CN111952604A - Integrated oxygen reduction catalytic electrode and application thereof - Google Patents
Integrated oxygen reduction catalytic electrode and application thereof Download PDFInfo
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Abstract
The invention discloses an integrated oxygen reduction catalytic electrode and application thereof, wherein the electrode comprises a three-dimensional conductive network consisting of a high-density carbon-based material and an oxygen reduction catalyst loaded on the three-dimensional conductive network, the three-dimensional conductive network has a three-dimensional porous structure, and the porosity of the three-dimensional conductive network is 0.05-5.5 cm3The pore size is 0.5 nm-15 mu m; wherein the density of the high-density carbon-based material is 0.2-4.5 g/cm3The specific surface area is 10 to 2500m2Between/g; the content of the oxygen reduction catalyst in the electrode is 0.1-30%. The invention can effectively improve the effective active area of the cathode oxygen reduction reaction by loading the oxygen reduction catalyst in the pore canal of the high-density carbon carrier, and further accelerate the reduction reaction of cathode dissolved oxygen, namelyHigh cathode discharge performance. Due to the improvement of the catalytic performance of the cathode, the discharge performance of the metal-dissolved oxygen seawater battery is greatly improved, the battery volume is small, and the power density and the energy density are higher. The invention is mainly applied to seawater and can be expanded to various water body environments such as salt water, salt water lakes and the like.
Description
Technical Field
The invention belongs to the technical field of electrodes, and particularly relates to an integrated oxygen reduction catalytic electrode and application thereof.
Background
With the deep development of marine research and marine resource development activities, marine equipment such as marine monitoring, marine engineering, marine military activities, marine lifesaving and undersea vehicles, particularly marine deep water exploration and resource development and production activities, are vigorously developed. Limited modes of shore power transmission by cables, power supply by ships or power supply by rechargeable batteries are far from meeting the increasingly prominent requirements of offshore activities, and deep development and ocean scientific research and production activities of people are greatly limited. People have been seeking for many years to produce a relatively long-acting independent power supply suitable for marine activities, under which condition seawater batteries with wide application prospects are produced, wherein the dissolved oxygen seawater batteries are developed rapidly.
The cathode of the dissolved oxygen seawater battery in the prior art is generally made of inert conductive materials such as graphite, carbon steel or copper alloy, and the electrifying density of the cathode is generally less than 1.5mA/cm2The catalytic efficiency of the seawater dissolved oxygen reduction is low, the reaction speed is slow, the stability is poor, the generation of electric energy is seriously inhibited, and the development, application and popularization of the seawater battery are also greatly restricted. At present, commercial seawater dissolved oxygen batteries, such as a battery disclosed in CN 109962247A (a preparation method of a platinum carbon fiber electrode deposited by high-efficiency oxygen catalytic activity), adopt a carbon fiber brush as the anode of a seawater battery. Because the carbon fiber electrode of the battery is not subjected to surface modification treatment, the carbon fiber electrode has few active functional groups and few electrocatalytic active sites, so that the electrocatalytic performance of dissolved oxygen in seawater in the cathode reduction reaction of the battery is very low, and the battery can only work under extremely low current density, so that the power density output characteristic of the battery is poor, and in order to meet the power requirement of the seawater battery, a large amount of carbon fiber materials are required, and the volume and the weight of the battery are inevitably increased.
The prior art solutions to the above mentioned problem of low carbon electrode activity are: the catalytic activity is improved by coating/supporting a catalyst on the surface of the conductive substrate material. However, the conventional manner of coating a catalyst onto a conductive substrate causes several problems: firstly, the catalyst layer is easy to be pulverized and peeled off under the influence of scouring of seawater flow or other factors, so that the effective catalytic area is reduced, and the discharge performance of the battery is further reduced; secondly, the binder is used as a catalytic inert component, occupies a certain volume of the catalyst layer, influences the effective contact area of the catalyst and the seawater, and reduces the volume energy density of the electrode due to the fact that the conductive substrate occupies a large proportion in the whole electrode; and thirdly, the thickness of the coating type catalyst layer is limited along with the progress of the discharge reaction, and when the surface layer catalyst begins to gradually deactivate or fails under the influence of biological fouling and the like, the discharge performance of the whole electrode is greatly influenced.
Based on this, the invention aims to provide an integrated oxygen reduction catalytic electrode aiming at the defects existing in the prior art, which adopts a high-density carbon network as a conductive carrier, has the advantages of high mechanical strength, rich and controllable pore structure, good conductivity and the like, and can simplify the electrode manufacturing process by directly using the integrated oxygen reduction catalytic electrode as a cathode. According to the invention, the structure and performance advantages of the integrated electrode are realized, the problem of material peeling is greatly avoided, and the performance stability is ensured; the adjustable pore structure ensures that good mass transfer and contact are also realized inside the reactor; the volume and the mass of the inactive components are reduced, and the energy density of the volume and the mass is improved; because of the integrated structure, the inner layer can still work well under the condition of outer layer inactivation, and the service life is prolonged. In addition, the oxygen reduction catalyst is loaded in the pore channel of the catalyst, so that the effective active area of the cathode oxygen reduction reaction can be further increased, the reduction reaction of cathode dissolved oxygen can be further accelerated, and the cathode discharge performance can be improved. The invention is mainly applied to seawater, can be expanded to various water body environments such as salt water, salt water lakes and the like, and has wide practical prospect.
Disclosure of Invention
The invention aims to: aiming at the defects of the prior art, the integrated oxygen reduction catalytic electrode is provided, a high-density carbon network is used as a conductive carrier, the integrated oxygen reduction catalytic electrode has the advantages of high mechanical strength, rich and adjustable pore structure, good conductivity and the like, and the electrode manufacturing process can be simplified by directly using the integrated oxygen reduction catalytic electrode as a cathode. According to the invention, the structure and performance advantages of the integrated electrode are realized, the problem of material peeling is greatly avoided, and the performance stability is ensured; the adjustable pore structure ensures that good mass transfer and contact are also realized inside the reactor; the volume and the mass of the inactive components are reduced, and the energy density of the volume and the mass is improved; because of the integrated structure, the inner layer can still work well under the condition of outer layer inactivation, and the service life is prolonged. In addition, the oxygen reduction catalyst is loaded in the pore channel of the catalyst, so that the effective active area of the cathode oxygen reduction reaction can be further increased, the reduction reaction of cathode dissolved oxygen can be further accelerated, and the cathode discharge performance can be improved. The invention is mainly applied to seawater, can be expanded to various water body environments such as salt water, salt water lakes and the like, and has wide practical prospect.
In order to achieve the purpose, the invention adopts the following technical scheme:
the integrated oxygen reduction catalytic electrode comprises a three-dimensional conductive network consisting of high-density carbon-based materials and an oxygen reduction catalyst loaded on the three-dimensional conductive network, wherein the three-dimensional conductive network has a three-dimensional porous structure, and the porosity of the three-dimensional conductive network is 0.05-5.5 cm3The pore size is 0.5 nm-15 mu m; wherein the density of the high-density carbon-based material is 0.2-4.5 g/cm3The specific surface area is 10 to 2500m2Between/g; the content of the oxygen reduction catalyst in the electrode is 0.1-30%. The invention adopts the high-density carbon-based three-dimensional conductive network loaded oxygen reduction catalyst as the catalytic cathode of devices such as seawater batteries, simplifies the electrode preparation process of the traditional coating electrode, has good plasticity to flexibly adjust the macroscopic shape of the electrode according to the actual application requirement, and facilitates the strengthening of mass transfer by the microscopic three-dimensional porous network and the hydrophilic surface of the material, thereby improving the electrical polarity and prolonging the service life. In addition, the integrated oxygen reduction catalytic electrode can be used as a cathode by directly cutting the material into sheets or rods without a current collector.
As an improvement of the integrated oxygen reduction catalytic electrode, the porosity of the three-dimensional conductive network is 0.5-3 cm3The pore size is 5 nm-5 mu m.
As an improvement of the integrated oxygen reduction catalytic electrode, the density of the high-density carbon-based material is 1.0-4.0 g/cm3The specific surface area is 50-500 m2/g。
As an improvement of the integrated oxygen reduction catalytic electrode, the content of the oxygen reduction catalyst in the electrode is 1-10%.
As an improvement of the integrated oxygen reduction catalytic electrode, the content of the oxygen reduction catalyst in the electrode is 2-6%.
As an improvement of the integrated oxygen reduction catalytic electrode, the high-density carbon-based material is graphene oxide, aminated graphene, carbon oxide tube/carbon black, graphite, activated carbon, and carbon nitride (C)3N4) Carbon fiber, carbon sheet.
As an improvement of the integrated oxygen reduction catalytic electrode of the present invention, the oxygen reduction catalyst is: the metal is a single atom, a metal nano cluster, a metal nano particle or a diatomic, polyatomic or alloy of two or more of the metals, or at least one of metal oxide, nitride, phosphide and sulfide, and the metal is at least one of Fe, Co, Ni, Cu, Zn, Mg, Mn, Pt, Au and Pb.
As an improvement of the integrated oxygen reduction catalytic electrode, the load mode of the oxygen reduction catalyst on the three-dimensional conductive network is anchoring, limited domain or composite.
The preparation method of the integrated catalytic cathode at least comprises the following steps:
adding a carbon-based component and a catalyst precursor into a solvent according to a mass ratio of 1: 1-10: 1, dispersing to obtain a mixed solution, placing the mixed solution into a reaction container, heating to 50-200 ℃, reacting for 2-24 hours, preparing a catalyst precursor-carbon-based composite gel material by virtue of van der Waals force interaction between functional groups on the surface of carbon sheets under hydrothermal/solvothermal conditions, wherein attractive force or repulsive force exists locally between the carbon sheets due to surface functional group difference, placing the obtained gel material into deionized water for soaking to remove solvent and impurities, and specifically placing the obtained gel material into deionized water for soaking for 2-7 days to remove solvent and impurities;
drying the gel material obtained in the step one at 0-200 ℃ to obtain a high-density carbon catalytic material precursor; in the process, the gel continuously undergoes capillary shrinkage, the higher the drying temperature is, the higher the density and hardness of the formed porous carbon material are, and the hardness of the prepared graphene porous carbon material shows a trend that the hardness is increased firstly and then is basically kept unchanged due to different drying times.
Step three, putting the high-density carbon catalytic material precursor obtained in the step two into a high-temperature tubular furnace or a microwave reactor for pyrolysis reduction to obtain a high-density carbon-catalyst composite compact porous material;
and step four, cutting or polishing the high-density carbon-catalyst composite compact porous material prepared in the step three into a required shape which can be a sheet, a block or a rod, so as to obtain the dissolved oxygen seawater battery integrated catalytic cathode.
Wherein, the carbon-based component in the step one is at least one of graphene oxide, aminated graphene and carbon oxide tubes.
The catalyst precursor in the step one comprises at least one metal compound selected from metal organic compounds, inorganic metal salts, organic metal salts, metal hydroxycarbonates, chlorine-containing metal acids and metal complexes;
wherein the metal organic compound comprises at least one of a metal phthalocyanine compound, a metal porphyrin compound, a metal thiourea compound and an acetylacetone metal compound;
the inorganic metal salt is metal chloride and/or metal nitrate, and the organic metal salt is metal acetate;
the metal in the metal organic compound, the inorganic metal salt, the organic metal salt and the metal basic carbonate is one of Fe, Co, Ni, Cu, Zn, Mg and Mn;
the metal acid or metal complex containing chlorine H2AuCl6、H2PtCl6、H2PdCl6。
Adding an auxiliary component into the mixed solution obtained in the first step, wherein the auxiliary component is a reducing agent and/or a pH regulator; the reducing agent is hydrazine hydrate or sodium ascorbate, and the pH regulator is dilute hydrochloric acid, ammonia water, potassium hydroxide or sodium hydroxide dilute solution. The purpose of adding the auxiliary component is to promote the gelling effect by influencing the surface functional groups and the charge condition of the crosslinked carbon sheet layer. The reducing agent is hydrazine hydrate or sodium ascorbate, which mainly influences the crosslinking force of the carbon substrate by changing the number of oxidation functional groups on the carbon substrate; the pH regulator is an acidic regulator: dilute hydrochloric acid, alkaline regulator: ammonia, potassium hydroxide, sodium hydroxide, which primarily regulate the number of functional groups (e.g., -COOH) between the gel-forming sheets by pH control, thereby modulating the interaction forces (van der waals forces) between the gel-forming sheets.
Wherein, the solvent in the step one is at least one of water, ethanol, methanol, dimethylformamide, ethylene glycol, methyl pyrrolidone and dimethyl sulfoxide.
Wherein, the dispersion method in the step one is at least one of mechanical stirring, magnetic stirring, ultrasonic dispersion and ball milling dispersion.
And drying in the step two is carried out in a vacuum forced air dryer, and the drying time is 0.1-5 days.
Wherein, according to the difference of pyrolysis time and the difference of catalyst precursor, the catalyst in the high-density carbon-catalyst in the third step is: the metal is a single atom, a metal nano cluster, a metal nano particle or a diatomic, polyatomic or alloy of two or more of the metals, or at least one of metal oxide, nitride, phosphide and sulfide, and the metal is one of Fe, Co, Ni, Cu, Zn, Mg, Mn, Pt, Au and Pb.
And the pyrolysis reduction reaction in the third step specifically comprises the steps of placing the high-density carbon catalytic material in a tubular reaction furnace, heating for 0.1-24 hours at 800-1200 ℃ under the condition of introducing protective gas or mixed gas of the protective gas and reducing gas, wherein the protective gas is at least one of nitrogen, argon and helium, and the reducing gas is at least one of ammonia, hydrogen and carbon monoxide.
Or placing the high-density carbon catalytic material in a microwave reactor for microwave irradiation, wherein the power is 800-1600W, and the irradiation time is 0.1-30 min.
Wherein, 0.1-30% of other materials are also added in the first step, and the other materials are carbon nano tubes, carbon black, graphite, activated carbon or polyvinyl alcohol, sucrose, glucose and carbon nitride (C)3N4) And two-dimensional transition metal carbides (MXenes). The other components are mainly materials with Fermi level difference with the carbon-based components, and the purpose of adding the components is to initiate electron transfer through 'co-doping' through the Fermi level difference and realize the improvement of the catalytic performance of oxygen reduction. The optimal content of the component is 15-25%, and the adding content has great influence on the improvement degree of the catalytic performance depending on the specific added materials.
In addition, the invention also provides the use of the integrated oxygen reduction catalytic electrode: the method is mainly used for the dissolved oxygen seawater battery.
The inventors of the present application have found that the problems of the prior art can be effectively solved using the integrated high-density carbon electrode. The integrated catalytic cathode prepared by the method adopts high-density porous carbon, and the carbon material is crosslinked, shrunk and densified to obtain a material with the outstanding characteristics of high specific surface area and high density. The characteristic has outstanding application potential in seawater batteries, can remarkably improve the volume energy density, reduce the battery volume and facilitate the loading and passage of the pore size structure confinement catalyst particles. Meanwhile, the invention is based on a three-dimensional conductive network of high-density porous carbon, and an oxygen reduction catalyst is loaded on the three-dimensional conductive network so as to improve the performance of the seawater battery.
Specifically, the integrated high-density porous carbon electrode has good mechanical strength and large specific surface area, so that the catalyst is anchored or confined in pores, a large effective mass transfer interface is obtained, and performance slide caused by peeling of a catalyst layer is avoided; the electrode material is modified or hydrophilic material is used, so that the electrode has good hydrophilicity and wettability, the effective contact of the electrode to seawater is improved, the mass transfer is enhanced, and the effective utilization of low-content dissolved oxygen can be enhanced; when the electrode is constructed, the nano carbon materials with certain biotoxicity, such as graphene and the like, are used, so that part of marine organism adhesion can be effectively reduced, and the influence of biological fouling is reduced; the thick and dense electrode is easy to prepare, and even if the surface catalyst sites are inactivated or invalid, the internal catalyst can continuously work to prolong the service life of the electrode; the integrated electrode can simplify the electrode preparation process, reduce the quality of inactive components of the battery and improve the volume energy density of the whole electrode. Therefore, the preparation of the integrated cathode has important significance for the dissolved oxygen seawater battery.
In summary, the present invention has at least the following advantages over the prior art:
firstly, the invention is used as an integrated cathode conductive carrier of the seawater battery based on the high-density carbon network, has the advantages of high mechanical strength, rich and adjustable pore structure, good conductivity and the like, can be directly used as a catalyst carrier and a current collector, and simplifies the electrode manufacturing process.
Secondly, the effective active area of the cathode oxygen reduction reaction can be effectively increased by loading the oxygen reduction catalyst in the pore channel of the high-density carbon carrier, the reduction reaction of cathode dissolved oxygen is further accelerated, and the cathode discharge performance is improved. Due to the improvement of the catalytic performance of the cathode, the discharge performance of the metal-dissolved oxygen seawater battery is greatly improved, the battery volume is small, and the power density and the energy density are higher. Has good response capability under the low oxygen environment.
The invention is mainly applied to seawater, can be expanded to various water body environments such as salt water, salt water lakes and the like, and has wide practical prospect.
Drawings
Fig. 1 shows a physical change process diagram of the high-density carbon catalytic material precursor obtained after the catalyst precursor-carbon-based composite gel gradually removes moisture and shrinks.
Fig. 2 shows two electrode shapes of a sheet-like pole piece and a rod-like pole piece made of the integrated electrode of example 1.
Fig. 3 shows an SEM image of the catalytic material prepared using the tube furnace temperature programmed heating method according to example 1.
Fig. 4 shows an SEM image of the catalytic material prepared by the microwave irradiation method according to example 2.
Detailed Description
The present invention and its advantageous effects are described in detail below with reference to the accompanying drawings and the embodiments, but the embodiments of the present invention are not limited thereto.
Example 1
The embodiment provides a preparation method of an integrated oxygen reduction catalytic electrode, which at least comprises the following steps:
adding a carbon-based component and a catalyst precursor into a solvent (mass ratio is 1:1), adding an auxiliary component, dispersing to obtain a mixed solution, placing the mixed solution into a reaction container, heating to 70 ℃, reacting for 12 hours to prepare a catalyst precursor-carbon-based composite gel material, and placing the obtained gel material into deionized water for soaking to remove solvent and impurities;
drying the gel material obtained in the step one at 70 ℃ to obtain a high-density carbon catalytic material precursor;
step three, putting the high-density carbon catalytic material precursor obtained in the step two into a high-temperature tubular furnace for pyrolysis reduction to obtain a high-density carbon-catalyst composite compact porous material;
and step four, cutting or polishing the high-density carbon-catalyst composite compact porous material prepared in the step three into a required shape to obtain the integrated oxygen reduction catalytic electrode.
Wherein the carbon-based component in the first step is graphene oxide, and the precursor of the catalyst is iron phthalocyanine; the solvent is dimethyl sulfoxide, and the dispersing method is mechanical stirring.
And the drying mode in the second step is drying in a vacuum forced air drier for 1 day.
The catalyst of the high-density carbon-catalyst in the third step is graphene-monoatomic iron catalyst. The pyrolysis reduction reaction comprises the specific steps of placing the high-density carbon catalytic material in a tubular reaction furnace, and heating for 3 hours at 900 ℃ under the condition of introducing inert gas argon. The resulting catalyst was then treated with 20 wt.% dilute sulfuric acid for 0.5h (to remove small amounts of agglomerated iron nanoparticles), filtered to give a solid material, and repeatedly rinsed with deionized water until neutral. And finally drying the filter residue to obtain the required high-density carbon-monoatomic catalyst.
Fig. 1 shows a physical change process diagram of the high-density carbon catalytic material precursor obtained after the catalyst precursor-carbon-based composite gel gradually removes moisture and shrinks.
Fig. 2 shows two electrode shapes of a sheet-like pole piece and a rod-like pole piece made of the integrated electrode of example 1.
Fig. 3 shows an SEM image of the catalytic material prepared using the tube furnace temperature programmed heating method according to example 1.
Example 2
The difference from example 1 is that in the third step, the high-density carbon catalytic material is placed in a microwave reactor, an inert gas argon gas is filled in a microwave reaction bottle in advance, the microwave reaction time is 60-90 s, in this example, 90s, and the graphene-monoatomic iron catalyst composite dense porous material is prepared, which is the same as example 1 and is not described herein again.
Fig. 4 shows an SEM image of the catalytic material prepared by the microwave irradiation method according to example 2.
Example 3
The embodiment provides a preparation method of an integrated oxygen reduction catalytic electrode, which at least comprises the following steps:
adding a carbon-based component and a catalyst precursor into a solvent (mass ratio is 1:1), adding an auxiliary component, dispersing to obtain a mixed solution, placing the mixed solution into a reaction container, heating to 70 ℃, reacting for 12 hours to prepare a catalyst precursor-carbon-based composite gel material, and placing the obtained gel material into deionized water to soak for solvent desolvation and impurity removal;
drying the gel material obtained in the step one at 100 ℃ to obtain a high-density carbon catalytic material precursor;
step three, putting the high-density carbon catalytic material precursor obtained in the step two into a high-temperature tubular furnace for pyrolysis reduction to obtain a high-density carbon-catalyst composite compact porous material;
and step four, cutting or polishing the high-density carbon-catalyst composite compact porous material prepared in the step three into a required shape to obtain the integrated oxygen reduction catalytic electrode.
Wherein the carbon-based component in the step one is ammoniated graphene, and the catalyst precursor is copper acetylacetonate; the auxiliary component is sodium ascorbate, the mass ratio of the addition amount of the sodium ascorbate to the aminated graphene is 2:1, the solvent is ethanol, and the dispersion method is magnetic stirring.
And the drying in the second step is drying in a vacuum forced air drier for 1 day.
The catalyst of the high-density carbon-catalyst in the third step is a graphene-copper nanoparticle catalyst. The pyrolysis reduction reaction comprises the specific steps of placing the high-density carbon catalytic material in a tubular reaction furnace, and heating for 3 hours at 1000 ℃ under the condition of introducing inert gas argon.
Example 4
The difference from embodiment 3 is that in the third step, the high-density carbon catalytic material is placed in a microwave reactor, inert gas argon is introduced into a microwave reaction bottle, the microwave reaction time is 90-120 s, in this embodiment, 120s, and the graphene-copper nanoparticle catalyst composite dense porous material is prepared, which is the same as embodiment 3 and is not described herein again.
Example 5
The embodiment provides a preparation method of an integrated oxygen reduction catalytic electrode, which at least comprises the following steps:
adding a carbon-based component and a catalyst precursor into a solvent (mass ratio is 7:1), adding an auxiliary component, dispersing to obtain a mixed solution, placing the mixed solution into a reaction container, heating to 120 ℃, reacting for 8 hours to prepare a catalyst precursor-carbon-based composite gel material, and placing the obtained gel material into deionized water to soak for solvent desolvation and impurity removal;
drying the gel material obtained in the step one at 90 ℃ to obtain a high-density carbon catalytic material precursor;
step three, putting the high-density carbon catalytic material precursor obtained in the step two into a high-temperature tubular furnace for pyrolysis reduction to obtain a high-density carbon-catalyst composite compact porous material;
and step four, cutting or polishing the high-density carbon-catalyst composite compact porous material prepared in the step three into a required shape to obtain the integrated oxygen reduction catalytic electrode.
Wherein, the carbon-based component in the step one is carbon oxide tube, and the catalyst precursor is ferric chloride; the auxiliary component pH regulator is dilute hydrochloric acid, the addition amount is 5 mu L, the solvent is methyl pyrrolidone, and the dispersion method is ultrasonic dispersion.
And the drying in the step two is carried out in a vacuum forced air drier for 3 days.
The catalyst of the high-density carbon-catalyst in the third step is carbon tube-iron particle catalyst. The pyrolysis reduction reaction comprises the specific steps of placing the high-density carbon catalytic material in a tubular reaction furnace, and heating for 18 hours at 1000 ℃ under the condition of introducing inert gas argon.
Example 6
The difference from embodiment 5 is that in the third step, the high-density carbon catalytic material is placed in a microwave reactor, and argon is introduced into a microwave reaction bottle, the microwave reaction time is 120-300 s, in this embodiment 300s, to prepare the graphene-iron particle catalyst composite dense porous material, which is the same as embodiment 5 and is not described herein again.
Example 7
The embodiment provides a preparation method of an integrated oxygen reduction catalytic electrode, which at least comprises the following steps:
adding a carbon-based component and a catalyst precursor into a solvent (mass ratio is 7:1), adding other materials (accounting for 20%), adding an auxiliary component, dispersing to obtain a mixed solution, placing the mixed solution into a reaction container, heating to 150 ℃, reacting for 3 hours to prepare a catalyst precursor-carbon-based composite gel material, and placing the obtained gel material into deionized water to soak for desolvation and impurity removal;
drying the gel material obtained in the step one at 80 ℃ to obtain a high-density carbon catalytic material precursor;
step three, putting the high-density carbon catalytic material precursor obtained in the step two into a high-temperature tubular furnace or a microwave reactor for pyrolysis reduction to obtain a high-density carbon-catalyst composite compact macroscopic body;
and step four, cutting or polishing the high-density carbon-catalyst composite compact macroscopic body prepared in the step three into a required shape to obtain the integrated oxygen reduction catalytic electrode.
The carbon-based component in the step one is graphene oxide, the catalyst precursor is iron phthalocyanine, other materials are carbon nanotubes, and auxiliary components are a reducing agent and a pH regulator; the reducing agent is sodium ascorbate, the addition amount of the reducing agent is 2 times of that of the graphene oxide, the pH regulator is dilute hydrochloric acid, the addition amount of the pH regulator is 5 mu L, the solvent is dimethylformamide, and the dispersion method is mechanical stirring.
And the drying in the second step is drying in a vacuum forced air drier for 4 days.
The catalyst of the high-density carbon-catalyst in the third step is graphene/carbon nano tube-monoatomic iron nano particle catalyst. The specific steps of the pyrolysis reduction reaction are that the high-density carbon catalytic material is placed in a tubular reaction furnace and heated for 5 hours at 950 ℃ under the condition of introducing inert gas nitrogen.
Example 8
The difference from embodiment 7 is that in the third step, the high-density carbon catalytic material is placed in a microwave reactor, inert gas argon is introduced into a microwave reaction bottle, and the microwave reaction time is 60-300 s, so as to prepare the graphene/carbon nanotube-monatomic iron catalyst composite dense porous material, which is the same as embodiment 7 and is not repeated here.
Examples 9 to 12
The differences from examples 1, 3, 5 and 7 are that the catalyst precursor is changed into cobalt phthalocyanine, nickel phthalocyanine, cobalt porphyrin or nickel porphyrin, and the rest conditions are the same, and the description is omitted here.
Examples 13 to 16
The differences from examples 2, 4, 6 and 8 are that the catalyst precursor is changed into cobalt phthalocyanine, nickel phthalocyanine, cobalt porphyrin or nickel porphyrin, and the rest conditions are the same, and the description is omitted here.
Example 17
The difference from example 7 is that the other material added is carbon nitride (C)3N4) To prepare graphene/C3N4Monatomic iron catalyst, the remaining conditions being the same and not described in detail here.
Example 18
The difference from example 8 is that the other material added is carbon nitride (C)3N4) To prepare graphene/C3N4Monatomic iron catalyst, the remaining conditions being the same and not described in detail here.
Example 19
Different from the embodiment 7, the catalyst precursor is changed into metal basic carbonate to prepare the graphene/C3N4Metal oxide catalysts, the remaining conditions being the same and not described in detail here.
Example 20
Different from the embodiment 8, the catalyst precursor is changed into metal basic carbonate to prepare the graphene/C3N4Metal oxide catalysts, the remaining conditions being the same and not described in detail here.
Example 21
The difference from example 7 is that the catalyst precursor is changed to a metal thiourea compound to prepare the graphene/carbon nanotube-metal sulfide catalyst, and the rest conditions are the same and are not repeated here.
Example 22
The difference from embodiment 8 is that the catalyst precursor is changed into a metal thiourea compound to prepare the graphene/carbon nanotube-metal sulfide catalyst, and the rest conditions are the same and are not repeated here.
Comparative example 1
Different from the embodiment 1, the prepared dense porous carbon-based catalytic material is fully ground, uniformly mixed with a binder according to the mass ratio of 9:1, coated on a conductive substrate, dried in a vacuum drying oven, and then subjected to sheet punching or cutting to prepare the anode material of the seawater battery. The conductive substrate material is foam nickel, and the adhesive is Nafion.
Comparative example 2
Different from the embodiment 2, the prepared compact porous carbon-based catalytic material is fully ground, uniformly mixed with the binder according to the mass ratio of 9:1, coated on a conductive substrate, dried in a vacuum drying oven, and then subjected to sheet punching or cutting to prepare the anode material of the seawater battery. The conductive substrate material is foam nickel, and the adhesive is Nafion.
The experimental data show that: the coated electrodes (comparative examples 1 and 2) had poor long-term stability and lower volumetric energy density than the integral electrodes (examples 1 and 2). The electrodes of the examples 1 and 2 and the comparative examples 1 and 2 and the AZ31B magnesium alloy are assembled into the dissolved oxygen seawater battery, the battery numbers are S1, S2, D1 and D2, and the relevant data of the parameter indexes such as the initial potential, the half-wave potential, the catalytic life and the like of the catalyst of each battery are basically consistent. At 0.5mA cm-2After discharging for 10h at the current density of (1.4V), the discharge voltage of the battery D1 assembled by the coated electrode gradually decays from about 1.4V to below 1.2V, and the discharge voltage of D2 gradually decays from 1.45V to below 1.2V, while the voltage of the integrated electrode of the corresponding embodiment is basically kept unchanged, and S1 and S2 have small decays less than 0.03V. Meanwhile, in the aspect of volume specific power, the volume specific power of the integrated electrode is larger, wherein S1 can reach 15.2 mW.L-1S2 is 16.0 mW.L-1Are all significantly greater than the power density of the coated electrode (D1 is 7.9 mW. L)-1(ii) a D2 is 8.2 mW.L-1). All four are superior to 2.7 mW.L of SWB1200 commercial dissolved oxygen seawater cell developed by Kongsberg Simrad based on carbon fiber brush cathode-1(Sea-water battery for subsea control systems, Journal of Power Sources,1997,65: 253-. The test is carried out in a low dissolved oxygen environment, the test environment is natural seawater (seawater comes from Bohai sea area near Tianjin) with the dissolved oxygen content of 1mg/L, and the result shows that: the integrated electrode can still keep stable volume specific power for a long time, and S1 reaches 7.3 mW.L-1S2 reaching 7.8 mW.L-1The initial power density is similar to that of the coating electrode, and the volume specific power is kept at 7.0 mW.L after the continuous test for one week-1Above, the stability is significantly superior to that of a coated electrode. Wherein the initial volume specific power of the coated electrode was 6.7 mW.L in D1-1D2 is 6.9 mW.L-1After one week of discharge, the voltage rapidly decays to 3.4 mW.L-1D1 was attenuated to 3.1 mW.L-1D2 attenuation to 3.4 mW.L-1The attenuation rate is as high as more than 50%.
The electrode is expanded to a 3.5% sodium chloride brine system, the integrated electrode still keeps good dissolved oxygen response capacity, and the volume specific power can reach 7.8 mW.L-1. The decay rate after one week of discharge is less than 5%.
The high-density carbon-copper nanoparticle catalysts prepared according to examples 3 and 4 showed lower catalytic activity than the iron catalysts prepared in examples 1 and 2. Under the condition of oxygen saturation, the half-wave potential of the catalyst in example 1 in the natural seawater is 4.92V, the half-wave potential of the catalyst in example 2 in the natural seawater is 5.45V, and the half-wave potential of the material prepared in example 3 is only 3.78V, and the half-wave potential of the material prepared in example 4 is 3.94V.
Comparing examples 1 and 2 with examples 9 to 12 and examples 13 to 16, it can be seen that the iron, cobalt and nickel metal catalysts all show high ORR catalytic activity, and all of them maintain high volume specific power under low oxygen condition, and the activity of the catalyst treated by microwave is better than that of the catalyst obtained by heat treatment. The activity of the iron and cobalt catalysts prepared by the same preparation method is slightly superior to that of the nickel catalyst, and specific catalyst index parameters are shown in the following table. In the low oxygen test, the initial volume specific power of example 9 obtained under different heat treatment conditions was 7.0 mW.L-1Example 10 shows 6.1 mW.L-1Example 11 is 6.7 mW.L-1Example 12 is 6.7 mW.L-1(ii) a The initial volume specific power of example 13 obtained under different microwave irradiation conditions was 7.3 mW.L-1Example 10 shows 6.4 mW.L-1Example 11 is 6.7 mW.L-1Example 12 is 6.8 mW.L-1。
Experimental data show that different catalyst precursors have a greater impact on the resulting catalyst composition. The activity of the transition metal monatomic catalyst is better than the activity of the nano-particles, and the activity of the metal catalyst is better than the activity of the oxide and the sulfide of the same metal.
The specific catalyst parameters for each example are shown in the following table:
description of the drawings: the catalytic performance parameters (including half-wave potential and initial potential) of the catalyst ORR are tested under the condition that natural seawater is saturated by oxygen (a test seawater sample is from a Bohai offshore sea area near Tianjin). The testing device is a three-electrode testing system, the working electrode is a rotating disc electrode coated with a catalyst, the counter electrode is a metal platinum sheet, and the reference electrode is an Ag/AgCl electrode. ② the low oxygen volume specific power is tested under the oxygen content with the dissolved oxygen content of 1mg/L (the test seawater sample comes from the Bohai offshore area near Tianjin). Anode electrode of 2X 0.5cm3AZ31 magnesium alloy ingots, cathodes, prepared according to the examples described above.
The experimental result shows that the integrated electrode has obvious effect on maintaining the long-term discharge stability, and is mainly embodied in the following three layers: firstly, the high-density porous carbon network highly-confined/anchored catalyst reduces the voltage loss caused by the stripping of cathode materials; secondly, the volume energy density of the whole body is improved because the inactive components such as a binder and a conductive substrate are not required to be added; thirdly, the chemical stability of the carbon material enables the integrated electrode to be different from a coating type electrode, the corrosion resistance of a conductive substrate and the corrosion resistance of a catalytic material are separately considered, and the electrode preparation process is simplified. Meanwhile, the catalytic material prepared by the microwave method shows better stability than the catalytic material subjected to heat treatment, and the ultra-fast temperature rise can be realized in the microwave irradiation process, so that the metal precursor is quickly pyrolyzed, a catalyst which is more uniformly distributed and has a smaller size is formed, and more catalytic active sites are exposed.
The invention is mainly applied to seawater, can be expanded to various water body environments such as salt water, salt water lakes and the like, and has wide practical prospect.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and the above embodiments are only used for explaining the claims. The scope of the invention is not limited by the description. Any changes or substitutions that can be easily made by those skilled in the art within the technical scope of the present disclosure are included in the scope of the present invention.
Claims (9)
1. The integrated oxygen reduction catalytic electrode is characterized in that the electrode is formed by integrally constructing a three-dimensional conductive network consisting of high-density carbon-based materials and an oxygen reduction catalyst loaded in the three-dimensional conductive network, the three-dimensional conductive network has a three-dimensional porous structure, and the porosity of the three-dimensional conductive network is 0.05-5.5 cm3The pore size is 0.5 nm-15 mu m; wherein the density of the high-density carbon-based material is 0.2-4.5 g/cm3The specific surface area is 10 to 2500m2Between/g; the content of the oxygen reduction catalyst in the electrode is 0.1-30%.
2. The integrated oxygen-reducing catalytic electrode according to claim 1, wherein the porosity of the three-dimensional conductive network is 0.5-3 cm3The pore size is 5 nm-5 mu m.
3. The integrated oxygen-reducing catalytic electrode of claim 1, wherein the high densityThe density of the carbon-based material is 1.0-4.0 g/cm3The specific surface area is 50-500 m2/g。
4. The integrated oxygen-reducing catalytic electrode according to claim 1, wherein the content of the oxygen-reducing catalyst in the electrode is 1 to 10%.
5. The integrated oxygen-reducing catalytic electrode according to claim 1, wherein the content of the oxygen-reducing catalyst in the electrode is 2 to 6%.
6. The integrated oxygen-reducing catalytic electrode according to claim 1, wherein the high-density carbon-based material is graphene oxide, aminated graphene, carbon oxide tube/carbon black, graphite, activated carbon, carbon nitride (C)3N4) Carbon fiber, carbon sheet.
7. The integrated oxygen-reducing catalytic electrode of claim 1, wherein the oxygen-reducing catalyst is: the metal is a single atom, a metal nano cluster, a metal nano particle or a diatomic, polyatomic or alloy of two or more of the metals, or at least one of metal oxide, nitride, phosphide and sulfide, and the metal is at least one of Fe, Co, Ni, Cu, Zn, Mg, Mn, Pt, Au and Pb.
8. The integrated oxygen-reducing catalytic electrode of claim 1, wherein the oxygen-reducing catalyst is supported in the three-dimensional conductive network in an anchored, confined or composite manner.
9. Use of the monolithic oxygen reduction catalytic electrode of claim 1: the method is mainly used for the dissolved oxygen seawater battery.
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