KR101808304B1 - Complex catalyst for oxygen reduction reaction comprising metal catalyst coated with zwiterionic molecules, and its preparation method - Google Patents

Abstract

The present invention provides an invention for enhancing the oxygen reduction activity of a Pt electrode in a phosphoric acid and a KOH solution by positively utilizing a direct electrostatic interaction between a metal nanoparticle having a charge and a counter ion having opposite charges. In particular, the present invention provides a catalyst capable of adsorbing L-cystine having an amphoteric property on the surface of Pt to improve oxygen reduction activity in both alkali and phosphoric acid solutions.

Description

TECHNICAL FIELD The present invention relates to a composite catalyst for an oxygen reduction reaction comprising a metal catalyst coated with an amphoteric ionic compound,

The present invention relates to a composite catalyst for an oxygen reduction reaction comprising a metal catalyst coated with an amphoteric ionic compound and a method for producing the same.

The development of nanotechnology has been accompanied by the development of molecular engineering. In particular, various types of organic molecules have been mainly applied to the synthesis of nanoparticles required for energy applications such as quantum dot, fuel cell, and lithium ion battery. For example, oleylamine, PVP, and CTAB are widely used to control nanoparticle size and structure. Thus, in solution-based synthesis, organic molecules play an important role in nanoparticle production. In recent years, small organic molecules have been applied directly to electrochemical surface modification as well as particle size and structure control in fuel cell catalyst designs. From the viewpoint of the electronic structure of the catalyst, the effects of the metal surface modification by the organic ligand on the catalytic activity in the oxygen reduction reaction and the formic acid oxidation reaction have been reported. During the synthesis of metal nanoparticles, the electronic structure of the metal surface has been altered by the electron-withdrawing or electron-donating power of functionalized organic ligands. In addition, it has been reported that Pt (111) surface modification by calix arene molecules can have selectivity in oxygen reduction reaction and hydrogen oxidation reaction. These unusual molecular patterns act as molecular sieves on the Pt surface and have important physical properties.

On the other hand, from the electrochemical point of view, the behavior of the bystander ions must be considered because of the interaction with the surface of the catalyst and the reactant present in the electrolyte. Particularly, in a phosphoric acid fuel cell using an alkaline fuel cell and a phosphoric acid solution using a KOH solution, hydroxyl ions and phosphate ions as toxic bumper ions cling strongly to the Pt surface, It has a fatal effect on the reduction reaction activity. In the KOH solution, the hydrated K ⁺ ions also stick to the Pt surface and interfere with the adsorption of oxygen. Therefore, degradation of the catalyst is slow due to the use of an alkali solution having a low acidity in an alkali fuel cell, and since a polymer membrane impregnated with a phosphoric acid solution is used in a phosphoric acid fuel cell, operation at a high temperature of 100 ° C or higher can be performed, Despite its advantages, it is difficult to produce an efficient catalyst without considering the electrochemical poisoning by the bystander ions.

In this regard, the Markovic group studied the effect of the bidentate ions on the electrochemical properties of the catalyst at the interface between phosphoric acid and KOH solution. The CN molecules adsorbed on the Pt (111) The results of this study are as follows. In the phosphoric acid solution, the CN molecules regularly patterned on the surface of the Pt interfere with the strong adsorption of the physically bulky phosphorus ions by the third-body effect, so that the Pt site for the oxygen reduction reaction can be produced. However, the function of such CN molecules has had a very negative effect on the alkali solution. The hydrated K + ions strongly interfere with the CN molecules with high electronegativity and blocked the active site of Pt. These results show that it is possible to control the behavior of the bystander ions in the electrolyte through the surface modification method using small molecules. However, this study was a defensive approach to avoid direct electrostatic interactions to increase the electrochemical activity of the catalyst. The CN molecules patterned on the Pt surface were physically able to block the phosphate ions, but were insufficient to prevent electrostatic interception by hydrated K + ions.

K. J. J. Mayrhofer, G. K. H. Wiberg, M. Arenz, J. Electrochem. Soc. 2008, 155, P1-P5. [3] S. L. Mayo, B. D. Olafson, and W. A. Goddard, J. Phys. Chem. 1990, 94, 8897-8909. A. D. Becke, J. Chem. Phys. 1993, 98, 5648-5652. C. Lee, W. Yang, R. G. Parr, Phys. Rev. B 1988, 37, 785-789. P. J. Hay, W. R. Wadt, J. Chem. Phys. 1985, 82, 299-310. Suite 2012: Jaguar version 7.9, S., LLC, New York, NY, 2012. H. Kim, J.-M. Choi, W. A. Goddard, J. Phys. Chem. Lett. 2012, 3, 360-363. G. Kresse, Phys. Rev. B 1996, 54, 11169-11186. M. Levitt, M. Hirshberg, R. Sharon, K. E. Laidig, V. Daggett, J. Phys. Chem. B 1997,101, 5051-5061. P. C. Hariharan, J. A. Pople, Theoret. Chim. Acta 1973,28, 213-222. J. Chandrasekhar, J. G. Andrade, R. v. R. Schleyer, J. Am. Chem. Soc. 1981, 103,5609-5612. T. Clark, J. Chandraaekhar, G. W. Spitznagel, P. v. R. Schleyer, J. Comput. Chem. 1983, 4, 294-301. D. Beblov, B. Roux, J. Chem. Phys. 1994, 100, 9050-9063. A. K. Rappe, W. A. Goddard, J. Phys. Chem. 1991,95, 3358-3363. S. Plimpton, J. Comput. Phys. 1995, 117, 1-19.

The present invention provides an invention for enhancing the oxygen reduction activity of a Pt electrode in a phosphoric acid and a KOH solution by positively utilizing a direct electrostatic interaction between a metal nanoparticle having a charge and a counter ion having opposite charges. In particular, the present invention provides a catalyst capable of adsorbing L-cystine having an amphoteric property on the surface of Pt to improve oxygen reduction activity in both alkali and phosphoric acid solutions.

One aspect of the present invention relates to a carbon support-supported composite catalyst comprising (a) a carbon support, (b) a metal catalyst supported on the carbon support, and (c) an amphoteric ion compound layer coated on the surface of the metal catalyst will be.

Another aspect of the present invention relates to an alkali or phosphoric acid fuel cell comprising a catalyst according to various embodiments of the present invention.

Another aspect of the present invention relates to (A) a method for manufacturing a carbon-supported supported catalyst, which comprises immersing a metal catalyst supported on a carbon support in an amphoteric ionic compound solution, mixing, washing and drying.

L-cystine is a functional molecule known for the production of self-assembled monolayer (SAM) on Au surfaces for bio-applications because of the strong interaction between -SH group and Au. In electrochemical applications, SAMs such as 3-mercaptopropionic acid with -COOH group, 4-mercaptopyridine with pyridine N atoms, and 4- (4-pyridyl) phenyl) methanethiol were used to determine the functional group (-) or (+) charge due to deprotonation and protonation. In the case of SAM made with L-cystine, it has also been confirmed that amphoteric ionic properties are exhibited by functional groups such as -COOH and -NH ₂ depending on the type of electrolyte (alkali or acidic solution). Therefore, L-cystine adsorbed on the Pt surface has two functional groups, which can be (-) or (+) charged in KOH and phosphate solution due to deprotonation and protonation.

In the KOH solution, L-cystine with (-) charge on the Pt surface can push off OH ^- ions that interfere with adsorption of oxygen molecules during the oxygen reduction reaction from the Pt surface. It also captures hydrated K + ions at the end of L-cystine with a length of about 5 Å and allows it to stay away from the Pt surface. In phosphate solution, it is difficult for phosphate ions to penetrate to the Pt surface by strong hydrogen bonding between (+) charge of L-cystine and -NH _{3 of} phosphoric acid molecule and L-cystine. Phosphate ions can also be located as far as the length of L-cystine, which is helpful for improving the oxygen reduction activity of Pt.

1 is 0.1 M KOH and 0.05 MH ₃ PO ₄ in treated non-supported Pt in the solution and on the surface of the polycrystalline L- cystine -decorated Pt polycrystalline (a, b) CVs and (c, d) ORR The polarization curve. A 130 μM L-cystine solution was used for L-cystine adsorption.
2A is a STEM and EDX mapping image for an L-cystine-decored Pt / C catalyst. In the EDX mapping image, the red, green, and blue dots represent Pt, sulfur, and carbon, respectively. The upper part of FIG. 2B is the Pt _4f core-level XPS spectrum of the L-cystine-decomposed and untreated Pt / C catalyst and the lower part is the S _2p core-level XPS spectrum of the L-cystine-deconated Pt nanoparticles. Figure 2 is a 0.1 M KOH and 0.05 MH ₃ PO ₄ in treated non-impregnated in the solution of the Pt / C and L- cysteine -decorated Pt / C (a, b) CVs and (c, d) ORR polarization curves. A 130 μM L-cysteine solution was used for the preparation of L-cystine-deconated Pt / C catalyst.
Figure 3 is a graph showing the results of a comparison between the untreated Pt / C catalyst supported on (a) 0.1 M HClO ₄ , (b) 0.1 M KOH, (c) 0.05 MH ₃ PO ₄ solution, and L-cystine- / C is the ORR polarization curve for the catalyst.

Hereinafter, various aspects and various embodiments of the present invention will be described in more detail.

One aspect of the present invention relates to a carbon support-supported composite catalyst comprising (a) a carbon support, (b) a metal catalyst supported on the carbon support, and (c) an amphoteric ion compound layer coated on the surface of the metal catalyst will be.

At this time, the amphoteric ionic compound is a compound containing a proton-withdrawing group, a donating functional group, and a metal catalytic functional group.

Also, the carbon support-supported composite catalyst is used for an oxygen reduction reaction in a basic or acidic solution.

According to one embodiment, the proton acceptor functional group is selected from a primary amine group, a secondary amine group, a tertiary amine group, an aldehyde group, and a ketone group. Also, the proton donating functional group is selected from a carboxyl group and a hydroxyl group. Also, the metal-catalyzed functional group is selected from a thiol group and a carbene group. The metal-catalyzed functional groups allow the amphoteric ionic compound to bind to the metal catalyst through strong interaction with the metal catalyst.

According to another embodiment, the proton acceptor functional group is an amine group, the proton donating functional group is a carboxyl group, and the metal catalyst bonding functional group is a thiol group.

According to another embodiment, the metal catalyst may be at least one selected from the group consisting of Pt, Pd, PtM alloys (M = transition metal elements such as Ni, Co, Fe, Cu, Pd), PdM alloys (M = Element). Further, the amphoteric ionic compound is one selected from L-cystine, homocysteine, and L-methionine.

According to another embodiment, the metal catalyst is Pt and the amphoteric ionic compound is L-cystine.

According to another embodiment, the EDX mapping analysis using Cs-STEM and the S atom line scanning analysis of the STEM show that the amphoteric ion compound is not adsorbed on the carbon support but adsorbed only on the metal catalyst, Is provided.

According to another embodiment, the amphoteric ionic compound forms a self assembled monolayer (SAM) on the surface of the metal catalyst.

According to another embodiment, the XPS analysis shows that the XPS peak of the metal catalyst coated with the amphoteric ion compound is shifted in the direction of high energy compared with the XPS peak of the metal catalyst not coated with the amphoteric ion compound layer, A support-supported composite catalyst is provided. The migration is carried out when the metal ion is Pt, the Pt _4f peak is moved in an energy direction of 0.2 to 0.5 eV, preferably 0.3 to 0.4 eV, most preferably about 0.35 eV.

According to another embodiment, a S _2p XPS spectrum analysis provides a carbon support-supported composite catalyst wherein a peak is observed at 163.5 eV.

According to another embodiment, the electrochemical surface area (ESA) of the metal catalyst is reduced by 0.1 to 20% by the amphoteric ionic compound. As shown in FIGS. 2C and 2D, the composite catalyst coated with the amphoteric ion compound exhibited higher activity in the oxygen reduction reaction than the catalyst without the amphoteric ion compound coating, but the electrochemical surface area reduction of the metal catalyst As shown in FIG. 3, when the amount of the catalyst is less than 0.1%, the effect is not exhibited at all. When the amount of the catalyst is more than 20%, the activity of the reduction reaction is significantly lower than that of the catalyst without the amphoteric compound .

Another aspect of the present invention relates to a fuel cell comprising a catalyst according to various embodiments of the present invention. The fuel cell is an alkaline fuel cell or a phosphoric acid fuel cell.

Another aspect of the present invention relates to (A) a method for manufacturing a carbon-supported supported catalyst, which comprises immersing a metal catalyst supported on a carbon support in an amphoteric ionic compound solution, mixing, washing and drying.

According to one aspect, the metal catalyst is Pt and the amphoteric ionic compound is L-cystine.

According to another aspect, the amphoteric ionic compound solution has a concentration of 1 to 130 [mu] M. When the concentration of the amphoteric ionic compound solution is less than 1 μM, the reduction of the electrochemical surface area of the metal catalyst is less than 0.1%, so that the effect of improving the oxygen reduction activity is not exhibited at all. When the concentration exceeds 130 μM, The surface area reduction exceeded 20% and the activity for the oxygen reduction reaction was significantly lowered.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope and content of the present invention can not be construed to be limited or limited by the following Examples. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the present invention as set forth in the following claims. It is natural that it belongs to the claims.

Example

Preparation of Pt polycrystalline RDE by sputtering

A Pt polycrystalline film was directly deposited on the RDE tip (1 cm in diameter) in an Ar atmosphere using an RF magnetron sputter system with a vertically aligned 4-inch polycrystalline Pt target. Except for the RDE tip GC (area = 0.283 cm < ² >). The RDE holder was made so that the RDE could stand vertically without falling down when depositing the Pt, and the holder had a rectangular shape with six holes (diameter = 1 cm) to hold six RDEs together x 5 x 1 cm). Base and working pressures were adjusted to 4 x 10 ^-6 and 5 mTorr, respectively. The working distance between the sputter target and the substrate was 20 cm, and Pt deposition was performed for 60 minutes at 20 W power.

Preparation of L-cystine-deconated Pt catalyst

To make a 130 μM L-cystine solution, 3.25 mg of L-cystine was dissolved in 200 mL of deionized water for 30 minutes and mixed well. RDE tip To decorate L-cystine on a Pt polycrystalline surface on a GC mounted on a GC, RDE tips with a Pt polycrystalline surface were immersed in 130 μM L-cystine solution for 1 minute and then washed repeatedly with deionized water And then dried in an oven at 60 DEG C for 5 minutes.

To introduce L-cystine into the Pt nanoparticle system, a 20 wt% Pt / C commercial catalyst was set as the standard Pt. 50 mg of Pt / C was added to 130 μM L-cystine solution, mixed thoroughly with ultrasonics for 20 minutes, filtered with excess deionized water, and dried in an oven at 60 ° C. for 12 hours to obtain L-cystine -decorated Pt / C catalyst. In order to investigate the effect of L-cystine coverage on oxygen reduction activity, Pt / C catalyst was added to a concentrated L-cystine solution at a concentration of 250, 500 μM and the catalyst was prepared in the same manner.

Physical property observation

Cs-corrected STEM was used for the surface structure and elemental analysis of L-cystine-decomposed Pt / C catalyst. STEM images, EDX mapping images, and line profiles (not shown) were also measured using Cs-corrected STEM. Synchrotron-based XPD was measured on the 8A1 beamline of the Pohang Accelerator Laboratory to investigate the electronic structure changes of Pt / C with and without L-cystine. The obtained XPS data was curve fitted using XPSPEAK 4.1 software. The zeta potential of Pt / C catalysts (not shown) was measured in a pH-adjusted electrolyte via a Zeta Plus zeta potential analyzer. The pH of the electrolyte was adjusted by adjusting the concentration of KOH and H ₃ PO ₄ solution, and the zeta potential was measured 15 times for each sample and the average value was taken.

Electrochemical property observation

To investigate the effect of L-cysteine adsorption on the Pt polycrystalline surface as a model system, a solution of 5 mVs ^-1 from 0.05 V to 0.7 V in Ar-saturated 0.1 M HClO ₄ , 0.1 M KOH, 0.05 MH ₃ PO ₄ solution The CV of untreated Pt polycrystalline and L-cystine-decon- plated Pt polycrystalline surface was measured with a scanning speed of. The catalyst of the ESA was calculated using a charge density of hydrogen desorbed H _upd region of the measured CV at 0.1 M HClO ₄ solution. The adsorption current density of OH and phosphate anions (not shown) was obtained by subtracting the electric double layer current density measured from the 0.1 M KOH and 0.05 MH ₃ PO ₄ solutions from the CV current density. The oxygen reduction activity of the electrode was measured by scanning a 5 mVs ^-1 electrode while rotating the RDE between O ₂ -saturated 0.1 M HClO ₄ , 0.1 M KOH and 0.05 MH ₃ PO ₄ at a voltage between 0.05 V and 1.05 V at 1600 rpm Speed. The oxygen gas was continuously blown during the oxygen reduction reaction activity test. In order to investigate the effect of L-cystine adsorption on the Pt / C catalyst as an actual system, a catalyst ink was prepared by mixing L-cystine-decolated Pt / C catalyst, Nafion ionomer and IPA. 5 [mu] L of Pt / C catalyst ink was dropped on GC with an area of 0.196 cm < ² > and dried in an oven at 60 [deg.] C to remove all of the solvent on the catalyst surface. Untreated Pt / C catalysts were also compared with L-cystine-deconated Pt / C catalysts in all solutions. The loading amount of Pt loaded on carbon is about 48 μg. The catalyst of the ESA was calculated to have a charge density in the region of the _upd H measured in CV 0.1 M HClO ₄ solution. To verify the stability of L-cystine adsorbed on the Pt nanoparticles, 100 voltage cycles were run at a scan rate of 20 mVs ^-1 at a voltage between 0.05 V and 1.05 V in 0.1 M KOH and 0.05 MH ₃ PO ₄ solution . The oxygen reduction reaction activity test of Pt / C catalysts was performed under the same conditions as the experimental conditions of the Pt polycrystalline surface. In order to minimize contamination of the Pt surface from impurities due to glass leaching in alkali solution, a fresh KOH solution was newly prepared for each electrochemical measurement, and most electrochemical data were obtained in 20 minutes. Only 100 voltage cycle tests between 0.05 V and 1.05 V to see the stability of L-cystine adsorbed on Pt nanoparticles were carried out for about 2.78 hours. However, since the positive potential limit was 1.05 V, which is much higher than 0.5 V, it seems that the contamination of the Pt surface hardly occurred during the stability test.

Effect of L-cystine adsorption on Pt polycrystalline surface

First, the effect of L-cystine adsorption on the Pt polycrystalline surface with simple structure was investigated during the oxygen reduction reaction. Fig. As shown in 1a and b, above the surface of the Pt L- cystine absorption degree was measured by comparing the H _upd of the non-treated sample and L- cysteine -decorated sample. H _upd area of L- cystine -decorated sample is reduced than the untreated samples, but the Pt surface adsorption of L- cystine molecules to find out yirwojim, in the KOH or phosphoric acid solution, the adsorption of OH- and phosphate ions in the ambiguous region H _upd It is difficult to accurately obtain the electrochemically active area of Pt substantially because it forms an ambiguous electric double layer. Therefore, we measured the CV area in the HClO ₄ solution with little adsorption of ClO ₄ ^- ions and found the H _upd area, from which the adsorption of L-cystine was accurately determined. In conclusion, it was found that L-cystine adsorption reduced about 20% of the electrochemically active area of L-cystine-deconded Pt (compared to untreated samples).

On the other hand, the electrochemical properties of L-cysteine-decored samples in KOH and phosphoric acid solutions were significantly different from untreated samples. In the KOH solution, the OH adsorption peak area at a voltage between 0.45 V and 0.6 V was reduced by about 48% compared to the untreated sample. These results show that the direct electrostatic interaction of the OH ^- ions with the Pt surface in IHP is greatly reduced. Phosphoric acid ion adsorption peaks were observed at about 0.55 V in the phosphoric acid solution, and both peaks appeared in the untreated sample and the L-cystine-decored sample. However, calculation of the phosphate ion adsorption charge was found to be about 42% less than the untreated sample. This is a result of the fact that the direct interaction of the phosphate ion with the Pt surface was also reduced by the -NH ₃ ⁺ of the L-cystine molecule bearing the (+) charge in the IHP.

As a result, the L-cystine-decreated sample showed a much higher oxygen reduction activity than the untreated sample due to the charge of the L-cystine molecule changing the Pt surface charge depending on the type of the electrolyte solution. Enhanced oxygen reduction activity in KOH and impregnation solution of L-cysteine-decored samples is due to direct electrostatic interactions between L-cystine and bidentate ions with zwitterionic properties, as predicted from the CV data. I think. The results obtained using Pt polycrystalline as such a simple model system demonstrate that our hypothesis of the role of L-cystine with amphoteric properties is credible. However, we extended the range to Pt nanoparticle surfaces to ensure that the same results could be obtained in real systems rather than in these model systems. The use of nanoparticles also helped to find additional physical significance because the handling of samples for multiple measurements is much easier than when using polycrystalline.

Effect of L-cystine adsorption on Pt nanoparticles (Pt / C) supported on carbon

L-cystine was adsorbed on a Pt / C catalyst substantially used as a fuel cell catalyst. The commercialized Pt / C catalyst had a particle size of about 2.6 nm, and the catalyst was immersed in a 130 μM L-cysteine solution for L-cystine adsorption. However, although L-cystine is attached to the surface of Pt nanoparticles, it is difficult to directly observe the surface of nanoparticles adsorbed on very small organic molecules by TEM, and it is difficult to discriminate them from the surface structure of untreated Pt / C. Therefore, we first focused on finding physical evidence that L-cystine selectively adsorbed onto the Pt surface rather than the carbon support. As a result of EDX mapping using Cs-STEM, it was confirmed that the S element possessed by L-cystine was observed only on the surface of Pt nanoparticles, not on the carbon surface. This suggests that L-cystine is adsorbed only on the surface of Pt particles by specific chemisorption rather than by any kind of physisorption. The presence of L-cystine on the Pt surface can also be seen by S-atom line scanning of STEM. Crucially, XPS measurements confirmed that chemisorption occurred due to the strong interaction between -SH and Pt of L-cystine. When Pt XPS peak of Pt-decorated Pt / C shifted to energy direction about 0.35 eV higher than untreated Pt / C and peak appeared near 163.5 eV in S XPS spectra, electron transfer from Pt to S occurred It was proved that stable SAM was formed.

For the same reason as on the Pt polycrystalline surface, the electrochemically active areas of the Pt / C samples were measured in the HClO ₄ solution and the area was reduced by about 20% when the 130 μM L-cystine solution was used . However, the use of 250 μM and 500 μM L-cystine solution resulted in a gradual increase in area reduction to 50% or 80%. The binary also be the concentration of the KOH with the phosphoric acid solution H _upd area from within CV using L- cystine solution could be confirmed reduced. We also looked at the electrochemical stability of L-cystine adsorbed on Pt nanoparticles. We concluded that the CV shape is stable through no change when 100 CV cycles from 0.05 V to 1.05 V are run.

As can be seen from FIGS. 2c and d, the adsorption peaks of OH and phosphate ions are significantly reduced as in the Pt polycrystalline experiment. The catalytic activity of L-cysteine-decomposed Pt / C catalysts was also significantly higher than that of untreated samples. On the other hand, if the adsorption degree of L-cystine is increased by 20% or more, the oxygen reduction activity is lowered not only in HClO ₄ but also in KOH and phosphoric acid electrolyte. This is because too much L-cystine adsorption is thought to be due to too much of the active site on the Pt surface, and thus the amount of adsorption of the organic molecules on the surface of the catalyst is also very important .

However, further experimental data were needed to clearly demonstrate the change in the charge of Pt nanoparticles due to L-cystine adsorption. Thus, the zeta potential of Pt / C catalysts was measured to directly identify changes in the charge of the Pt nanoparticles. The zeta potential between the stern layer and the slipping layer is influenced by ions such as H ⁺ and OH ^- which are related to the pH of the electrolyte solution. However, the bystander ions such as hydrated K ⁺ ions and phosphate ions also have ionic charge and adsorbed property, which has a great influence on the zeta potential. Interestingly, it was confirmed that L-cysteine-deconated Pt / C had more (+) charge than KOH and no (-) charge in phosphoric acid. This can be the conclusive evidence that the adsorption of L-cystine influences the Pt surface charge change depending on the type of electrolyte. The KOH, ^-COO-L- cysteine -decorated the Pt nanoparticles band charges OH in slipping layer - (), ^- by the shown said to have a charge-to the relatively reduced to be able to push the ion (). Conversely, in phosphoric acid, it is assumed that (+) electric charge is generated by -NH ³⁺ , so that phosphate ion may be pulled rather than H + ion to have a (+) electric charge reduced on the slipping plane. The results of this zeta potential change became more evident as the concentration of KOH and phosphoric acid solution increased. Therefore, the properties of surface charge change of bifunctional Pt nanoparticles were confirmed, and it was proved that the change of CV and oxygen reduction reaction activity controlled the behavior of the bystander ions in KOH and phosphoric acid solution well.

Claims (14)

1. A carbon support-supported composite catalyst comprising (a) a carbon support, (b) a metal catalyst supported on the carbon support, and (c) an amphoteric ion compound layer coated on the surface of the metal catalyst,
The amphoteric ionic compound is a compound comprising a proton-withdrawing group, a donating functional group, and a metal catalytic functional group,
The carbon support-supported composite catalyst is for an oxygen reduction reaction in a basic or acidic solution,
As a result of the EDX mapping analysis using Cs-STEM and the S atom line scanning analysis of the STEM, the amphoteric ion compound is not adsorbed on the carbon support but adsorbed only on the metal catalyst. The method of claim 1, wherein the proton acceptor functional group is selected from an amine group, a primary amine group, a secondary amine group, a tertiary amine group, an aldehyde group, and a ketone group;
Wherein the proton donating functional group is selected from a carboxyl group and a hydroxyl group;
Wherein the metal catalyst-bonding functional group is selected from a thiol group and a carbene group. 3. The composite catalyst for supporting a carbon support according to claim 2, wherein the proton acceptor functional group is an amine group, the proton donor functional group is a carboxyl group, and the metal catalytic functional group is a thiol group. The method of claim 1, wherein the metal catalyst is selected from the group consisting of Pt, Pd, PtM alloy (M = Ni, Co, Fe, Cu, Pd) 1 species);
Wherein the amphoteric ionic compound is one selected from L-cystine, homocysteine and L-methionine. 5. The carbon support-carrying composite catalyst according to claim 4, wherein the metal catalyst is Pt and the amphoteric ion compound is L-cysteine. delete The carbon support-supported composite catalyst according to claim 1, wherein the amphoteric ion compound forms a self assembled monolayer (SAM) on the surface of the metal catalyst. The XPS analysis according to claim 7, characterized in that the XPS peak of the metal catalyst coated with the amphoteric ion compound is observed in a higher energy direction as compared with the XPS peak of the metal catalyst not coated with the amphoteric ion compound layer By weight based on the total weight of the catalyst. 9. The carbon support-supported composite catalyst according to claim 8, wherein a peak is observed at 163.5 eV as a result of S _2p XPS spectrum analysis. The carbon support-supported composite catalyst according to claim 1, wherein the electrochemical surface area (ESA) of the metal catalyst is reduced by 0.1 to 20% by the zwitterionic compound. 11. A fuel cell comprising a catalyst according to any one of claims 1 to 5 and 7 to 10, wherein the fuel cell is an alkali fuel cell or a phosphoric acid fuel cell. (A) immersing a metal catalyst supported on a carbon support in an amphoteric ionic compound solution, mixing, washing and drying the carbon supported catalyst composite catalyst,
The carbon support-supported composite catalyst comprises (a) a carbon support, (b) a metal catalyst supported on the carbon support, and (c) an amphoteric ion compound layer coated on the surface of the metal catalyst,
The amphoteric ionic compound is a compound comprising a proton-withdrawing group, a donating functional group, and a metal catalytic functional group,
The carbon support-supported composite catalyst is for an oxygen reduction reaction in a basic or acidic solution,
As a result of the EDX mapping analysis using Cs-STEM and the S atom line scanning analysis of the STEM, the amphoteric ion compound is not adsorbed on the carbon support but adsorbed only on the metal catalyst. . 13. The method of claim 12, wherein the metal catalyst is Pt and the zwitterionic compound is L-cystine. 14. The method of claim 13, wherein the amphoteric ionic compound solution has a concentration of 1 to 130 [mu] M.

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