temperature of the water splitting reaction during the process, preferably, the temperature of the water splitting reaction is adjusted by a fan or a circulating condensed water device.

The present invention will be described in detail below by way of examples.

Preparation Example 1

Preparation of Zn-CoNG nanofoam:

1) Dissolve 3.391 g of zinc nitrate (Zn(NO ₃ ) ₂ .6H ₂ O, 19 mmol) and 0.175 g of cobalt nitrate (Co(NO ₃ ) ₂ .6H ₂ O, 1 mmol) in 40 mL of methanol and 40 mL of ethanol, respectively. , stirring for 30min to form a pink transparent solution A;

2) get 3.94g of 2-methylimidazole dissolved (2-MI, 48mmol) in 40mL methanol and 40mL ethanol mixed solution to form transparent solution B;

3) Slowly add solution A to B, and continue stirring for 24h (25°C), centrifuge, wash 3 times with ethanol, and dry in vacuum at 60°C for one night to obtain light purple powder.

4) The obtained light purple powder was heat-treated for 2h at 910°C in a flowing _N2 atmosphere (flow rate 50sccm), controlled at a heating rate of 5°C/min, naturally cooled to room temperature, and finally a black sample was obtained.

The Zn-CoNG nanofoams prepared above were characterized, and the results were as follows:

1) The XRD characterization diagram is shown in Figure 1;

2) The SEM characterization diagram is shown in Figure 2;

3) The TEM characterization diagram is shown in Figure 3;

4) The HRTEM characterization diagram is shown in Figure 4;

5) HRTEM element surface scan is shown in Figure 5

It can be seen from Figures 1-5 that the Zn-CoNG nanofoam prepared above is composed of two-dimensional Zn, Co, N co-doped graphene nanosheets stacked and assembled.

Preparation Example 2

Preparation of ZnNG nanofoam:

1) Dissolve 3.569 g of zinc nitrate (Zn(NO ₃ ) ₂ .6H ₂ O, 12 mmol) in a mixed solution of 40 mL of methanol and 40 mL of ethanol, and stir for 30 min to form a transparent solution A;

2) Dissolve 3.94g of 2-methylimidazole (2-MI, 48mmol) in a mixed solution of 40mL of methanol and 40mL of ethanol to form a transparent solution B;

3) Slowly add solution A to B, and continue stirring for 24h (25°C), centrifuge, wash 3 times with ethanol, and dry under vacuum at 60°C for one night to obtain a white powder.

4) The obtained white powder was heat-treated for 2h at 910°C under flowing _N2 atmosphere (flow rate 50sccm), controlled at a heating rate of 5°C/min, naturally cooled to room temperature, and finally a black sample was obtained.

Example 1

Application of Zn-CoNG Nanofoam Piezoelectric Catalytic Water Splitting for Hydrogen Production

Step 1: Measure 70mL of deionized water and pour it into a glass reactor with a volume of about 200mL, add 5mg of Zn-CoNG nanofoam (catalyst), and ultrasonicate for 1min to completely disperse the solid powder (the frequency of ultrasonic waves is 40kHz, and the ultrasonic generator The power is 50W) to form a uniform suspension; add a ground joint with a valve to the glass reactor, seal the joint with a sealing film, close the joint valve, and use a vacuum pump to pump air from the branch pipe port to the reactor for 1h, Close the branch valve, open the joint valve, fill with high-purity argon gas for 1 minute, then close the joint valve, open the branch pipe valve, and evacuate for 20s. After repeating this operation for 6 times, fill in argon gas for 3 minutes, close each valve, and add the top of the ground joint. Airtight soft plug, spare;

Step 2: Immerse the bottom of the above-mentioned reactor into the water of the ultrasonic machine (50W, 40kHz), and keep the water level in the ultrasonic machine and the liquid level in the reactor flush. After fixing the position, ultrasonicate for 1 hour, and keep the whole process away from light. During this period, a circulating condensation device was used to keep the temperature of the reaction system stable at about 25 °C;

Step 3: After the reaction is over, use a gas sampling needle to pierce the air-tight soft plug, extract 4 mL of gas from the reactor, inject it into the gas chromatograph, and detect the H content by a thermal conductivity cell detector (TCD ₎ . _The standard curve was converted to the actual H volume. After testing, in this example, the hydrogen production rate of Zn-CoNG nanofoam mechanically catalyzed water splitting was 213.6 μmol·h ^-1 ·g ^-1 .

Example 2

Application of Zn-CoNG Nanofoam Piezoelectric Catalytic Water Splitting for Hydrogen Production

Step 1: Measure 70mL aqueous methanol solution (wherein the methanol volume is 5mL, and the water volume is 65mL, pour it into a glass reactor with a volume of about 200mL, add 5mg Zn-CoNG nanofoam (catalyst), ultrasonicate 1min to completely disperse the solid powder ( The frequency of the ultrasonic wave is 40kHz, and the power of the ultrasonic generator is 50W) to form a uniform suspension; add a ground joint with a valve to the glass reactor, seal the joint with sealing film, close the joint valve, and use a vacuum pump to remove The branch pipe mouth was pumped to the reactor for 1 hour, the branch pipe valve was closed, the joint valve was opened, high-purity argon gas was charged for 3 minutes, then the joint valve was closed to open the branch pipe valve, and the vacuum was pumped for 20 s. Valve, add air-tight soft plug to the top of the ground joint, spare;

Step 2: Immerse the bottom of the above-mentioned reactor into the water of the ultrasonic machine (50W, 40kHz), and keep the water level in the ultrasonic machine and the liquid level in the reactor flush. After fixing the position, ultrasonicate for 1 h, and keep the whole process away from light. During this period, a circulating condensation device was used to keep the temperature of the reaction system stable at about 15 °C;

Step 3: After the reaction is over, use a gas sampling needle to pierce the air-tight soft plug, extract 4 mL of gas from the reactor, inject it into the gas chromatograph, and detect the H content by a thermal conductivity cell detector (TCD ₎ . _The standard curve was converted to the actual H volume.

After testing, in this example, the piezoelectric catalytic cracking rate of Zn-CoNG nanofoam for hydrogen production is 690.4 μmol·h ^-1 ·g ^-1 .

Comparative Example 1

Hydrogen production performance of pure water under the action of ultrasonic waves

Step 1: Measure 70mL of deionized water and pour it into a glass reactor with a volume of about 200mL, add a ground joint with a valve to the glass reactor, seal the joint with sealing film, close the joint valve, and use a vacuum pump to remove The branch pipe mouth was pumped to the reactor for 1 hour, the branch pipe valve was closed, the joint valve was opened, high-purity argon gas was charged for 3 minutes, then the joint valve was closed to open the branch pipe valve, and the vacuum was pumped for 20 s. Valve, add air-tight soft plug to the top of the ground joint, spare;

Step 2: Immerse the bottom of the above-mentioned reactor into the water of the ultrasonic machine (50W, 40kHz), and keep the water level in the ultrasonic machine and the liquid level in the reactor flush. After fixing the position, ultrasonicate for 1 hour, and keep the whole process away from light. During this period, a circulating condensation device was used to keep the temperature of the reaction system stable at about 25 °C;

Step 3: After the reaction is over, use a gas sampling needle to pierce the air-tight soft plug, extract 4 mL of gas from the reactor, inject it into the gas chromatograph, and detect the H content by a thermal conductivity cell detector (TCD ₎ . _The standard curve was converted to the actual H volume.

According to the test, under this condition, the hydrogen production rate of pure water under the action of ultrasonic wave (50W, 40kHz) is 110.3μmol·h ^-1 ·g ^-1 .

Comparative Example 2

Hydrogen production performance of methanol aqueous solution under stirring

Step 1: Measure 70 mL of methanol aqueous solution (among which the methanol volume is 5 mL and the water volume is 65 mL), pour it into a glass reactor with a volume of about 200 mL, add a magnet, add a ground joint with a valve to the glass reactor, Seal the joint with sealing film, close the joint valve, use a vacuum pump to evacuate the reactor from the branch pipe mouth for 1 hour, close the branch pipe valve and open the joint valve, fill with high-purity argon for 3 minutes, then close the joint valve and open the branch pipe valve, and evacuate for 20s , after repeating this operation for 6 times, fill with argon gas for 3 minutes, close each valve, and add an air-tight soft plug to the top of the ground joint for standby;

Step 2: Immerse the bottom of the above-mentioned reactor into the water of the ultrasonic machine (50W, 40kHz), and keep the water level in the ultrasonic machine and the liquid level in the reactor flush. After fixing the position, ultrasonicate for 1 hour, and keep the whole process away from light. During this period, a circulating condensation device was used to keep the temperature of the reaction system stable at about 25 °C;

Step 3: After the reaction is over, use a gas sampling needle to pierce the air-tight soft plug, extract 4 mL of gas from the reactor, inject it into the gas chromatograph, and detect the H content by a thermal conductivity cell detector (TCD ₎ . _The standard curve was converted to the actual H volume.

According to the test, the hydrogen production rate of pure water under the action of ultrasonic wave (50W, 40kHz) is 145.3μmol·h ^-1 ·g ^-1 .

Comparative Example 3

Application of ZnNG Nanofoam Piezoelectric Catalytic Water Splitting for Hydrogen Production

Step 1: Measure 70 mL of deionized water and pour it into a glass reactor with a volume of about 200 mL, add 5 mg of ZnNG nanofoam (catalyst), and ultrasonicate for 1 min to completely disperse the solid powder (the frequency of the ultrasonic wave is 40 kHz, and the power of the ultrasonic generator is 40 kHz). 50W) to form a uniform suspension; add a ground joint with a valve to the glass reactor, seal the joint tightly with parafilm, close the joint valve, use a vacuum pump to pump air from the branch pipe port to the reactor for 1h, close the branch pipe The valve opens the joint valve, fills with high-purity argon gas for 1min, then closes the joint valve, opens the branch pipe valve, and evacuates for 20s. After repeating this operation for 6 times, fill in argon gas for 3min, close each valve, and add an airtight seal to the top of the ground joint. Soft plug, spare;

Step 2: Immerse the bottom of the above-mentioned reactor into the water of the ultrasonic machine (50W, 40kHz), and keep the water level in the ultrasonic machine and the liquid level in the reactor flush. After fixing the position, ultrasonicate for 1 hour, and keep the whole process away from light. During this period, a circulating condensation device was used to keep the temperature of the reaction system stable at about 25 °C;

Step 3: After the reaction is over, use a gas sampling needle to pierce the air-tight soft plug, extract 4 mL of gas from the reactor, inject it into the gas chromatograph, and detect the H content by a thermal conductivity cell detector (TCD ₎ . _The standard curve was converted to the actual H volume. After testing, in this example, the rate of ZnNG nanofoam mechanical catalytic cracking of water to produce hydrogen was 200.5 μmol·h ^-1 ·g ^-1 .

Comparative Example 4

Application of ZnNG Nanofoam Piezoelectric Catalytic Water Splitting for Hydrogen Production

Step 1: Measure 70mL aqueous methanol solution (wherein the methanol volume is 5mL, the water volume is 65mL, pour it into a glass reactor with a volume of about 200mL, add 5mg ZnNG nanofoam (catalyst), ultrasonicate 1min to completely disperse the solid powder (ultrasonic The frequency is 35kHz, and the power of the ultrasonic generator is 55W) to form a uniform suspension; add a ground joint with a valve to the glass reactor, seal the joint with a sealing film, close the joint valve, and use a vacuum pump from the branch pipe mouth. The reactor was pumped for 1 h, closed the branch valve, opened the joint valve, filled with high-purity argon gas for 3 minutes, then closed the joint valve and opened the branch pipe valve, and vacuumed for 20 s. Add an air-tight soft plug to the top of the ground joint, spare;

Step 2: Immerse the bottom of the above-mentioned reactor into the water of the ultrasonic machine (50W, 40kHz), and keep the water level in the ultrasonic machine and the liquid level in the reactor flush. After fixing the position, ultrasonicate for 1 h, and keep the whole process away from light. During this period, a circulating condensation device was used to keep the temperature of the reaction system stable at about 15 °C;

Step 3: After the reaction is over, use a gas sampling needle to pierce the air-tight soft plug, extract 4 mL of gas from the reactor, inject it into the gas chromatograph, and detect the H content by a thermal conductivity cell detector (TCD ₎ . _The standard curve was converted to the actual H volume.

After testing, in this example, the piezoelectric catalytic cracking rate of ZnNG nanofoam for hydrogen production was 411.6 μmol·h ^-1 ·g ^-1 .

The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the specific details of the above-mentioned embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. These simple modifications All belong to the protection scope of the present invention. In addition, it should be noted that the specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner under the condition of no contradiction. In order to avoid unnecessary repetition, the present invention has The combination method will not be specified otherwise.

In addition, the various embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the contents disclosed in the present invention.

Claims (9)

1. A method for water piezoelectric catalytic cracking by using a Zn-pong nano-foam catalyst, which is characterized by comprising the following steps:

1) dispersing water and Zn-CoNG nano foam to form turbid liquid, and then adjusting the system atmosphere to a protective gas atmosphere;

2) applying mechanical energy to the system to carry out water decomposition reaction under the condition of keeping out of the sun;

the Zn-CoNG nano foam is formed by stacking and assembling two-dimensional Zn, Co and N Co-doped graphene nano sheets.

2. The method according to claim 1, wherein the Zn-pong nanofoam has a spongy cell structure with a pore size distribution in the range of 2-100 nm;

preferably, the Zn-CoNG nanofoam is prepared by the following method: firstly, dispersing a zinc source and a cobalt source in an organic solvent to form a first solution; then, dispersing 2-methylimidazole in an organic solvent to form a second solution; then, mixing the first solution and the second solution, carrying out contact reaction and post-treatment to obtain light purple powder; finally, carrying out heat treatment on the light purple powder under protective gas;

preferably, the molar ratio of the zinc source to the cobalt source to the 2-methylimidazole is 19: 1: 40-60 parts;

preferably, the contact reaction satisfies at least the following conditions: the reaction temperature is 15-35 ℃, and the reaction time is 20-30 h;

preferably, the heat treatment satisfies at least the following conditions: the temperature is 900 ℃ and 950 ℃, the time is 1-3h, and the temperature rise speed is 5 ℃/min; preferably, in the first solution, the ratio of the zinc source to the organic solvent is 19 mmol: 70-100 mL; in the second solution, the dosage ratio of the 2-methylimidazole to the organic solvent is 48 mmol: 70-100 mL;

preferably, the post-treatment comprises in sequence: centrifuging, washing with ethanol for 2-3 times, and vacuum drying at 60 deg.C for 12-24 hr;

preferably, the protective gas is in a flowing state, and the flow rate is 40-60 sccm;

preferably, the zinc source is selected from at least one of zinc nitrate, zinc sulfate and zinc chloride, and the cobalt source is selected from at least one of cobalt nitrate, cobalt sulfate and cobalt chloride.

3. The method as claimed in claim 1, wherein in step 1), the mass concentration of Zn-CoNG nanofoam in the suspension is 0.01-0.1 mg/mL.

4. The method according to claim 1, wherein in the dispersion, a sacrificial agent is further added, the sacrificial agent being selected from at least one of methanol, ethanol, triethanolamine, and lactic acid;

more preferably, the volume ratio of the water to the sacrificial agent is (10-500): 5.

5. the method according to claim 1, wherein in step 2), the water splitting reaction at least satisfies the following condition: the water decomposition temperature is 2-80 ℃, and the water decomposition time is 0.5-20 h.

6. The method of claim 1, wherein the mechanical energy is applied by at least one of grinding, stirring, sonic irradiation, gas flow disturbance, liquid flow;

preferably, the mechanical energy is applied by ultrasonic irradiation, and the ultrasonic irradiation satisfies at least the following conditions: the frequency of the ultrasonic wave is 21-100kHz, and the power of the ultrasonic generator is 10-300W;

preferably, the mechanical energy is applied by stirring at a stirring rate of 500-3000 rpm.

7. The method according to any one of claims 1 to 5, wherein in step 1), the dispersion is carried out by means of ultrasound, said ultrasound satisfying at least the following conditions: the ultrasonic time is 0.5-20min, the frequency of the ultrasonic wave is 21-100kHz, and the power of the ultrasonic generator is 10-300W.

8. The method according to any one of claims 1 to 5, wherein in step 1), the system atmosphere adjustment comprises: i) vacuumizing the system for 1-2 h; ii) filling the protective gas into the system for 1-5 min; iii) vacuumizing the system for 15-25 s; repeating steps ii) and iii)5-7 times;

preferably, the shielding gas is selected from at least one of nitrogen, argon and helium.

9. The method according to any one of claims 1 to 5, wherein the temperature of the water splitting reaction is regulated by a fan or a circulating condensate device.

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