WO2019200895A1 - Single-atom air cathode, battery, electrochemical system and bioelectrochemical system - Google Patents

Abstract

Provided are a single-atom air cathode, a battery, an electrochemical system, and a bioelectrochemical system. The cathode comprises: a current collector layer, and a catalyst layer, wherein the catalyst layer is disposed on the current collector layer, and the catalyst layer comprises an atomic-level dispersed metal catalyst.

Description

Single atom air cathode, battery, electrochemical system and bioelectrochemical system

Priority information

This application claims the patent application No. 201810341661.9 submitted to the State Intellectual Property Office of China on April 17, 2018, and the patent application number 201820542336.4 submitted to the State Intellectual Property Office of China on April 17, 2018. Equity, and the full text is incorporated herein by reference.

Technical field

The present application relates to the fields of environment, materials, and energy, and in particular, to cathodes, batteries, and electrochemical systems.

Background technique

Environmental issues and energy issues are two major problems facing the development of contemporary society. Purifying wastewater while taking into account energy recovery is a new challenge for wastewater treatment technology. The bioelectrochemical system represented by a microbial fuel cell is an emerging sewage treatment technology that can convert the chemical energy in the pollutant into electric energy while treating the sewage. The microbial fuel cell can oxidize the organic matter in the sewage by using the electric generating microorganism attached to the anode, and the cathode receives the electron to complete the oxygen reduction reaction.

However, the performance of current cathodes, batteries, and electrochemical systems still needs to be improved.

Summary of the invention

This application proposes a cathode. The cathode includes: a collector layer; and a catalyst layer disposed on the collector layer, the catalyst layer including an atomic-level dispersed metal catalyst. Thus, the use of an atom-level dispersed metal catalyst to catalyze the oxygen reduction reaction in the cathode not only has the advantages of good catalytic activity, high metal utilization rate, low cost, etc., but also can improve the electron utilization rate when the cathode is used in an electrochemical system. , thereby improving the electrical performance of the electrochemical system.

According to an embodiment of the present application, the cathode further includes: a diffusion layer disposed on a side of the collector layer away from the catalyst layer, or disposed on the catalyst layer away from the collector layer One side. Thus, when the cathode is an air cathode, the diffusion layer can be in contact with air, facilitating diffusion of oxygen into the air cathode, further improving the use effect of the cathode.

According to an embodiment of the present application, the atomic-level dispersed metal catalyst includes a support and an active metal supported on the support, the active metal including at least one of Fe, Co, and Ni. Thus, the atomic-stage dispersed metal catalyst is various in type, and the active metal is supported on the carrier, whereby the stability of the catalyst layer can be improved, and the use performance of the cathode can be further improved.

According to an embodiment of the present application, the atomic-level dispersed metal catalyst is prepared under a low temperature environment. Thereby, an atom-level dispersed metal catalyst having good performance can be easily prepared, and the use performance of the cathode can be further improved.

In another aspect of the application, the application proposes a battery. According to an embodiment of the present application, the battery includes: a cathode as described above; and an anode electrically connected to the cathode. Thus, the battery has all of the features and advantages of the cathode described above, and the battery has high power generation efficiency and good operational stability.

According to an embodiment of the present application, the battery has a power density of not less than 2000 mW/m ² when the external resistance is 50 ohms. Thereby, the power generation efficiency of the battery is high, and the use effect of the battery is further improved.

According to an embodiment of the present application, the current density of the battery after 500 hours of operation is not more than 5%. Thereby, the battery has better running stability, and the use effect of the battery is further improved.

In yet another aspect of the present application, the present application proposes an electrochemical system. According to an embodiment of the present application, the electrochemical system includes: a housing defining a reaction space therein; and a modular electrode assembly disposed in the reaction space, the modular The electrode assembly further includes: a hollow cathode socket including: a plurality of air cathodes disposed on sidewalls of the hollow cathode socket, the air cathode including The catalyst layer described above; an anode, the anode being electrically connected to the air cathode. Thus, the electrochemical system not only has all the features and advantages of the catalyst layer described above, that is, the catalytic activity of the air cathode is good, the metal utilization rate is high, the cost is low, and the like, and the electrochemical system is also set. The modular electrode assembly integrates multiple air cathodes and anodes in the same reaction space, further improving the electrical performance of the electrochemical system.

According to an embodiment of the present application, the hollow cathode slot includes a plurality of the sidewalls and a bottom surface, and the plurality of sidewalls and the bottom surface define a hollow space inside the hollow cathode slot, The side of the side wall adjacent to the hollow space is in contact with the atmosphere. Thereby, in the case where a plurality of air cathodes are integrated in the same hollow space, each air cathode can be sufficiently contacted with the air to further react, thereby further improving the power generation performance of the electrochemical system.

According to an embodiment of the present application, the anode is disposed between the hollow cathode socket and the housing. Thereby, the use effect of the electrochemical system is further improved.

According to an embodiment of the present application, the modular electrode assembly further includes an anode socket, and the anode is disposed on a sidewall of the anode socket. Thereby, the anode slot can be easily removed for easy replacement of the anode, and when a plurality of anodes are provided in the system, a plurality of anodes can be easily disposed in the same anode slot, further improving The use of electrochemical systems.

According to an embodiment of the present application, the air cathode includes a plurality of sub-cathodes. Thus, by providing a plurality of sub-cathodes, an air cathode having a large area can be easily prepared, and the prepared air cathode has high surface flatness and good performance, and further improves the use effect of the electrochemical system.

According to an embodiment of the present application, a plurality of the sub-cathodes are connected in parallel or in series. Thereby, the plurality of sub-cathodes are connected in a plurality of ways, and can be combined as needed to form an air cathode, which further improves the use effect of the electrochemical system.

According to an embodiment of the present application, the air cathode further includes a conductive support frame, the plurality of sub-cathodes being directly disposed on the conductive support frame, the conductive support frame being electrically connected to the anode. Thereby, it is possible to easily electrically connect the plurality of sub-cathodes to the anode, thereby further improving the use effect of the electrochemical system.

According to an embodiment of the present application, the air cathode further includes a plurality of wires, the plurality of wires being connected in one-to-one correspondence with the plurality of sub-cathodes, and the plurality of wires are electrically connected to the anode. Thereby, it is possible to easily electrically connect the plurality of sub-cathodes to the anode, thereby further improving the use effect of the electrochemical system.

According to an embodiment of the present application, the anode is at least one of a carbon brush, carbon cloth, carbon paper, carbon felt, activated carbon, and graphite. When the electrochemical system is a bioelectrochemical system, the anode can increase the adhesion ability of the microorganism, and the cost of the electrochemical system can be further saved.

According to an embodiment of the present application, the anode is a planar electrode, and the electrochemical system further includes a separator disposed between the air cathode and the anode. Thereby, the membrane can slow down the contamination rate of the air cathode, further improving the electrical production performance of the electrochemical system.

DRAWINGS

1 shows a schematic structural view of a cathode according to an embodiment of the present application;

2 shows a flow chart of a method of preparing an atom-level dispersed metal catalyst according to an embodiment of the present application;

3 shows a schematic structural view of a cathode according to another embodiment of the present application;

4 shows a schematic structural view of a cathode according to still another embodiment of the present application;

FIG. 5 is a schematic structural view of a cathode according to still another embodiment of the present application; FIG.

6 is a schematic structural view of a battery according to an embodiment of the present application;

Figure 7 shows a schematic structural view of an electrochemical system according to an embodiment of the present application;

Figure 8 shows a schematic structural view of an electrochemical system according to another embodiment of the present application;

9 shows a schematic structural view of an electrochemical system according to still another embodiment of the present application;

Figure 10 shows a schematic structural view of an electrochemical system according to still another embodiment of the present application;

Figure 11 shows a schematic structural view of an air cathode according to an embodiment of the present application;

FIG. 12 is a schematic structural view of an air cathode according to another embodiment of the present application; FIG.

Figure 13 is a graph showing the electrical performance test of an electrochemical system according to some embodiments and comparative examples of the present application;

Figure 14 is a graph showing the electrical performance test of a bioelectrochemical system according to further embodiments and comparative examples of the present application;

Figure 15 shows a graph of operational stability testing of an electrochemical system in accordance with some embodiments and comparative examples of the present application.

Reference mark:

10: catalyst layer; 20: collector layer; 30: diffusion layer; 40: support layer; 110: cathode; 100: shell; 200: reaction space; 300: modular electrode assembly; 310: hollow cathode slot; 311: sidewall; 320: air cathode; 321: sub-cathode; 322: conductive support; 323: wire; 330: anode; 350: external resistance; 360: anode socket; 1000: electrochemical system.

detailed description

The embodiments of the present application are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are intended to be illustrative only, and are not to be construed as limiting.

It should be noted that the features and effects described in the various aspects of the present application may be applied to each other, and are not described herein again.

This application is based on the discovery and recognition of the following facts and issues by the inventors:

Current electrochemical systems have problems of poor electrical performance and high production costs. The inventors discovered through in-depth research and a large number of experiments that this is caused by the poor catalytic efficiency and high cost of the catalyst of the cathode in the electrochemical system. Especially in bioelectrochemical systems, the oxygen reduction reaction of the cathode is one of the key factors limiting the electrical performance of the bioelectrochemical system. The oxygen reduction reaction is mainly driven by the cathode catalyst, and the catalyst cost currently used for the cathode. It is higher and has lower catalytic efficiency. For example, the conventional cathode uses platinum carbon as a catalyst, platinum is expensive, resources are scarce, and its catalytic performance is significantly degraded when the cathode is contaminated for a long period of time. In one aspect of the application, the application proposes a cathode. According to an embodiment of the present application, referring to FIG. 1, the cathode 110 includes a catalyst layer 10 and a collector layer 20. Wherein, the catalyst layer 10 is disposed on the collector layer 20, and the catalyst layer 10 includes an atomic-level dispersed metal catalyst. Thus, the use of an atom-level dispersed metal catalyst for catalyzing the oxygen reduction reaction in the cathode 110 not only has the advantages of good catalytic activity, high metal utilization rate, but also can improve the electron utilization rate when the cathode 110 is used in an electrochemical system. Improve the electrical performance of the electrochemical system.

According to an embodiment of the present application, the atomic-level dispersed metal catalyst may include a support and an active metal supported on the support. According to the embodiment of the present application, the specific type of the carrier is not particularly limited as long as the atom-level dispersed metal catalyst can be uniformly dispersed therein. Specifically, the carrier may be graphene, mesoporous carbon, carbon nanotube, Carbon black or activated carbon. According to the embodiment of the present application, the specific kind of the active metal is not particularly limited as long as it can catalyze the oxygen reduction reaction, and specifically, the active metal may include at least one of Fe, Co, and Ni. Specifically, the active metal may be a unit metal, such as a single Co, a single Ni, a single Fe, or a binary metal, such as a Fe/Co binary metal, a Fe/Ni binary metal, a Co/Ni dual element. The metal, the active metal may also be a ternary metal such as a Fe/Co/Ni ternary metal. Thus, the atom-level dispersed metal catalyst has many types and sources, and the oxygen reduction efficiency of the cathode is improved, and the production cost is lowered.

According to the embodiment of the present application, the preparation method of the atom-level dispersed metal catalyst is not particularly limited as long as the active metal can be dispersed as a metal mono atom. For example, the atom-level dispersed metal catalyst can be prepared by a dipping method, an etching method, a photo-assisted synthesis method, a metal organic framework-assisted synthesis method, or the like, whereby the atom-level dispersed metal catalyst in the catalyst layer 10 can have various preparation methods. Therefore, it is relatively easy to obtain, and it can be easily applied to the cathode to improve the efficiency of the cathode oxygen reduction reaction.

According to a specific embodiment of the present application, the atomic-level dispersed metal catalyst may be prepared under a low temperature environment. Thereby, an atom-level dispersed metal catalyst having good performance can be easily prepared, and the use performance of the cathode can be further improved. According to the embodiment of the present application, the low-temperature solution synthesis method can be used to prepare a high-metal loading atomic-level dispersed metal catalyst on a large scale, which can improve the effective utilization ratio of the metal atom and reduce the application cost of the metal catalyst. Specifically, the nucleation can be suppressed by the ultra-low temperature liquid phase, so that the concentration of the metal atom in the solution is lower than the nucleation limit threshold of the metal monomer concentration, thereby obtaining a solution containing the atomic-level dispersed metal, and then obtaining the atomic level by further loading process. Disperse the metal catalyst. Thereby, the atom-scale dispersed metal catalyst can be synthesized on a large scale in an ultra-low temperature solution environment.

The various steps of the method are described in detail below according to a specific embodiment of the present application:

According to an embodiment of the present application, referring to FIG. 2, the method includes:

S100: mixing a metal compound with a first solvent to form a metal precursor solution

According to an embodiment of the present application, in this step, the metal compound is mixed with the first solvent to form a metal precursor solution. According to an embodiment of the present application, the metal compound may be a soluble compound of at least one of Fe, Co, and Ni, and the first solvent may include water, ethanol, ethylene glycol, acetone, chloroform, diethyl ether, tetrafluorohydrofuran, At least one of dimethylformamide and formaldehyde. Thus, the metal precursor solution formed by mixing the above solute and the solvent can be used as a source of the atomic-level dispersed metal in the subsequent step. According to an embodiment of the present application, the concentration of the metal precursor solution may be 0.001-1.0 mol/L, and specifically, may be 0.005 mol/L, 0.008 mol/L, 0.01 mol/L, 0.02 mol/L, 0.05 mol/ L, 0.08 mol/L, 1.0 mol/L, and the like.

According to an embodiment of the present application, the atomic-level dispersed metal prepared by the method may include at least one of Fe, Co, and Ni. According to an embodiment of the present application, the atomic-level dispersed metal prepared by the method may be a unit metal catalyst, for example, an atom-level dispersed metal iron catalyst may be prepared by the method, or an atom-level dispersed metal cobalt catalyst may be prepared by the method, or may be utilized. This method produces an atomically dispersed metal nickel catalyst. According to an embodiment of the present application, the atomic-level dispersed metal prepared by the method may also be a binary metal catalyst, for example, an atom-level dispersed iron/cobalt binary metal catalyst may be prepared by the method, or an atomic level may be prepared by the method. A dispersed iron/nickel binary metal catalyst is used, or an atomically dispersed cobalt/nickel binary metal catalyst is prepared by this method. According to an embodiment of the present application, the atomic-level dispersed metal prepared by the method may also be a ternary metal catalyst. For example, an atom-level dispersed iron/cobalt/nickel ternary metal catalyst can be prepared by this method. Thus, the preparation of unit, binary and ternary metal catalysts can be achieved by this method.

According to a specific embodiment of the present application, the metal compound may be a soluble compound of Fe, or a soluble compound of Co, or a soluble compound of Ni, or a soluble compound of Fe, Co mixed, or A soluble compound in which Fe and Ni are mixed, or a soluble compound in which Co and Ni are mixed, or a soluble compound in which Fe, Co, and Ni are mixed. Thus, unit, binary, and ternary metal catalysts can be prepared separately.

S200: mixing a reducing agent with a second solvent to form a reducing agent solution

According to an embodiment of the present application, in this step, a reducing agent is mixed with a second solvent to form a reducing agent solution. According to an embodiment of the present application, the reducing agent may include NaBH ₄ , KBH ₄ , N ₂ H ₄ , N ₂ H ₅ OH, formaldehyde, formic acid, ascorbic acid, Na ₂ SO ₃ , K ₂ SO _{3 ,} and H ₂ C ₂ O _{4 .} At least one of the second solvent may include at least one of water, ethanol, ethylene glycol, acetone, chloroform, diethyl ether, tetrafluorohydrofuran, dimethylformamide, and formaldehyde. Thus, in the subsequent process, the reducing agent solution formed by mixing the above solute and the solvent can be reacted with the metal precursor solution, and the reducing agent is reduced to obtain a solution containing the atomic-level dispersed metal. According to an embodiment of the present application, the concentration of the reducing agent solution may be 0.001 to 10.0 mol/L, and specifically, may be 2 mol/L, 5 mol/L, 7 mol/L, and 8 mol/L. It should be noted that the first solvent is water when it is not the same as the second solvent.

S300: mixing the carrier material with the third solvent to form a dispersion

According to an embodiment of the present application, in this step, the carrier material is mixed with a third solvent to form a dispersion. According to an embodiment of the present application, the carrier material may be a doped carbon nanomaterial. According to an embodiment of the present application, in the doped carbon nanomaterial, the dopant atoms may form defects on the surface of the carbon nanomaterial, thereby increasing the adsorption of the carrier material on the metal atom, thereby increasing the carrier material to the metal atom. The amount of load. According to a particular embodiment of the present application, the support material may include at least one of nitrogen-doped mesoporous carbon (CMK-3), nitrogen-doped graphene, and graphite phase carbonized nitrogen (gC ₃ N ₄ ). Thus, a high metal loading atomically dispersed metal catalyst can be obtained using the above materials.

According to an embodiment of the present application, the third solvent may include at least one of water, ethanol, ethylene glycol, acetone, chloroform, diethyl ether, tetrafluorohydrofuran, dimethylformamide, and formaldehyde. Thereby, the above solute and the solvent can be mixed to form a dispersion, and in the subsequent step, the metal atom is adsorbed by the solute in the dispersion to obtain a carrier-supported atomic-level dispersed metal catalyst. According to an embodiment of the present application, the concentration of the dispersion may be 0.1-10 g/L, and specifically, may be 2.5 g/L, 3.5 g/L, 4.5 g/L, 5.5 g/L, 6.5 g/L, 7.5. g/L, 8.5 g/L, 9.5 g/L.

S400: mixing a metal precursor solution with a reducing agent solution to obtain a solution containing an atomic-level dispersed metal

According to an embodiment of the present application, in this step, the metal precursor solution is mixed with the reducing agent solution to obtain a solution containing an atomic-level dispersed metal. According to an embodiment of the present application, the metal precursor solution may be mixed with the reducing agent solution at a low temperature environment of -100 to 0 °C. Those skilled in the art will appreciate that there is a nucleation limit threshold for the concentration of the metal monomer during solution synthesis. When the concentration of the metal monomer is below this threshold, a solution containing the atomic-level dispersed metal can be obtained. In the prior art, the concentration of metal monomers is often controlled by a microfluidic method. By creating a local low concentration, increasing the specific surface area, reducing the diffusion dimension, etc., the reactants are mixed at a low speed, thereby controlling the mass and heat transfer. The preparation process of the above microfluidic method is too complicated, the yield is low, and the large-scale preparation of the atom-level dispersed metal catalyst is severely inhibited.

According to the embodiment of the present application, the nucleation barrier can be significantly increased by lowering the temperature, and nucleation is effectively suppressed, thereby increasing the concentration of dispersed metal atoms in the solution. Moreover, after the temperature is lowered, the dispersed metal atoms can be effectively adsorbed on different carrier surfaces, thereby facilitating the large-scale synthesis of atom-level dispersed metal catalysts in an ultra-low temperature solution environment. The inventors have found that when the temperature is higher than the above temperature range, the concentration of metal atoms dispersed in the solution is low, and the effective utilization ratio of the metal atoms is low. When the temperature is lower than the above temperature range, the reaction kinetics and thermodynamics are too slow to efficiently prepare metal monoatoms. Thus, the temperature can be set within the above temperature range, and the atomic-level dispersed metal catalyst can be synthesized on a large scale.

According to an embodiment of the present application, in order to carry out the reaction process of the reducing agent solution and the metal precursor solution in the above temperature range, the metal precursor solution and the reducing agent may be first used before mixing the metal precursor solution and the reducing agent solution. The solution is kept in a low temperature chamber for a certain period of time, for example, for 30 minutes. Thereby, the concentration of metal atoms in the solution can be further increased, and the utilization ratio of the metal atoms can be further improved.

The manner of mixing the metal precursor solution and the reducing agent solution is not particularly limited, and those skilled in the art can design according to specific conditions. For example, according to a specific embodiment of the present application, the injection pump can be used to control the drop rate, the metal precursor solution is added dropwise to the stirred reducing agent solution, or the reducing agent solution is added dropwise to the stirred metal precursor solution, thereby The metal precursor solution is sufficiently reacted with the reducing agent solution to obtain a solution containing an atomic-level dispersed metal. According to an embodiment of the present application, the atomic-level dispersed metal may include at least one of Fe, Co, and Ni. Thereby, a plurality of atomic-scale dispersed metal catalysts containing the above metals can be prepared simply and efficiently.

According to the embodiment of the present application, the relative amounts of the metal precursor solution and the reducing agent solution can be determined by a chemical reaction equation, and the amount of the reducing agent solution can be made much larger than the metal in order to fully react the metal precursor solution with the reducing agent solution. The amount of precursor solution is such that all metal atoms in the metal precursor solution are reduced.

According to an embodiment of the present application, the metal precursor solution is added dropwise to the agitation reduction

In the solution, or when the reducing agent solution is added dropwise to the stirred metal precursor solution, the dropping rate may be 0.5-50 mL/h, and the stirring rate may be 0-3000 rpm. Thereby, the metal precursor solution and the reducing agent solution can be sufficiently reacted to obtain a solution containing an atomic-level dispersed metal. According to a specific embodiment of the present application, the dropping rate may be 2.5 mL/h, 7.5 mL/h, 15 mL/h, 30 mL/h, 45 mL/h.

S500: adding a dispersion to a solution containing an atomic-level dispersed metal and stirring to obtain an atom-level dispersed metal catalyst

According to an embodiment of the present application, in this step, the dispersion is added to a solution containing an atomic-level dispersed metal and stirred to obtain an atom-level dispersed metal catalyst. According to an embodiment of the present application, an atom-level dispersed metal catalyst supported by a carbon nanomaterial is obtained by adsorbing a metal atom in an atom-level dispersed metal solution by using a solute in the dispersion. According to the embodiment of the present application, the doped carbon nanomaterial has a strong adsorption effect on the metal atom, thereby increasing the loading of the carrier material on the metal atom and improving the effective utilization of the metal atom.

According to the embodiment of the present application, mixing the dispersion with a solution containing an atomic-level dispersed metal in a low-temperature environment of -100 to 0 ° C can ensure that the metal in the solution containing the atomic-level dispersed metal is adsorbed to the atom in the form of atoms. On the support material, an atomic-scale dispersed metal catalyst supported on the support material is obtained.

According to the embodiment of the present application, after the dispersion is mixed with the solution containing the atomic-level dispersed metal, the mixed solution is stirred to promote adsorption of the carrier material to the atom-level dispersed metal, and then the solution is subjected to centrifugation or vacuum filtration treatment. And drying at room temperature in order to obtain a high metal loading atomically dispersed metal catalyst. According to an embodiment of the present application, the stirring rate may be 0-3000 rpm, and the stirring time may be 0-300 min.

According to an embodiment of the present application, in order to increase the thermal stability of the atomic-level dispersed metal catalyst, the method may further include: placing the atomic-level dispersed metal catalyst prepared through the above steps in a gas atmosphere for annealing treatment. According to an embodiment of the present application, the gas atmosphere may be a high vacuum, nitrogen, argon or hydrogen argon mixture, the amount of gas may be 50-600 sccm, and the annealing treatment temperature may be 200-1200 °C. Thereby, a thermally stable atomic-level dispersed metal catalyst can be obtained. The specific steps regarding the annealing treatment are not particularly limited, and those skilled in the art can design according to specific conditions.

In summary, the atomic-scale metal catalyst prepared by the low-temperature solution method according to the embodiment of the present application has the advantages of large density, high yield, high efficiency, strong applicability, and can significantly reduce large-scale commercial application of atomic-scale metal catalysts. The cost, therefore, is applied to the cathode according to the embodiment of the present application, which has advantages such as good catalytic activity, high metal utilization rate, and the like, and can reduce the production cost.

According to the embodiment of the present application, the specific type of the cathode 110 is not particularly limited as long as the oxygen reduction reaction can be performed on the cathode. According to some embodiments of the present application, after the catalyst layer 10 is disposed on the collector layer 20 to form the cathode 110, the cathode 110 may be directly immersed in the electrolyte, and then by aeration, oxygen may reach the cathode, and oxygen may be on the cathode. An oxygen reduction reaction occurs. According to further embodiments of the present application, referring to FIG. 3 and FIG. 4, the cathode 110 may also be an air cathode, and the cathode 110 may further include a diffusion layer 30, which may be in contact with air (not shown), so that The reduction reaction is carried out by using oxygen in the air to realize the function of using the cathode 110.

According to some embodiments of the present application, referring to FIG. 3, the diffusion layer 30 may be disposed on a side of the collector layer 20 away from the catalyst layer 10 and in contact with an electrolyte (not shown). Thereby, the diffusion layer 30 is in contact with the air so that oxygen can diffuse into the cathode 110, the collector layer 20 can enrich current, and improve the conductivity of the cathode 110, and the catalyst layer 10 can be utilized under the action of an atom-level dispersed metal catalyst. The electrons are reduced in reaction with oxygen, which in turn can improve the use effect of the cathode 110.

According to further embodiments of the present application, referring to FIG. 4, the cathode 110 may further have a structure in which the diffusion layer 30 is in contact with air (not shown), and the catalyst layer 10 is formed on the side of the diffusion layer 30 away from the air. The collector layer 20 is formed on the side of the catalyst layer 10 away from the diffusion layer 30, and is in contact with the electrolyte (not shown). Further, the use effect of the cathode 110 can be improved.

In order to further improve the use effect of the cathode 110, according to an embodiment of the present application, referring to FIG. 5, the cathode 110 may further have a support layer 40, the support layer 40 may be formed between the catalyst layer 10 and the diffusion layer 30, and the support layer 40 It can be formed from a stainless steel mesh. Thereby, the cathode layer 110 can be provided with a better support structure through the support layer 40, and the support layer 40 and the collector layer 20 are respectively located on both sides of the catalyst layer 10, which can provide good protection for the catalyst layer 10 and prevent the actual use. The loss of powdering of the catalyst layer 10 during the process adversely affects the use effect of the cathode 110. In addition, the support layer 40 composed of a stainless steel mesh can further improve the conductivity of the cathode 110, thereby further improving the performance of the cathode 110.

The inventors have found that the atom-level dispersed metal catalyst has a highly dispersed catalytic active site, and therefore, the atomic-level dispersed metal catalyst has good catalytic activity, high catalytic efficiency, high metal utilization rate, and low cost. The inventors have found through extensive research and a large number of experiments that atomic-level dispersed metal catalysts can be applied to cathodes and applied to electrochemical systems as well as bioelectrochemical systems, thereby improving the efficiency of oxygen reduction of cathodes and improving electrochemical systems. The electronic utilization rate, which in turn increases the electrical performance of the electrochemical system. Moreover, the inventors have found that the cathode structure according to the specific embodiment of the present application is particularly advantageous for the adhesion of the above-described atomic-level dispersed metal catalyst. Under the above electrode structure, not only the atomic-level dispersed metal catalyst can be easily fixed in the catalyst layer, but also the fixed catalyst layer has good stability. Moreover, the atomic-level dispersed metal catalyst is used in the cathode, and the reduction reaction of the cathode by air also has a good catalytic effect.

According to an embodiment of the present application, the cathode 110 may be prepared by the following method:

(1) 150-300mg carbon black powder and 650-750mg polytetrafluoroethylene binder are mixed, after multiple rolling, and pressed with support material (stainless steel mesh) at 4.5-10MPa, and then at 340 ° C High temperature stability for 10-40min, the diffusion layer 30 can be obtained;

(2) The catalyst layer 10 is formed by mixing 60-300 mg atom-level dispersed metal catalyst with 24-350 μL of a polytetrafluoroethylene binder, and then uniformly coating the side of the stainless steel mesh of the diffusion layer 30 prepared in the step (1). ;

(3) The collector layer 20 formed of the stainless steel mesh is pressed together with the structure prepared in the step (2) at 4.5-10 MPa, and heated at 60-100 ° C for 20-60 min to obtain an air cathode 320.

In summary, the cathode not only has good catalytic activity, high metal utilization rate, low cost, and is simple and easy to prepare, and is suitable for large-area production.

In another aspect of the application, the application proposes a battery. According to an embodiment of the present application, referring to FIG. 6, the battery may include the cathode 110 and the anode 330 described above, and the anode 330 is electrically connected to the cathode 110. Thus, the battery has all the features and advantages of the cathode described above. Since the catalyst in the cathode described above is an atomic-level dispersed metal catalyst, the catalytic activity is high and the stability is good, so the battery is produced. The efficiency is also high and the running stability is good.

According to an embodiment of the present application, the battery has a power density of 2000 mW/m ² when the external resistance is 50 ohms. Thereby, the power generation efficiency of the battery is high, and the use effect of the battery is further improved. Specifically, when the external resistance of the battery is 50 ohms, the power density can reach 2540 mW/m ² , which further improves the use effect of the battery.

According to an embodiment of the present application, the current density of the battery after 500 hours of operation is not more than 5%. Thereby, the battery has better running stability, and the use effect of the battery is further improved. Specifically, after the battery is operated for 700 hours, the current density attenuation may not exceed 5%, which further indicates that the battery has good running stability, and further improves the use effect of the battery.

According to an embodiment of the present application, the battery may be a fuel cell or a microbial fuel cell as long as an oxygen reduction reaction occurs at the cathode thereof. When the battery is a microbial fuel cell, the electrogenetic microorganism adheres to the surface of the anode, whereby the organic substance in the medium can be oxidatively decomposed by the electrogenic microorganism, and electrons and protons are generated, and electrons are received through the cathode, and the metal is dispersed through the atomic level. The catalyst catalyzes the oxygen reduction reaction and produces water. According to an embodiment of the present application, the anode may be formed of at least one of a carbon brush, a carbon cloth, a carbon fiber cloth, and granular activated carbon. Specifically, a carbon cloth or a carbon brush can be cut to an appropriate size and heat-treated at 450 ° C for 30 minutes in a muffle furnace to obtain an anode. Thereby, the anode can be easily obtained, thereby reducing the production cost of the microbial fuel cell.

Moreover, those skilled in the art will appreciate that improvements to the microbial fuel cell according to embodiments of the present application are also within the scope of the present application without the inventive effort. For example, according to one embodiment of the present application, in a microbial fuel cell, the anode and the air cathode may be disposed perpendicular to each other; according to another embodiment of the present application, a separator may further be provided between the cathode and the anode. Therefore, those skilled in the art can make corresponding adjustments to the microbial fuel cell according to the embodiment of the present application according to actual conditions, and select a more suitable structure to constitute the microbial fuel cell, as long as the features according to the embodiments described above are satisfied. Just fine.

In yet another aspect of the present application, the present application proposes an electrochemical system. According to an embodiment of the present application, referring to FIG. 7, the electrochemical system 1000 may include a housing 100 and a modular electrode assembly 300 defining a reaction space 200 in the housing 100, and the modular electrode assembly 300 is disposed in the reaction space 200. . According to an embodiment of the present application, the modular electrode assembly 300 may include a hollow cathode socket 310 and an anode 330. The hollow cathode slot 310 may include a plurality of air cathodes 320 and a plurality of anodes 330 electrically connected to the air cathodes 320, and a plurality of air cathodes 320 may be disposed on the side walls 311 of the hollow cathode slots 310, and The plurality of air cathodes 320 may include the catalyst layer described above. Thus, the electrochemical system 1000 not only has all the features and advantages of the catalyst layer described above, that is, the catalytic activity of the air cathode 320 is good, the metal utilization rate is high, the cost is low, and the like, and the electrochemical system 1000 The plurality of air cathodes 320 and the anodes 330 are also organically integrated in the same reaction space 200 by providing the modular electrode assembly 300, further improving the power generation performance of the electrochemical system 1000.

According to an embodiment of the present application, the hollow cathode slot 310 may include a plurality of sidewalls 311 and a bottom surface (not shown), and the plurality of sidewalls 311 and the bottom surface define a hollow space inside the hollow cathode slot 310. The side of the side wall 311 near the hollow space is in contact with the atmosphere. Thereby, not only the plurality of air cathodes 320 can be integrated in the same hollow space, but also each air cathode 320 can be sufficiently contacted with air to further improve the electrical performance of the electrochemical system 1000.

The inventors have found that current electrochemical systems generally contain only one air cathode and one anode, and the overall power generation efficiency is limited during operation. Moreover, the air cathode is generally disposed on the top or side of the electrochemical system due to the need to contact the atmosphere. According to the electrochemical system of the embodiment of the present application, on the one hand, the air cathode adopts an atomic-level dispersed metal catalyst to catalyze the oxygen reduction reaction, and the catalytic reaction efficiency is high, the stability is good, and the electron utilization rate and the production in the electrochemical system are improved. Electrical performance; on the other hand, by providing a hollow cathode slot, a plurality of air cathodes can be disposed on the sidewall of the hollow cathode slot, that is, integrating multiple air cathodes in the same electrochemical system, saving not only Space, and can ensure that each air cathode can be in full contact with air, and the oxygen reduction reaction of each air cathode does not affect each other. Thereby, the electron utilization rate and the electricity generation performance in the electrochemical system are further improved. Moreover, the hollow cathode slot can be easily disassembled to facilitate the replacement of the electrodes, or the power of the entire system can be adjusted according to the actual treated water supply (can be achieved by increasing or decreasing the number of electrodes), thereby improving the electricity. The flexibility and practicality of the chemical system.

According to the embodiment of the present application, the specific number of the plurality of air cathodes 320 is not particularly limited, and those skilled in the art can perform the setting according to actual needs. For example, 2-10 air cathodes 320 may be provided, and 2, 3 or 4 air cathodes 320 may be provided. According to an embodiment of the present application, the specific number of the anodes 330 is also not particularly limited. For example, 1-10 anodes 330 may be provided, and one, two, three or four anodes 330 may be provided. According to the embodiment of the present application, the manner in which the air cathode 320 is connected to the anode 330 is not particularly limited as long as each of the air cathodes 320 has an anode 330 connected thereto. Specifically, the air cathode 320 and the anode 330 may be connected in one-to-one correspondence, or the plurality of air cathodes 320 may be connected to one anode 330, or one air cathode 320 may be connected to the plurality of anodes 330.

According to the embodiment of the present application, the shape of the hollow cathode slot 310 is not particularly limited, and a person skilled in the art can make a reasonable design according to the number of air cathodes 320 to be provided. Specifically, the hollow cathode slot 310 may be a triangular prism type, a hexahedral type, or an octahedral type. For example, according to some embodiments of the present application, referring to FIG. 7, the hollow cathode slot 310 may be a hexahedral type, and two air cathodes 320 may be disposed on the sidewall 311 of the hollow cathode slot, and the two air cathodes 320 may be Relative settings can also be set adjacently. According to other embodiments of the present application, referring to FIG. 8, four air cathodes 320 may be disposed on the four side walls 311 of the hexahedral hollow cathode slot 310. According to still other embodiments of the present application, referring to FIG. 9, the hollow cathode slot 310 may be of a triangular prism type, and three air cathodes 320 may be disposed on three side walls of the triangular prism hollow cathode slot 310.

According to an embodiment of the present application, the material of the anode 330 is not particularly limited, and when the electrochemical system is a bioelectrochemical system, the anode 330 is only required to facilitate microbial attachment. Specifically, the anode 330 may be at least one of a carbon brush, carbon cloth, carbon paper, carbon felt, activated carbon, and graphite. Specifically, the anode 330 may include a carbon brush or a plurality of carbon brushes. Similarly, when the anode is a carbon cloth, it may be a single layer of carbon cloth or a combination of multiple layers of carbon cloth separated by a separator. Thereby, the adhesion ability of the microorganism at the anode can be further improved, and the cost of the electrochemical system can be saved.

According to an embodiment of the present application, the specific shape of the anode 330 is not particularly limited, and when the anode 330 is a planar electrode, such as carbon paper or carbon cloth, the electrochemical system 1000 may further include an air cathode 320 and an anode 330. Inter-membrane (not shown). According to the embodiment of the present application, the specific material of the separator is not particularly limited, and may be, for example, glass fiber, plastic mesh, nylon cloth, or the like. Thus, the separator can prevent short-circuiting between the air cathode and the anode, further shorten the vertical distance between the cathode and the anode, improve the electrode reaction efficiency, enhance ion diffusion between the electrodes, and slow down the cathode contamination rate. According to the embodiments of the present application, those skilled in the art can make corresponding adjustments to the electrochemical system according to the embodiments of the present application according to actual conditions, and select a more suitable structure to constitute the electrochemical system, as long as the above described according to the present application is satisfied. The features of the embodiments are sufficient.

According to an embodiment of the present application, the arrangement and position of the anode 330 are not particularly limited. For example, referring to FIG. 7, the anode 330 may be disposed between the hollow cathode slot 310 and the housing 100. Thereby, the use effect of the electrochemical system is further improved. According to an embodiment of the present application, referring to FIG. 10, the modular electrode assembly 300 may further include an anode socket 360, and the anode 330 may also be disposed on a sidewall of the anode socket 360. According to an embodiment of the present application, the anode socket 360 can be disposed around the hollow cathode slot 310, whereby the anode socket 360 can be easily removed for easy replacement of the electrodes. When a plurality of anodes 330 are included in the system, the anodes 360 can be used to easily integrate the plurality of anodes 330 into the same electrochemical system, which not only saves space, but also does not affect each anode, and can also be processed according to actual conditions. In the case of incoming water, adjust the power of the entire system (can be achieved by increasing or decreasing the number of electrodes). Thereby, the use effect of the electrochemical system 1000 is further improved.

According to an embodiment of the present application, the electrochemical system 1000 may further include a plurality of external resistors 350 disposed between the air cathode 320 and the anode 330 and electrically connected to the air cathode 320 and the anode 330. According to the embodiment of the present application, the total resistance of the plurality of external resistors 350 during operation of the electrochemical system 1000 is not particularly limited. For example, it may be 0 ohms, that is, short-circuit operation, or may be infinite, that is, open circuit operation, or It is 2-1000 ohms. Thereby, the use effect of the electrochemical system is further improved.

According to an embodiment of the present application, referring to FIG. 11 and FIG. 12, the air cathode 320 may include a plurality of sub-cathodes 321 . Thereby, the air cathode 320 having a large area can be easily prepared by using the plurality of sub-cathodes 321, and the air cathode 320 obtained has high surface flatness and good performance, and further improves the use effect of the electrochemical system. According to the embodiment of the present application, the connection manner of the plurality of sub-cathodes 321 is not particularly limited, and the plurality of sub-cathodes 321 may be connected in series or in parallel. Thereby, the plurality of sub-cathodes are connected in various ways, and can be combined as needed to form the air cathode 320, thereby further improving the use effect of the electrochemical system.

It should be noted that, in practical industrial applications, when a whole air cathode having a large area is produced, the current manufacturing method is difficult to ensure the smoothness and the use performance of the surface. Therefore, the air cathode 320 according to the embodiment of the present application is described. By providing a plurality of sub-cathodes 321 having a small area and connecting them in series or in parallel, the air cathode 320 having a large area and good performance can be easily prepared, which is more advantageous for the industrial application of the electrochemical system 1000. According to a particular embodiment of the present application, each air cathode may comprise a plurality of equally sized sub-cathodes arranged in an array. Thereby, the area of each sub-cathode is relatively moderate, and the sub-cathode can be prepared simply and quickly, and the quality of the catalyst layer can be ensured. The plurality of sub-cathodes are connected by a simple series or parallel connection to constitute a monolithic air cathode, and each of the sub-cathodes may have a structure of a cathode including a diffusion layer as described above. The specific structure of the cathode has been described in detail above and will not be described herein.

According to an embodiment of the present application, when the hollow cathode slot 310 is formed of a conductive material, the plurality of sub-cathodes 321 may be directly disposed on the sidewall of the hollow cathode slot 310; according to an embodiment of the present application, when hollow When the cathode slot 310 is formed of a non-conductive material, such as formed of plastic, according to an embodiment of the present application, referring to FIG. 11, the air cathode 320 may further include a conductive support frame 322, and the plurality of sub-cathodes 321 may be disposed on the conductive support frame. At 322, the conductive support frame 322 is electrically coupled to the anode 330. According to the embodiment of the present application, the material of the conductive support frame 322 is not particularly limited as long as the sub-cathode 321 can be fixed to the surface thereof and can be made conductive. For example, the conductive support frame 322 can be a stainless steel mesh. Thereby, the plurality of sub-cathodes 321 can be easily electrically connected to the anode 330, and the use effect of the electrochemical system 1000 can be further improved.

According to an embodiment of the present application, when the hollow cathode slot 310 is formed of a non-conductive material, for example, formed of plastic, referring to FIG. 12, the conductive support frame may be formed without using a conductive material, but by means of providing a wire, A series or parallel connection of the plurality of sub-cathodes 321 is achieved. Specifically, the air cathode 320 may further include a plurality of wires 323 that are in one-to-one correspondence with the plurality of sub-cathodes 321 and are electrically connected to the anodes 330. Thereby, a plurality of sub-cathodes 321 can be directly disposed on the side wall 311 of the hollow cathode socket, and then each sub-cathode is electrically connected to the anode 330 through a plurality of wires, which simplifies the preparation process and further improves the electrochemistry. The effect of the system 1000.

It is to be noted that the specific type of the electrochemical system according to the embodiment of the present application is not particularly limited as long as the cathode thereof undergoes an oxygen reduction reaction. For example, it may be a fuel cell, a microbial fuel cell, a microbial electrolysis cell or a microbial desalination battery, etc., and the electrochemical system according to the embodiment of the present application has a wide application scenario, for example, it can be used for treating domestic sewage, industrial sewage, etc., and The organic matter in the sewage is converted into electric energy by microorganisms, and at the same time as the pollution is eliminated, the available energy is generated, and the energy consumption is low and the efficiency is high.

The solution of the present application will be explained below in conjunction with the embodiments. Those skilled in the art will appreciate that the following examples are merely illustrative of the application and are not to be construed as limiting the scope of the application. Where specific techniques or conditions are not indicated in the examples, they are carried out according to the techniques or conditions described in the literature in the art or in accordance with the product specifications. The reagents or instruments used are not specified by the manufacturer and are conventional products that are commercially available.

Example 1: Preparation of atomic-scale dispersed Co catalyst

(1) Configuring reaction solution A: 0.01 M CoCl ₂ solution, the solvent is a water/ethanol mixed solvent having a volume ratio of 1:9; preparing a reducing agent solution B: 5.0 M N ₂ H ₅ OH hydrazine hydrate solution containing 0.05 M KOH; A carrier dispersion C: 2.5 mg mL ^{-1 of} a nitrogen-doped mesoporous carbon dispersion was prepared.

(2) The above reaction solution A and carrier dispersion C are placed in a cryostat, cooled to minus 60 ° C and held for 30 minutes; using a syringe pump to control the drop rate, 5 mL of the above CoCl ₂ reaction solution A is 0.125 mL min ^-1 The rate was dropwise added to 20 mL of the reducing solution B; the above mixed liquid was further reacted at minus 60 ° C for 2 hours, and then 20 mL of the above carrier dispersion C was mixed, and stirring was continued for 3-5 hours.

(3) The mesoporous carbon-supported cobalt monoatomic sample prepared in the step (2) was recovered and washed by low temperature vacuum filtration, and then naturally dried at room temperature.

(4) The sample prepared in the step (3) is thermally activated under the following conditions: the temperature is raised to 900 ° C in 90 minutes, the temperature is kept for 60 minutes, the temperature is naturally cooled to room temperature, and the gas condition is 500 sccm high purity argon gas, thereby obtaining a thermally stable atomic level. Disperse the Co catalyst.

Example 2: Preparation of a cathode containing an atomic-stage dispersed Co catalyst

(1) Preparation of diffusion layer: 212 mg of carbon black powder was mixed with 705.5 mg of polytetrafluoroethylene binder (mass fraction of 60%), 1.4 mL of absolute ethanol was added, ultrasonically heated for 20 seconds in a water bath, and uniformly stirred until it was sticky. Mud. The mud was placed on a plastic plate and repeatedly rolled twice with a roller to make the diffusion layer material mix more uniformly, and then rolled onto a stainless steel mesh of a support material, pressed with a powder tableting machine at 4.5 MPa for 10 minutes, and then placed. It was fired in a muffle furnace at 340 ° C for 20 min, taken out and cooled to room temperature.

(2) Preparation of catalyst layer and cathode: Weighed 60 mg of the atom-scale dispersed Co catalyst prepared in Example 1, and added 70 μL of a polytetrafluoroethylene binder (mass fraction of 60%), 388 μL of deionized water, and stirred under ultrasonication. Mix for 20s, then evenly spread on the stainless steel mesh of the diffusion layer, cover a piece of stainless steel mesh (ie, collector layer) on the upper side, press it together at 10MPa for 10min, then dry in an oven at 80 °C for 30min, remove and cool to room temperature. It was cut into a circle having a diameter of 3 cm, that is, a cathode containing an atomic-stage dispersed Co catalyst was obtained.

Example 3: Fabrication of an electrochemical system containing atomically dispersed Co catalyst

The reactor adopts a double chamber configuration with an anode chamber length of 4 cm. The upper middle portion has a hole with a diameter of 1 cm for placing a platinum electrode as an anode; the cathode chamber is 2 cm long with a hole having a diameter of 1 cm for placement. For the reference electrode, the two chambers are separated by a cation exchange membrane. The titanium piece and the cathode containing the atomic-stage dispersed Co catalyst prepared in Example 2 were attached, and then fixed by a cathode baffle, and then fixed by screws and screws at the four corners of the reactor, and the reactor (ie, electrochemical system) was assembled. . The electrolyte was 50 mM phosphate buffer.

Comparative Example 1: Preparation of an electrochemical system containing a Co nanoparticle catalyst

For other production methods, reference is made to Example 3, except that in the cathode of the comparative example, the catalyst is Co nanoparticle.

Comparative Example 2: Preparation of an electrochemical system containing a platinum-carbon catalyst

For other production methods, reference is made to Example 3, except that in the cathode of the comparative example, the catalyst is a platinum carbon catalyst.

Comparative Example 3: Preparation of an electrochemical system containing an activated carbon catalyst

For other production methods, reference is made to Example 3, except that in the cathode of the comparative example, the catalyst is an activated carbon catalyst.

Electricity production performance test

Evaluation of air cathode performance by chronoamperometry

The cathode reduction current of the electrochemical system produced in Example 3 and Comparative Examples 1-3 was measured by chronoamperometry. After the electrochemical system was opened for 3 hours, the measurement was started from a starting potential of 0.2 V (the reference electrode was Ag/AgCl), and one set was measured every 0.1 V, and the end potential was -0.4 V (the reference electrode was Ag/AgCl). The steady current value under each set of potential is taken as the current density (current density i=U/(RA), U is the output voltage, R is the external resistance value, and A is the cathode area) with the effective cathode area of 7 cm ² . Referring to Figure 13, at a potential of 0.2 V to -0.4 V, the reduction current of the cathode containing the atomic-dispersed Co catalyst is higher than that of the cathode containing Co nanoparticles, platinum carbon, and activated carbon. Taking -0.4V as an example, the air cathode containing the atomic-dispersed Co catalyst obtained the highest current density of 26 A/m ² , while the platinum carbon air cathode had a current density of only 16 A/m ² , obviously, according to the embodiment of the present application. The cathode containing the atomic-dispersed Co catalyst has superior electrical properties than the conventional electrode widely used at present.

Example 4: Preparation of a microbial fuel cell containing an atomic-grade dispersed Co catalyst

The carbon brush was used as the anode, and the anaerobic electrogenic bacteria were attached. The anode material was calcined at 450 ° C for 30 min in a muffle furnace for pretreatment. The reactor adopts a single-chamber configuration with a thickness of 4 cm. There are two side-by-side holes of 6 mm in diameter at the upper part of the reaction chamber, one for placing the anode carbon brush and the other for placing the reference electrode; the cavity and the yin and yang The pole plates are sealed and fixed by O-rings and gaskets, and the titanium plate and the air cathode containing the atomic-level dispersed Co catalyst prepared in Example 2 are attached, and then fixed by the cathode baffle, and the screw is used at the four corners of the reactor. After the screw is fixed, the reactor (ie microbial fuel cell) is assembled. The inoculation source was effluent from a microbial fuel cell anode that had been operated normally. The substrate was 50 mM phosphate buffer to prepare a concentration of 1 g/L sodium acetate, and 12.5 mL/L mineral and 5 mL/L vitamin were added.

Comparative Example 4: Preparation of a microbial fuel cell containing a Co nanoparticle catalyst

The manner of preparation was as described in Example 4, except that in the air cathode in the comparative example, the catalyst was Co nanoparticles.

Comparative Example 5: Preparation of a microbial fuel cell containing a platinum carbon catalyst

The manner of preparation was as described in Example 5, except that in the air cathode of the comparative example, the catalyst was a platinum carbon catalyst.

Comparative Example 6: Preparation of a microbial fuel cell containing an activated carbon catalyst

The manner of preparation was as described in Example 6, except that in the air cathode of the comparative example, the catalyst was an activated carbon catalyst.

Electricity production performance test

Determination of polarization curve by rapid external resistance change method

The polarization curves of the microbial fuel cells produced in Example 4 and Comparative Examples 4-6 were measured using a rapid change external resistance method. The rapid change of the external resistance method means that the external resistance is replaced and the microbial fuel cell is stabilized in a short period of time in the operation cycle of the microbial fuel cell, and the reactor is stabilized under the external resistance of 5000 Ω after replacing the 1 g/L sodium acetate substrate. Hour, record the output voltage and anode potential, and then reduce the external resistance every 20min, so that the external resistance is 1000Ω, 500Ω, 300Ω, 200Ω, 100Ω, 50Ω, 30Ω, 20Ω, 10Ω, 5Ω, 2Ω, and record the resistance in real time. Stable output voltage and anode potential, according to the data can calculate the power density P = Ui under each external resistance, where the current density i = U / (RA), U is the output voltage, R is the external resistance value, A is Cathode area. Taking the current density i as the abscissa and the area power density P as the ordinate, the area power density curve is plotted, as shown in FIG. It can be seen from the figure that the maximum power density of the cathode of the microbial fuel cell containing the atomic-grade dispersed Co catalyst is about 2500 mW/m ² , the maximum power density of the Co nanoparticle air cathode is about 2100 mW/m ² , and the maximum of the activated carbon air cathode. the maximum power density of a power density of about 1600mW / m ^2, an air cathode is a carbon platinum maximum power density of 1500mW / m ² or so, apparently atomically dispersed Co ,, containing catalyst microbial fuel cell is higher than a Co-containing nanoparticles, platinum Microbial fuel cells with carbon and activated carbon.

In summary, the atomic-grade dispersed Co catalyst has good catalytic performance and high catalytic efficiency. Both the electrochemical system using atomic-scale dispersed Co catalyst and the microbial fuel cell have better electrical performance.

Running stability test

The operational stability tests were carried out on the microbial fuel cells produced in Example 4 and Comparative Example 5. The running stability test tests the output voltage U of the battery at different times under certain external resistance conditions, and calculates the current density value i (i=U/(RA), U when the battery is running at different times according to the data. For the output voltage, R is the external resistance value, A is the cathode area), for example, under the external resistance condition of testing the battery 50Ω, running at 50h, 100h, 150h, 200h, 250h, 300h, 350h, 400h, 450h, 500h, 550h Output voltage at 600h, 650h, and 700h. In order to further prove the stability of the microbial fuel cell performance of the atomic-grade dispersed Co catalyst, the microbial fuel cell containing platinum carbon catalyst scraped the biofilm on the air cathode surface after running for 200 h, and then continued to test it at different times. The output voltage of the time, and calculate its current density value, the test results are shown in Figure 15. It can be seen from the figure that the microbial fuel cell containing atomically dispersed Co catalyst has very stable electricity production performance and hardly changes with the running time of the battery. After 700 hours of operation, the current density value is still relatively stable. Compared to the beginning, there is almost no decline. The microbial fuel cell containing platinum carbon catalyst has a significant decrease in power generation performance with the increase of battery running time. After 700 hours of operation, its electricity production performance is only 65% at the beginning. After the biofilm of the cathode is scraped off, the electricity production performance of the microbial fuel cell containing platinum carbon catalyst is improved, indicating that the air cathode containing the platinum carbon catalyst is easily contaminated, hindering its contact with air, and hindering the oxygen reduction reaction of the cathode. And reduce the decomposition ability of the anode to the organic matter, thereby causing a decrease in the power generation performance of the battery. On the air cathode containing the atomic-grade dispersed Co catalyst, the microorganisms are not easy to aggregate, and the anti-pollution ability is strong, and the electricity generation performance is relatively stable, and the cycle performance is good. As can be seen from the comparison, the atomic-stage dispersed Co catalyst has good catalytic performance and high stability, and the microbial fuel cell containing the atom-level dispersed Co catalyst has better power generation stability.

Example 5: Fabrication of an electrochemical system containing two air cathodes

The other manufacturing method is the same as that in Embodiment 3, except that the electrode of the electrochemical system adopts a modular electrode assembly. Referring to FIG. 7, the hollow cathode slot 310 is a hexahedron type, and two air cathodes 320 are placed in a hollow cathode slot. On both side walls of the 310, the air cathode 320 contains the catalyst layer containing the atomic-level dispersed Co catalyst prepared by the method of Embodiment 2, and the hollow cathode slot 310 is filled with air and then inserted into the reaction space filled with the matrix. In 200, each of the air cathodes 320 is connected to the carbon brush anode 330 to which the anaerobic electrogenic bacteria are attached, and the external resistance 350 is connected to obtain an electrochemical system containing two air cathodes.

Example 6: Fabrication of an electrochemical system containing three air cathodes

The other manufacturing method is the same as that of Embodiment 5, with reference to FIG. 9 , except that the hollow cathode slot 310 used is a triangular prism type, and three air cathodes 320 are placed on three sidewalls of the hollow cathode slot 310, wherein The air cathode 320 contains the catalyst layer containing the atomic-stage dispersed Co catalyst prepared by the method of Example 2.

Example 7: Fabrication of an electrochemical system containing four air cathodes

The other manufacturing method is the same as that of Embodiment 4, with reference to FIG. 8, except that four air cathodes 320 are placed on the four sidewalls of the hollow cathode slot 310, wherein the air cathode 320 is prepared according to the method of Embodiment 2. A catalyst layer containing an atomic-stage dispersed Co catalyst.

The embodiments of the present application have been described in detail above. However, the present application is not limited to the specific details in the foregoing embodiments. Various simple modifications may be made to the technical solutions of the present application within the technical concept of the present application. It belongs to the scope of protection of this application.

It should be further noted that the specific technical features described in the above specific embodiments may be combined in any suitable manner without contradiction.

In addition, any combination of various embodiments of the present application may be made as long as it does not contradict the idea of the present application, and it should also be regarded as the content disclosed in the present application.

In the description of the present application, it is to be understood that the orientation or positional relationship of the terms "upper", "lower" and the like is based on the orientation or positional relationship shown in the drawings, for convenience of description of the present application and simplified description. Instead of indicating or implying that the device or component referred to must have a particular orientation, constructed and operated in a particular orientation, it is not to be construed as limiting the invention.

Claims (17)

1. A cathode comprising:

   Collector layer;

   a catalyst layer, the catalyst layer being disposed on the collector layer, the catalyst layer comprising an atomically dispersed metal catalyst.
2. The cathode of claim 1 further comprising:

   a diffusion layer disposed on a side of the collector layer away from the catalyst layer or on a side of the catalyst layer away from the collector layer.
3. The cathode according to claim 1, wherein said atom-level dispersed metal catalyst comprises a carrier and an active metal supported on said carrier, said active metal comprising at least one of Fe, Co and Ni.
4. The cathode according to claim 1, which is prepared in a low temperature environment.
5. A battery comprising:

   a cathode according to any one of claims 1 to 4;

   An anode, the anode being electrically connected to the cathode.
6. The battery according to claim 5, wherein said battery has a power density of not less than 2000 mW/m ² when the external resistance is 50 ohms.
7. The battery according to claim 5, wherein the battery has a current density attenuation of no more than 5% after 500 hours of operation.
8. An electrochemical system comprising:

   a housing defining a reaction space therein;

   a modular electrode assembly disposed in the reaction space, the modular electrode assembly further comprising:

   a hollow cathode socket, the hollow cathode socket comprising: a plurality of air cathodes disposed on sidewalls of the hollow cathode socket, the air cathode comprising claims 1-4 a catalyst layer according to any one of the invention;

   An anode, the anode being electrically connected to the air cathode.
9. The electrochemical system according to claim 8, wherein said hollow cathode socket includes a plurality of said side walls and a bottom surface, and said plurality of said side walls and said bottom surface define a hollow inside said hollow cathode socket The space, the side of the side wall adjacent to the hollow space is in contact with the atmosphere.
10. The electrochemical system of claim 8 wherein said anode is disposed between said hollow cathode slot and said housing.
11. The electrochemical system of claim 8 wherein said modular electrode assembly further comprises:

    An anode socket, the anode being disposed on a sidewall of the anode socket.
12. The electrochemical system of claim 8 wherein said air cathode comprises a plurality of sub-cathodes.
13. The electrochemical system of claim 12 wherein a plurality of said sub-cathodes are connected in parallel or in series.
14. The electrochemical system of claim 12, said air cathode further comprising a conductive support frame disposed directly on said conductive support frame, said conductive support frame being electrically coupled to said anode.
15. The electrochemical system according to claim 12, wherein said air cathode further comprises a plurality of wires, said plurality of wires being connected in one-to-one correspondence with said plurality of sub-cathodes, and said plurality of wires are electrically connected to said anode .
16. The electrochemical system according to claim 8, wherein the anode is at least one of a carbon brush, carbon cloth, carbon paper, carbon felt, activated carbon, and graphite.
17. The electrochemical system of claim 8, the anode being a planar electrode, the electrochemical system further comprising: a membrane disposed between the air cathode and the anode.

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