CN102569829B - Metal catalyst composition modified by nitrogen-containing compound and membrane electrode assembly thereof - Google Patents

Abstract

The invention relates to a metal catalyst composition modified with a nitrogen-containing compound and a membrane electrode assembly. The catalyst composition can be applied to the electrode surface and includes a metal catalyst and a nitrogen-containing compound, wherein the nitrogen-containing compound is a A substituted or unsubstituted five-membered nitrogen-containing heterocyclic ring, and at least one of the cathode catalyst layer and the anode catalyst layer of the membrane electrode assembly is composed of the catalyst composition containing the nitrogen-containing compound of the present invention. When the metal catalyst composition is used as a cathode catalyst, it can effectively reduce the poisoning phenomenon. When it is used as an anode catalyst, it has the effect of reducing the reaction overpotential. In addition, after the metal catalyst of the present invention is combined with a nitrogen-containing compound, its steric hindrance increases, thereby improving the dispersion of catalyst particles and thereby increasing reaction activity.

Description

Metal catalyst composition modified by nitrogen-containing compound and membrane electrode group thereof

technical field

The invention relates to a catalyst and a membrane electrode group, in particular to a metal catalyst and a membrane electrode group applied to a fuel cell.

Background technique

Due to the demand for clean energy, fuel cells have been mass-produced and used in different fields such as industry, housing, and transportation. Direct methanol fuel cell (DMFC), also known as micro fuel cell. Direct Methanol Fuel Cells convert methanol gas into electricity, providing portable power that enables laptops or other handheld electronic devices to last longer.

Generally speaking, in a direct methanol fuel cell device, if methanol penetrates into the cathode, it will cause the poisoning of the cathode catalyst. At the same time, the direct methanol fuel cell has the problem of anode over-potential, which leads to a decrease in discharge voltage and a decline in activity, especially It is more significant when using high concentration methanol as fuel.

Contents of the invention

The invention relates to a metal catalyst modified by a nitrogen-containing compound, which utilizes the lone pair (lone pair) of nitrogen in the nitrogen-containing compound to coordinate with the d orbital domain of the metal catalyst, occupying the position where the metal catalyst combines with carbon monoxide (CO), And effectively disperse the catalyst, thereby increasing the electrochemical surface area (Electochemical SurFace Active Area, ECSA) of the catalyst, so as a cathode catalyst, it can prevent the catalyst from being poisoned, and as an anode catalyst, it has the effect of reducing its reaction overpotential. In addition, after the metal catalyst is combined with nitrogen-containing compounds, its steric hindrance increases, thereby improving the dispersion of catalyst particles and increasing the reactivity.

The second object of the present invention is to provide a membrane electrode group applicable to fuel cells, which uses the nitrogen-containing compound-modified metal catalyst of the present invention as an electrode catalyst, thereby preventing the catalyst from being poisoned and reducing the reaction rate. Potential and the effect of increasing reactivity

In order to achieve the above object, the present invention adopts the following technical solutions.

A catalyst composition that can be applied to the surface of an electrode. The catalyst composition includes a metal catalyst and a nitrogen-containing compound, wherein the nitrogen-containing compound is a five-membered nitrogen-containing heterocyclic ring with substituents or no substituents.

Further, the nitrogen-containing compound is an unsaturated five-membered nitrogen-containing heterocycle with or without substituents.

Further, the nitrogen-containing compound has a chemical structure represented by the following general formula (I):

Among them, R ₁ -R ₅ are independently hydrogen, alkyl, NH ₂ or NR ₆ R ₇ , R ₆ and R ₇ are independently alkyl, hydroxyl or alkoxy, and X ₁ , X ₂ , X ₃ , X ₄ and X ₅ are independently carbon or nitrogen, and at least one of X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ is nitrogen.

Further, the nitrogen-containing compound has a chemical structure represented by the following general formula (II):

Among them, S ₁ -S ₇ are independently hydrogen, alkyl, NH ₂ or NS ₈ S ₉ , S ₈ and S ₉ are independently alkyl, hydroxyl or alkoxy, and Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ independently represent carbon or nitrogen, and at least one of Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ is nitrogen.

Further, the nitrogen-containing compound is selected from the following group including pyrrole, pyrroline, imidazole, imidazoline and triazole compounds and their derivatives.

Further, the nitrogen-containing compound is N-methylpyrrole, 1,2,3-triazole, 1,2,4-triazole, 2-methyl-2-imidazoline or 2,4-dimethyl- 2-imidazoline.

Further, the metal catalyst is a pure metal catalyst or a metal catalyst with a carrier.

Further, the weight ratio of the metal catalyst to the nitrogen-containing compound ranges from about 1:5 to 10:1.

A membrane electrode group applicable to fuel cells, comprising: a polymer membrane with proton conductivity; a cathode catalyst layer and an anode catalyst layer respectively located on both sides of the polymer membrane; and respectively located on the cathode catalyst layer and two gas diffusion layers on the anode catalyst layer, wherein at least one of the cathode catalyst layer and the anode catalyst layer is composed of a catalyst composition comprising a metal catalyst and a nitrogen-containing compound, the nitrogen-containing compound being A five-membered nitrogen-containing heterocyclic ring with or without substituents.

Further, the nitrogen-containing compound applicable to the membrane electrode assembly of the fuel cell in the present invention is an unsaturated five-membered nitrogen-containing heterocyclic ring with or without substituents.

Further, the nitrogen-containing compound applicable to the membrane electrode assembly of the fuel cell in the present invention has a chemical structure represented by the following general formula (I):

Among them, R ₁ -R ₅ are independently hydrogen, alkyl, NH ₂ or NR ₆ R ₇ , R ₆ and R ₇ are independently alkyl, hydroxyl or alkoxy, and X ₁ , X ₂ , X ₃ , X ₄ and X ₅ are independently carbon or nitrogen, and at least one of X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ is nitrogen.

Further, the nitrogen-containing compound applicable to the membrane electrode assembly of the fuel cell in the present invention has a chemical structure represented by the following general formula (II):

Among them, S ₁ -S ₇ are independently hydrogen, alkyl, NH ₂ or NS ₈ S ₉ , S ₈ and S ₉ are independently alkyl, hydroxyl or alkoxy, and Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ independently represent carbon or nitrogen, and at least one of Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ is nitrogen.

Further, the nitrogen-containing compound applicable to the membrane electrode assembly of the fuel cell in the present invention is selected from the following group including pyrrole, pyrroline, imidazole, imidazoline and triazole compounds and their derivatives.

Further, the nitrogen-containing compound applicable to the membrane electrode assembly of the fuel cell in the present invention is N-methylpyrrole, 1,2,3-triazole, 1,2,4-triazole, 2-methyl- 2-imidazoline or 2,4-bismethyl-2-imidazoline.

Further, the metal catalyst applicable to the membrane electrode assembly of the fuel cell in the present invention is a pure metal catalyst or a supported metal catalyst.

Further, the weight ratio of the metal catalyst to the nitrogen-containing compound applicable to the membrane electrode assembly of the fuel cell in the present invention is in the range of about 1:2 to 25:1.

It can be seen that the present invention provides a catalyst composition that can be applied to the surface of an electrode, which includes a metal catalyst and a nitrogen-containing compound, wherein the nitrogen-containing compound is a five-membered nitrogen-containing heterocycle, and the nitrogen-containing compound is a Unsaturated five-membered nitrogen-containing heterocycle with or without substituents.

Further, the nitrogen-containing compound has a chemical structure represented by the following general formula (I):

Among them, R ₁ -R ₅ are independently hydrogen, alkyl, NH ₂ or NR ₆ R ₇ , R ₆ and R ₇ are independently alkyl, hydroxyl or alkoxy, and X ₁ , X ₂ , X ₃ , X ₄ and X ₅ are independently carbon or nitrogen, and at least one of X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ is nitrogen.

Further, the nitrogen-containing compound has a chemical structure represented by the following general formula (II):

Among them, S ₁ -S ₇ are independently hydrogen, alkyl, NH ₂ or NS ₈ S ₉ , S ₈ and S ₉ are independently alkyl, hydroxyl or alkoxy, and Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ may independently represent carbon or nitrogen, and at least one of Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ is nitrogen.

The present invention also provides a membrane electrode assembly applicable to fuel cells, which includes a polymer membrane with proton conductivity, a cathode catalyst layer and an anode catalyst layer respectively located on both sides of the polymer membrane, and The cathode catalyst layer and the two gas diffusion layers on the anode catalyst layer. Wherein, at least one of the cathode catalyst layer and the anode catalyst layer is composed of a catalyst composition including a metal catalyst and a nitrogen-containing compound, and the nitrogen-containing compound is a five-membered nitrogen-containing heterocyclic ring.

Further, the nitrogen-containing compound has a chemical structure represented by the following general formula (I):

Among them, R ₁ -R ₅ are independently hydrogen, alkyl, NH ₂ or NR ₆ R ₇ , R ₆ and R ₇ are independently alkyl, hydroxyl or alkoxy, and X ₁ , X ₂ , X ₃ , X ₄ and X ₅ are independently carbon or nitrogen, and at least one of X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ is nitrogen.

Further, the nitrogen-containing compound has a chemical structure represented by the following general formula (II):

Among them, S ₁ -S ₇ are independently hydrogen, alkyl, NH ₂ or NS ₈ S ₉ , S ₈ and S ₉ are independently alkyl, hydroxyl or alkoxy, and Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ may independently represent carbon or nitrogen, and at least one of Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ is nitrogen.

Further, the nitrogen-containing compound may be selected from the following group including pyrrole, pyrroline, imidazole, imidazoline, triazole compounds and derivatives thereof. The metal catalyst can be a pure metal catalyst or a metal catalyst with a carrier. The weight ratio of the metal catalyst to the nitrogen-containing compound ranges from about 1:2 to 25:1.

In order to make the technical features and advantages of the present invention more comprehensible, the following will describe in detail with examples and accompanying drawings.

Description of drawings

Fig. 1 is a schematic structural view of a fuel cell membrane electrode assembly of the present invention.

Fig. 2 is a schematic diagram of the relationship between the oxidation peak current of the platinum/carbon cathode and the potential of the present invention.

Fig. 3 is a schematic diagram of the relationship between the current and the potential measured by cyclic voltammetry for the platinum/carbon cathode of the present invention.

4(a)-4(b) are schematic diagrams showing the relationship between the current and the potential obtained in the first and twentieth cycles of the oxygen reduction reaction test of the platinum/carbon cathode of the present invention.

Detailed ways

The invention relates to a metal catalyst modified by a nitrogen-containing compound. The lone pair (lone pair) of nitrogen in the nitrogen-containing compound is used to coordinate with the d orbital of the metal catalyst to occupy the position where the metal catalyst combines with carbon monoxide (CO) to prevent Or reduce the possibility of catalyst being poisoned.

In addition, after the metal catalyst is combined with nitrogen-containing compounds, its steric hindrance increases, which can improve the dispersion effect of catalyst particles, reduce the activity loss caused by aggregation, and improve the reaction activity. In addition, the nitrogen-containing compound-modified metal catalyst of the present invention can also reduce its overpotential when used as an anode.

The invention relates to a novel metal catalyst composition modified by a nitrogen-containing compound, which comprises a metal catalyst and at least one nitrogen-containing compound. The weight ratio range of the metal catalyst active part (without carrier) to the nitrogen-containing compound of the aforementioned metal catalyst composition is between about 1: 2 to about 25: 1; the preferred weight ratio of the metal catalyst active part to the nitrogen-containing compound The range is between about 4:1 to about 8:1.

The "metal catalyst" of the present invention includes various metal catalysts commonly used in fuel cells, and its scope includes pure metal catalysts or metal catalysts with supports. Pure metal catalyst materials such as: platinum (Pt), platinum-ruthenium (Ru), platinum-cobalt (Co), platinum-rhodium (Rh), platinum-tin (Sn), platinum-nickel (Ni), platinum-gold (Au) combined or alloyed with the aforementioned materials; the aforementioned are only common materials, but the metal catalyst material of the present invention is not limited to the aforementioned materials. The catalyst carrier can be a carbon carrier, including carbon black, carbon nanotubes, porous carbon materials, sea urchin-shaped carbon materials, and the like. The change and adjustment of the above-mentioned metal catalyst materials should be understood by the inventors in the field, and it is also within the scope of protection of the present invention.

Among them, the nitrogen-containing compound of the present invention is a substituted or unsubstituted five-membered nitrogen-containing heterocyclic compound. The nitrogen-containing compound can be a five-membered aromatic ring compound or a non-aromatic, five-membered heterocyclic compound.

The nitrogen-containing compound can be represented by the following general formula (I):

Among them, R ₁ -R ₅ are independently hydrogen, alkyl, amino (NH ₂ ) or tertiary amino (NR ₆ R ₇ ), R ₆ and R ₇ are independently alkyl, hydroxyl, alkoxy or other derivatives electron group, and X ₁ , X ₂ , X ₃ , X ₄ and X ₅ are independently carbon or nitrogen, and at least one of X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ is nitrogen.

Alternatively, the nitrogen-containing compound can be represented by the following general formula (II):

Among them, S ₁ -S ₇ are independently hydrogen, alkyl, amino (NH ₂ ) or tertiary amino (NS ₈ S ₉ ), and S ₈ and S ₉ are independently alkyl, hydroxyl, alkoxy or other derived groups. electron group, and Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ can independently represent carbon or nitrogen, and at least one of Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ is nitrogen.

For example, the above five-membered nitrogen-containing heterocyclic compounds generally include pyrrole, pyrroline, imidazole, imidazoline, and triazole compounds and their derivatives. For example: N-methylpyrrole (N-methylpyrrole), alkyl imidazole (alkyl imidazole) series, 1,2,3-triazole (1,2,3-triazole), 1,2,4-triazole ( 1,2,4-triazole), 2-methyl-2-imidazoline (2-methyl-2-imidazoline), 2-phenyl-imidazoline (2-phenyl-2-imidazoline) or 2,4-bismethyl Base-2-imidazoline (2,4-dimethyl-2-imidazoline), etc.

Common catalyst preparation methods include colloid method (Colloid method), microemulsion method (Microemulsion method) and impregnation method (Impregnation method).

Taking the carbon black carrier catalyst as an example, the colloid method needs to be operated in a dry nitrogen environment, using anhydrous solvents and anhydrous metal salts, first adding the metal salts to the solvent and stirring to dissolve. Then slowly drop the reducing agent into the metal salt solution. When the solution turns black or hydrogen gas is generated, it means that the reduction is complete and a stable and dispersed colloidal solution is formed. After stirring for a period of time, add carbon black as a catalyst carrier and stir for a while. After a period of time, the solvent was removed, washed with ethanol and dried to obtain the alloy catalyst. The particle size of the catalyst prepared by this method is small, about 1.5nm-3nm, and the dispersion is good. The impregnation method is the most common and simple method. First, the metal salts are dissolved in a solvent, then carbon black is added for impregnation and stirring, and then a reducing agent is added for reduction. According to different preparation conditions, the dispersibility and particle size of the obtained catalyst are also different, and the particle size is about 2-20nm.

In addition to being applied to fuel cells, the novel catalyst of the present invention can also be widely used in different fields, such as air batteries and other electrochemical cells.

Generally speaking, the basic components of a fuel cell include electrodes, separation/exchange membranes, and current collectors. Electrodes are where the electrochemical reactions of fuel oxidation and oxidant reduction occur, and can be divided into anodes and The cathode (Cathode) has two parts, the membrane separates the oxidant and the reductant and conducts protons at the same time.

For a direct methanol fuel cell, when the methanol fuel is decomposed into hydrogen ions (protons) and electrons by the catalyst at the anode, the current is generated by the flow of electrons, and the hydrogen ions pass through the proton exchange membrane and the oxygen and electrons from the cathode. The electrons of the circuit combine to produce water and heat. The electrodes of the direct methanol fuel cell are presented in the structure of membrane electrode group.

Fig. 1 is a schematic diagram of the structure of a fuel cell membrane electrode assembly. As shown in Figure 1, the membrane electrode group 10 is a polymer proton exchange membrane (abbreviated as an exchange membrane; PEM) with the separator/polymer membrane 100 in the middle, and the separator/polymer membrane 100 uses a solid polymer electrolytic material such as: nano Nafion ion polymer membrane is used to transmit protons and must block the passage of electrons and gases. The outer sides of the proton exchange membrane 100 are catalyst reaction layers 110 , including an anode catalyst layer 110A and a cathode catalyst layer 110C, where the electrochemical reactions of the anode and cathode are carried out respectively. The outer sides of the catalyst reaction layer 110 (the anode catalyst layer 110A and the cathode catalyst layer 110C) are gas diffusion layers 120 . The anode catalyst material is, for example, platinum (Pt)/ruthenium (Ru)/carbon powder, and the cathode catalyst material is, for example, platinum/carbon (Pt/C). According to an embodiment of the present invention, the electrode (cathode or anode) preparation material can also be Pt/C, PtRu/C, PtRu or Pt.

When preparing an electrode catalyst according to an embodiment of the present invention, the electrode catalyst material includes a metal salt and a carbon carrier (such as carbon black), a perfluorocarbon sulfonic acid (perfluorocarbon sulfonic acid) solution, and an alcohol/water mixture And the nitrogen-containing compound of the present invention is dispersed and mixed under ultrasonic vibration and stirring to prepare catalyst slurry. The catalyst slurry is coated on the gas diffusion layer with a doctor blade to form a so-called gas diffusion electrode, which is dried in vacuum for use in subsequent processes. Next, the gas diffusion electrode (cathode/anode) obtained above is thermocompressively bonded to the proton exchange membrane according to the sequence of anode-proton exchange membrane-cathode to complete the preparation of the membrane electrode assembly.

In the following experiments, a battery electrode (anode or cathode) prepared with the novel metal catalyst modified with the nitrogen-containing compound of the present invention was compared with an electrode prepared with the unmodified metal catalyst.

The experimental method used is briefly described below. The measurement methods used in the following experiments, including the electrochemical active area (Electrochemical SurFace Active Area, ECSA), methanol oxidation reaction (Methanol Oxidation Reaction, MOR), and oxygen reduction reaction (Oxygen Reduction Reaction, ORR), are the catalyst slurry The material is placed on the surface of the glassy carbon (GC) disc of the Rotation Disc Electrode (RDE), and measured after drying. The preparation method of the electrode for measurement is as follows:

Prepare the required amount of solvent, Nafion solution and metal catalyst according to the weight specified in the ratio table, after stirring, dispersing and defoaming, drop the sample slurry on the surface of the rotating disk electrode glassy carbon disc (RDE GCdisc), 60 °C for 2 hours in vacuum.

[Measurement of ECSA (Electochemical SurFace Active Area)]

Electrolyte (0.5M sulfuric acid) was continuously fed with nitrogen gas to maintain anaerobic state, the measurement environment was at room temperature, and electrochemical cycle potential scanning (Cyclic Voltammetry; CV) was performed, and the scanning setting conditions were as follows:

Scan rate (Scan rate): 5mV/s

Potential range: 1.0 to 0V vs. Reversible hydrogen electrode (RHE)

CV scans were performed at an electrode rotation speed of 0 rpm, and spectrogram data were recorded.

The spectrum judgment method is to compare the integrated area of the hydrogen absorption peak reduction current (scanning from high potential to low potential) value of the three platinum electrode surfaces at about 0.05 to 0.3V, which is proportional to ECSA.

[MOR (Methanol Oxidation Reaction) measurement]

The method is the same as the aforementioned ECSA measurement method, and the composition of the electrolyte is changed to 0.5M sulfuric acid + 1M methanol. The way to judge the spectrum is to compare the integrated area of the methanol oxidation current (scanning from low potential to high potential) value from 0.3V to 0.7V, which is proportional to the activity of the catalyst to oxidize methanol, and the onset potential is the initial potential of the oxidation peak , indicating the onset of methanol oxidation.

"ORR (Oxygen Reduction Reaction) measurement]

Electrolyte (0.5M sulfuric acid; 0.1M methanol should be mixed in when measuring the resistance to methanol), and oxygen was introduced for 30 minutes, and then the rotating electrode was placed, and oxygen was continuously introduced. The measurement environment was room temperature, and electrochemical cycle potential scanning was performed. (Cyclic Voltammetry; CV), the scan setting conditions are as follows:

Scan rate (Scan rate): 5mV/s

Potential range: 1.1 to 0.5V vs. RHE (hydrogen reference electrode)

CV scans were performed at an electrode rotation speed of 1600 rpm, and spectrogram data were recorded. The way to judge the spectrum is to compare the current value of 0.6V, which is inversely proportional to the reaction activity (the larger the negative value, the larger the reduction current). In addition, in the methanol tolerance test (Experiment 4), the peak value of the methanol oxidation peak at 0.6V to 0.8V is compared. The later the methanol oxidation peak appears, the less it reacts to methanol, that is, it is less likely to be poisoned, and there is oxidation. When the peak appears, compare its value, which is inversely proportional to the methanol tolerance (the larger the positive value, the larger the oxidation current, indicating that the catalyst activity is easily affected by methanol).

Experiment 1: Different nitrogen-containing compounds with PtRu/C as anode catalysts:

Carry out the so-called methanol oxidation reaction (Methanol Oxidation Reaction, MOR) activity analysis, electrolyte solution (0.5M sulfuric acid+1M methanol), and the metal catalyst uses the metal catalyst with carrier (its metal catalyst part accounts for 70wt%), and its 70wt% The metal catalyst part of PtRu/C: nitrogen-containing compound weight ratio = 1: 1.6. The control group was unmodified 70% PtRu/C, which contained no nitrogen-containing compounds.

Table 1

It can be seen from the data in Table 1 that compared with the control group, the metal catalyst modified with nitrogen-containing compounds has a lower overpotential (about 10-20mV lower), and the MOR oxidation peak current value is increased by about 1.5-2 times, thereby improving the activity. Therefore, when using different nitrogen-containing compounds to modify PtRu/C as an anode catalyst, the catalyst particles combined with nitrogen-containing compounds can reduce the overpotential of the anode and increase the activity of the anode catalyst. It can also be seen from Table 1 that among the nitrogen-containing compounds, five-membered heterocyclic compounds have better effect, while pyridine (pyridine) has a general effect.

Experiment 2: Different ratios of nitrogen-containing compounds (triazole) and PtRu/C as anode catalysts:

Carry out the so-called methanol oxidation reaction (MOR) activity analysis, electrolyte (0.5M sulfuric acid +1M methanol), and the metal catalyst uses the metal catalyst with support (its metal catalyst part accounts for 70wt%), and its 70wt% PtRu/C Metal catalyst part: nitrogen-containing compound weight ratio = 2.5:1 to 30:1.

Table 2

It can be seen from the data in Table 2 that, compared with the control group, the addition of nitrogen-containing compounds at a ratio of 2.5:1 to 30:1 has the effect of increasing the catalyst activity and reducing the anode overpotential, but the effect of adding a ratio of 10:1 is better.

Experiment 3: Different nitrogen-containing compounds and Pt/C as cathode catalyst (metal catalyst: nitrogen-containing compound (imidazoline) addition ratio = 4: 1):

Conduct activity test, oxygen reduction reaction test ORR—introduce oxygen into the acid solution, use cyclic voltammetry to scan 1.1 to 0.5V (with Reversible Hydrogen Electrode, RHE as the comparison standard), and compare its current density at the same potential (A /g), its value is directly proportional to the (oxygen reduction activity/electrochemical active area) of the catalyst; the electrochemical active area test ECSA-similar to ORR, but the solution does not pass into oxygen, and directly utilizes cyclic voltammetry to scan 1.0 to 0V (in the order of Reversible Hydrogen Electrode, RHE as a comparison standard), compare the current value of the active area of the integral hydrogen adsorbed on the surface of the catalyst, which is proportional to the active surface area of the catalyst, and the electrolyte is sulfuric acid. Referring to FIG. 2 and FIG. 3 , it can be found that the addition of nitrogen-containing compound (imidazole) significantly increases the activity of the cathode catalyst, its ECSA is increased by about 1 times, and its ORR current is increased by about 60% (at 0.6V).

Experiment 4: Different nitrogen-containing compounds and Pt/C are used as cathode catalysts (metal catalyst: nitrogen-containing compound (imidazole) addition ratio = 8: 1):

To test the anti-poisoning ability, add methanol solution (0.5M sulfuric acid + 0.1M methanol) to ORR, see Figure 4(a)-(b), it is found that the catalyst electrode with nitrogen-containing compounds will be poisoned later (that is, the anti-CO poisoning ability is lower High), it was observed that the methanol oxidation peak did not appear in the first cycle of ORR, until the twentieth cycle, the oxidation peak current of the nitrogen-containing compound electrode was still low (closer to zero), indicating that the addition of nitrogen-containing compounds did help Improve the anti-poisoning ability of the catalyst.

In this embodiment, the direct methanol fuel cell is used to represent the possible application range and mode of the nitrogen-containing compound described in the present invention, but the field or design of the actual application is not limited to the content described in the embodiment or experiment, and can be transferred to other relevant Fields, structures or products, and within the understanding of inventors in the field.

Claims (10)

1. A catalyst composition, which can be applied to the electrode surface, is characterized in that, the catalyst composition comprises a metal catalyst and a nitrogen-containing compound, to prevent or reduce the catalyst from being poisoned by carbon monoxide, and the nitrogen-containing compound is a substituent Or an unsaturated five-membered nitrogen-containing heterocyclic ring without substituents, the nitrogen-containing compound has a chemical structure represented by the following general formula (I): Among them, R ₁ -R ₅ are independently hydrogen, alkyl, NH ₂ or NR ₆ R ₇ , R ₆ and R ₇ are independently alkyl, hydroxyl or alkoxy, and X ₁ , X ₂ , X ₃ , X ₄ and X ₅ are independently carbon or nitrogen, and at least one of X ₁ , X ₂ , X ₃ , X ₄ , and X ₅ is nitrogen; Alternatively, the nitrogen-containing compound has a chemical structure represented by the following general formula (II): Among them, S ₁ -S ₇ are independently hydrogen, alkyl, NH ₂ or NS ₈ S ₉ , S ₈ and S ₉ are independently alkyl, hydroxyl or alkoxy, and Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ independently represent carbon or nitrogen, and at least one of Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ is nitrogen. 2. The catalyst composition as claimed in claim 1, wherein the nitrogen-containing compound is selected from the following group comprising pyrrole, pyrroline, imidazole, imidazoline and triazole compounds and their derivatives. 3. The catalyst composition as claimed in claim 2, characterized in that, the nitrogen-containing compound is N-methylpyrrole, 1,2,3-triazole, 1,2,4-triazole, 2 methyl- 2-imidazoline or 2,4-bismethyl-2-imidazoline. 4. The catalyst composition according to claim 1, characterized in that the metal catalyst is a pure metal catalyst or a metal catalyst with a support. 5. The catalyst composition as claimed in claim 1, wherein the weight ratio of the metal catalyst to the nitrogen-containing compound ranges from 1:2 to 25:1. 6. A membrane electrode group applicable to fuel cells, characterized in that it comprises: A polymer membrane with proton conductivity; a cathode catalyst layer and an anode catalyst layer respectively located on both sides of the polymer membrane; and two gas diffusion layers respectively located on the cathode catalyst layer and the anode catalyst layer, Wherein at least one of the cathode catalyst layer and the anode catalyst layer is composed of the catalyst composition as claimed in claim 1 . 7. The membrane electrode group applicable to fuel cells as claimed in claim 6, characterized in that the nitrogen-containing compound is selected from the group consisting of pyrrole, pyrroline, imidazole, imidazoline and triazole compounds and derivatives thereof of groups. 8. The membrane electrode group applicable to fuel cells as claimed in claim 7, characterized in that the nitrogen-containing compound is N-methylpyrrole, 1,2,3-triazole, 1,2,4-triazole , 2-methyl-2-imidazoline or 2,4-dimethyl-2-imidazoline. 9. The membrane electrode assembly applicable to fuel cells according to claim 6, characterized in that the metal catalyst is a pure metal catalyst or a metal catalyst with a carrier. 10 . The membrane electrode assembly applicable to fuel cells as claimed in claim 6 , wherein the weight ratio of the metal catalyst to the nitrogen-containing compound ranges from 1:2 to 25:1. 11 .