A method for preparing a single-atom catalyst based on a microsecond pulse discharge system
By using a microsecond-level pulsed discharge system to prepare single-atom catalysts, the problem of low efficiency in rapid Joule heating methods was solved, achieving efficient preparation and forming unique single-atom coordination structures, thus improving catalyst performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING INST OF TECH
- Filing Date
- 2023-08-30
- Publication Date
- 2026-06-26
AI Technical Summary
In the existing technology, the rapid Joule heating method for preparing single-atom catalysts has low efficiency, a limited number of support defects, and affects the coordination structure of metal atoms and the support, as well as the amount of oxygen doping in the air, resulting in poor catalyst performance.
By employing a microsecond-level pulse discharge system and designing the inner and outer diameters and current distribution of the discharge cavity, a highly efficient pulse discharge process is achieved, generating a strong electromagnetic field and plasma, which promotes the rapid decomposition of metal salts on the carrier and the formation of unique single-atom coordination structures.
This significantly improves the preparation efficiency of single-atom catalysts, generates more defects in the support, and allows oxygen from the air to participate in coordination, forming a unique single-atom coordination structure, thus enhancing the performance of the catalyst.
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Figure CN117753335B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing single-atom catalysts based on a microsecond-level pulsed discharge system, belonging to the field of catalyst technology. Background Technology
[0002] Single-atom catalysts (SACs) are active MN / O / S groups composed of a single metal atom (M) and adjacent coordinating atoms (N / O / S) on a support. They not only offer 100% atom utilization efficiency and precise active centers but also possess tunable coordination electronic structures. Furthermore, due to their simple structure, they are often considered model catalysts for studying structure-performance relationships. As a unique type of catalyst, SACs have been extensively reported in photocatalysis and electrocatalysis, and are widely used in the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and carbon dioxide reduction reaction (CO2RR). However, in these single-atom catalysts, the atomically dispersed metal has high surface energy and is prone to aggregation; therefore, the choice of support is essential for stabilizing the metal atoms. Carbon-based materials, due to their ease of doping with heteroatoms (N, O, S, etc.) and defect strategies, can enhance the anchoring of metal atoms. In addition, non-carbon supports, including metal oxides, carbides, nitrides, and phosphides, are also frequently studied as supports for stabilizing metal atoms.
[0003] In recent years, numerous publications have reported the preparation of single-atom catalysts using the rapid Joule heating method. The metal atoms in these catalysts include Pt, Ni, Co, and Ru, and the supports include graphene, C3N4, TiO2, and carbon nanotubes. The working principle of the rapid Joule heating method for preparing single-atom catalysts is quite simple: rapid and stable charging / discharging generates a high current density on the single-atom support. The Joule heating effect conducts the instantaneously generated high temperature to the metal salt. For metal salts with low decomposition temperatures, they decompose directly; while for metal salts with higher decomposition temperatures, they first melt due to thermal conduction. Since the molten metal salt is a conductor, it also undergoes a pulsed discharge effect under the influence of the high current. The generated high temperature further decomposes the metal salt, and the resulting metal atoms are anchored to the support, forming a single-atom catalyst. However, the rapid Joule heating method only has a temperature effect, with a slow heating rate (on the order of tens of milliseconds). Therefore, the efficiency of preparing single-atom catalysts using this method is low, and the number of defects in the prepared single-atom catalyst support is limited. This affects the coordination structure of the metal atoms and support in the single-atom catalyst, as well as the amount of oxygen doping from the air, thus influencing the structure and performance of the single-atom catalyst to some extent. Therefore, there is an urgent need to develop a new, efficient, and rapid method for preparing high-performance single-atom catalysts. Summary of the Invention
[0004] In order to overcome the defects of the existing technology, one of the objectives of the present invention is to provide a microsecond-level pulse discharge system. The pulse discharge system achieves the repeatability of the pulse discharge process and the uniformity of the current distribution by designing the inner and outer diameters of the discharge processing cavity, and performs pulse discharge with a period of hundreds of microseconds on the sample to be processed placed in the discharge cavity.
[0005] The second objective of this invention is to provide a method for preparing single-atom catalysts based on the microsecond-level pulsed discharge system described in this invention. The method utilizes the temperature effect of the pulsed discharge system to achieve a heating rate on the order of hundreds of microseconds, significantly improving the preparation efficiency of single-atom catalysts. Furthermore, the pulsed discharge generates a strong electromagnetic field and plasma, causing more defects in the support and allowing oxygen elements in the air to participate in the coordination of the single-atom catalyst, forming a unique single-atom coordination structure, thus obtaining a single-atom catalyst.
[0006] The objective of this invention is achieved through the following technical solutions.
[0007] A microsecond-level pulsed discharge system includes a capacitor bank, an air switch, and a discharge chamber connected in sequence via wires to form a closed loop. The capacitor bank consists of several capacitors connected in parallel and is connected to an external power source. The external power source charges the capacitor bank, which in turn supplies power to the pulsed discharge system. A Rogowski coil is installed on the wire between the capacitor bank and the discharge chamber. The Rogowski coil is connected to an external oscilloscope for monitoring the current and voltage values of the discharge system. Electrodes are connected to both ends of the discharge chamber, and the interior of the discharge chamber is filled with sample powder.
[0008] The discharge cavity is made of a conductive material, and its inner diameter (d) should meet the following requirements: Wherein, L is the inductance of the pulse discharge system, and C is the energy storage capacitor of the pulse discharge system;
[0009] The outer diameter (D) of the discharge cavity is 1.6 to 2.0 times the inner diameter, and the length (l) of the discharge cavity is 2 to 5 times the inner diameter, in order to ensure the repeatability of the discharge process and the uniformity of the current distribution.
[0010] Preferably, the inner diameter of the discharge cavity is less than or equal to 10 mm; the density of the powder sample filling the discharge cavity is 30% to 80% to avoid explosion.
[0011] Further preferably, the specific structure of the discharge cavity is as follows: the material of the discharge cavity is copper, tungsten, molybdenum or graphite; the main structure of the discharge cavity is a hollow cylinder with openings at both ends, and the cylinder is filled with sample powder; the rod ends of the two T-shaped copper plugs are machined with external threads, and the inner walls of the openings at both ends of the discharge cavity are machined with internal threads; the rod ends of the T-shaped copper plugs pass through the copper washer, the wiring hole at one end of the copper flat strip and another copper washer in sequence, and are threadedly connected to the openings at both ends of the discharge cavity; the wiring holes at the other ends of the two copper flat strips are respectively connected to the two electrodes.
[0012] A method for preparing a single-atom catalyst based on the microsecond-level pulsed discharge system of the present invention, wherein the method comprises filling a support sample loaded with metal salt into the discharge cavity and performing several pulsed discharge treatments to prepare a single-atom catalyst;
[0013] The process parameters of the pulse discharge treatment are as follows: the voltage of the pulse discharge is 6-12kV, the loop current is 400-600kA, and the period of the pulse discharge system is 160 microseconds; under the voltage and loop current conditions, the current and voltage curves formed are sinusoidal underdamped waveforms, and the generated thermal shock promotes the rapid decomposition of metal salts, and the metal atoms are captured by the carrier to form a highly dispersed single-atom coordination structure. Rapid cooling avoids the aggregation of metal atoms.
[0014] Preferably, the metal salt is a soluble metal nitrate or a metal chloride; and the carrier is a carbon-based material.
[0015] More preferably, the metal salt is copper nitrate, nickel nitrate, copper chloride, nickel chloride, or chloroplatinic acid; and the carrier is graphene (GR), reduced graphene oxide (r-GO), nitrogen-doped graphene (N-GR), carbon nanotubes, activated carbon, or graphene aerogel (GA).
[0016] Beneficial effects
[0017] (1) This invention provides a microsecond-level pulsed discharge system, which can generate a pulsed current with a period of hundreds of microseconds and an amplitude of hundreds of kiloamperes. This pulsed current can be used to induce phase transitions in materials and to prepare new materials. The pulsed discharge system achieves repeatability of the pulsed discharge process and uniformity of current distribution through the design of the inner and outer diameters of the discharge processing chamber, and the temperature rise rate can reach 10. 9 Its power and input energy are far higher than those of traditional Joule heating (K / s).
[0018] (2) This invention provides a method for preparing single-atom catalysts based on a microsecond-level pulsed discharge system. The strong Joule heating effect of the pulsed discharge pulse current causes the metal salt to decompose and undergo micro-explosion within microseconds, forming plasma clusters. Under the constraint of the electromagnetic pinch effect of the pulsed discharge, the plasma clusters are rapidly cooled, causing the metal atoms to anchor at the defect sites of the support, thus realizing the preparation of single-atom catalysts. Moreover, unlike rapid Joule heating which only has a temperature effect, the pulsed discharge method not only has a temperature effect, but also has a much higher heating rate than rapid Joule heating. It also generates a strong electromagnetic field and plasma, causing more defects in the support and allowing oxygen elements in the air to participate in the coordination of the single-atom catalyst, forming a unique single-atom coordination structure.
[0019] (3) This invention provides a method for preparing single-atom catalysts based on a microsecond-level pulsed discharge system. The pulsed discharge method can generate a large current to rapidly thermally shock the conductive carrier, causing the temperature to rise rapidly. This causes the metal salt loaded on the carrier to directly sublimate and decompose into metal atoms and gas. The gaseous charged particles migrate on the carrier surface under the action of a strong electromagnetic field. The metal atoms can be captured and anchored by defects on the carrier to form single-atom catalysts. Moreover, the pulsed discharge can also cause the air in the local area inside the cavity to break down and form plasma. This not only introduces more defects on the carrier to anchor more metal single atoms, but also ionizes the oxygen in the air, increasing the oxygen content of the carrier. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the pulse discharge system described in this invention;
[0021] Figure 2 for Figure 1 Schematic diagram of the discharge cavity structure;
[0022] Figure 3 This is a current-time curve of pulsed discharge in Example 2;
[0023] Figure 4 The image shows an aberration-corrected scanning transmission electron microscopy image of the graphene-supported copper single-atom catalyst prepared in Example 2.
[0024] Figure 5 The X-ray absorption near-edge structure spectra of the graphene-supported copper single-atom catalyst and the reference sample prepared in Example 2 are shown.
[0025] Figure 6 The image shows an aberration-corrected scanning transmission electron microscopy image of the graphene-supported nickel single-atom catalyst prepared in Example 3.
[0026] Figure 7 The image shows an aberration-corrected scanning transmission electron microscopy image of the graphene aerogel-supported platinum single-atom catalyst prepared in Example 4.
[0027] Among them, 1-external power supply, 2-capacitor group, 3-air switch, 4-discharge cavity, 5-electrode, 6-Rogerski coil, 4.1-copper plug, 4.2-washer, 4.3-copper flat strip, 4.4-sample. Detailed Implementation
[0028] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the methods described are conventional methods, and the raw materials described are available from publicly available commercial sources.
[0029] In the following embodiments:
[0030] (1) The reduced graphene oxide (r-GO) support loaded with copper nitrate was prepared by the following method: First, 100 mg of copper nitrate was dissolved in deionized water to prepare 50 mL of copper nitrate aqueous solution with a mass fraction of 0.2%. Then, 100 mg of reduced graphene oxide was added to the copper nitrate aqueous solution and stirred for 30 minutes. The solution was then rapidly cooled with liquid nitrogen and freeze-dried to obtain a uniformly reduced graphene oxide (r-GO) support loaded with copper nitrate.
[0031] (2) The graphene (GR) support loaded with nickel chloride was prepared by the following method: First, 300 mg of nickel chloride was dissolved in deionized water to prepare 60 mL of nickel chloride aqueous solution with a mass fraction of 0.5%. 120 mg of graphene was added to the nickel chloride aqueous solution and stirred for 30 minutes. The solution was then rapidly cooled with liquid nitrogen and freeze-dried to obtain a graphene (GR) support uniformly loaded with nickel chloride.
[0032] (3) The graphene aerogel (GA) carrier loaded with chloroplatinic acid was prepared by the following method: First, 250 mg of chloroplatinic acid was dissolved in deionized water to prepare 50 mL of chloroplatinic acid aqueous solution with a mass fraction of 0.5%.
[0033] Add 40 mg of graphene oxide to 20 mL of deionized water, stir for 30 minutes, pour into a 25 mL hydrothermal reactor, heat to 180 °C, keep warm for 6 hours, and remove after cooling to obtain graphene hydrogel.
[0034] The graphene hydrogel was immersed in the 0.5% chloroplatinic acid aqueous solution for 3 hours and then freeze-dried to obtain a graphene aerogel (GA) carrier uniformly loaded with chloroplatinic acid.
[0035] Example 1
[0036] This embodiment provides a microsecond-level pulse discharge system, such as Figure 1As shown, the pulse discharge system includes a capacitor bank 2, an air switch 3, and a discharge chamber 4 connected in sequence via wires to form a closed loop. The capacitor bank 2 consists of two capacitors connected in parallel. The capacitor bank 2 is connected to an external power supply 1, which charges the capacitor bank 2 and supplies power to the pulse discharge system. A Rogowski coil 6 is installed on the wire between the capacitor bank 2 and the discharge chamber 4. The Rogowski coil 6 is connected to an external oscilloscope for monitoring the current and voltage values of the discharge system. Electrodes 5 are connected to both ends of the discharge chamber 4, and the interior of the discharge chamber 4 is filled with sample powder 4.4.
[0037] The specific structure of the discharge cavity 4 is as follows: Figure 2 As shown: the discharge chamber 4 is made of copper; the main structure of the discharge chamber 4 is a hollow cylinder with open ends, and the cylinder is filled with sample powder; the rod ends 4.1 of the two T-shaped copper plugs are both machined with external threads, and the rod ends of the T-shaped copper plugs 4.1 pass through the copper washer 4.2, the wiring hole at one end of the copper flat strip 4.3, and the other copper washer 4.2 in sequence, and are threaded to the internal threads machined on the inner wall of the openings at both ends of the discharge chamber 4; the wiring hole at the other end of the copper flat strip 4.3 is connected to the electrode;
[0038] During installation, first, fit a copper washer 4.2 onto the external thread of a T-shaped copper plug 4.1 screw. Then, fit the wiring hole at one end of the copper flat strip into the T-shaped copper plug 4.1 screw, and then fit another copper washer 4.2. Next, connect the external thread of the T-shaped copper plug 4.1 screw to the internal thread of the inner wall of the discharge cavity opening at one end. At this time, fill the discharge cavity with powder sample from the other end opening until the density reaches 30% to 80%. Finally, install another T-shaped copper plug 4.1 into the other end opening of the discharge cavity in the same way. The wiring holes at the other end of the copper flat strip leading out from the openings at both ends of the discharge cavity are connected to the two electrodes (positive and negative), respectively. The copper flat strip 4.3 acts as a conductor.
[0039] The discharge cavity is made of copper, and its inner diameter (d) satisfies the following:
[0040] Wherein, L is the inductance of the pulse discharge system, and C is the energy storage capacitor of the pulse discharge system, that is, the capacitance of the capacitor bank in the discharge system; in the pulse discharge system described in the following embodiments, the energy storage capacitor C of the pulse discharge system is 245μF, and the inductance L of the discharge system is 2.08μH.
[0041] L and C can be determined and calculated based on short-circuit pulse discharge experiments reported in existing literature. Specifically, a short-circuit discharge experiment is designed by directly connecting the positive and negative electrodes of the pulse discharge system with copper strips to short-circuit it. The current oscillation period T and the current amplitude I of the first two half-waves are measured by measuring the current oscillation period T and the current amplitude I of the first two half-waves displayed on an external oscilloscope connected to the Rogowski coil in the pulse discharge system. m1 and I m2 Based on formulas (1) and (2), the inductance L of the pulse discharge system can be calculated:
[0042]
[0043]
[0044] The inductance L of this pulse discharge system can be obtained by taking the average value of three short-circuit tests; in the discharge system described in this invention, the inductance L of the discharge system is tested and calculated to be 2.08μH.
[0045] Example 2
[0046] This embodiment provides a method for preparing a reduced graphene oxide-supported copper single-atom catalyst based on the microsecond-level pulsed discharge system described in Example 1. The method involves filling the discharge cavity with a support sample loaded with metal salt, achieving a density of 30% to 50%, and performing three pulsed discharge treatments to obtain the single-atom catalyst.
[0047] The metal salt-loaded support sample is a reduced graphene oxide (r-GO) support loaded with copper nitrate.
[0048] The discharge cavity 4 has an inner diameter d = 9 mm, an outer diameter D = 16 mm, and a length l = 20 mm.
[0049] The process parameters for the pulse discharge treatment are as follows: the pulse discharge voltage is 6kV, the loop current is 500kA, and the pulse discharge system period is 160 microseconds.
[0050] The current-time curve of pulse discharge is as follows: Figure 3 As shown, under the voltage and loop current conditions, the current and voltage curves formed are sinusoidal underdamped waveforms. The sample and the discharge cavity form a local parallel circuit. The first amplitude of the current in the loop reaches 500kA. Rapid Joule heating is generated on the reduced graphene oxide, which promotes the decomposition of copper nitrate, producing copper atoms and nitrogen oxides. Due to the large number of defects on r-GO, and the nitrogen oxides being subjected to high temperature and plasma, nitrogen elements can be doped into r-GO. Copper atoms form a coordination structure with nitrogen and oxygen atoms and are anchored on r-GO to form a single-atom catalyst.
[0051] The single-atom catalyst prepared in Example 2 was characterized using aberration-corrected scanning transmission electron microscopy, and the results are as follows: Figure 4 As shown, isolated bright spots are distributed on the matrix. Considering the huge difference in atomic numbers between carbon and copper, the black matrix is identified as reduced graphene oxide, and the isolated bright spots are identified as copper single atoms.
[0052] To further identify the single-atom coordination structure, synchrotron radiation was used to test the sample and reference sample. Figure 5 The X-ray absorption near-edge structure spectra of the single-atom catalyst sample and the reference sample (pure copper and copper oxide) prepared in Example 2 show that the coordination structure of copper in the single-atom catalyst sample is significantly different from that in the reference sample. This further illustrates that the single-atom catalyst prepared by the method of the present invention has a unique single-atom coordination structure of copper on the reduced graphene oxide.
[0053] Example 3
[0054] This embodiment provides a method for preparing a graphene-supported nickel single-atom catalyst based on the microsecond-level pulsed discharge system described in Example 1. The method involves filling a support sample loaded with metal salt into the discharge cavity with a density of 40% to 50%, and performing five pulsed discharge treatments to obtain the single-atom catalyst.
[0055] The metal salt-loaded support sample is a graphene (GR) support loaded with nickel chloride.
[0056] The discharge cavity 4 has an inner diameter d = 10 mm, an outer diameter D = 18 mm, and a length l = 24 mm.
[0057] The process parameters for the pulse discharge treatment are as follows: the pulse discharge voltage is 6kV, the loop current is 500kA, and the pulse discharge system period is 160 microseconds.
[0058] Under the voltage and loop current conditions, the resulting current and voltage curves are sinusoidal underdamped waveforms. The sample and the discharge cavity form a local parallel circuit. The first amplitude of the current in the loop reaches 500kA, which generates rapid Joule heating on the reduced graphene, causing nickel chloride to decompose and producing nickel atoms and chlorine gas. Five repeated pulse discharges decompose all the nickel chloride and form nickel single-atom structures on the graphene.
[0059] The single-atom catalyst prepared in Example 3 was characterized using aberration-corrected scanning transmission electron microscopy, and the results are as follows: Figure 6 As shown, isolated bright spots are distributed on the matrix. Considering the huge difference in atomic numbers between carbon and nickel, the black matrix is identified as graphene, and the isolated bright spots are identified as nickel single atoms.
[0060] To further identify the single-atom coordination structure, synchrotron radiation was used to test the sample and the reference sample. It can be seen that the coordination structure of nickel in the single-atom catalyst sample is significantly different from that of the reference sample (pure nickel, nickel oxide), which further illustrates that the single-atom catalyst prepared by the method described in this invention has a unique single-atom coordination structure of nickel on graphene.
[0061] Example 4
[0062] This embodiment provides a method for preparing a graphene-supported platinum single-atom catalyst based on the microsecond-level pulsed discharge system described in Example 1. The method involves filling a support sample loaded with metal salt into the discharge cavity with a density of 50% to 80%, and performing five pulsed discharge treatments to obtain the single-atom catalyst.
[0063] The metal salt-loaded support sample is a graphene (GR) support loaded with chloroplatinic acid.
[0064] The discharge cavity 4 has an inner diameter d = 10 mm, an outer diameter D = 18 mm, and a length l = 45 mm. The process parameters for the pulse discharge treatment are as follows: the pulse discharge voltage is 10 kV, the circuit current is 600 kA, and the period of the pulse discharge system is 160 microseconds.
[0065] Under the voltage and loop current conditions, the resulting current and voltage curves are sinusoidal underdamped waveforms. The sample and the discharge cavity form a local parallel circuit. The first amplitude of the current in the loop reaches 600kA, which generates rapid Joule heating on the graphene aerogel, causing chloroplatinic acid to decompose and producing platinum atoms and chlorine gas. After 5 repeated pulse discharges, platinum atoms migrate and anchor on the graphene aerogel to form a platinum single-atom catalyst.
[0066] The single-atom catalyst prepared in Example 4 was characterized using aberration-corrected scanning transmission electron microscopy, and the results are as follows: Figure 7 As shown, isolated bright spots are distributed on the matrix. Considering the huge difference in atomic numbers between carbon and platinum, the black matrix is identified as graphene aerogel, and the isolated bright spots are identified as platinum single atoms.
[0067] To further identify the single-atom coordination structure, synchrotron radiation was used to test the sample and the reference sample. It can be seen that the coordination structure of platinum in the single-atom catalyst sample is significantly different from that of the reference sample (pure platinum, platinum oxide). This further illustrates that the single-atom catalyst prepared by the method described in this invention has a unique single-atom coordination structure of platinum on graphene aerogel.
[0068] The above description is merely a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A microsecond-level pulse discharge system, characterized in that: The pulse discharge system includes a capacitor bank, an air switch, and a discharge chamber that are connected in sequence via wires to form a closed loop; The capacitor bank consists of several capacitors connected in parallel. The capacitor bank is connected to an external power source, which charges the capacitor bank and supplies power to the pulse discharge system. A Rogowski coil is installed on the wire between the capacitor bank and the discharge chamber. The Rogowski coil is connected to an external oscilloscope to monitor the current and voltage values of the discharge system. Electrodes are connected to both ends of the discharge chamber, and the interior of the discharge chamber is filled with sample powder. The discharge cavity is made of a conductive material, and its inner diameter (d) should meet the following requirements: Where L is the inductance of the pulse discharge system and C is the energy storage capacitor of the pulse discharge system; The outer diameter of the discharge cavity is 1.6 to 2.0 times the inner diameter, and the length of the discharge cavity is 2 to 5 times the inner diameter; The density of the powder sample filling the discharge cavity is 30%-80%; The specific structure of the discharge cavity is as follows: the material of the discharge cavity is copper, tungsten, molybdenum or graphite; the main structure of the discharge cavity is a hollow cylinder with openings at both ends, and the cylinder is filled with sample powder; the rod ends of the two T-shaped copper plugs are machined with external threads, and the inner walls of the openings at both ends of the discharge cavity are machined with internal threads. The rod ends of the T-shaped copper plugs pass through the copper washer, the wiring hole at one end of the copper flat strip and another copper washer in sequence, and are threaded to the openings at both ends of the discharge cavity; the wiring holes at the other ends of the two copper flat strips are connected to the two electrodes respectively.
2. The microsecond-level pulse discharge system according to claim 1, characterized in that: The inner diameter of the discharge cavity is less than or equal to 10 mm.
3. A method for preparing a single-atom catalyst based on the microsecond-level pulsed discharge system described in claim 1 or 2, characterized in that: The method involves filling a metal salt-loaded support sample into a discharge cavity and performing several pulse discharge treatments to prepare a single-atom catalyst. The process parameters for the pulse discharge treatment are as follows: the voltage of the pulse discharge is 6~12kV, the circuit current is 400~600kA, and the period of the pulse discharge system is 160 microseconds.
4. The method for preparing single-atom catalysts using a microsecond-level pulsed discharge system according to claim 3, characterized in that: The metal salt is a soluble metal nitrate or metal chloride; the carrier is a carbon-based material.
5. The method for preparing a single-atom catalyst using a microsecond-level pulsed discharge system according to claim 4, characterized in that: The metal salt is copper nitrate, nickel nitrate, copper chloride, nickel chloride, or chloroplatinic acid; the carrier is graphene, reduced graphene oxide, nitrogen-doped graphene, carbon nanotubes, activated carbon, or graphene aerogel.