Preparation method of anode titanium-based porous transmission layerTechnical Field
The invention belongs to the technical field of electrochemistry, and relates to a preparation method of an anode titanium-based porous transmission layer.
Background
The Proton Exchange Membrane (PEM) electrolyzer mainly comprises end plates, bipolar plates, diffusion layers, catalyst layers, proton exchange membranes and gaskets, and the anode titanium-based porous transmission layer plays roles in water transportation, air exhaust, heat conduction, electric conduction and the like in the anode oxygen evolution reaction, and is the integration of gas, liquid, electricity and heat four-phase fluid fields. When the electrolytic reaction occurs in the PEM electrolytic tank, the anode of the electrolytic tank is in an acidic environment, and the electrolytic voltage is usually higher than 1.6V, so that titanium materials with good stability, namely a porous sintered titanium plate and a titanium fiber felt, are usually selected in practical application, but a titanium film is gradually generated on the surface of the titanium material without surface treatment in an oxidizing environment, so that the conductivity of the electrode is greatly reduced.
In order to solve the oxidation problem of the titanium material, methods such as electroplating, vapor deposition, magnetron sputtering and the like are generally adopted to add an oxidation-resistant noble metal coating such as ruthenium oxide, iridium oxide and the like on the surface of the titanium material, and the noble metal oxides have high corrosion resistance, can protect the titanium fiber felt from being corroded easily in an acidic environment, improve the service life of the titanium fiber felt, have low resistance and high catalytic activity, improve the efficiency of a catalyst in a catalytic layer, effectively reduce the loading capacity of the catalyst layer and improve the battery efficiency. Patent CN109518168a discloses a preparation method of an active titanium-based electrode plate with a high-stability coating, which uses titanium as a base material, forms a main body multi-metal catalytic layer of the titanium-based catalytic layer by using a pyrolysis method, and forms a compact oxide titanium-based protective layer by combining a sol-gel method and an electrochemical deposition method. Patent CN114990604a discloses a catalyst-supported diffusion layer of PEM water electrolysers and a method for its preparation. A double-layer coating layer is prepared on the diffusion layer, and comprises a metal diffusion layer matrix, a corrosion-resistant middle layer and a catalytic active layer. Patent CN115125558a discloses a method for preparing a metal-based conductive porous transport layer and its application in water electrolysis cell. And (3) scraping metal-based conductive material powder on the surface of the titanium felt to obtain the metal-based conductive porous transmission layer.
However, the traditional method for forming the coating by the pyrolysis method has weak bonding force between the coating and the substrate, and has complex process by carrying out acid corrosion and other treatments before the coating, while the electrochemical deposition method has the disadvantages of uneven coating, large roughness and magnetron sputtering coating on the surface of the substrate, and the noble metal oxide film deposited by the Chemical Vapor Deposition (CVD) technology not only can cover the surface of the substrate, but also can be deposited in pores of the substrate.
Therefore, a new preparation method of the anode titanium-based porous transmission layer with simpler process, better corrosion resistance and higher conductivity needs to be developed.
Disclosure of Invention
The invention aims to provide a preparation method of an anode titanium-based porous transmission layer, and the prepared titanium-based porous transmission layer has the characteristics of being more corrosion-resistant, lower in resistance, stronger in conductivity, more uniform in thickness and longer in service life of a titanium fiber felt.
The aim of the invention can be achieved by the following technical scheme:
The preparation method of the anode titanium-based porous transmission layer is characterized by comprising the following specific preparation steps of:
S1, paving a titanium fiber felt through a dry method, wherein the concrete forming steps of the titanium fiber felt are as follows:
Firstly carding fiber bundles into single fluffy fibers through air current carding, then paving and forming the single fluffy fibers in a lapping machine, rolling the single fluffy fibers in a roll squeezer, and then sintering the single fluffy fibers in a vacuum sintering furnace at 900-1500 ℃ with the vacuum degree of less than or equal to 3X 10-2 Pa, and then carrying out multi-roll flattening and 2-3 times of operation to obtain a titanium fiber felt;
S2, preparing a metal composite material:
Fully dissolving polyethylene glycol solid in absolute ethyl alcohol, adding a coupling agent, fully stirring for 0.5-1 h in a stirrer, adding metal precursor powder after uniformly stirring, firstly stirring for 15-20 min at a low speed at a rotating speed of 100-150 r/min, and then stirring for 2-3 h at a high speed at a rotating speed of 800-1200 r/min to obtain metal slurry;
Adding polyvinyl alcohol, a cationic surfactant and polyaniline into metal slurry, fully stirring, performing ultrasonic treatment for 0.5h, wherein the mass ratio of polyethylene glycol to absolute ethyl alcohol to metal precursor to cationic surfactant to coupling agent to polyvinyl alcohol to polyaniline is 2:15-20:20-25:1-2:0.5-1:0.5-1, reacting for 5-10 min by a microwave method, filtering, and drying the solid in a 100 ℃ oven for 2-4 h to obtain the metal composite material;
S3, preparing a titanium-based anode gas transmission layer:
Washing the titanium fiber felt with absolute ethyl alcohol and deionized water, drying the titanium fiber felt by a drying oven, placing the titanium fiber felt in a chemical vapor deposition furnace, introducing carrier gas hydrogen for preheating at 200-500 ℃, preserving heat for 10-50 min, then gasifying the prepared metal composite material, introducing a deposition box, introducing carrier gas carbon dioxide and hydrogen, forming an oxidized metal coating on the surface of a titanium fiber felt substrate, wherein the thickness of the coating is 1-30 mu m, and cooling to obtain the titanium-based anode gas transmission layer.
As a preferable technical scheme of the invention, in the step S1, the diameter of the titanium fiber is 10-30 μm, and the length is 30-80 mm.
As a preferable technical scheme of the invention, in the step S1, the thickness of the titanium fiber felt is 0.1-1.0 mm, the porosity is 50-90%, the gram weight of the single-layer felt is 50-600 g/m2, and the single-layer felt or the multi-layer felt is selected for rolling and forming in the rolling process.
In a preferred embodiment of the present invention, in step S2, the cationic surfactant is one of guar gum, dodecyl trimethyl ammonium bromide, octadecyl trimethyl ammonium chloride, and a cationic antistatic agent.
In step S2, the average molecular weight of the polyethylene glycol is 800-1200.
In a preferred embodiment of the present invention, in step S2, the coupling agent is one of a silane coupling agent, a phthalate coupling agent, a borate coupling agent, and an aluminate coupling agent.
In the step S2, the metal precursor is one or more of iridium, ruthenium, platinum, palladium, osmium, rhodium halides or metal organic compounds, and the chemical vapor deposition coating can be plated for multiple times and matched with different metal precursors.
As a preferable technical scheme of the invention, in the step S3, the flow of the hydrogen for preheating is 300-700 mL/min,
As a preferable technical scheme of the invention, in the step S3, the flow rates of the hydrogen and the carbon dioxide which are simultaneously introduced are respectively 300-700 mL/min and 100-400 mL/min, the pressure of chemical vapor deposition is 800-1200 Pa, and the temperature is 300-800 ℃.
The invention has the beneficial effects that:
(1) The conductive capacity of the titanium-based porous transmission layer is increased by adding polyaniline with conductivity into the metal precursor, so that an effective charge conduction channel exists between the titanium fiber felt and the metal oxide coating, titanium passivation caused by poor charge conduction due to lack of conductive substances between the titanium fiber felt and the traditional metal oxide coating is inhibited, meanwhile, metal organic ions are better dispersed in an organic solvent by adding a cationic surfactant, the number of charges in the organic solvent is increased, the charge transfer between the titanium fiber felt and the surface coating is further increased, and the addition of a coupling agent enables each component to exist stably, and meanwhile, the adhesive force between the coating and the titanium fiber felt is improved.
(2) Preparing a porous titanium felt by utilizing a titanium fiber air-laid felt forming technology, depositing a layer of noble metal film on the surface of titanium fiber by utilizing a chemical vapor deposition technology, improving the corrosion resistance and oxidation resistance of the titanium fiber felt, simultaneously introducing a carbon dioxide and hydrogen mixed gas to prevent the titanium fiber felt from being oxidized, reducing the risk of falling of an oxidized metal coating, ensuring that the titanium fiber felt has high conductivity and high number of active sites, and improving the catalytic efficiency. In addition, the titanium fiber felt is paved by adopting a dry method, so that water resources are saved, meanwhile, the acid pretreatment process in the traditional preparation of the titanium-based diffusion layer is reduced, the process steps are simplified, and the environmental pollution is reduced. And the noble metal oxide film is prepared by adopting a chemical vapor deposition technology, has the characteristics of high dispersion, high coverage, high purity, low resistance and the like, has the characteristics of uniform particle size, strong bonding force with a matrix and the like, improves the non-uniformity of a platinum coating of an anode titanium-based diffusion layer in a traditional PEM electrolytic cell, enlarges active sites, and simultaneously has the catalytic effect that the coating can catalyze electrode reaction and reduces the dosage of a catalyst in a catalytic layer. The dense iridium oxide or ruthenium oxide thin film formed by the chemical vapor deposition method is more corrosion-resistant, and the service life of the titanium fiber felt can be prolonged.
Drawings
The present invention is further described below with reference to the accompanying drawings for the convenience of understanding by those skilled in the art.
FIG. 1 is a polarization curve after the anode gas transfer layer prepared in examples and comparative examples is assembled into an electrolytic cell.
Detailed Description
In order to further describe the technical means and effects adopted by the present invention for achieving the intended purpose, the following detailed description is given below with reference to the embodiments, structures, features and effects according to the present invention.
Example 1
The titanium fiber felt is paved by a dry method, and the concrete forming steps of the titanium fiber felt are as follows:
adopting titanium fiber with the diameter of 15 mu m and the length of 50mm, carding by air flow, molding in a lapping machine, pressing and reinforcing by a roller press, sintering in a vacuum sintering furnace at the sintering temperature of 1200 ℃ and the vacuum degree of 2X 10-2 Pa, and then rolling and leveling to obtain titanium fiber felt with the thickness of 0.23mm and the porosity of 85%;
preparing a metal composite material:
Fully dissolving 2g of polyethylene glycol solid in 20g of absolute ethyl alcohol, adding 1g of coupling agent, fully stirring for 0.5-1 h in a stirrer, uniformly stirring, adding 20g of iridium hexafluoride (IrF6) powder which is a metal organic precursor, firstly stirring at a low speed for 20min at a rotating speed of 150r/min, and then stirring at a high speed for 3h at a rotating speed of 1200r/min to obtain metal slurry;
Adding 1g of polyvinyl alcohol, 1g of cationic surfactant and 1g of polyaniline into the metal slurry, fully stirring, performing ultrasonic treatment for 0.5h, reacting for 10min by a microwave method, filtering, and drying in a 100 ℃ oven for 3h to obtain the treated IrF6 precursor;
preparing a titanium-based anode gas transmission layer:
washing a titanium fiber felt with absolute ethyl alcohol and deionized water, drying, placing the titanium fiber felt in a chemical vapor deposition furnace, introducing carrier gas H2 for preheating, keeping the flow rate of hydrogen at 400mL/min, preserving the temperature at 400 ℃ for 30min, gasifying the treated IrF6, introducing a deposition box, introducing carrier gas carbon dioxide and hydrogen, wherein the flow rate of hydrogen is 400mL/min, the flow rate of carbon dioxide is 300mL/min, the pressure of the deposition box is 700Pa, the temperature is 700 ℃, an oxidized metal coating is formed on the surface of the titanium fiber felt, the thickness of the coating is 20 mu m, and the titanium-based anode gas transmission layer IrO2 @titanium fiber felt is obtained, and finally IrO2 @titanium fiber felt is 0.25mm.
Example 2
The titanium fiber felt is paved by a dry method, and the concrete forming steps of the titanium fiber felt are as follows:
Adopting titanium fiber with the diameter of 20 mu m and the length of 50mm, carding by air flow, molding in a lapping machine, pressing and reinforcing by a roller press, sintering in a vacuum sintering furnace at 1300 ℃ and the vacuum degree of 2X 10-2 Pa, and then rolling and leveling to obtain titanium fiber felt with the thickness of 0.23mm and the porosity of 85%;
preparing a metal composite material:
Fully dissolving 2g of polyethylene glycol solid in 20g of absolute ethyl alcohol, adding 1g of coupling agent, fully stirring for 0.5-1 h in a stirrer, uniformly stirring, adding 20g of metal organic precursor ruthenium hexafluoride (RuF6) powder, firstly stirring at a low speed for 20min at a rotating speed of 150r/min, and then stirring at a high speed for 3h at a rotating speed of 1200r/min to obtain metal slurry;
Adding 1g of polyvinyl alcohol, 1g of cationic surfactant and 1g of polyaniline into the metal slurry, fully stirring, performing ultrasonic treatment for 0.5h, reacting for 10min by a microwave method, filtering, and drying in a 100 ℃ oven for 3h to obtain a treated RuF6 precursor;
preparing a titanium-based anode gas transmission layer:
Washing a titanium fiber felt with absolute ethyl alcohol and deionized water, drying, placing the titanium fiber felt in a chemical vapor deposition furnace, introducing carrier gas hydrogen for preheating, keeping the flow of the hydrogen at 400mL/min, keeping the temperature at 400 ℃ for 30min, gasifying the treated RuF6, introducing a deposition box, introducing carrier gas carbon dioxide and hydrogen, wherein the flow of the hydrogen is 400mL/min, the flow of the carbon dioxide is 300mL/min, the pressure of the deposition box is 700Pa, the temperature is 750 ℃, an oxidized metal coating is formed on the surface of the titanium fiber felt substrate, the thickness of the coating is 20 mu m, and the titanium-based anode gas transmission layer RuO2 @titanium fiber felt is obtained, and finally RuO2 @titanium fiber felt is 0.25mm.
Example 3
The titanium fiber felt is paved by a dry method, and the concrete forming steps of the titanium fiber felt are as follows:
Adopting titanium fiber with the diameter of 20 mu m and the length of 50mm, carding by air flow, molding in a lapping machine, pressing and reinforcing by a roller press, sintering in a vacuum sintering furnace at the sintering temperature of 1200 ℃ and the vacuum degree of 2X 10-2 Pa, and then rolling and leveling to obtain titanium fiber felt with the thickness of 0.37mm and the porosity of 80%;
preparing a metal composite material:
Fully dissolving 2g of polyethylene glycol solid in 20g of absolute ethyl alcohol, adding 1g of coupling agent, fully stirring for 0.5-1 h in a stirrer, uniformly stirring, adding 20g of iridium hexafluoride (IrF6) powder which is a metal organic precursor, firstly stirring at a low speed for 20min at a rotating speed of 150r/min, and then stirring at a high speed for 3h at a rotating speed of 1200r/min to obtain metal slurry;
Adding 1g of polyvinyl alcohol, 1g of cationic surfactant and 1g of polyaniline into the metal slurry, fully stirring, performing ultrasonic treatment for 0.5h, reacting for 10min by a microwave method, filtering, and drying in a 100 ℃ oven for 3h to obtain the treated IrF6 precursor;
preparing a titanium-based anode gas transmission layer:
Washing a titanium fiber felt with absolute ethyl alcohol and deionized water, drying, placing the titanium fiber felt in a chemical vapor deposition furnace, introducing carrier gas H2 for preheating, wherein the flow is 400mL/min, the temperature is 200-500 ℃, preserving heat for 10-50 min, then gasifying the treated IrF6, introducing a deposition box, simultaneously introducing carrier gas carbon dioxide and hydrogen, wherein the flow of the hydrogen is 400mL/min, the flow of the carbon dioxide is 300mL/min, the pressure of the deposition box is 700Pa, the temperature is 600 ℃, forming an iridium oxide coating on the surface of the titanium fiber felt, the thickness of the coating is 30 mu m, and finally obtaining the titanium-based anode gas transmission layer IrO2 @titanium fiber felt, and the IrO2 @titanium fiber felt is 0.40mm.
Comparative example 1
Adopting titanium fiber with the diameter of 20 mu m and the length of 50mm, carding by air flow, molding in a lapping machine, pressing and reinforcing by a roller press, sintering in a vacuum sintering furnace at the sintering temperature of 1200 ℃ and the vacuum degree of 2X 10-2 Pa, and then rolling and leveling to ensure that the thickness of the titanium fiber felt is 0.37mm and the porosity is 80%;
Firstly cleaning the titanium fiber felt with a methanol solution, then immersing the titanium fiber felt in a 15% oxalic acid solution for 20min, repeatedly washing the titanium fiber felt with deionized water until the surface of the titanium fiber felt is neutral, and finally drying the titanium fiber felt to obtain a titanium fiber felt substrate to be deposited;
Preparing conductive metal slurry, namely taking 2g of phenolic resin and 1g of dispersing agent, completely dissolving in 30g of isopropanol, adding 35g of iridium powder, and uniformly stirring and dispersing to obtain the conductive metal slurry containing the iridium powder;
And (3) scraping the slurry containing the iridium powder on the pretreated titanium fiber felt, and then drying in an oven at 120 ℃ for 1h to obtain the iridium-coated titanium fiber felt.
As can be seen from fig. 1, the polarization curve of example 1 has the most gentle trend and the lowest slope, and the larger the maximum current density, the best the power performance of this cell. The maximum slope of the polarization curve of comparative example 1 demonstrates the good performance of the porous transport layer prepared by the present invention when used in the composition of proton exchange membrane fuel cells.
The present invention is not limited in any way by the above-described preferred embodiments, but is not limited to the above-described preferred embodiments, and any person skilled in the art will appreciate that the present invention can be embodied in the form of a program for carrying out the method of the present invention, while the above disclosure is directed to equivalent embodiments capable of being modified or altered in some ways, it is apparent that any modifications, equivalent variations and alterations made to the above embodiments according to the technical principles of the present invention fall within the scope of the present invention.