Preparation method of bimetallic catalyst based on aerosol jet printing and catalyst

Abstract

The present invention discloses a method for preparing a bimetallic catalyst based on aerosol jet printing and the catalyst. The method includes adding a complexing agent, a metal salt, and a templating agent in a preset amount into a solvent and mixing uniformly to prepare a precursor printing ink; forming aerosol droplets by ultrasonic atomization of the printing ink through aerosol jet printing technology, and transporting the aerosol droplets to a printing head through a carrier gas, and ejecting the aerosol droplets onto the surface of a current collector under the constraint of a certain sheath gas to in-situ print and deposit the precursor material, and adjusting the thickness of the precursor material by the number of cycles; placing the precursor material in a sealed environment and performing high-temperature calcination pyrolysis treatment under an inert atmosphere; then naturally cooling the precursor material to room temperature, and then washing a preset number of times to remove the template, and drying to obtain a carbon-supported bimetallic self-supported highly efficient oxygen evolution electrocatalyst. The present invention solves the problems of long reaction cycle, poor conductivity and stability of the catalyst in the prior art when preparing a self-supported OER catalyst.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical energy materials, and particularly relates to a preparation method and a catalyst of a bimetallic catalyst based on aerosol jet printing. Background Art

[0002] Currently, the slow kinetic process of the oxygen evolution half-reaction in water electrolysis severely limits the water decomposition efficiency. Moreover, noble metal-based catalysts such as RuO2 and IrO2 with excellent OER (oxygen evolution) catalytic performance are restricted in their practical applications due to problems such as high cost and poor stability. Therefore, developing an efficient and easily available non-noble metal OER catalyst to promote the reaction kinetics is of great significance for the development of water electrolysis. Research shows that transition metal alloys exhibit higher catalytic efficiency than single metals because the combination of bimetals enhances their inherent polarity, promotes charge transfer, provides a synergistic effect, optimizes the electronic structure, and reduces the reaction barrier, thus significantly improving the catalytic activity in multiple valence states.

[0003] Currently, the commonly used hydrothermal in-situ growth method for preparing self-supporting OER catalyst materials has certain disadvantages: its reaction cycle is long, the reaction process is carried out in a closed system, and the reaction process cannot be directly observed; it is only limited to the preparation of oxide powders, and there are few preparations of non-oxides; it requires high-temperature and high-pressure steps, and its safety performance is poor, making it highly dependent on production equipment. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a preparation method and a catalyst of a bimetallic catalyst based on aerosol jet printing, aiming to solve at least one problem proposed in the background art.

[0005] The embodiments of the present invention are implemented as follows:

[0006] A preparation method of a bimetallic catalyst based on aerosol jet printing, the method comprising:

[0007] Adding a complexing agent, a metal salt, and a templating agent in a preset amount to a solvent and mixing evenly to prepare a precursor printing ink;

[0008] Forming aerosol droplets by ultrasonic atomization of the printing ink, and transporting the aerosol droplets to a printing nozzle through a carrier gas, and jetting the aerosol droplets onto the surface of a current collector placed on a printing stage under the constraint of a certain sheath gas to in-situ print and deposit a precursor material, and adjusting the thickness of the precursor material by the number of printing cycles, wherein the current collector is treated by low-temperature oxygen plasma hydrophilization;

[0009] Placing the precursor material in a sealed environment and performing high-temperature calcination pyrolysis treatment under an inert atmosphere;

[0010] The pyrolyzed precursor material is naturally cooled to room temperature, then washed a preset number of times to remove the template, and dried to obtain a carbon-supported bimetallic self-supported electrocatalyst.

[0011] Further, in the above method for preparing a bimetallic catalyst based on aerosol jet printing, the complexing agent is one or more of citric acid monohydrate, sucrose, and glucose; the metal salts include a metal iron salt and a metal cobalt salt; the metal iron salt is any one of iron(III) nitrate nonahydrate, iron(III) chloride hexahydrate, anhydrous iron(III) chloride, iron(II) chloride tetrahydrate, and iron(II) sulfate heptahydrate; the metal cobalt salt is any one of cobalt(II) nitrate hexahydrate, cobalt(II) acetate tetrahydrate, and cobalt(II) chloride hexahydrate; the templating agent is any one of sodium chloride, potassium chloride, and sodium silicate; and the solvent is one or more of ultrapure water, ethanol, isopropyl alcohol, and terpineol.

[0012] Further, in the above method for preparing a bimetallic catalyst based on aerosol jet printing, the amount of the solvent used is 50 - 150 ml, the amount of the complexing agent used is 5 - 15 mmol, the stoichiometric ratio of the amount of the metal iron salt used to the amount of the metal cobalt salt used is any one of 2:1, 1:1, and 1:2, and the amount of the templating agent used is 5 - 15 g.

[0013] Further, in the above method for preparing a bimetallic catalyst based on aerosol jet printing, the current collector is one of carbon fiber paper, carbon fiber cloth, graphite paper, nickel foam, and copper foam, and the low-temperature oxygen plasma treatment time is 60 - 600 s.

[0014] Further, in the above method for preparing a bimetallic catalyst based on aerosol jet printing, the atomization frequency is 1.7 - 2.2 MHz, the atomization power is 10 - 30 W, and the carrier gas and the sheath gas are one or more of air, nitrogen, and argon; the distance between the printing nozzle and the upper surface of the current collector is 2 - 10 mm, and the printing speed is 5 - 50 mm / s.

[0015] Further, in the above method for preparing a bimetallic catalyst based on aerosol jet printing, the printing is performed by aerosol jet printing, and any pattern drawn by CAD software can be printed. During the printing process, the material conveying air flow is 50 - 150 sccm, the sheath air flow is 60 - 180 sccm, the heating temperature of the printing stage is 30 - 100 °C, the printing area is 0.2 - 500 cm2, and the number of printing layers is 10 - 30 layers.

[0016] Further, in the above method for preparing a bimetallic catalyst based on aerosol jet printing, the sealed environment is a tube furnace, the inert atmosphere is nitrogen or argon, the pyrolysis treatment temperature is 600 - 800 °C, and the heating rate is 1 - 6 °C / min.

[0017] Further, in the above method for preparing a bimetallic catalyst based on aerosol jet printing, the cleaning is performed by rinsing and soaking with ultrapure water / deionized water / weakly acidic aqueous solution, the preset number of times is 2 - 3 times, and the drying temperature is 40 - 80 °C.

[0018] Another object of the present invention is to provide an oxygen evolution electrocatalyst of carbon-supported iron-cobalt compound, which is prepared by the above preparation method.

[0019] Compared with the prior art, the present invention uses aerosol jet printing technology to add a complexing agent, a metal salt, and a templating agent into a solvent in a preset amount to prepare a printing ink; the printing ink is atomized by ultrasonic atomization to form aerosol droplets, which are transported to a printing head by a carrier gas, and the precursor material is deposited on the surface of a current collector, and then the precursor material is placed in a sealed environment and subjected to high-temperature calcination pyrolysis treatment under an inert atmosphere; the precursor material after pyrolysis treatment is naturally cooled to room temperature, and then washed a preset number of times to remove the template, and dried to obtain a carbon-supported bimetallic self-supported electrocatalyst. In the whole process, the reaction cycle is greatly reduced, and the reaction does not need to be carried out in a completely closed environment, the reaction process can be observed, there is no high-pressure step in the reaction process, the safety is relatively high, and the dependence on equipment is not strong.

[0020] In addition, the present invention has at least the following beneficial effects:

[0021] 1. Using a cheap transition metal salt solution as a precursor, a highly active OER electrocatalyst is prepared based on the micro-reaction process of aerosol jet printing technology, and its catalytic activity under alkaline conditions is higher than that of the material prepared by spray drying method. The prepared catalyst has the advantages of simple synthesis method and low cost.

[0022] 2. During the high-temperature calcination process of the sample after in-situ printing deposition, the carbon precursor pyrolyzes in-situ in the presence of metal ions and induces growth on the surface of the current collector, generating a strong physical interfacial bonding force between it and the current collector, which can be directly used for testing without a binder, and to a certain extent, avoiding the problem of large-area shedding of the material caused by the oxygen evolved during testing.

[0023] 3. The precursor ink is atomized by ultrasonic atomization to form micron-scale aerosol droplets with uniform size, and a uniform jet with stable flux is formed through the micro-scale confined reaction space constructed by the sheath gas. The aerosol droplets act as microreactors to strengthen the micro-reaction process, realize in-situ regulation of the micro-structure, and significantly improve the uniformity of the deposited film.

[0024] 4. By preheating the substrate, the micro-reaction process of the droplets is strengthened, the interfacial bonding between the droplets and the current collector is improved, and the contact internal resistance is reduced, thereby improving the conductivity.

[0025] 5. By in-situ depositing salt templates such as sodium chloride and catalyst precursors on the surface of the current collector through an aerosol jet printing process, and after high-temperature calcination and subsequent template removal treatment, a honeycomb catalyst with a high specific surface area can be obtained, which can expose more bimetallic active sites and further improve the OER activity.

[0026] 6. This catalyst has excellent OER catalytic activity and cyclic stability under alkaline conditions. Description of the Drawings

[0027] Figure 1 It is a flowchart of a preparation method of a bimetallic catalyst based on aerosol jet printing in an embodiment of the present invention;

[0028] Figure 2 It is a comparative graph of LSV polarization curve data of catalysts prepared in Example 1 of the present invention and the comparative example;

[0029] Figure 3 It is a graph of i-t long-term stability data of the catalyst prepared in Example 1 of the present invention;

[0030] Figure 4 It is a comparative graph of LSV polarization curve data of the catalyst prepared in Example 1 of the present invention before and after the stability test.

[0031] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific Embodiments

[0032] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0034] Aerosol jet printing is a non-contact, direct-writing digital additive manufacturing technology with a maximum printing accuracy up to the micron level. The aerosol jet printing technology has the following functional features: a wide range of precision adjustment; high repeat positioning accuracy; a wide range of applicable materials; good boundary controllability; sheath gas confinement to transport the gas flow to prevent nozzle clogging; high atomization efficiency; a wide range of applicable ink viscosities, etc. In addition, since micron-scale aerosol droplets can serve as microreactors with excellent heat and mass transfer capabilities, they can achieve excellent microstructural control under milder conditions that cannot be achieved by traditional techniques such as hydrothermal methods.

[0035] Therefore, a preparation method of a bimetallic catalyst and a catalyst based on aerosol jet printing are proposed based on the aerosol jet printing technology to solve some problems existing in the preparation of self-supporting OER catalysts in the prior art.

[0036] Among them, please refer to Figure 1 , the preparation method includes:

[0037] Step S10, adding a complexing agent, a metal salt, and a templating agent in preset amounts to a solvent and mixing evenly to prepare a precursor printing ink.

[0038] Specifically, the complexing agent is one or more of citric acid monohydrate, sucrose, and glucose. The metal salt includes a metal iron salt and a metal cobalt salt. The metal iron salt is any one of iron(III) nitrate nonahydrate, iron(III) chloride hexahydrate, anhydrous iron(III) chloride, iron(II) chloride tetrahydrate, and iron(II) sulfate heptahydrate. The metal cobalt salt is any one of cobalt(II) nitrate hexahydrate, cobalt(II) acetate tetrahydrate, and cobalt(II) chloride hexahydrate. The templating agent is any one of sodium chloride, potassium chloride, and sodium silicate. The solvent is one or more of ultrapure water, ethanol, isopropanol, and terpineol.

[0039] More specifically, the solvent usage amount is 50 - 150 ml, for example, 50, 100, and 150 ml. The complexing agent usage amount is 5 - 15 mmol, for example, 5, 10, and 15 mmol. The stoichiometric ratio of the metal iron salt usage amount to the metal cobalt salt usage amount is any one of 2:1, 1:1, and 1:2, for example, 2:1 and 1:1. The templating agent usage amount is 5 - 15 g, for example, 5, 10, and 15 g.

[0040] In addition, in some preferred embodiments of the present invention, the complexing agent is one of citric acid monohydrate or sucrose, and the usage amount is 8 - 12 mmol; the templating agent is one of sodium chloride, potassium chloride, and sodium silicate, and the usage amount is 8 - 12 g; the solvent is one or more of ultrapure water, ethanol, and isopropanol, and the usage amount is 80 - 120 ml.

[0041] Step S11: The printing ink is formed into aerosol droplets through ultrasonic atomization, and is transported to the printing nozzle by a carrier gas. Under the constraint of a certain sheath gas, the aerosol droplets are sprayed onto the surface of the current collector placed on the printing stage to in-situ print and deposit the precursor material, and the thickness of the precursor material is adjusted by the number of printing cycles. Among them, the current collector is treated by low-temperature oxygen plasma hydrophilization.

[0042] Furthermore, the current collector is one of carbon fiber paper, carbon fiber cloth, graphite paper, nickel foam, and copper foam. The treatment time of low-temperature oxygen plasma is 60 - 600 s. In some preferred embodiments of the present invention, the current collector is one of carbon fiber paper, nickel foam, and copper foam, and the treatment time of low-temperature oxygen plasma is 100 - 400 s.

[0043] Furthermore, in the step of forming the printing ink into aerosol droplets through ultrasonic atomization, transporting the aerosol droplets to the printing nozzle by a carrier gas, spraying the aerosol droplets onto the surface of the current collector placed on the printing stage under the constraint of a certain sheath gas to in-situ print and deposit the precursor material, and adjusting the thickness of the precursor material by the number of printing cycles, the atomization frequency is 1.7 - 2.2 MHz, the atomization power is 10 - 30 W, and the carrier gas and the sheath gas are one or more of air, nitrogen, and argon; the distance between the printing nozzle and the upper surface of the current collector is 2 - 10 mm, and the printing speed is 5 - 50 mm / s. In some preferred embodiments of the present invention, the atomization power is 15 - 25 W; the carrier gas and the sheath gas are randomly combined with one or more of nitrogen and argon; the printing distance is 2 - 6 mm; the printing speed is 8 - 12 mm / s.

[0044] In addition, in the above steps, aerosol jet printing is used for printing, and any pattern drawn by CAD software can be printed. During the printing process, the material conveying air flow is 50 - 150 sccm, the sheath air flow is 60 - 180 sccm, the heating temperature of the printing stage is 30 - 100 °C, the printing area is 0.2 - 500 cm², and the number of printing layers is 10 - 30 layers. In some preferred embodiments of the present invention, the material conveying air flow is 80 - 120 sccm; the sheath air flow is 90 - 150 sccm; the heating temperature of the printing stage is 40 - 70 °C; the printing area is 0.5 - 300 cm², the printed pattern is any regular pattern such as a circle, a square, a rectangle, and a regular polygon; the number of printing layers is 15 - 25 layers.

[0045] Step S12: The precursor material is placed in a sealed environment and subjected to high-temperature calcination pyrolysis treatment under an inert atmosphere.

[0046] In the step of subjecting the precursor material to high-temperature calcination pyrolysis treatment in a sealed environment under an inert atmosphere, the sealed environment is a tubular furnace, the inert atmosphere is nitrogen or argon, the pyrolysis treatment temperature is 600 - 800 °C, the heating rate is 1 - 6 °C / min, and in some preferred embodiments of the present invention, the heating rate is 2 - 5 °C / min.

[0047] Step S13: Naturally cool the precursor material after pyrolysis treatment to room temperature, then wash it a preset number of times to remove the template, and obtain a carbon-supported bimetallic self-supported electrocatalyst after drying.

[0048] In the step of naturally cooling the precursor material after pyrolysis treatment to room temperature, then washing it a preset number of times to remove the template, and obtaining a carbon-supported bimetallic self-supported electrocatalyst after drying, the washing is carried out by rinsing and soaking with ultrapure water / deionized water / weak acidic aqueous solution, the preset number of times is 2 - 3 times, the drying temperature is 40 - 80 °C, and in specific implementation, the drying environment can use an oven.

[0049] On the other hand, the present invention also provides a carbon-supported iron-cobalt compound oxygen evolution electrocatalyst, which is prepared by the above-mentioned preparation method.

[0050] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to relevant embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0051] Example 1

[0052] Step 1: Add 10 mmol of citric acid monohydrate, 14 mmol of ferric nitrate nonahydrate, 7 mmol of cobalt nitrate hexahydrate (the stoichiometric ratio of the usage amount of metal iron salt to the usage amount of metal cobalt salt is 2:1), and 10 g of sodium chloride to 100 ml of ultrapure water, mix and stir for more than 5 h until uniform to obtain a precursor ink.

[0053] Step 2: Set the frequency of the ultrasonic nebulizer to 1.7 MHz and the power to 24 W; both the carrier gas and the sheath gas use high-purity nitrogen; the printing distance is 3 mm; the printing speed is 10 mm / s; cut the carbon paper to 1.5 cm * 1.5 cm and perform low-temperature oxygen plasma hydrophilic treatment for 300 s, then place it on the printing stage, the material conveying gas flow is 90 sccm; the sheath gas flow is 120 sccm; the heating temperature of the printing stage is 50 °C; the printing area is a 1 cm * 1 cm square; perform aerosol jet printing under the process parameters of 20 printing layers to in-situ deposit the precursor material on the surface of the carbon paper.

[0054] Step 3: Place the product from Step 2 in a tube furnace and perform high-temperature calcination pyrolysis treatment under a nitrogen atmosphere. The calcination temperature is 700 °C, the heating rate is 2 °C / min, and the holding time is 1 h;

[0055] Step 4: After the product in Step 3 is naturally cooled to room temperature, rinse and soak it with ultrapure water 2 - 3 times repeatedly, and obtain a honeycomb-shaped carbon-supported bimetallic self-supported electrocatalyst after drying.

[0056] Example 2

[0057] Step 1: Add 10 mmol of citric acid monohydrate, 10.5 mmol of ferric nitrate nonahydrate, 10.5 mmol of cobalt nitrate hexahydrate (the stoichiometric ratio of the usage amount of metal iron salt to the usage amount of metal cobalt salt is 1:1), and 10 g of sodium chloride to a mixed solution of 80 ml of ultrapure water and 20 ml of ethanol, and stir for more than 5 h until homogeneous to obtain a precursor ink;

[0058] Step 2: Set the frequency of the ultrasonic nebulizer to 1.7 MHz and the power to 24 W; both the carrier gas and the sheath gas are high-purity nitrogen; the printing distance is 2 mm; the printing speed is 12 mm / s; Cut the carbon paper to 1.5 cm * 1.5 cm and perform low-temperature oxygen plasma hydrophilic treatment for 300 s, then place it on the printing stage. The material conveying gas flow is 80 sccm; the sheath gas flow is 120 sccm; the heating temperature of the printing stage is 50 °C; the printing area is a 1 cm2 circle; Perform aerosol jet printing under the process parameters of 20 printing layers to in-situ deposit the precursor material on the surface of the carbon paper;

[0059] Step 3: Place the product from Step 2 in a tube furnace and perform high-temperature calcination pyrolysis treatment under a nitrogen atmosphere. The calcination temperature is 700 °C, the heating rate is 2 °C / min, and the holding time is 1 h;

[0060] Step 4: After the product in Step 3 is naturally cooled to room temperature, rinse and soak it with ultrapure water 2 - 3 times repeatedly, and obtain a honeycomb-shaped carbon-supported bimetallic self-supported electrocatalyst after drying.

[0061] Example 3

[0062] Step 1: Add 10 mmol of citric acid monohydrate, 7 mmol of ferric nitrate nonahydrate, 14 mmol of cobalt nitrate hexahydrate (the stoichiometric ratio of the usage amount of metal iron salt to the usage amount of metal cobalt salt is 1:2), and 10 g of sodium chloride to 80 ml of ultrapure water and 20 ml of isopropanol and mix and stir for more than 5 h until homogeneous to obtain a precursor ink;

[0063] Step 2: Set the frequency of the ultrasonic nebulizer to 1.7 MHz and the power to 24 W; both the carrier gas and the sheath gas are high-purity nitrogen; the printing distance is 3 mm; the printing speed is 10 mm / s; cut the carbon paper to 1.5 cm * 1.5 cm and perform low-temperature oxygen plasma hydrophilic treatment for 300 s, then place it on the printing stage, the material delivery gas flow is 90 sccm; the sheath gas flow is 120 sccm; the heating temperature of the printing stage is 50 °C; the printing area is an equilateral triangle of 1 cm2; perform aerosol jet printing under the process parameters of 20 printing layers, and in-situ deposit the precursor material on the surface of the carbon paper;

[0064] Step 3: Place the product in Step 2 in a tube furnace and perform high-temperature calcination pyrolysis treatment under a nitrogen atmosphere, the calcination temperature is 700 °C, the heating rate is 2 °C / min, and the holding time is 1 h;

[0065] Step 4: After the product in Step 3 is naturally cooled to room temperature, rinse and soak it with ultrapure water 2 - 3 times repeatedly, and obtain a honeycomb-shaped carbon-supported bimetallic self-supported electrocatalyst after drying.

[0066] Example 4

[0067] Step 1: Add 10 mmol of citric acid monohydrate, 14 mmol of ferric nitrate nonahydrate, 7 mmol of cobalt nitrate hexahydrate (the stoichiometric ratio of the usage amount of metal iron salt to the usage amount of metal cobalt salt is 2:1), and 10 g of sodium chloride to a mixed solution of 100 ml of ultrapure water, stir for more than 5 h until homogeneous as the precursor ink;

[0068] Step 2: Set the frequency of the ultrasonic nebulizer to 1.7 MHz and the power to 24 W; both the carrier gas and the sheath gas are high-purity nitrogen; the printing distance is 2 mm; the printing speed is 12 mm / s; cut the carbon paper to 1.5 cm * 1.5 cm and perform low-temperature oxygen plasma hydrophilic treatment for 300 s, then place it on the printing stage, the material delivery gas flow is 90 sccm; the sheath gas flow is 120 sccm; the heating temperature of the printing stage is 50 °C; the printing area is a 1 cm * 1 cm square; perform aerosol jet printing under the process parameters of 20 printing layers, and in-situ deposit the precursor material on the surface of the carbon paper;

[0069] Step 3: Place the product in Step 2 in a tube furnace and perform high-temperature calcination pyrolysis treatment under a nitrogen atmosphere, the calcination temperature is 600 °C, the heating rate is 2 °C / min, and the holding time is 1 h;

[0070] Step 4: After the product in Step 3 is naturally cooled to room temperature, rinse and soak it with ultrapure water 2 - 3 times repeatedly, and obtain a honeycomb-shaped carbon-supported bimetallic self-supported electrocatalyst after drying.

[0071] Example 5

[0072] Step 1: Add 10 mmol of citric acid monohydrate, 14 mmol of ferric nitrate nonahydrate, 7 mmol of cobalt nitrate hexahydrate (the stoichiometric ratio of the usage amount of metal iron salt to the usage amount of metal cobalt salt is 2:1), and 10 g of sodium chloride into a mixed solution of 100 ml of ultrapure water, and stir for more than 5 h until uniform to obtain a precursor ink;

[0073] Step 2: Set the frequency of the ultrasonic nebulizer to 1.7 MHz and the power to 24 W; both the carrier gas and the sheath gas are high-purity nitrogen; the printing distance is 3 mm; the printing speed is 10 mm / s; Cut the carbon paper into 1.5 cm * 1.5 cm and perform low-temperature oxygen plasma hydrophilic treatment for 300 s, then place it on the printing stage, the material conveying air flow is 90 sccm; the sheath air flow is 120 sccm; the heating temperature of the printing stage is 50 °C; the printing area is a 1 cm * 1 cm square; perform aerosol jet printing under the process parameters of 20 printing layers to in-situ deposit the precursor material on the surface of the carbon paper;

[0074] Step 3: Place the product in Step 2 in a tubular furnace and perform high-temperature calcination pyrolysis treatment under a nitrogen atmosphere, the calcination temperature is 800 °C, the heating rate is 2 °C / min, and the holding time is 1 h;

[0075] Step 4: After the product in Step 3 is naturally cooled to room temperature, rinse and soak it with ultrapure water 2 - 3 times repeatedly, and obtain a honeycomb-like carbon-supported bimetallic self-supported electrocatalyst after drying.

[0076] To compare with the above embodiments of the present invention, the present invention also proposes the following comparative examples.

[0077] Comparative Example 1

[0078] Step 1: Add 10 mmol of citric acid monohydrate, 14 mmol of ferric nitrate nonahydrate, 7 mmol of cobalt nitrate hexahydrate, and 10 g of sodium chloride into 100 ml of ultrapure water and mix and stir for more than 5 h until uniform to obtain a precursor ink;

[0079] Step 2: Deliver the precursor ink to the spray gun through the peristaltic pump of the spray dryer. Under the action of compressed air, the precursor ink is atomized into extremely fine droplets at the outlet of the spray gun, which will greatly increase the contact area between the precursor ink and the hot air. Therefore, the small droplets are quickly dried to form a precursor microsphere material composed of citric acid and metal salts;

[0080] Step 3: Place the product in Step 2 in a tubular furnace and perform high-temperature calcination pyrolysis treatment under a nitrogen atmosphere, the calcination temperature is 700 °C, the heating rate is 2 °C / min, and the holding time is 1 h;

[0081] Step 4: After the product in Step 3 is naturally cooled to room temperature, it is rinsed and soaked with ultrapure water for 2 - 3 times repeatedly, and a honeycomb carbon-supported bimetallic self-supported electrocatalyst is obtained after drying.

[0082] The catalysts obtained in Example 1 and the comparative example were respectively subjected to OER electrochemical performance tests. Specifically, the obtained catalysts were configured into inks according to a certain ratio. The configuration method was as follows: 5 mg of the catalyst was ultrasonically dispersed in a mixed solution composed of 250 μL of ultrapure water, 250 μL of isopropanol, and 25 μL of nafion (5 wt%) for 1 h, and then 8 μL of the above ink was taken in two portions and drop-coated on a glassy carbon electrode and naturally dried at room temperature to serve as a working electrode. An electrochemical workstation was used for the OER electrochemical performance test. The electrolyte was 1 M KOH, the reference electrode was a Hg / HgO electrode, and the counter electrode was a graphite rod. The test results are as Figures 1 to 3 shown.

[0083] Combined with Figure 2 it can be clearly seen that compared with the comparative example, Example 1 has the best OER activity. Specifically, when the current density of Example 1 is 10 mA cm-2, the overpotential required is only 215 mV; when the current density is 20 mA cm-2, the overpotential required is only 240 mV.

[0084] Combined with Figure 3 it can be clearly seen that after the catalyst of Example 1 undergoes a long-term stability test of 30000 s, its current retention rate even rises to about 104%, indicating that the catalyst material has excellent stability in an alkaline medium. This is because a highly active iron-cobalt-based hydroxide gradually forms on the surface of the catalyst material in an alkaline solution to promote the performance improvement.

[0085] Combined with Figure 4 it can be clearly seen that after the stability test, the activity of the material is further enhanced. Specifically, after the stability test of Example 1, when the current density is 20 mA cm -2 , the overpotential required is only 215 mV. This is significantly higher than the performance before the stability test (the overpotential was 240 mV). This result corresponds to the increase in current in the stability curve in Figure 2 .

[0086] Based on the above embodiments, comparative examples, and analysis and test results, the catalyst prepared by the method for preparing a carbon-supported bimetallic self-supported electrocatalyst provided by the present invention exhibits excellent OER electrocatalytic activity. Through aerosol jet printing, the precursor ink is ultrasonically atomized into micro-droplets, which are precisely controlled by the carrier gas flow and the sheath gas flow to be in-situ deposited on the surface of the current collector. During the high-temperature calcination and pyrolysis treatment process, new metal or carbon compounds grow in-situ inside. Compared with the materials prepared by the traditional spray drying method, this can significantly change the electronic structure of the materials, effectively reduce the internal resistance between interfaces, generate a strong electronic interaction, enhance the charge transport ability, provide more active sites, and thus improve the kinetics of OER, showing excellent electrocatalytic OER activity in alkaline electrolytes.

[0087] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A method for preparing a bimetallic catalyst based on aerosol jet printing, characterized in that, The method includes: Adding a complexing agent, a metal salt, and a templating agent in preset amounts into a solvent and mixing evenly to prepare a precursor printing ink; Forming aerosol droplets from the printing ink through ultrasonic atomization, transporting the aerosol droplets through a carrier gas to a printing nozzle, and ejecting the aerosol droplets onto the surface of a current collector placed on a printing stage under the constraint of a certain sheath gas to in-situ print and deposit a precursor material, and adjusting the thickness of the precursor material through the number of printing cycles, wherein the current collector is subjected to low-temperature oxygen plasma hydrophilic treatment; Placing the precursor material in a sealed environment and performing high-temperature calcination pyrolysis treatment under an inert atmosphere; Naturally cooling the pyrolysis-treated precursor material to room temperature, then washing a preset number of times to remove the template, and drying to obtain a carbon-supported bimetallic self-supported electrocatalyst; The complexing agent is one or more of citric acid monohydrate, sucrose, and glucose; the metal salt includes a metal iron salt and a metal cobalt salt; the metal iron salt is any one of iron(III) nitrate nonahydrate, iron(III) chloride hexahydrate, anhydrous iron(III) chloride, iron(II) chloride tetrahydrate, and iron(II) sulfate heptahydrate; the metal cobalt salt is any one of cobalt(II) nitrate hexahydrate, cobalt(II) acetate tetrahydrate, and cobalt(II) chloride hexahydrate; the templating agent is any one of sodium chloride, potassium chloride, and sodium silicate; the solvent is one or more of ultrapure water, ethanol, isopropanol, and terpineol.

2. The method for preparing a bimetallic catalyst based on aerosol jet printing according to claim 1, wherein The usage amount of the solvent is 50 - 150 ml, the usage amount of the complexing agent is 5 - 15 mmol, the stoichiometric ratio of the usage amount of the metal iron salt to the usage amount of the metal cobalt salt is any one of 2:1, 1:1, and 1:2, and the usage amount of the templating agent is 5 - 15 g.

3. The method for preparing a bimetallic catalyst based on aerosol jet printing according to claim 1, wherein, The current collector is one of carbon fiber paper, carbon fiber cloth, graphite paper, nickel foam, and copper foam, and the low-temperature oxygen plasma treatment time is 60 - 600 s.

4. The method for preparing a bimetallic catalyst based on aerosol jet printing according to claim 1, characterized in that, The atomization frequency is 1.7 - 2.2 MHz, the atomization power is 10 - 30 W, and the carrier gas and the sheath gas are one or more of air, nitrogen, and argon; the distance between the printing nozzle and the upper surface of the current collector is 2 - 10 mm, and the printing speed is 5 - 50 mm / s.

5. The method for preparing a bimetallic catalyst based on aerosol jet printing according to claim 1, wherein The printing is carried out by aerosol jet printing, and any pattern drawn by CAD software can be printed. During the printing process, the material conveying gas flow is 50 - 150 sccm, the sheath gas flow is 60 - 180 sccm, the heating temperature of the printing stage is 30 - 100 °C, and the printing area is 0.2 - 500 cm 2 , and the number of printing layers is 10 - 30 layers.

6. The method for preparing a bimetallic catalyst based on aerosol jet printing according to claim 1, wherein The sealed environment is a tube furnace, the inert atmosphere is nitrogen or argon, the pyrolysis treatment temperature is 600 - 800 °C, and the heating rate is 1 - 6 °C / min.

7. The method for preparing a bimetallic catalyst based on aerosol jet printing according to claim 1, wherein The washing is carried out by rinsing and soaking with ultrapure water / deionized water / weakly acidic aqueous solution, the preset number of times is 2 - 3 times, and the drying temperature is 40 - 80 °C.

8. An oxygen evolution electrocatalyst based on carbon-supported iron cobalt compound, characterized in that, The carbon-supported iron-cobalt compound oxygen evolution electrocatalyst is prepared by the preparation method according to any one of claims 1 to 7.

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