Ordered nanostructure membrane electrode and preparation method thereof

A nanostructure, membrane electrode technology, applied in the direction of nanotechnology, nanotechnology, battery electrodes, etc., can solve the problems of low power density, low catalyst utilization rate, low electrochemical reaction activity of methanol, etc., and achieve the effect of improving catalytic activity

Active Publication Date: 2016-11-23

上海氢锐科技有限公司

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AI-Extracted Technical Summary

Problems solved by technology

[0003] However, the current passive DMFC still faces some technical difficulties in practical application: (1) Methanol permeates through the diaphragm, which reduces the fuel utilization rate and battery operating voltage; (2) The electrochemical reaction activity of methanol is not high, that is, the utilization of the catalyst (3) ...

Method used

The direct methanol fuel cell assembly of the ordered platinum nanowire electrocatalyst electrode gained of the present embodiment gained and the fuel cell that the Nafion115 membrane of the prior art forms are tested, as shown in Figure 5, be that catalyst loading is 2.0mg ·cm-2, 1.5mg·cm-2, 1.0mg·cm-2 and 0.5mg·cm-2 performance test spectrum, it can be known from the spec...

Abstract

The invention provides an ordered nanostructure membrane electrode and a preparation method thereof. The method comprises the steps of coating of a micropore layer, preparation of a binder, bonding of a porous template and a substrate, preparation of a mixed electroplating solution, preparation of a nano array, post-treatment of a product and lamination of a membrane electrode assembly. The core technology of the preparation method is preparation of an ordered nano array catalyst electrode; a nano-structure containing platinum or a platinum alloy is deposited in a porous template mainly through a template method electrodeposition path; and the porous template and the binder are removed to obtain the one-dimensional ordered nano array catalyst electrode which directly grows on the micropore layer, thereby obtaining the membrane electrode through lamination. The ordered nanostructure can be applied to the membrane electrode assembly without a transfer printing or pressing method. A novel porous electrode structure is provided; the preparation technology of the membrane electrode assembly is innovated; the catalytic activity of the electrode and the utilization rate of a noble metal are greatly improved; and the battery performance can be further greatly improved by applying the ordered nanostructure membrane electrode to a fuel cell.

Application Domain

Material nanotechnologyCell electrodes +1

Technology Topic

AlloyNanostructure +13

Image

Examples

Experimental program(4)

Example Embodiment

[0051] Such as figure 1 As shown, the present invention provides a method for preparing an ordered nanostructured membrane electrode applied to a fuel cell. The preparation method of the ordered nanostructured membrane electrode at least includes the following steps:

[0052] S1, providing a substrate and a porous template, the substrate comprising carbon paper and an electrode microporous layer coated on the carbon paper;

[0053] S2, preparing an adhesive, and bonding the porous template and the electrode microporous layer through the adhesive;

[0054] S3, preparing a mixed electroplating solution, and preparing a nano-array on the surface of the electrode microporous layer by electrodeposition;

[0055] S4, post-treatment of the deposited product, including removing the porous template and the binder, thereby preparing an ordered nano-array catalytic electrode;

[0056] S5, using the ordered nano-array catalytic electrode as a cathode and/or an anode, placing a proton exchange membrane between the cathode and the anode and forming a membrane electrode by hot pressing.

[0057] The method for preparing the ordered nanostructured membrane electrode of the present invention will be described in detail below.

[0058] First, step S1 is performed: providing a substrate and a porous template. The substrate includes carbon paper and an electrode microporous layer coated on the carbon paper.

[0059] The specific process of coating the microporous layer of the electrode is: mixing carbon powder, polytetrafluoroethylene (Polytetrafluoro Ethylene, PTFE) solution, and isopropanol (Iso-Propyl Alcohol, IPA) aqueous solution, and then sonicating it for 30 to 150 minutes. Coating on carbon paper with a mass fraction of 0~40% PTFE, the loading capacity is 0~2.0mg·cm -2 The carbon powder mixed with the PTFE solution and the IPA aqueous solution is sintered at a temperature of 100 to 500° C. for 10 to 60 minutes to obtain the electrode microporous layer.

[0060] The carbon powder may be a carbon nanotube material, a carbon fiber material or a carbon microsphere material. Of course, the carbon powder may also be other suitable carbon materials, which is not limited here.

[0061] The porous template is an anodic aluminum oxide template, a titanium dioxide nanotube template, or a polycarbonate porous template. Of course, the porous template may also be other suitable porous materials, which is not limited here.

[0062] Then, step S2 is performed: an adhesive is prepared, and the porous template is bonded to the electrode microporous layer through the adhesive.

[0063] The specific method of configuring the binder is: mixing Polyvinylidene Fluoride (PVDF) and N-Methyl Pyrrolidone (NMP) and magnetically stirring at 20~80℃ for 1~10h. A PVDF solution with a mass fraction of 2% to 15% is used as a binder.

[0064] The specific method for bonding the porous template and the substrate is: 2.0~15.0mg·cm -2 The PVDF solution is coated on the electrode microporous layer, and then a porous template with a double through hole diameter of 50-400 nm is bonded on the electrode microporous layer and left to stand for 0-30 minutes.

[0065] Then, step S3 is performed: preparing a mixed electroplating solution, and preparing a nano-array on the surface of the electrode microporous layer by electrodeposition.

[0066] The preparation method of the mixed electroplating solution is as follows: the platinum precursor or the platinum precursor and the noble metal compound are mixed with the acid solution and the lead salt to prepare the mixed electroplating solution, and then stand for 0-24 hours. Wherein, the platinum precursor can be one or a mixture of sodium chloroplatinate and chloroplatinic acid, and the noble metal compound can be palladium chloride, nickel chloride, chromium chloride, nickel nitrate, chromium nitrate Or ruthenium trichloride, the acid solution can be perchloric acid or dilute sulfuric acid, and the lead salt can be lead acetate or lead nitrate. In this embodiment, the concentration of the platinum precursor in the mixed electroplating solution is 1-10 mM, the concentration of the noble metal compound is 1-10 mM, the acid concentration is 0.01-0.2 M, and the lead salt concentration is 0.02 ~0.4mM.

[0067] The method of electrodeposition in this step is as follows: first, the bonded substrate and the porous template, and the electroplating solution are loaded into the deposition device; then, the carbon paper is used as the working electrode, and the microporous layer side Direct contact with the electroplating solution, platinum wire as the counter electrode, saturated calomel electrode as the reference electrode, and cyclic voltammetry for electrodeposition; the electrodeposition voltage is set to -1.0~0V, and the electrodeposition time is set to 1000~15000s Electrodeposition is carried out under the protection of nitrogen; after the electrodeposition is completed, the deposition device is disassembled, and the electrode microporous layer deposited with platinum or platinum alloy nano-array is allowed to stand for 4-24 hours. The morphology and size of the platinum or platinum alloy nanoarray can be adjusted by the deposition time and the concentration of the mixed electroplating solution, and the platinum or platinum alloy nanoarray finally obtained can be nanowires or nanotubes.

[0068] It should be noted that the nanoarray grown by electrodeposition is grown on the surface of the electrode microporous layer, and the nanoarray passes through the double through holes of the porous template.

[0069] Then, step S4: post-processing of the deposited product is performed; including removing the porous template and the binder, so as to prepare an ordered nano-array catalytic electrode.

[0070] The specific process is: the nanoarray prepared by electrodeposition is dissolved to remove the porous template. For example, if the porous template is an alkaline or amphoteric template such as anodized aluminum oxide template or titanium dioxide nanotube template, use the concentration setting 1.0-3.0M lye to dissolve the porous template; if the porous template is a polycarbonate porous template, use carbon tetrachloride, chloroform or tetrahydrofuran solvent to dissolve the porous template, and then use water, Alternate washing with ethanol for several times, and vacuum drying at a temperature of 30-100° C., to obtain the ordered nano-array catalytic electrode. The ordered nano-array catalytic electrode is used as a cathode and/or anode in a membrane electrode of a direct methanol fuel cell.

[0071] Finally, step S5 is performed: using the ordered nano-array catalytic electrode as the cathode and/or anode, placing a proton exchange membrane between the cathode and the anode and forming a membrane electrode by hot pressing.

[0072] A layer of Nafion resin is attached to the surface of the ordered nano-array electrode by spraying or scraping, and after drying treatment, under the conditions of 130℃ and 3-6MPa, hot-pressing to form a "triad of cathode, anode and proton exchange membrane" One" membrane electrode assembly.

[0073] The present invention also provides an ordered nanostructured membrane electrode, which is prepared by the above preparation method. The structure of the membrane electrode includes: a cathode, an anode, and protons formed between the cathode and the anode by hot pressing. Exchange membrane. Wherein, the cathode and the anode may both be the ordered nano-array catalytic electrode prepared by the present invention, or only the anode or the cathode may be the ordered nano-array catalytic electrode prepared by the present invention.

[0074] The ordered nano-array catalytic electrode at least includes: a substrate including carbon paper and an electrode microporous layer coated on the carbon paper; and a nano-array deposited on the surface of the electrode microporous layer.

Example Embodiment

[0075] Example one

[0076] This embodiment provides a method for preparing an ordered platinum nanowire film electrode, which includes the following steps:

[0077] Weigh 20.0mg of carbon nanotubes, 40.4mg of 12.39% polytetrafluoroethylene (PTFE) solution, and 200mg of isopropyl alcohol (IPA) aqueous solution (IPA: H 2 O=1:1), and ultrasonic 120min after mixing; use a spatula to smear 2.0mg·cm on carbon paper containing 20% PTFE -2 Carbon nanotubes; then sintered at 350°C for 30 minutes to obtain a cathode microporous layer.

[0078] Weigh polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) to prepare a mixed solution with a mass fraction of PVDF of 8.14%; magnetically stirred at 25° C. for 8 hours to obtain a PVDF solution as a binder.

[0079] Pipette about 50.0mg of PVDF solution on the cathode microporous layer and use a spatula to make the PVDF solution about 32.0mg coated on the microporous layer, and then apply a porous anodic aluminum oxide template (AAO template) with a double-pass pore size of 200nm. Bonding on the cathode microporous layer and standing for 10 minutes, waiting for the cathode microporous layer to bond with the AAO template.

[0080] 1.0g chloroplatinic acid hexahydrate (H 2 PtCl 6 ·6H 2 O) Pour into a 50ml volumetric flask and add water to the graduation line, then use a pipette to measure 25.896ml to a 100ml volumetric flask; then measure 0.847ml perchloric acid to a 100ml volumetric flask; then weigh 7.6mg lead acetate to a 100ml volumetric flask, Mix to prepare electroplating solution and let stand for 12h.

[0081] Put the bonded substrate and the AAO template into the deposition device, take 25ml of the electroplating solution after standing still and pour into the deposition device; use the carbon paper as the working electrode, and the microporous layer side directly Liquid contact, platinum wire as counter electrode, saturated calomel electrode as reference electrode; set the deposition voltage range -0.5~0V, deposition time 10000s; use cyclic voltammetry for electrodeposition under nitrogen protection; remove after electrodeposition Turn on the device, and let the cathode microporous carbon paper deposited with platinum nanowires stand for 12 hours.

[0082] Use 2.0M NaOH solution to remove the AAO template on the carbon paper of the cathode microporous layer deposited with platinum nanowires, then use NMP to remove the PVDF binder, and then alternately wash with water and ethanol for several times, and at a temperature of 75°C Dry under vacuum to obtain platinum nanowire electrocatalyst electrode.

[0083] The platinum nanowire electrocatalyst obtained in this example was characterized, such as figure 2 As shown, the X-ray diffraction pattern (XRD pattern) of the electrode microporous layer and the platinum nanowire electrocatalyst is obtained, and the entire diffraction area is scanned at an angle of 2θ as the abscissa of the X-ray diffraction spectrum; the diffraction angles (2θ) are different The intensity of the diffraction peak is taken as the ordinate. Such as image 3 The electron scanning image (SEM image) of the platinum nanowire electrocatalyst of this embodiment is shown, and the diameter of the platinum nanowire electrocatalyst can be measured from the electronic scanning imaging system to be about 200 nm. Such as Figure 4 Shown is the transmission electron microscope image (TEM image) of the platinum nanowire electrocatalyst of this embodiment. The length of the platinum nanowire electrocatalyst can be measured from the transmission electron microscope system to be 3 to 5 μm.

[0084] The platinum nanowire catalytic electrode of this embodiment is compared with a commercial Pt black (Johnson Matthey) catalyst, and the ordered platinum nanowire catalytic electrode obtained in this embodiment is used in the cathode catalyst layer to obtain a direct methanol fuel cell assembly; The existing technology Nafion115 membrane composes the fuel cell:

[0085] (1) Anode support layer: carbon paper TGPH060, waterproof material with a mass fraction of 20% (Toray); anode microporous layer: carbon powder Vulcan XC-72R (1.0mg·cm -2 ) (Cabot Company) and PTFE (Dupont Company) with a mass fraction of 20%; anode catalyst layer: Pt-Ru/C (4.0mg·cm -2 ), a perfluorosulfonic acid-polytetrafluoroethylene copolymer (Nafion) solution (Dupont) with a mass fraction of 5.03%.

[0086] (2) Cathode support layer: carbon paper TGPH060, a waterproof material with a mass fraction of 20%; cathode microporous layer: carbon nanotubes (2mg·cm -2 ) And PTFE with a mass fraction of 12.89%; the cathode catalytic layer of this embodiment: the platinum nanowires of this embodiment and a Nafion solution with a mass fraction of 5.03%; the cathode catalytic layer of the prior art: platinum nanoparticles with a mass fraction of 5.03% Nafion solution.

[0087] (3) Nafion 115 membrane (Dupont company).

[0088] The Pt-Ru/C in the anode catalyst layer is all from Johnson Matthey Company (abbreviated as JM Company); the Pt/C in the cathode catalyst layer is all from JM Company.

[0089] The direct methanol fuel cell assembly obtained from the ordered platinum nanowire electrocatalyst electrode obtained in this example and the fuel cell composed of Nafion 115 membrane in the prior art were tested, such as Figure 5 The catalyst loading shown is 2.0 mg cm -2 , 1.5mg·cm -2 , 1.0mg·cm -2 And 0.5mg·cm -2 The performance test chart at the time. From the chart, it can be seen that the prepared membrane electrode assembly is used for performance testing on a direct methanol fuel cell, and a direct methanol fuel cell using the ordered platinum nanowire catalytic electrode obtained in this example The power density is high, and its performance is better than that of direct methanol fuel cells using commercial catalysts (JM).

Example Embodiment

[0090] Example two

[0091] This embodiment provides a method for preparing an ordered platinum nanotube film electrode, including the following steps:

[0092] Weigh 60.0 mg carbon nanotubes, 179.2 mg PTFE solution with a mass fraction of 8.37%, and 600 mg IPA aqueous solution (IPA: H 2 O=1:1), and ultrasonic 120min after mixing; use a spatula to smear 2.0mg·cm on carbon paper containing 20% PTFE -2 Carbon nanotubes; then sintered at 350°C for 30 minutes to obtain a cathode microporous layer.

[0093] Weigh PVDF and NMP to prepare a mixed solution with a mass fraction of PVDF of 5.28%; magnetically stir at 25°C for 8 hours to obtain a PVDF solution as a binder.

[0094] Take about 50mg of PVDF solution and apply it on the cathode microporous layer and use a spatula to make the PVDF solution about 32mg coated on the microporous layer, and then bond the AAO template with a double-pass aperture of 200nm to the cathode microporous layer Put it on and stand for 10 minutes, and wait for the cathode microporous layer to bond with the AAO template.

[0095] 1.0g H 2 PtCl 6 ·6H 2 Pour O into a 50ml volumetric flask and add water to the graduation line, then use a pipette to measure 7.769ml to a 100ml volumetric flask; then measure 0.254ml perchloric acid into a 100ml volumetric flask; then weigh 2.3mg of lead acetate into a 100ml volumetric flask and mix Prepare the electroplating solution and let it stand for 12h.

[0096] Load the bonded substrate and the AAO template into the deposition device, take 25ml of the electroplating solution after standing still, and pour it into the deposition device; use the carbon paper as the working electrode, and the microporous layer is directly connected to the electroplating Liquid contact, platinum wire as counter electrode, saturated calomel electrode as reference electrode; set the deposition voltage range -0.5~0V, deposition time 10000s; use cyclic voltammetry for electrodeposition under nitrogen protection; remove after electrodeposition The device was turned on and the cathode microporous carbon paper deposited with platinum nanotubes was allowed to stand for 12 hours.

[0097] Use 2.0M NaOH solution to remove the AAO template on the carbon paper of the cathode microporous layer deposited with platinum nanotubes, then use NMP to remove the PVDF binder, and then alternately wash with water and ethanol for several times, and at a temperature of 75°C Dry under vacuum to obtain platinum nanotube electrocatalyst electrode.

[0098] The platinum nanowire electrocatalyst obtained in this example was characterized, such as Image 6 The electron scanning image (SEM image) of the platinum nanowire electrocatalyst of this embodiment is shown, and the diameter of the platinum nanowire electrocatalyst can be measured from the electronic scanning imaging system to be about 200 nm.

PUM

Property	Measurement	Unit
Diameter	200.0	nm

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