Method for preparing high-entropy alloy / biochar composite material by using carbon thermal shock method and application of high-entropy alloy / biochar composite material

Abstract

The invention relates to the technical field of nano material synthesis and CO2 conversion, in particular to a method for preparing a high-entropy alloy / biochar composite material by using a carbon thermal shock method and application of the high-entropy alloy / biochar composite material. According to the preparation method, metal salt precursors are compounded on biomass through circulating soaking, then Joule heat is adopted for carbon thermal shock, the precursors are reduced into the high-entropy alloy, and the high-entropy alloy / biochar composite material is prepared. The biochar in the prepared composite material is of a two-dimensional sheet structure, and the high-entropy alloy is spherical particles and is uniformly loaded on the biochar. The composite material has a high-entropy effect and a photothermal effect, so that the number and energy of current carriers can be obviously improved, the current carrier kinetics is improved, the catalytic reaction is promoted, and carbon dioxide can be efficiently reduced into carbon monoxide and methane.

Description

Technical Field

[0001] The present invention relates to the field of nanomaterial synthesis technology and CO2 conversion technology, and in particular to a method for preparing a high entropy alloy / biochar composite material by using a carbon thermal shock method and its application. Background Art

[0002] The combustion of fossil fuels, such as coal, oil and natural gas, is the main source of carbon dioxide emissions. Therefore, reducing the use of fossil fuels and finding clean energy alternatives are key strategies for addressing climate change. Converting waste carbon dioxide into valuable energy products, especially natural gas such as hydrogen, methane and carbon monoxide, and reducing dependence on fossil fuels can drive the economy towards a more sustainable direction.

[0003] Waste biomass including straw, corn cobs, paulownia wood, wood sponge, etc. can be converted into biochar through high-temperature pyrolysis. This process not only helps to reduce the environmental burden of agricultural waste, but also produces biochar materials with high added value. And biochar is widely used in various fields due to its porosity, high specific surface area and rich surface functional groups. Biochar modified by physical or chemical methods is also a relatively good carrier.

[0004] High entropy alloys (HEAs) are a class of alloys composed of five or more main elements, with the atomic fraction of each main element greater than 5% and less than 35%. The concept of high entropy alloys breaks through the limitations of traditional alloy composition. Through the arrangement and combination of multiple components and the content adjustment, the alloy is endowed with excellent mechanical properties and functional properties, and has shown excellent performance in the photocatalytic conversion of carbon dioxide by high entropy alloys.

[0005] The carbon thermal shock method is an advanced material preparation technology for synthesizing high entropy alloy nanoparticles. This method can synthesize high entropy alloy nanoparticles with a single-phase structure in a very short time through a rapid high-temperature heating and rapid cooling process. So far, there has been no report on the preparation of biochar-loaded high entropy alloys using the carbon thermal shock method. Summary of the invention

[0006] Based on the above technical background, the present invention provides a method for preparing a composite material of high entropy alloy (HEAs) using waste biomass as a carbon source and a carrier. The present invention uses metal salt precursors, straw, corn cobs, paulownia wood, wood sponge and other waste biomass as raw materials, with low raw material cost, large output and high potential utilization value. By using Joule heat equipment to synthesize catalysts by carbon thermal shock method on the load material, high added value recycling of low-value solid waste is achieved.

[0007] In order to achieve the purpose of the present invention, the following technical scheme is adopted: a method for preparing a high entropy alloy / biochar composite material by using a carbon thermal shock method, specifically comprising the following steps:

[0008] (1) Dissolve various metal salt precursors in deionized water and stir them magnetically to fully dissolve them.

[0009] (2) Using a wet impregnation method, the waste biomass is soaked in the solution prepared in (1), the ratio of metal salt precursor to biomass is 0.003-0.007 mol:1 g, and the soaking is repeated 3-6 times. Drying is performed after each soaking.

[0010] (3) The sample prepared in (2) was placed in a Joule heating device and HEAs / biochar composites were synthesized by carbon thermal shock method under nitrogen atmosphere.

[0011] (4) The prepared HEAs / biochar composite material is placed in a mixed solution of deionized water and ethanol for ultrasonic treatment, and then dried for later use.

[0012] Furthermore, the biomass includes wood sponge, paulownia wood, and corn cob.

[0013] Furthermore, the metal salt precursor includes one or more of copper salt, manganese salt, nickel salt, iron salt and cobalt salt.

[0014] In certain embodiments of the present invention, when the metal salt precursor is composed of multiple metal salts, the molar mass of each metal salt is the same.

[0015] Preferably, the metal salt precursor includes copper salt, manganese salt, nickel salt, iron salt and cobalt salt, and the molar mass of each metal salt is the same.

[0016] Furthermore, the discharge voltage of the Joule heat treatment in the carbon thermal shock method is 150-300V, the discharge time is 0.1-10s, and the number of discharges is 1-10 times. The resistance of the HEAs / biochar composite material prepared by the present invention needs to be measured before the Joule heat treatment, and the resistance should be controlled to be ≤6Ω; the maximum temperature generated by the discharge parameters of the Joule heat equipment provided by the present invention is 1000-3500℃.

[0017] The high entropy alloy / biochar composite material prepared by the above method is applied to convert carbon dioxide into a mixture of carbon monoxide and methane.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] The present invention uniformly loads each metal salt precursor on the biomass through cyclic immersion, and then rapidly heats it to a high temperature through Joule heating. This high-temperature treatment can not only rapidly decompose the metal precursor and form liquid metal, thereby achieving uniform mixing of multiple elements, but also can carbonize the biomass to produce sufficient pores and attachment sites.

[0020] The present invention makes full use of biomass as a carbon source for carbon thermal shock reduction of metal salt precursors, and also uses high-temperature carbonization of biomass as a carrier of HEAs, organically combining the two together, which solves the problems of waste of waste biomass and environmental pollution on the one hand, and solves the shortcomings of poor thermal stability of HEAs without carriers, easy agglomeration and inactivation on the other hand. In addition, the plasma resonance effect generated under illumination efficiently couples light energy and thermal energy to overcome the energy barrier in the catalytic process, enhances the number and energy of effective carriers in the CO2 reduction reaction, and thus accelerates the catalytic reaction, increasing the production of carbon monoxide and methane. In addition, the high entropy alloy / biochar composite material prepared by the present invention is of an integral structure, can float on water, and is convenient for water vapor to evaporate and react with CO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 XRD patterns of HEAs / biochar composite materials prepared in Examples 1 to 5 and Comparative Examples 1-2;

[0022] Figure 2 TEM image of the HEAs / biochar composite material sample prepared in Example 1;

[0023] Figure 3 Thermal images of the HEAs / biochar composites prepared in Examples 1 to 5 and Comparative Examples 1-2;

[0024] Figure 4 The photocatalytic conversion of carbon dioxide into carbon monoxide and methane yields of the HEAs / biochar composites prepared in Examples 1 to 5 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0025] Example 1

[0026] (1) Take 1 g of wood sponge, wash it with water, soak it in deionized water for one day, and dry it for later use;

[0027] (2) Weigh 0.003 mol of each of the precursors Cu(CH3COO)2·H2O, Mn(CH3COO)2·4H2O, Ni(CH3COO)2·4H2O, Fe(NO3)3·9H2O, and Co(NO3)2·6H2O, add 200 mL of deionized water, stir magnetically to mix well, and set aside;

[0028] (3) taking 50 mL of the solution prepared in (2) in batches and soaking the wood sponge in (1), each time for one day, drying after completion, and repeating the cycle 3 times;

[0029] (4) Place the sample into a 10 mm inner diameter fully covered graphite paper quartz tube, plug both ends of the quartz tube with 10 mm diameter graphite electrode plugs, slowly compress the plugs and measure the resistance until the resistance is about 1.0 ohm, stop compressing; install and align the temperature probe, close the vacuum box, fill with nitrogen and exhaust the air; set the discharge voltage to 180 V, the discharge time to 1 second, and repeat the discharge three times. After the three discharges are completed, cool to room temperature and take out the quartz tube, pour out the reacted powder in the quartz tube, which is the HEAs / wood sponge composite material, and its XRD spectrum is as follows: Figure 1 As shown, the peak of the composite material corresponds to the card (JCPDS: 47-1417), indicating that the material was successfully synthesized; TEM images are shown in Figure 2 As shown in the figure, high entropy alloy (HEAs) solid solution microspheres are uniformly loaded on the two-dimensional sheet-like biochar. Figure 3 As shown, the prepared material has good photothermal capacity.

[0030] (5) A photocatalytic experiment for reducing CO2 was carried out in a 100 mL photochemical reactor. First, 30 mL of deionized water and 3 g of the composite material were added to the photochemical autoclave, and then the reactor was filled with CO2 gas. The gas in the reaction pool was then discharged until the pressure was equal to atmospheric pressure. These steps were performed three times to ensure that the reactor was loaded with only pure carbon dioxide. The light source was a 300 W xenon lamp, and the reaction solution was exposed to light for 5 h through a transparent window on the top of the visible light reactor. The extracted reaction gas was analyzed using a gas chromatograph;

[0031] The yields of carbon monoxide and methane products of HEAs / wood sponge composites are shown in Figure 4 As shown, the concentrations reached 3.76 mmol and 5.82 mmol, respectively.

[0032] Example 2

[0033] (1) Take 1 g of corn cob, wash it with water, soak it in deionized water for one day, and dry it for later use;

[0034] (2) Weigh 0.004 mol of each of the precursors Cu(CH3COO)2·H2O, Mn(CH3COO)2·4H2O, Ni(CH3COO)2·4H2O, Fe(NO3)3·9H2O and Co(NO3)2·6H2O, add 200 mL of deionized water, stir magnetically to mix well, and set aside;

[0035] (3) taking 50 mL of the solution prepared in (2) in batches and soaking the corn cobs in (1) for one day each time. After completion, drying was performed, and the cycle was repeated 4 times;

[0036] (4) Load the sample into a 10 mm inner diameter fully covered graphite paper quartz tube, plug both ends of the quartz tube with 10 mm diameter graphite electrode plugs, slowly compress the plugs and measure the resistance until the resistance is about 1.0 ohm, then stop compressing; install and align the temperature probe, close the vacuum box, fill with nitrogen and expel the air. Set the discharge voltage to 150 V, the discharge time to 1 second, and repeat the discharge three times. After the three discharges are completed, cool to room temperature, take out the quartz tube, and pour out the reacted powder in the quartz tube, which is the HEAs / corn cob composite material. The XRD spectrum of the HEAs / corn cob composite material is shown in Figure 2. Figure 1 As shown, the peaks of the composite material correspond to the characteristic peaks of Example 1, indicating that the material was successfully synthesized. Thermal imaging of HEAs / corncob composite material Figure 3 As shown, the prepared material also has good photothermal capacity;

[0037] The experimental process of CO2 photocatalytic reduction is as in Example 1. The yields of carbon monoxide and methane products of HEAs / corncob composite materials are shown in Figure 2. Figure 4 As shown, the concentrations reached 3.66 mmol and 5.67 mmol, respectively.

[0038] Example 3

[0039] (1) Take 1 g of straw, wash it with water, soak it in deionized water for one day, and dry it for later use;

[0040] (2) Weigh 0.007 mol each of the precursors Cu(CH3COO)2·H2O, Mn(CH3COO)2·4H2O, Ni(CH3COO)2·4H2O, Fe(NO3)3·9H2O and Co(NO3)2·6H2O, add 200 mL of deionized water, stir magnetically to mix well, and set aside;

[0041] (3) taking 50 mL of the solution prepared in (2) in batches and soaking the straw in (1), each time for one day, drying after completion, and repeating the cycle 6 times;

[0042] (4) Place the sample into a 10 mm inner diameter fully covered graphite paper quartz tube, plug both ends of the quartz tube with 10 mm diameter graphite electrode plugs, slowly compress the plugs and measure the resistance until the resistance is about 1.0 ohm, then stop compressing; install and align the temperature probe, close the vacuum box, fill with nitrogen and exhaust the air; set the discharge voltage to 300 V, the discharge time to 1 second, and repeat the discharge three times. After the three discharges are completed, cool to room temperature, take out the quartz tube, pour out the reacted powder in the quartz tube, which is the HEAs / straw composite material; the XRD spectrum of the HEAs / straw composite material is shown in Figure 1 As shown, the peaks of the composite material correspond to the characteristic peaks of Example 1, indicating that the material was successfully synthesized. The thermal imaging of the HEAs / straw composite material Figure 3 As shown, the prepared material has good photothermal capacity;

[0043] The experimental process of CO2 photocatalytic reduction is as in Example 1. The yields of carbon monoxide and methane products of HEAs / straw composite materials are shown in Figure 2. Figure 4 As shown, the concentrations reached 3.45 mmol and 6.24 mmol, respectively.

[0044] Example 4

[0045] (1) Take 1 g of Paulownia wood, wash it with water, soak it in deionized water for one day, and dry it for later use;

[0046] (2) Weigh 0.004 mol of each of the precursors Cu(CH3COO)2·H2O, Mn(CH3COO)2·4H2O, Ni(CH3COO)2·4H2O, Fe(NO3)3·9H2O and Co(NO3)2·6H2O, add 200 mL of deionized water, stir magnetically to mix well, and set aside;

[0047] (3) taking 50 mL of the solution prepared in (2) in batches and soaking the Paulownia wood in (1) for one day each time. After completion, drying was performed, and the cycle was repeated three times;

[0048] (4) Load the sample into a 10 mm inner diameter fully covered graphite paper quartz tube, plug both ends of the quartz tube with 10 mm diameter graphite electrode plugs, slowly compress the plugs and measure the resistance until the resistance is about 1.0 ohm, stop compressing; install and align the temperature probe, close the vacuum box, fill with nitrogen and exhaust the air; set the discharge voltage to 250 V, the discharge time to 1 second, and repeat the discharge three times. After the three discharges are completed, cool to room temperature, take out the quartz tube, pour out the reacted powder in the quartz tube, which is the HEAs / Paulownia wood composite material. The XRD spectrum is as follows Figure 1 As shown, the peaks of the composite material correspond to the characteristic peaks of Example 1, indicating that the material was successfully synthesized. Thermal imaging of HEAs / Paulownia wood composite material Figure 3As shown, the prepared material also has good photothermal capacity;

[0049] The experimental process of CO2 photocatalytic reduction is the same as in Example 1. The yields of carbon monoxide and methane products of HEAs / Paulownia wood composite materials are shown in Figure 2. Figure 4 As shown, the concentrations reached 3.96 mmol and 5.93 mmol, respectively.

[0050] Example 5

[0051] (1) Take 1 g of wood sponge, wash it with water, soak it in deionized water for one day, and dry it for later use;

[0052] (2) Weigh 0.003 mol of each of the precursors Cu(CH3COO)2·H2O, Mn(CH3COO)2·4H2O, Ni(CH3COO)2·4H2O, Fe(NO3)3·9H2O, and Co(NO3)2·6H2O, add 200 mL of deionized water, stir magnetically to mix well, and set aside;

[0053] (3) taking 50 mL of the solution prepared in (2) in batches and soaking the wood sponge in (1), each time for one day, drying after completion, and repeating the cycle 4 times;

[0054] (4) Place the sample into a 10 mm inner diameter fully covered graphite paper quartz tube, plug both ends of the quartz tube with 10 mm diameter graphite electrode plugs, slowly compress the plugs and measure the resistance until the resistance is about 1.0 ohm, then stop compressing; install and align the temperature probe, close the vacuum box, fill with nitrogen and exhaust the air; set the discharge voltage to 200 V, the discharge time to 1 second, and repeat the discharge three times. After three discharges, cool to room temperature, take out the quartz tube, and pour out the reacted powder in the quartz tube, which is the HEAs / wood sponge composite material. The XRD spectrum is as follows: Figure 1 As shown, the peak of the composite material corresponds to that of Example 1, indicating that the material was successfully synthesized. Figure 3 As shown, the prepared material has good photothermal capacity;

[0055] The experimental process of CO2 photocatalytic reduction is as in Example 1. The yields of carbon monoxide and methane products of HEAs / wood sponge composite materials are shown in Figure 2. Figure 4 As shown, the concentrations reached 3.55 mmol and 5.47 mmol, respectively.

[0056] Comparative Example 1

[0057] (1) Take 1 g of wood sponge biomass, wash it with water, soak it in deionized water for one day, and dry it for later use;

[0058] (2) Prepare 200 mL of deionized water for later use;

[0059] (3) taking 50 mL of the deionized water in (2) in batches and soaking the biomass in (1) for one day each time. After completion, drying is performed, and the cycle is repeated 5 times;

[0060] (4) Load the sample into a 10 mm inner diameter fully covered graphite paper quartz tube, plug both ends of the quartz tube with a 10 mm diameter graphite electrode plug, slowly compress the plug and measure the resistance until the resistance is about 1.0 ohm and stop compressing; install and align the temperature probe, close the vacuum box, fill with nitrogen and expel the air; set the calcination setting discharge voltage to 140 V, the discharge time to 1 second, and repeat the discharge 3 times. After 3 discharges, cool to room temperature and take out the quartz tube, pour out the reacted powder in the quartz tube, which is the HEAs / wood sponge composite material. The XRD spectrum of the HEAs / wood sponge composite material is shown in the figure. Figure 1 As shown, the discharge voltage is too low and the characteristic peak of HEAs does not appear. Thermal imaging Figure 3 As shown, compared with the embodiment without HEAs loading, the photothermal effect is not significant;

[0061] The experimental process of CO2 photocatalytic reduction is as in Example 1. The yields of carbon monoxide and methane products of HEAs / wood sponge composite materials are shown in Figure 2. Figure 4 As shown, there are only 0.4 mmol and 1.2 mmol respectively.

[0062] Comparative Example 2

[0063] (1) Take 1 g of wood sponge, wash it with water, soak it in deionized water for one day, and dry it for later use;

[0064] (2) Weigh 0.003 mol of each of the precursors Cu(CH3COO)2·H2O, Mn(CH3COO)2·4H2O, Ni(CH3COO)2·4H2O, Fe(NO3)3·9H2O, and Co(NO3)2·6H2O, add 200 mL of deionized water, stir magnetically to mix well, and set aside;

[0065] (3) taking 50 mL of the solution prepared in (2) in batches and soaking the wood sponge in (1), each time for one day, drying after completion, and repeating the cycle 3 times;

[0066] (4) Load the sample into the magnetic boat, place it in the tube cavity of the tube furnace, fix it with a plug, and then pass nitrogen to expel the air; set the calcination temperature to 400℃, the heating rate to 5℃ / min, and the calcination time to 2 hours. After calcination, cool it to room temperature and take out the calcined sample. The XRD spectrum is as follows Figure 1 As shown, compared with Example 1, there is an additional characteristic peak of high entropy spinel (JCPDS: 22-1084), indicating that impurities exist in the material synthesis.

[0067] The experimental process of CO2 photocatalytic reduction is the same as in Example 1, and the yields of carbon monoxide and methane products are shown in the figure Figure 4 As shown, there are only 1.2 mmol and 2.3 mmol respectively.

[0068] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for preparing a high entropy alloy / biochar composite material using a carbon thermal shock method, characterized in that: The following steps are involved: (1) soaking the biomass in a metal salt precursor solution for cyclic soaking; (2) High entropy alloy / biochar composites were synthesized by carbon thermal shock method under protective atmosphere.

2. The method for preparing a high entropy alloy / biochar composite material using a carbon thermal shock method according to claim 1, characterized in that: The ratio of the metal salt precursor to the biomass is 0.003-0.007 mol:1g.

3. The method for preparing a high entropy alloy / biochar composite material using a carbon thermal shock method according to claim 1, characterized in that: The metal salt precursor includes a mixture of one or more of copper salt, manganese salt, nickel salt, iron salt and cobalt salt.

4. The method for preparing a high entropy alloy / biochar composite material using a carbon thermal shock method according to claim 1, characterized in that: The cyclic soaking is performed for 3 to 6 cycles, each cycle soaking time is 1 hour, and drying treatment is performed after each cycle soaking is completed.

5. The method for preparing a high entropy alloy / biochar composite material by using a carbon thermal shock method according to claim 1, characterized in that: The carbon thermal shock method uses Joule heat equipment; the parameters of the carbon thermal shock method are: discharge voltage is 150-300V, discharge time is 0.1-10s, and discharge times are 1-10 times.

6. A high entropy alloy / biochar composite material prepared by the method according to any one of claims 1 to 5.

7. Use of the high entropy alloy / biochar composite material as claimed in claim 5 in photocatalytic reduction of carbon dioxide.

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