CN110931808A

CN110931808A - Pd-WO3Anode electrocatalyst of/C proton exchange membrane fuel cell and its preparing method and use

Info

Publication number: CN110931808A
Application number: CN201911094669.0A
Authority: CN
Inventors: 崔香枝; 施剑林; 黄为民
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2019-11-11
Filing date: 2019-11-11
Publication date: 2020-03-27

Abstract

The invention relates to Pd-WO₃a/C proton exchange membrane fuel cell anode electrocatalyst, a preparation method and application thereof, and the Pd-WO₃the/C proton exchange membrane fuel cell anode electrocatalyst comprises: carbon black substrate, and Pd nanocrystal particle and WO supported on carbon black substrate₃Nanocrystals of said WO₃The content of the nano-crystalline grains is 15-30 wt%, and the loading capacity of the Pd nano-crystalline grains is 2-8 wt%.

Description

Pd-WO3Anode electrocatalyst of/C proton exchange membrane fuel cell and its preparing method and use

Technical Field

The invention relates to an electro-oxidation catalyst for anode hydrogen of a proton exchange membrane fuel cell, in particular to Pd and WO₃An anode electrocatalyst co-loaded with carbon black and a preparation method thereof.

Background

Proton Exchange Membrane Fuel Cells (PEMFCs) have the characteristics of low-temperature quick start, high specific power, high specific energy and the like, and are considered as one of the first clean and efficient power generation technologies in the 21 st century. On the one hand, the catalyst of the PEMFCs which is commercialized at present uses the precious metal Pt, and the amount of the precious metal Pt is 20-40 wt%, and the high cost and limited storage amount of Pt make the popularization and application of the PEMFCs difficult. On the other hand, the anode fuel source of PEMFCs is mainly reformed hydrogen such as hydrogen produced by coal chemical industry, and contains a certain amount of CO, and CO molecules are very easily adsorbed on the surface of the Pt catalyst and cover active sites, so that poisoning of the Pt catalyst is caused, which affects the performance and life of the pem fuel cell, and thus, it is still difficult to commercialize PEMFCs comprehensively. Therefore, the research of a non-Pt anode catalyst material system with high activity, low cost and CO poisoning resistance is an important problem which needs to be solved urgently in promoting the popularization and application of the PEMFCs.

WO₃Has special electrochemical catalytic performance, and can form a hydrogen-tungsten bronze type compound H with hydrogen in an acid environment_xWO₃The catalyst has good proton conductivity, and can reduce the adsorption of CO on the catalyst and improve the CO poisoning resistance of the catalyst. However, WO₃Poor conductivity and few active sites are an important reason for limiting the use of the catalyst as an anode catalyst. Chinese patent 1 (publication No. CN109745969A) discloses a carbon-supported ultra-small-size (about 3 nm) noble metal nanoparticle catalyst and a preparation method thereof, namely adding activated carbon, platinum nitrate or palladium nitrate into water and ethanol to form suspension, adopting rapid atomization drying to prepare a solid powdery precursor, and calcining the obtained solid powdery precursor in a reducing atmosphere (hydrogen and argon) at the temperature of 300-650 ℃ to obtain a material with ultra-small-size noble metal supported on the surface of the activated carbon. In the preparation method, the mass ratio of the noble metal (Pd or Pt) to the commercial activated carbon is (0.5-5): 100, but it is only a preparation method of a precious metal catalyst, and does not relate to the use of PEMFCs anode or cathode catalysts, and even to the invention of the CO resistance of PEMFCs anodes. Chinese patent 2 (publication No. CN 101615677A) discloses an electrocatalyst for a fuel cell membrane electrode, a preparation method thereof and a fuel cell membrane electrode, namely a water-retaining substance (such as WO)₃) The organic precursor is dissolved in a volatile organic solvent (B)Alcohol), then adding the pretreated carbon carrier, stirring at room temperature, vacuum drying at 40-70 ℃, and heat treating with inert gas at 200-600 ℃ to obtain the carbon carrier deposited with water-retaining substances, namely the composite carrier; and then the noble metal Pt is subjected to post-treatment and deposited on the composite carrier. The water-retaining substance of the invention (WO)₃) Is 0.3-10 wt%, the noble metal is Pt and the content of Pt is as high as 10-60 wt%. The high-content noble metal Pt is difficult to popularize and apply to the proton exchange membrane fuel cell in the world environment with limited resource reserves of the existing noble metals such as Pt and the like. Chinese patent No. 3 (publication No. CN103657648A) discloses a fuel cell electrocatalyst Pt/WO₃The preparation method of the/C is to use mesoporous SiO₂Synthesis of mesoporous WO as template₃Then the mesoporous WO is added₃And carbon black (XC-72R) into a non-aqueous solvent to obtain a mixed carrier WO by physical mixing₃C, loading Pt particles to the mixed WO by a method of ethylene glycol reduction₃In a/C carrier. WO obtained by physical mixing method in the invention₃in/C support, mesoporous WO₃Easily segregated and separated from the carbon black, so that the Pt catalyst cannot be uniformly distributed in the WO₃The interface of/C, against WO₃The function of the cocatalyst is exerted; meanwhile, the noble metal in the invention is Pt and the content thereof reaches 10-30 wt%, WO₃The proportion of the Pt is only 0.1-1% of that of the Pt, and the use amount of the high Pt in the catalyst is not beneficial to the Pt/WO of the composite material₃And C, popularization and application in the PEMFCs.

Disclosure of Invention

In order to overcome the defects that the existing Pt-based hydrogen anode catalyst is high in price and not suitable for large-scale commercial application, the invention provides a WO capable of serving as a PEMFCs anode catalyst₃Carbon matrix composite catalyst co-modified with Pd nanoparticles (i.e., Pd-WO)₃a/C proton exchange membrane fuel cell anode electrocatalyst) and a method of making the same.

In one aspect, the invention provides a Pd-WO₃a/C proton exchange membrane fuel cell anode electrocatalyst, said Pd-WO₃the/C proton exchange membrane fuel cell anode electrocatalyst comprises: carbon black baseBase and WO supported on carbon black substrate₃Nanocrystals and Pd nanocrystals, WO₃The content of the nano-crystalline grains is 15-30 wt%, and the loading capacity of the Pd nano-crystalline grains is 2-8 wt%.

In the present disclosure, Pd and WO₃Nanoparticles (nanocrystals) are commonly supported on a carbon black substrate (conductive carbon substrate), and in Pd-WO₃In the case of/C electrocatalysts, WO₃The nano-particles are formed in situ on the conductive carbon matrix, and the Pd nano-particles are loaded on WO₃on/C, the active sites in the Pd nano particles are convenient to expose; WO₃And the Pd nano-particles are uniformly distributed and are well crystallized. Wherein a conductive carbon black substrate is used as a conductive matrix to enhance WO₃And noble metals Pd and WO are simultaneously introduced₃Pd and WO are used as active sites₃And the conductive carbon black three-phase interface to improve the catalytic activity of the active sites, thereby constructing the electro-catalyst material for non-Pt anode hydrogen oxidation.

Preferably, said WO₃The size of the nano crystal grain is 4-8 nm, and the size of the Pd nano crystal grain is 2-6 nm.

Preferably, the carbon black substrate is one of conductive carbon black, acetylene black, carbon nanotubes and graphene.

In another aspect, the present invention provides a Pd-WO as described above₃The preparation method of the/C proton exchange membrane fuel cell anode electrocatalyst comprises the following steps:

(1) dissolving a tungsten source precursor into a mixed solution of alcohol and water to prepare a tungsten salt precursor solution;

(2) adding a conductive carbon black substrate material into the obtained tungsten salt precursor solution, reacting for 12-48 hours at room temperature (15-35 ℃), heating to 60-100 ℃ until the solvent is evaporated to dryness, and obtaining a mixture of a tungsten source precursor and carbon black;

(3) carrying out heat treatment on the obtained mixture of the tungsten source precursor and the carbon black for 1-5 hours at 300-600 ℃ in a protective atmosphere to obtain WO₃@ C composite material;

(4) subjecting the obtained WO₃Adding the @ C composite material into a palladium salt solution, uniformly mixing, and addingHeating to 40-60 ℃ until the solvent is evaporated to dryness to obtain palladium salt and WO₃Mixtures of @ C;

(5) mixing the obtained palladium salt with WO₃The mixture of @ C being placed in a reducing atmosphere, e.g. H₂/Ar(5vol.％H₂) Or H₂/Ar(7vol.％H₂) Carrying out thermal reduction at 150-300 ℃ to obtain the Pd-WO₃an/C proton exchange membrane fuel cell anode electrocatalyst.

Preferably, the tungsten source precursor is selected from at least one of tungstic acid, phosphotungstic acid, ammonium tungstate and sodium tungstate; the volume ratio of the alcohol to the water in the mixed liquid of the alcohol and the water is 1: (0.5-2), wherein the alcohol is at least one of ethanol, isopropanol and n-butanol; the conductive carbon black substrate material is at least one selected from conductive carbon black, acetylene black, carbon nanotubes and graphene.

Preferably, in the step (3), the protective atmosphere is a nitrogen atmosphere or an argon atmosphere; the time of the heat treatment is 1-3 hours.

Preferably, in the step (4), the solute of the palladium salt solution is at least one selected from palladium nitrate, palladium chloride, chloropalladic acid and sodium chloropalladate.

Preferably, in the step (5), the reducing atmosphere is a hydrogen/argon mixed gas containing 5% of hydrogen; the thermal reduction time is 1-4 hours.

Preferably, in the step (2) or the step (4), stirring is simultaneously carried out in the process of drying by distillation; the stirring mode is manual stirring or magnetic stirring, and the rotating speed of the magnetic stirring is 200-400 revolutions per minute.

In a further aspect, the present invention provides a Pd-WO as described above₃The application of the/C proton exchange membrane fuel cell anode electrocatalyst in a proton exchange membrane fuel cell.

Has the advantages that:

(1) the invention prepares a non-Pt WO₃Based on PEMFCs Anode electrocatalysts, Pd and WO₃A composite material co-supported on a conductive carbon black substrate;

(2) the invention adopts liquid phase adsorption and low temperature heat treatment technology to mix Pd and WO₃Nanoparticle co-supported carbon blackOn the basis, the method is simple and easy to implement, the preparation conditions are mild, and energy is saved;

(3) in the present invention, Pd-WO obtained₃In the/C composite, Pd and WO₃The nano particles are uniformly distributed, and the composite material shows good hydrogen electrooxidation catalytic activity and CO resistance under the synergistic catalytic action of the nano particles and the nano particles;

(4) Pd-WO prepared by the invention₃When the/C composite material is used as an anode catalyst, the output power density of the battery reaches 350mW/cm²。

Drawings

FIG. 1 shows Pd-WO prepared by the present invention₃XRD pattern of the/C composite material, wherein ① corresponds to 2.5Pd-WO₃Diffraction pattern of/C, ② corresponds to 5Pd-WO₃Diffraction pattern of/C, ③ corresponds to 7.5Pd-WO₃Diffraction pattern of/C, ④ corresponds to 10Pd-WO₃A diffraction pattern of/C;

FIG. 2 shows Pd-WO prepared by the present invention₃SEM photograph (scale 500nm) of the/C composite, where A) and A1) correspond to 2.5Pd-WO prepared in example 1₃C, B) and B1) correspond to the 5Pd-WO prepared in example 2₃C, C) and C1) correspond to the 7.5Pd-WO prepared in example 3₃C, D) and D1) correspond to the 10Pd-WO prepared in example 5₃/C；

FIG. 3 shows 7.5Pd-WO prepared in example 3 of the present invention₃SEM pictures (A), elemental mapping (A1, A2, A3, A4) and Transmission Electron Microscope (TEM) pictures (B and C) of the/C composite;

FIG. 4 shows Pd-WO prepared in example 3 of the present invention₃the/C composite (A) and commercial catalyst 20 wt% Pt/C (B) were at 0.5M H₂SO₄H in solution at 1 vol.% CO₂The scanning speed of the electrochemical CV curve is 50mV s^-1；

FIG. 5 shows Pd-WO prepared by the present invention₃A cell voltage-current density relationship curve (A) and a cell output power density-current density relationship curve (B) when the/C composite material is used as an anode catalyst; wherein, the anode of the battery is Pd-WO₃C loading: 3mg/cm ²20 wt% Pt on cathodeC loading capacity: 0.4mg/cm²(ii) a The working temperature is 25 ℃ at room temperature; the anode hydrogen flow is 100sccm, and the cathode oxygen flow is 150 sccm;

FIG. 6 is a TEM photograph of the sample prepared in comparative example 1-2, in which (A) corresponds to WO in comparative example 1₃C, (B) corresponds to 2.5Pd/C in comparative example 2;

FIG. 7 is a graph of cell performance at room temperature for samples prepared in comparative examples 1-2, where (A) corresponds to WO in comparative example 1₃The cell performance at the anode was represented by/C, and (B) corresponds to the cell performance at the anode of 2.5Pd/C in comparative example 2.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

In this disclosure, Pd-WO₃In the/C composite material, Pd nanoparticles and WO₃The nano particles are loaded on the carbon black substrate together, and the particles are dispersed uniformly. Among them, WO₃The weight percentage of the nano-crystalline grains can be 15-30 wt%. The weight percentage of the Pd nano crystal particles can be 2-8 wt%. If Pd is not added, WO is obtained₃The battery of the/C composite material at room temperature is low; if WO is not added₃The performance of the obtained 2.5Pd/C composite material at the same cell test temperature (room temperature) is lower than that of 2.5Pd-WO with the same Pd content₃of/C, description WO₃The catalyst is beneficial to improving the electro-oxidation catalytic activity of Pd on hydrogen, and a synergistic catalytic effect exists between the Pd and the hydrogen.

In an alternative embodiment, WO₃The size of the nanoparticles can be 4-8 nm. The nanoparticles of Pd may have a size of 2-6 nm. The selected conductive carbon black substrate material (carbon black substrate for short) can be one of conductive carbon black, acetylene black, carbon nano tube and graphene.

In one embodiment of the present invention, the Pd-WO₃The preparation process of the/C composite material is mild, and the WO is prepared by adopting a liquid phase reaction and low temperature reduction method₃Pd nano particles are sequentially loaded on the carbon substrate, so that the Pd nano crystal particles are exposed on the outer surface and are easier to combine with hydrogen molecules to promoteReacting Pd and WO₃The occurrence of inter-synergistic effects. The method has mild preparation conditions and is easy to operate. Pd-WO is exemplified below₃/C proton exchange membrane fuel cell anode electrocatalyst (i.e. Pd-WO)₃a/C composite material).

And dissolving the tungsten source precursor into a mixed solution of alcohol and water to prepare a tungsten source precursor solution. The tungsten source precursor can be tungsten salt, and the obtained tungsten source precursor solution can also be called tungsten salt precursor solution. The tungsten source precursor may preferably be tungstic acid, phosphotungstic acid, ammonium tungstate, sodium tungstate, and the like. The volume ratio of alcohol to water in the mixed solution of alcohol and water may be 1: (0.5 to 2), preferably 1: 2. The alcohol is isopropanol, ethanol, n-butanol, etc., preferably ethanol. The content of the tungsten source precursor in the obtained tungsten source precursor solution can be 10-60 wt%.

Adding a carbon black substrate material (such as conductive carbon black, acetylene black, carbon nano tubes, graphene and the like) into the tungsten source precursor solution, uniformly stirring at room temperature (15-35 ℃), and then continuously stirring for a certain time to perform reaction. For example, the stirring reaction is continued for 12 to 48 hours, so that the tungsten source precursor sufficiently interacts with the functional groups on the surface of the carbon substrate to be adsorbed onto the conductive carbon black substrate. Then stirring under the heating condition, evaporating the solvents such as ethanol and the like to obtain the mixture of the tungsten source precursor and the carbon black. Wherein the heating temperature can be 60-100 deg.C to evaporate the mixed solution of alcohol and water. Preferably, during the evaporation of the solvent, manual stirring or magnetic stirring is performed to further promote the evaporation of the solvent. The rotation speed of the magnetic stirring can be 200-400 r/min.

Placing the mixture of the tungsten source precursor and the carbon black in a protective atmosphere for heat treatment to obtain WO₃@ C composite material. Wherein the protective atmosphere can be nitrogen or argon atmosphere. The temperature of the heat treatment may be 300-600 ℃. The time of the heat treatment can be 1-3 h.

Preparing palladium salt solution. The palladium salt is dissolved in acid such as hydrochloric acid, and is uniformly mixed to obtain palladium salt solution (or acid solution of palladium salt). The palladium salt can be palladium nitrate, palladium chloride, chloropalladic acid, sodium chloropalladate and the like. The concentration of the obtained palladium salt solution is 5-20 wt%.

Adding WO to palladium salt solution₃The @ C composite material is evenly stirred and the solvent is volatilized under the heating condition to obtain the palladium salt and the WO₃Mixtures of @ C. Wherein the heating condition is heating to 40-60 deg.C. Preferably, during the evaporation of the solvent, manual stirring or magnetic stirring is performed to further promote the evaporation of the solvent. The magnetic stirring speed can be 200-400 rpm.

Mixing palladium salt and WO₃After the mixture of @ C is placed in a reducing atmosphere for thermal reduction, Pd-WO is obtained₃a/C composite material. Wherein the reducing atmosphere may be a hydrogen/argon mixture containing 5vol.% or 7vol.% hydrogen. The temperature of the thermal reduction may be 150-300 ℃. The time for thermal reduction may be 1-4 h.

In one embodiment of the present invention, the Pd-WO mentioned above₃the/C electrocatalyst is used as an anode catalyst of a proton exchange membrane fuel cell. Due to Pd crystal grains and WO₃The synergistic catalytic mechanism among the nano particles ensures that the current density of the proton exchange membrane fuel cell prepared by the composite material can reach 900mA/cm at room temperature when the dosage of Pd is less²The power output of the battery is 340mW/cm²And has good CO poisoning resistance, greatly reduces the cost of the electrode catalyst, and has higher economic benefit.

The present invention will be described in further detail with reference to examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art in light of the foregoing description are intended to be included within the scope of the invention. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.

Example 1

(1) Firstly, 0.25g of ammonium metatungstate is dissolved in a mixed solution of 20 ml of ethanol and 40 ml of water, and the mixture is magnetically stirred uniformly to obtain a tungsten salt precursor solution;

(2) weighing 1.0g of conductive carbon black, adding the conductive carbon black into the tungsten salt precursor solution, magnetically stirring uniformly, continuously reacting for 40 hours, and then placing the mixture at 60 ℃ for magnetic stirring to slowly evaporate the solvent to obtain a mixture of tungsten salt and carbon powder;

(3) placing the mixture of tungsten salt and carbon powder in an atmosphere furnace at 350 ℃, and carrying out heat treatment for 3h under the nitrogen protection atmosphere to obtain WO₃a/C composite material;

(4) an acid solution containing 10 wt% of palladium nitrate was prepared. 0.05g of WO was taken₃Dispersing the/C into 20 ml of ethanol, adding 30 mu L of palladium nitrate solution after uniform dispersion, stirring for 6 hours by magnetic force, and then continuously stirring at 50 ℃ to slowly volatilize the solvent to obtain powder;

(5) the resulting powder was then placed in an atmosphere furnace under a reducing atmosphere (5% H)₂Ar) heat treated at 200 ℃ for 2h to give 2.5 wt% Pd-20 wt% WO₃Catalyst for the electrocatalysts described as 2.5Pd-WO₃/C。

The obtained 2.5Pd-WO₃In the/C electrocatalyst, tungsten oxide exhibited a good crystalline state, as shown in the XRD pattern (line ①) of FIG. 1, and no characteristic diffraction peak of Pd was observed because of the small amount of Pd, as seen from SEM photographs of A and A-1 of FIG. 2, Pd and WO₃The particles are in a particle state, but local agglomeration of Pd particles is generated; the cell performance at room temperature is shown in FIG. 5A (black line), and the maximum current density of the cell is 600mA/cm²At this time, the maximum battery is 120mW/cm²(indicated by the black line B in FIG. 5).

Example 2

(1) The preparation of the tungsten salt precursor solution was the same as in example 1;

(2) weighing 1.0g of conductive carbon black, adding the conductive carbon black into the tungsten salt precursor solution, uniformly stirring by magnetic force, continuously reacting for 48 hours, and then placing the mixture at 60 ℃ for magnetic stirring to slowly evaporate the solvent to obtain a mixture of tungsten salt and carbon powder;

(3) placing the mixture of tungsten salt and carbon powder in an atmosphere furnace at 400 ℃, and carrying out heat treatment for 2h under the nitrogen protection atmosphere to obtain WO₃a/C composite material;

(4) take 0.1g of WO₃Dispersing the mixture in 40 ml of ethanol, adding 200 mu l of palladium nitrate solution (5 wt%) after uniform dispersion, and carrying out magnetic fieldStirring for 6h, and stirring at 50 deg.C to slowly volatilize solvent to obtain powder;

(5) the resulting powder was then placed in an atmosphere furnace under a reducing atmosphere (5% H)₂Ar) heat treatment at 200 ℃ for 2h to obtain 5 wt% Pd-20 wt% WO₃Catalyst for the electrocatalysts, denoted 5Pd-WO₃/C。

The obtained 5Pd-WO was found to have a XRD pattern (line ②) as shown in FIG. 1₃The tungsten oxide in the/C electrocatalyst has good crystallization, and no characteristic diffraction peak of Pd is observed, which indicates that the Pd nano particles are uniformly dispersed and do not gather; SEM photographs in B and B-1 in FIG. 2 further show that granular Pd and WO₃No obvious particle aggregation is generated; when the anode catalyst is used, the maximum current density of the battery at room temperature is 900mA/cm²As shown by A (red line) in FIG. 5, the corresponding maximum cell output power density was 200mW/cm²(indicated by the B red line in FIG. 5).

Example 3

WO prepared in example 1₃Adding 10 wt% of palladium nitrate solution into ethanol suspension with uniformly dispersed/C electrocatalyst, magnetically stirring for 6 hr, stirring at 50 deg.C to slowly volatilize solvent, placing the obtained powder in an atmosphere furnace, and reducing in reducing atmosphere (5% H)₂Ar) was heat-treated at 200 ℃ for 2 hours to give 7.5 wt% Pd-20 wt% WO₃Catalyst for the catalyst, 7.5Pd-WO₃/C。

The 7.5Pd-WO₃The XRD pattern of/C is shown by line ③ in FIG. 1, not only the crystallization of tungsten oxide is good, but also the weak characteristic diffraction peak of Pd is observed preliminarily, and the Pd nano-particles are dispersed uniformly as shown by SEM photographs in C and C-1 in FIG. 2. from the element mapping in FIG. 3, the element C, O, W, Pd is dispersed more uniformly, the size of Pd nano-particles is 3-5nm as shown by TEM photographs in B and C in FIG. 3. the 7.5Pd-WO₃the/C shows obvious hydrogen desorption oxidation peak in the acid electrolyte, as shown in figure 4A, and when CO-containing hydrogen is introduced, no obvious change is found in the hydrogen oxidation peak current after 100 cycles, which indicates that the CO-containing hydrogen has good CO resistance. In contrast, 20 wt% P, which is commercially available under the same conditionsthe current peak at t/C is significantly reduced, i.e., Pt "poisons" CO, and thus the electrocatalytic activity gradually decays.

Example 4

WO prepared in example 2₃Adding palladium nitrate solution (5 wt%) into ethanol suspension with uniformly dispersed/C electrocatalyst, magnetically stirring for 6 hr, stirring at 50 deg.C to slowly volatilize solvent, placing the obtained powder in an atmosphere furnace, and reducing in reducing atmosphere (5% H)₂Ar) was heat-treated at 200 ℃ for 2 hours to give 7.5 wt% Pd-20 wt% WO₃Catalyst for the catalyst, 7.5Pd-WO₃/C。

To obtain 7.5Pd-WO₃The cell performance of the assembled MEA when the/C electrocatalyst is used as the anode catalyst and 20 wt% Pt/C is used as the cathode catalyst is shown as A (green line) in FIG. 5, and the maximum current density of the cell can reach 950mA/cm at room temperature²At this time, the maximum battery output power is 340mW/cm²(indicated by the green line B in FIG. 5).

Example 5

WO prepared in example 2₃the/C electrocatalyst is described in WO₃Adding palladium nitrate solution (20 wt%) into ethanol suspension with uniformly dispersed C to 60 μ L, magnetically stirring for 6 hr, further stirring at 50 deg.C to slowly volatilize solvent, placing the obtained powder in an atmosphere furnace, and reducing in reducing atmosphere (5% H)₂Ar) heat treatment at 200 ℃ for 2h to obtain 10 wt% Pd-20 wt% WO₃Catalyst for the electrocatalyst, 10Pd-WO₃/C。

The obtained 10Pd-WO₃In the/C complex, WO₃The phase of (A) remains substantially unchanged, but the diffraction peaks of Pd are gradually enhanced, as shown by the XRD pattern line ④ in figure 1 WO₃And Pd still retained the particle shape, but aggregation began to occur, as shown in FIGS. 2D and D-1. The calcination time of the composite was changed, and the composite was calcined in a muffle furnace at 550 ℃ for 7h, and the other operations were the same as in example 4. The 10Pd-WO₃The cell performance of the MEA assembled with the/C electrocatalyst as anode catalyst and 20 wt% Pt/C as cathode catalyst is shown in FIG. 5A (blue line), and the maximum current density of the cell can reach 600mA/cm at room temperature²At this time, the maximum battery output power is 180mW/cm²(shown by B blue line in FIG. 5), but in contrast to 7.5Pd-WO₃the/C is the difference of the anode, indicating that the preferred Pd incorporation is 7.5 wt%.

Comparative example 1

Preparation of Pd-free WO₃material/C, the process is as in example 1:

(3) placing the mixture of tungsten salt and carbon powder in an atmosphere furnace at 350 ℃, and carrying out heat treatment for 3h under the nitrogen protection atmosphere to obtain WO₃a/C composite material, in the form of WO₃/C。

Obtained WO₃in/C, WO₃The particles were uniformly dispersed on the carbon substrate (shown in fig. 6A), but the cell performance of the assembled MEA when it was used as an anode catalyst was as shown in fig. 7A, and the maximum current density of the cell at room temperature was only 130mA/cm²At this time, the maximum battery output power is 50mW/cm²Description of WO₃WO in C₃The electrocatalytic activity sites for hydrogen oxidation are weak.

Comparative example 2

Preparation of WO-free₃2.5 wt% Pd/C material, the process was the same as example 1:

(1) dispersing 0.05g of carbon powder into a mixed solution of 20 ml of ethanol and 40 ml of water, adding 30 mu l of palladium nitrate solution (10 wt%) after uniform dispersion, magnetically stirring for 6h, and then continuously stirring at 50 ℃ to slowly volatilize the solvent to obtain powder;

(2) the resulting powder was then placed in an atmosphere furnace under a reducing atmosphere (5% H)₂/Ar) was heat treated at 200 ℃ for 2h to give a 2.5 wt% Pd/C composite, noted as 2.5 Pd/C.

In the obtained 2.5Pd/C, Pd nano-crystalline grains are more uniformly dispersed in the carbon baseOn the body (shown in fig. 6B); the cell performance of the MEA assembled with the 2.5Pd/C as the anode catalyst is shown in FIG. 7B, and the maximum current density of the cell at room temperature is 300mA/cm²At this time, the maximum battery output power is 90mW/cm²Comparison of the same Pd content in 2.5Pd-WO₃Low of/C, description WO₃The method is favorable for improving the catalytic activity of Pd on hydrogen by electrooxidation.

Claims

1. Pd-WO₃the/C proton exchange membrane fuel cell anode electrocatalyst is characterized in that the Pd-WO₃the/C proton exchange membrane fuel cell anode electrocatalyst comprises: carbon black substrate, and Pd nanocrystal particle and WO supported on carbon black substrate₃Nanocrystals of said WO₃The content of the nano-crystalline grains is 15-30 wt%, and the loading capacity of the Pd nano-crystalline grains is 2-8 wt%.

2. Pd-WO according to claim 1₃a/C proton exchange membrane fuel cell anode electrocatalyst, characterized in, that said WO₃The size of the nano crystal grain is 4-8 nm, and the size of the Pd nano crystal grain is 2-6 nm.

3. Pd-WO according to claim 1₃the/C proton exchange membrane fuel cell anode electrocatalyst is characterized in that the carbon black substrate is one of conductive carbon black, acetylene black, carbon nano tubes and graphene.

4. Pd-WO as in any one of claims 1 to 3₃The preparation method of the/C proton exchange membrane fuel cell anode electrocatalyst is characterized by comprising the following steps:

(2) adding a conductive carbon black substrate material into the obtained tungsten salt precursor solution, reacting at room temperature for 12-48 hours, and heating to 60-100 ℃ until the solvent is evaporated to dryness to obtain a mixture of a tungsten source precursor and carbon black;

(3) subjecting the obtained product toCarrying out heat treatment on the mixture of the tungsten source precursor and the carbon black at 300-600 ℃ in a protective atmosphere to obtain WO₃@ C composite material;

(4) subjecting the obtained WO₃Adding the @ C composite material into a palladium salt solution, heating to 40-60 ℃ until the solvent is evaporated to dryness to obtain palladium salt and WO₃Mixtures of @ C;

(5) mixing the obtained palladium salt with WO₃Putting the mixture of @ C in a reducing atmosphere, and carrying out thermal reduction at 150-300 ℃ to obtain the Pd-WO₃an/C proton exchange membrane fuel cell anode electrocatalyst.

5. The production method according to claim 4, wherein the tungsten source precursor is selected from at least one of tungstic acid, phosphotungstic acid, ammonium tungstate, and sodium tungstate; the volume ratio of the alcohol to the water in the mixed liquid of the alcohol and the water is 1: (0.5-2), wherein the alcohol is at least one of ethanol, isopropanol and n-butanol; the conductive carbon black substrate material is at least one selected from conductive carbon black, acetylene black, carbon nanotubes and graphene.

6. The production method according to claim 4 or 5, wherein in the step (3), the protective atmosphere is a nitrogen atmosphere or an argon atmosphere; the time of the heat treatment is 1-3 hours.

7. The production method according to any one of claims 4 to 6, wherein in the step (4), the solute of the palladium salt solution is at least one selected from palladium nitrate, palladium chloride, chloropalladic acid, and sodium chloropalladate.

8. The production method according to any one of claims 4 to 7, wherein in the step (5), the reducing atmosphere is a hydrogen/argon mixed gas containing 5vol.% or 7vol.% of hydrogen gas; the thermal reduction time is 1-4 hours.

9. The production method according to any one of claims 4 to 8, wherein in step (2) or step (4), stirring is simultaneously performed during the evaporation to dryness; the stirring mode is manual stirring or magnetic stirring, and the rotating speed of the magnetic stirring is 200-400 revolutions per minute.

10. Pd-WO as set forth in any one of claims 1 to 3₃The application of the/C proton exchange membrane fuel cell anode electrocatalyst in a proton exchange membrane fuel cell.