KR20170058352A - Polymer electrolyte membrane water electrolysis anode and method for preparing the same using IrO₂electrodeposited porous carbon material, polymer electrolyte membrane water electrolysis apparatus and method using the same - Google Patents

Abstract

Provided are an anode for water-electrolyzing a polymer electrolyte membrane in which IrO_2 is electrodeposited on a hydrophilic porous carbon material, a manufacturing method thereof, and an apparatus and a method for water-electrolyzing a polymer electrolyte membrane using the same. A single cell for water-electrolyzing a polymer electrolyte membrane according to the present invention comprises: a polymer electrolyte membrane; a cathode which is formed on one side of the membrane; and an anode which is formed on the other side of the membrane. The anode comprises IrO_2 electrodeposited on the surface of carbon paper that is a hydrophilic porous carbon material. The polymer electrolyte membrane is a Nafion membrane, and the cathode is Pt/C. When the anode has an IrO_2 loading amount of 0.01 to 0.54 mg cm^-2, the single cell for water-electrolyzing a polymer electrolyte membrane represents a current density of 0.33 A cm^-2 to 1.6 A cm^-2 at 1.6 V, 90C, and 1.0 to 700 bars, or a current density of 1.5 A cm^-2 to 2.5 A cm^-2 at 1.6 V, 120C, and 1.0 to 700 bars. Accordingly, the present invention not only can reduce the consumption amount of iridium that is a precious metal, but also can represent excellent current density (excellent water electrolysis performance) by lowering the loading amount of IrO_2 used in the anode for water-electrolyzing a polymer electrolyte membrane. Further, the present invention not only can represent good catalytic activity, but also can reduce carbon corrosion when applying an iridium oxide electrodeposited porous carbon material to the anode for water-electrolyzing a polymer electrolyte membrane. Further, the present invention has a simple manufacturing process and can greatly reduce the manufacturing costs compared to conventional manufacturing processes.

Description

TECHNICAL FIELD The present invention relates to an anode for water electrolysis of a polymer electrolyte membrane using a porous carbon material having an electrolytic plating of iridium oxide, a method for producing the anode, and an apparatus and a method for preparing a polymer electrolytic membrane water electrolysis using the same. porous carbon material, polymer electrolyte membrane water electrolysis apparatus and method using the same}

This specification describes an anode for electrolysis of polyelectrolyte membranes using a porous carbon material having electrolytically plated iridium oxide, a method for producing the anode, and an apparatus and a method for electrolyzing polyelectrolyte membranes using the same.

Due to global climate change and depletion of fossil fuels, the shift to the hydrogen economy has received much attention in recent years. Hydrogen has many advantages as an alternative energy, does not produce environmental pollutants, and can be stored for a long period of time without significant loss.

Currently, hydrogen is produced by steam reforming of natural gas, but here a significant amount of CO ₂ is produced together. As a sustainable and environmentally friendly alternative, water electrolysis coupled with renewable energy sources, such as wind power or solar power, is expected as a viable alternative to hydrogen production.

However, the cost of hydrogen production due to water electrolysis is two to three times more expensive when compared to the reforming process. At present, about 96% of hydrogen is produced by fossil fuel based technology (48% natural gas reforming, 30% partial oxidation, 18% gasification) and only 4% of total hydrogen production is produced by electrolysis.

Among various types of water electrolysis techniques, polymer electrolytic membrane water electrolysis (PEMWE) method has a high purity (about 99.99% or more) of produced hydrogen, a high production rate, a small system volume, There are many advantages such as the use of harmless neutral water.

In a typical PEMWE, iridium or ruthenium-based electrocatalysts are used (1.0 - 5.0 mg / cm ² ) for the oxygen evolution reaction (OER) in the anode, Platinum catalysts (0.4 - 0.8 mg / cm ² ) are used for the hydrogen evolution reaction (HER), and these noble metal based electrocatalysts are responsible for one of the high system costs of PEMWE There is a need to lower the manufacturing cost.

However, in a MEA (membrane electrode assembly) using a PEMWE membrane manufactured by a conventional spraying method (for example, non-patent documents 4 and 6) and a sputtering method (for example, non-patent reference 7) IrO ₂ When loading is reduced, single cell performance is also significantly reduced, so that Ir or IrO ₂ It is also difficult to reduce the loading.

For example, Non-Patent Document 6 discloses that when IrO ₂ is loaded using a spraying method on a membrane in the production of an MEA, the IrO ₂ loading is 3.0 mg / cm ² in 0.5 mg / cm < ² >, the current density at 1.6 V was reduced from 1.33 to 0.67 A / cm < ² > As shown in Fig.

 A. Marshall, S. Sunde, M. Tsypkin, R. Tunold, International Journal of Hydrogen Energy 32 (2007) 2320-2324.  S. Song, H. Zhang, X. Ma, Z. Shao, R.T. Baker, B. Yi, International Journal of Hydrogen Energy 33 (2008) 4955-4961.  J. Cheng, H. Zhang, G. Chen, Y. Zhang, Electrochimica Acta 54 (2009) 6250-6256.  L. Ma, S. Sui, Y. Zhai, International Journal of Hydrogen Energy 34 (2009) 678-684.  G. Wei, Y. Wang, C. Huang, Q. Gao, Z. Wang, L. Xu, International Journal of Hydrogen Energy 35 (2010) 3951-3957.  H. Su, B.J. Bladergroen, V. Linkov, S. Pasupathi, S. Ji, International Journal of Hydrogen Energy 36 (2011) 15081-15088.  E. Slavcheva, I. Radev, S. Bliznakov, G. Topalov, P. Andreev, E. Budevski, Electrochimica Acta 52 (2007) 3889-3894.  V. Antonucci, A. Di Blasi, V. Baglio, R. Ornelas, F. Matteucci, J. Ledesma-Garcia, L.G. Arriaga, A. S. Arico, Electrochimica Acta 53 (2008) 7350-7356.  Wu Xu, Keith Scotta, Suddhasatwa Basu, Journal of Power Sources 196 (2011) 8918-8924.  V. Baglio, R. Ornelas, F. Matteucci, F. Martin, G. Ciccarella, I. Zama, L.G. Arriaga, V. Antonucci, A.S. Arico FUEL CELLS 09, 2009, No. 1. 3, 247-252.  Anita Skulimowska, Marc Dupont, Marta Zaton, Svein Sunde, Luca Merlo, Deborah J. Jones, Jacques Roziere, International Journal of Hydrogen Energy 39 (2014) 6307-6316.  David Aili, Martin Kalmar Hansen, Chao Pan, Qingfeng Li, Erik Christensen, Jens Oluf Jensen, Niels J. Bjerrum, International Journal of Hydrogen Energy 36 (2011) 6985-6993.  Varagunapandiyan Natarajan, Suddhasatwa Basu, Keith Scott, International Journal of Hydrogen Energy 38 (2013) 16623-16630.  Martin Kalmar Hansen, David Aili, Erik Christensen, Chao Pan, Soren Eriksen, Jens Oluf Jensen, Jens H. von Barner, Qingfeng Li, Niels J. Bjerrum, International Journal of Hydrogen Energy 37 (2012) 10992-11000.

In embodiments of the present invention, in one aspect, a polymer electrolyte membrane (membrane) capable of achieving excellent current density (excellent water electrolysis performance) while reducing the loading amount of IrO ₂ used in an anode of a water electrolysis of polyelectrolyte membrane An anode for water electrolysis, a method for producing the same, and a device and a method for electrolyzing a polymer electrolyte membrane using the same.

In an embodiment of the present invention, in another aspect, an anode for electrolysis of polyelectrolyte membrane water electrolysis, which has good catalytic activity when applied to an anode of a polyelectrolyte membrane water electrolysis and can reduce carbon corrosion, A polymer electrolytic membrane water electrolysis apparatus and method are provided.

Embodiments of the present invention, in another aspect, provide a polymer electrolyte membrane water electrolysis anode and a method of manufacturing the same, which can simplify a manufacturing process and can greatly reduce manufacturing cost, a polymer electrolyte membrane water electrolysis apparatus using the same, ≪ / RTI >

In embodiments of the present invention, the hydrophilic porous carbon material is doped with IrO ₂ Wherein the anode is provided with an electrolytic plating, particularly a electrolytic plating.

In embodiments of the present invention, the hydrophilic porous carbon material may further include IrO ₂ The present invention also provides a method for manufacturing an anode for water electrolysis of polyelectrolyte membranes.

In embodiments of the invention Further, the polymer electrolyte membrane, and an anode formed on the cathode, the other side of the film formed on one side of the membrane, the anode is IrO ₂ on the hydrophilic porous carbon material Wherein the electrolytic plating is carried out by using the electrolytic plating solution.

Embodiments of the present invention also provide a method of electrolyzing a polymer electrolyte membrane using the polymer electrolyte membrane water electrolysis apparatus.

According to the embodiments of the present invention, it is possible to reduce the amount of iridium used as a noble metal, while reducing the amount of IrO ₂ used in the anode of the polyelectrolyte membrane water electrolysis, and also to have excellent current density (excellent water electrolysis performance) . In addition, it can exhibit good catalytic activity when applied to an anode for water electrolysis of polyelectrolyte membranes, while reducing carbon corrosion. In addition, the manufacturing process is very simple compared to the conventional one, and the manufacturing cost can be greatly reduced.

Figure 1 is a graph of the linear potential scanning (LSV) curves for electrolytic plating solutions (0.1 M of iridium chloride hydrate, 0.04 M of oxalic acid, 0.01 M of hydrogen peroxide) and CP electrodes in pH adjusted water 1a] and the current density during electrolytic plating at constant potentials of 0.6 V, 0.7 V, 0.8 V, and 0.9 V (Fig. 1B).
FIG. 2 is a SEM image of an uncoated bare carbon paper (FIG. 2A), and an SEM image of an IrO ₂ / CP electrode produced by electrolytic plating according to the electrolytic plating potential in Examples and Comparative Examples of the present invention. (Fig. 2B (0.6V), Fig. 2C (0.7V), Fig. 2D (0.8V) and Fig. 2E (0.9V)]. For reference, the electroplating time for the IrO ₂ / CP electrode is 60 seconds.
Figure 3 according to an embodiment of the present invention, a graph showing the Ir4f XPS (X-ray photoelectron spectra ) of IrO ₂ electrolytic plating on the carbon paper.
FIG. 4 is a graph showing the current density during electrolytic plating at 0.7 V for various electrolytic plating times of 1 to 30 minutes (FIG. 4A) and the function of electric charge for electrolytic plating IrO ₂ is a graph showing the amount as for electrodeposition) [Figure 4b].
FIG. 5 is a graph showing the relationship between the IrO ₂ / CP produced by electrolytic plating at 0.7 V for 1 minute [FIG. 5A], 10 minutes [FIG. 5B], 20 minutes SEM image of the electrode.
FIG. 6 is a graph showing that in an embodiment of the present invention, IrO ₂ / CP electrode electroplated at 0.7 V, IrO ₂ 6A] and Ir (V) peak current reduction (Fig. 6B) as a function of the amount of loading (indicated by the electroplating time).
Figure 7 shows the polarization curves of a PEMWE single cell with an IrO ₂ / CP anode ( E _dep = 0.7 V; t _dep = 1 to 30 min) in an embodiment of the present invention.
8 is a graph showing the current density (closed circle) at 1.45 V and the current density at 1.6 V (open circle) [Fig. 8a] and mass activity (Fig. 8b). In FIG. 8B, data of the conventional literature are shown together.
9 is a graph showing the high-temperature hydrothermal performance of the Examples and Comparative Examples in Experiment 2. The X axis represents the current density (unit Acm ^{- 2} ) and the Y axis represents the voltage (unit: V).
FIG. 10 is a graph showing the results of Table 2 in Experiment 2. In Figure 10 X-axis loading amount (unit: mg cm ^-2), the current density in the Y-axis 1.6V: ^- represents the (in cm ² A). In Fig. 10, data of the conventional literature are also shown.

Hereinafter, exemplary embodiments of the present invention will be described in detail.

The present inventors, as the anode material of the polymer electrolyte membrane water electrolyzer, IrO ₂ on porous carbon jaeryosang And particularly by using a material formed through electrolytic plating, IrO ₂ It has been confirmed that the current density (excellent water electrolysis performance) can be achieved while reducing the loading amount and significantly reducing the content of iridium used as the noble metal.

In embodiments of the present invention, therefore, in one aspect, the hydrophilic porous carbon material is provided (present) with, in particular, electrodeposition where IrO ₂ is provided (present) Lt; / RTI >

The hydrophilic porous carbon material was coated with IrO ₂ Is subjected to electrolytic plating, the porous carbon material is coated with IrO ₂ (Or a molar phase) unique to electrolytic plating, which is different from the case of using another manufacturing method (for example, a spray method or a decal method).

That is, when the porous carbon material is doped with IrO ₂ Is formed by electrolytic plating, IrO ₂ As the particles (for example, spherical particles) start to be formed, the surface of the porous carbon material is coated with IrO ₂ Particles are generated and grown in a film form so that the surface of the porous carbon material is made of IrO ₂ Layer (or IrO ₂ (That is, surface-coated) with a predetermined thickness (which can also be expressed as a film), and the IrO ₂ particles formed by electrolytic plating have a form (structure) adhered to the IrO ₂ layer.

Thus, in an exemplary embodiment, the anode for water electrolysis of a polymer electrolyte membrane produced by electrolytic plating is a surface of a carbon material having an IrO ₂ Layer, and the corresponding IrO < _{2 >} Layer may be represented by a structure in which IrO ₂ particles are deposited.

In an exemplary embodiment, the IrO ₂ The thickness of the layer is 0.01 to 1 탆, preferably 10 to 210 nm, more preferably 70 to 210 nm, and IrO ₂ The particle size is 0.1 to 3 탆, preferably 0.25 to 1.2 탆.

In an exemplary embodiment, the IrO ₂ on the porous carbon material The loading amount may be 0.01 to 1.00 mg cm ^-2 or 0.01 to 0.54 mg cm ^-2 .

On the other hand, in order to increase the catalytic active surface area, a porous material is used as the carbon material. Further, since the aqueous solution-based electrolytic plating process is applied, the porous carbon material has hydrophilicity. In an exemplary embodiment, the porous carbon material is preferably carbon paper made of carbon fibers.

In an exemplary embodiment, the IrO ₂ Layer covers the surface of the porous carbon material, and is preferably covered so as not to expose the porous carbon material. I.e., the desired anode structure IrO the hydrophilic porous carbon material surface ₂ Layer is a carbon-free structure.

In an exemplary embodiment, the IrO ₂ Layer covers the surface of the porous carbon material, IrO2 < RTI ID = 0.0 _> The layer preferably has a structure free from cracks. That is, the preferred anode structure IrO the hydrophilic porous carbon material surface ₂ Layer covered with IrO ₂ The layer is a crack free structure.

In another aspect, also in the embodiment of the present invention, IrO ₂ in the hydrophilic porous carbon material The present invention also provides a method for manufacturing an anode for water electrolysis of polyelectrolyte membranes.

In an exemplary embodiment, at least one of the plating voltage and the plating time can be adjusted during electroplating on the porous carbon material.

In an exemplary embodiment, the plating voltage is preferably 0.6 to 0.9V. The plating time is preferably from 1 minute to 30 minutes.

According to another aspect of the present invention, there is provided a fuel cell comprising a polymer electrolyte membrane, a cathode formed on one side of the membrane, and an anode formed on the other side of the membrane, wherein the anode comprises IrO ₂ A water electrolysis apparatus for a polymer electrolyte membrane is provided.

In an exemplary embodiment, the anode made of the IrO ₂ electroplated porous carbon material (for example, carbon paper as described above) is formed on one side of a polymer electrolyte membrane (for example, a Nafion membrane), and a cathode For example, Pt / C formed by spraying platinum on a carbon paper) is formed on the surface of the membrane electrode assembly, a bipolar plate is bonded to the membrane electrode assembly, and an end plate is attached to the polymer electrolyte membrane, (Cell) can be produced.

In an exemplary embodiment, the polymer electrolyte membrane water electrolysis apparatus can achieve high performance even with a small catalytic amount (small amount of IrO ₂ loading).

For example, IrO ₂ Loading amount is 0.01 ~ 1.00 mg cm ^-2 and preferably 0.01 ~ 0.54 mg cm ^- when ^two days, 1.6 V, 90 ℃, 1.0 ~ 700bar ( or for example 1.0 ~ 50bar or 1.0 ~ 30bar or 1.0 ~ 2.5bar) 0.33 in A current density of A cm ^-2 to 1.6 A cm ^-2 can be shown. In this case, the cathode and the membrane may be a conventional cathode (e.g. Pt / C: the amount of cathode catalyst may be a typical catalytic amount, for example 0.4 mg / cm ² ) and a membrane (Nafion).

Alternatively, the anode IrO ₂ Loading amount is 0.01 ~ 1.00 mg cm ^-2 and preferably 0.01 ~ 0.54 mg cm ^{- 2} be when, 1.6 V, 120 ℃, 1.0 ~ 700 bar ( or for example 1.0 ~ 50bar or 1.0 ~ 30bar or 1.0 ~ 2.5bar) in A current density of 1.5 A cm ^-2 to 2.5 A cm ^-2 can be exhibited. In this case, the cathode and the membrane may be a conventional cathode (for example, a Pt / C: cathode catalyst amount may be a typical catalytic amount, for example, 0.4 mg / cm ² ) and a membrane (Nafion).

As such, the anode of the embodiments of the present invention, which exhibits high performance even with a small amount of catalyst, can be expressed at a variety of temperatures, such as lower temperatures or higher temperatures as well as above.

In an exemplary embodiment, the polymer electrolyte membrane water electrolyzer anode is IrO ₂ loading amount is 0.01 ~ 1.00 mg cm ^-2 and preferably 0.01 ~ 0.54 mg cm ^- when ^two days, 1.6 V, 90 ℃, 1.0 ~ 700bar (MA) of 74.7 to 0.64 A mg- ¹ at a pressure of ¹ to 50 bar (or for example 1.0 to 50 bar or 1.0 to 30 bar or 1.0 to 2.5 bar). In this case, the cathode and the membrane may be a conventional cathode (for example, a Pt / C: cathode catalyst amount may be a typical catalytic amount, for example, 0.4 mg / cm ² ) and a membrane (Nafion).

In addition, the anode IrO ₂ When the loading amount is 0.01 to 1.00 mg cm ^-2, preferably 0.01 to 0.54 mg cm ^-2 , 1.6 V, 120 ° C, 1.0 bar to 700 bar (or 1.0 to 50 bar or 1.0 to 30 bar or 1.0 to 2.5 bar, To 3.2 A mg ^-1 to 117 A mg ^-1 . In this case, the cathode and the membrane may be a conventional cathode (for example, a Pt / C: cathode catalyst amount may be a typical catalytic amount, for example, 0.4 mg / cm ² ) and a membrane (Nafion).

In another aspect of the present invention, there is provided a method for electrolyzing a polymer electrolyte membrane using the polymer electrolyte membrane water electrolysis apparatus.

Hereinafter, the present invention will be described in more detail by way of Examples and Experiments, but the present invention is not limited to the following description.

[Experiment 1]

Anode  Electroplating ( anodic electrodeposition )through IrO ₂ / CP  Produce

To prepare the electrolytic plating solution, 0.1 M iridium chloride hydrate (IrCl ₄ .H ₂ O) was dissolved in deionized water (DI water) and stirred for 30 minutes in a magnetic stirrer and mixed. Then, oxalic acid ((COOH) ₂ .2H ₂ O: 5 g L ^-1 ) and hydrogen peroxide (35% H ₂ O ₂ : 10 g L ^-1 ) were added and the obtained solution was mixed for 10 minutes. Anhydrous potassium carbonate was added to adjust the pH of the solution to 10.5, and then the electrodeposition solution was agitated for 3 days to be stabilized under stirring.

Anodic electrodeposition was performed using a three-electrode electrochemical cell. SIGNADUR® glass rod electrodes (diameter: 4 mm, HTW Germany) and saturated carbon electrodes (SCE, Hanna instruments Ltd.) are used as counter electrodes and reference electrodes, respectively, in the corresponding triode electrochemical cell . Carbon paper (CP) (thickness: 280 μm, TGPH-090, Toray Inc.) as a porous carbon material was placed on the bottom of the electrolytic plating cell.

A plating potential was applied to the carbon paper through an aluminum foil with a potentiostat instrument (AUT302N, AUTO LAB Ltd.). Linear sweep voltammetry (LSV) was performed in the plating solution in the range of 0.2V to 1.4V and the scan rate was 50 mV s- ¹ . IrO ₂ Electroplating was performed for various plating times (1 to 30 min) at constant potentials (0.6 V to 0.9 V).

IrO ₂ / CP Electrode Characteristic Analysis

Cyclic voltammetry (CV) at a scan rate of 5 mV s ^-1 in a range of -0.5 V to 1.5 V in 0.1 M HClO ₄ solution, (AUT302N, AUTO LAB Ltd.).

The morphology and composition of the IrO ₂ / CP electrodes were determined by scanning electron microscopy (SEM, S-4100, Hitachi Ltd.) and inductively coupled plasma mass spectrometry (ICP-MS, iCAP 6300 series, Thermo Ltd.). In addition, the composition of deposits was analyzed by X-ray photoelectron spectroscopy (XPS, PHI 5000 VersaProbe, Ulvac-PHI Ltd.) using Al K alpha (1486.6 eV) radiation.

IrO ₂ / PEMWE single cell test using CP electrodes

An IrO ₂ / CP anode and a Pt / C cathode having GDL (thickness: 280 μm, 5% PTFE, 10 BC, SGL group) were placed on both sides of a Nafion 212 membrane (thickness: 50 μm, DuPont co. A single cell of PEMWE (Polymer Electrolyte Membrane Electrolysis) was fabricated.

Pt / C cathodes were prepared by spraying catalyst ink on 10 BC (SGL carbon Ltd.). The catalyst ink was prepared by mixing 46.3% Pt / C (TKK) and deionized water and adding isopropanol alcohol and 5 wt% Nafion ionomer (DuPont co.).

The active area was 4 cm ² , and the Pt loading on the cathode side was fixed at 0.4 mg cm ^-2 . After cell combination, the cell temperature was increased to 90 ° C and the polarization curve for water electrolysis was measured (HCP-803, Biologics Ltd.). Preheated deionized water was injected into the anode side (15 mL min ^-1 ) and the current stabilized at various cell potentials from 1.35 V to 2.0 V (0.05 V intervals).

Results and discussion

Figure 1 is a graph of the linear potential scanning (LSV) curves for electrolytic plating solutions (0.1 M of iridium chloride hydrate, 0.04 M of oxalic acid, 0.01 M of hydrogen peroxide) and CP electrodes in pH adjusted water 1a] and the current density during electrolytic plating at constant potentials of 0.6 V, 0.7 V, 0.8 V, and 0.9 V (Fig. 1B).

1A, when the electrode potential was anodically swept toward the anode at 0 V (scan rate: 50 mV s ^{& lt} ; ^-1 >), the anode current at about 0.3 V gradually decreased while being polarized, Respectively. In the electroplating solution, the anode current is due to electrochemical oxidation of the ligand in the Ir complex compound. Accordingly, CO ₂ and IrO (may be referred to the oxygen evolution reaction, below OER) ₂ is formed, electrolytic plating of the IrO ₂ OER is shown. In the case of water having a similar pH (pH = 10.5), no current was observed.

For reference, the following reaction formula 1 shows the formation of CO ₂ and IrO ₂ during electrolytic plating.

[Reaction Scheme 1]

[Ir (COO) ₂ (OH) ₄ ] ^2- - > IrO ₂ + 2CO ₂ + 2H ₂ O + 2e ^-

Anodic electrodeposition was carried out at various electrolytic plating potentials ( E _dep ) ( _0.6-0.9 V) for 60 seconds.

As shown in FIG. 1B, the current density was gradually decreased at a more positive potential (i.e., a larger anode over potential): after 60 seconds the current density was 0.2 mA cm ^-2 (0.6 V) -> 1.2 mA cm ^-2 (0.7 V) -> 2.5 mA cm ^-2 (0.8 V) -> 3.8 mA cm ^-2 (0.9 V). However, oxygen evolution also occurred in the potential range, and the current density [or anodic charge] at each plating potential was not directly correlated with the amount of IrO ₂ .

When OER is also prominent, it is expected that the oxygen bubbles produced can block the surface of the electrolytically plated IrO ₂ and even physically separate from the IrO ₂ thin film.

2 is according to the Examples and Comparative Examples of the present invention, non-coated carbon paper (bare carbon paper) (comparative example) of the SEM image of Fig. 2a], an electrolyte prepared by electrolytic plating by the plating potential IrO ₂ / CP (Fig. 2B (0.6V), Fig. 2C (0.7V), Fig. 2D (0.8V) and Fig. 2E (0.9V)]. For reference, the electroplating time for the IrO ₂ / CP electrode is 60 seconds.

Referring to FIG. 2, morphological changes at 0.6V plating potential were not significant (see FIG. 2B), as compared to the initial surface morphology (see FIG. 2A) ₂ Only adsorbed particles were observed. Regarding, for example, if a spray method is used, an already prepared IrO ₂ If the plating method is used, the IrO ₂ is separated from the plating solution at a specific potential and is formed as adsorbed particles on the surface of the porous carbon material, and the adsorbed particles are further grown by the plating potential, .

When the electrolytic plating potential increases to 0.7 V (FIG. 2C), IrO ₂ The amount of plating also increased significantly, consistent with the significant current increase when the plating potential increased from 0.6V to 0.7V. If the anode potential 0.8V (Fig. 2d), which morphology of the IrO ₂ cover part was similar to the case of 0.7V, the electrolytic plating IrO ₂ A large number of cracks were observed in the layer. Although the overall current density was highest, when the plating potential increased to 0.9 V, IrO ₂ The surface coverage of the particles was almost reduced (see Figure 2e). This means that the IrO ₂ plating was almost hindered by rapid oxygen evolution. That is, both the IrO ₂ plating reaction and the oxygen generating reaction occur together. When the potential increases to 0.9 V, both reactions accelerate, but the oxygen generating reaction becomes more rapid. Thus, it is considered that the oxygen bubbles become very violent and the IrO ₂ blocks the surface to be plated, and furthermore, two phenomena occur in which a physical impact is applied to the already-plated IrO ₂ to separate from the electrode.

On the other hand, the reason why the total current density is the highest is that since the side reaction OER starts from about 0.61 V (based on pH 10.5) and the voltage increases, the reaction increases. As a result, the OER, which is a side reaction more than the plating current, This is because the current density has increased.

XPS analysis was performed on the samples prepared by electrolytic plating at 0.7 V for 5 minutes, and the binding energy region of Ir4f is shown in FIG.

Figure 3 according to an embodiment of the present invention, a graph showing the Ir4f XPS (X-ray photoelectron spectra ) of IrO ₂ electrolytic plating on the carbon paper.

Major peaks were observed around the binding energy of 65.4eV and 62.5eV, which was assigned to each 4f _5/2 and 4f _7/2. From the peak position, it was confirmed that the plating formed by the electrolytic plating was IrO ₂ . For reference, Ir4f _7/2 of IrO ₂ and appears at 62.0 ~ 63.7 eV, Ir metal appears at 60.6 eV and 61.0 eV.

E _dep was fixed at 0.7 V and the effect according to the plating time ( t _dep ) was observed (1 to 30 minutes).

FIG. 4 is a graph showing the current density during electrolytic plating at 0.7 V for various electrolytic plating times of 1 to 30 minutes (FIG. 4A) and the function of electric charge for electrolytic plating IrO ₂ is a graph showing the amount as for electrodeposition) [Figure 4b].

Referring to FIG. 4A, it is shown that the electroplating can be regenerated. The anodic current density increased initially and stabilized at about 1.5 mA cm ^-2 after 5 min.

The amount of plated catalyst on the CP during various plating times was analyzed by ICP and the resulting amount of IrO ₂ loading was plotted as a function of the integrated electric charge density (see FIG. 4b).

As the plating time increased, the loading amount almost linearly increased to 0.541 mg cm ^-2 ( t _dep = 30 min).

The anode current was used only for forming the IrO _2, IrO ₂ loading gradient to the electric charge (electric charge) (slope in IrO 2 loading vs. electric charge) was estimated to be about 0.181 C mg ^{- 1} .

When analyzed with a linear regression (linear regression) of the experimental data points, a slope value indicates that the 0.181 mg was C ^-1, which is (apparent coulombic efficiency) the apparent effect of Coulomb IrO ₂ coating of about 15.6%. Indicating that oxygen evolution is significant at 0.7V. In addition, the electroplated IrO ₂ , depending on charge dissipation, indicates that it can be separated especially during severe oxygen evolution.

Figure 5 shows the morphology of an electrolytically plated IrO ₂ / CP electrode for various plating times in an embodiment of the present invention, wherein it is shown at 0.7 V for 1 minute [Figure 5a], 10 minutes [Figure 5b], 20 minutes [ Fig. 5C] and SEM image of the IrO ₂ / CP electrode prepared by electrolytic plating for 30 minutes [Fig. 5D]. After performing electrolytic plating for one minute, film-like IrO ₂ plating with a small number of particles was observed. When the electroplating time increased to 10 minutes, a large number of spherical particles were formed. This means that the surface area of IrO ₂ is increased. As the plating time increased, the particle size gradually increased from about 0.7 ㎛ ( t _dep = 10 min) to 1.7 ㎛ ( t _dep = 30 min) and many cracks were formed to expose the carbon surface.

FIG. 6 is a graph showing that in an embodiment of the present invention, IrO ₂ / CP electrode electroplated at 0.7 V, IrO ₂ 6A] and Ir (V) peak current reduction (Fig. 6B) as a function of the amount of deposition (indicated by the electroplating time).

Specifically, FIG. 6A shows the CV curve of an IrO ₂ / CP electrode in a 0.1 M HClO ₄ solution. The smallest IrO ₂ The anode (0.8 V and 1.15 V) and cathode (0.75 V) peaks for Ir (III) / Ir (IV) redox were clearly observed for samples with loading ( t _dep = 1 min) Inset). With respect to Ir (IV) / Ir (V) redox activating only on surface atoms, the cathode peak was 1.35V. However, the corresponding anode peak was significantly overlapped with the OER peak. Therefore, when the intensity of the cathode peak at 1.3-1.1 V is higher than IrO ₂ And used to measure changes in active area (see FIG. 6B). The cathode current density increased linearly with IrO ₂ loading during a plating time of up to 10 minutes.

However, when performing the additional loading IrO ₂ (t _dep: 20 minutes and 30 minutes), the increase in the peak current density was slow, which, as expected from the larger particle sizes on the SEM image, IrO ₂ Indicates that usage is smaller. It should be noted that when the cathode peak is superimposed ( t _dep = 20 min and 30 min), the measured peak current is higher than the actual current for Ir (IV) / Ir (V). Furthermore, the IrO ₂ / CP samples with t _dep of 20 min and 30 min showed that the cathode peak potential shifted in the negative direction. This means that as the particle size increases, it is more strongly superimposed by the bulk reduction of Ir (IV) to Ir (III).

A single cell was fabricated using an IrO ₂ / CP electrode with various IrO ₂ loading as an anode and the water electrolysis performance was measured.

Figure 7 shows the polarization curves of a PEMWE single cell with an IrO ₂ / CP anode ( E _dep = 0.7 V; t _dep = 1 to 30 min) in an embodiment of the present invention.

For all cells, the cathode was prepared by spraying a catalyst ink (commercial Pt / C and ionomer) onto the CP. As the plating time increased to 10 minutes, the current density gradually improved, which is believed to be due to the higher catalytic activity for the oxygen generating reaction (see FIG. 7). IrO ₂ The current density at the lower cell voltage (<1.5 V) still increased when the loading amount increased ( t _dep > 10 min). However, the performance at typical operating voltages (1.8 - 2.0 V) was rather reduced.

8 is a graph showing the current density (closed circle) at 1.45 V and the current density at 1.6 V (open circle) [Fig. 8a] and mass activity (Fig. 8b).

Referring first to FIG. 8A, the current density at 1.45 V and 1.60 V is shown, where 1.45 V is the region primarily determined by the activation overpotential, and 1.6 V corresponds to the actual operating voltage.

Also, it was observed that the low overpotential performance was rapidly increased as the loading amount was increased (plating time increased to 5 minutes). However, when the plating time was longer than 5 minutes (that is, when the loading amount was further increased), the degree of performance improvement was relatively small. This is because IrO ₂ This means less use. The current density at 1.6 V showed a maximum at an IrO ₂ loading of 0.1 mg cm ^-2 ( t _dep = 10 min).

When the plating time is longer than 10 minutes, IrO ₂ The carbon substrates exposed between the platings appear to degrade at high operating voltages. The effect of this carbon corrosion was more apparent in the case of a single cell with the smallest IrO ₂ loading ( t _dep = 1 min). Therefore, it can be concluded that it is very important to obtain a high cell performance with good catalytic activity and little carbon corrosion, to prevent the carbon from being exposed to cracking at the time of loading with little or no IrO ₂ loading.

Conventional literature results and contrast

On the other hand, in comparison with the results of the conventional literature reports on IrO ₂ [Non-Patent Documents 1, 2, 3, 6, 7] and iridium black [Non-Patent Documents 2, 4, 5], the electroplated IrO ₂ / CP electrode. The results are shown in Table 1. For reference, the values in parentheses in the table below refer to anode loading (lower anode part and current density part) or cathode loading (lower cathode part), and the unit is mg cm ^-2 .

MEA Manufacturing Method Anode Cathode Membrane Temperature (℃) Current density at 1.6V
(A cm ^-2 ) Non-Patent
Document 1 Spray method
(Spraying) IrO ₂ (2.0) Pt / C (0.4) N115 80 0.75 Non-Patent Document 2 Spray method
(Spraying) Ir, IrO ₂ (3.0) Pt / C (0.5) N112 80 0.52 Non-Patent
Document 3 Spray method
(Spraying) IrO ₂ (1.5) Pt / C (0.5) N1035 80 0.68 Non-Patent Document 4 Brush method
(Brushing) Ir (1.5) Pt (1.0) N112 80 0.5 Non-Patent Document 5 Decal method
(Decal) Ir (3.8) Pt (2.3) N112 60 0.25 Non-Patent
Document 6 Spray method
(Spraying) IrO ₂ (0.5 to 4.0) Pt / C (0.5) N212 80 1.32
(3.0) Non-Patent Document 7 Sputtering method
(Sputtering) IrO ₂ (0.2) Pt / C (N.A.) N117 80 0.3 Example Electrolytic plating method
(Electrodeposition) IrO _{2 /} / CP
(0.01 to 0.54) Pt / C (0.4) N212 90 1.01 (0.1)

For reference, the spraying method is a method in which a catalyst used as an electrode is made into a slurry form and sprayed on a film or GDL through a spray gun, and the brush method is a method in which the slurry prepared is used by using a brush To a film or a GDL. The decal method is a method of depositing a slurry on a material to be transferred (usually Teflon or Capton material) with a blade, and then hot-pressing it on the film or GDL to deposit the slurry. The sputtering method is a method of colliding ionized argon or the like with a plasma in a vacuum chamber, and depositing atoms ejected by the collision onto a substrate.

Prior art, the high Ir or IrO ₂ loading ^- reporting the current density at 1.6V to 0.25 to 1.32 A cm ^-2 for the case of ^{(1.5 ~ 3.0 mg cm 2)} .

In contrast, in embodiments of the present invention, IrO ₂ The PEMWE performance (1.01 A cm ^-2 at 1.6 V) demonstrated by the electrolytically plated IrO ₂ / CP is very good, even though the loading is greatly reduced to 0.1 mg cm ^-2 , which is a promising result. That is quite a lot of conventional anode loading (> 1.5 mg cm ^{- 2)} is capable of achieving at a significantly lower loading amount PEMWE performance level that can be achieved in the case of.

Meanwhile, the current density at 1.6 V is divided by the anode loading and the resulting mass activity (MA) is shown in FIG. 8B. In FIG. 8B, the activities per mass of the respective anodes of Non-Patent Documents 1 to 7 shown in the above table are also shown. In case of Non-Patent Document 2, the case where Ir is used as an anode is indicated by a black square and the case where IrO ₂ is used as an anode is indicated by a white square.

In the case of the conventional literature, the anode loading in submicron units is 1.4 A mg ^-1 (0.5 mg cm ^-2 ) [Non-Patent Document 6] and 1.5 A mg ^-1 (0.2 mg cm ^-2 ) [Non-Patent Document 7] Improved MA was provided, with a gradual increase in MA as the loading amount was smaller. In contrast, the invention embodiment 0.03 mg cm ^- if the IrO ₂ / CP has the IrO ₂ loading amount of ² by showing the MA of 20.4 A ^-1 mg to give a stable cell performance.

[Experiment 2]

In addition to the above Experiment 1, this time, the performance of the electrolytic solution at a high temperature (120 ° C) was evaluated.

Other anode manufacturing and performance evaluation methods were the same as those of Experiment 1, except that the high temperature (120 ° C) electrolytic solution performance was evaluated. That is, the experimental delivery IrO ₂ / CP anode to the plating method, as in _{1 (E dep = 0.7 V;} t dep = 10 min, coating weight: 0.1 mg cm ^{- 2)} to having PEMWE prepare a single cell polarization curve (polarization curves ) ^Was measured at 120 ^° C. and the performance according to the pressure (1.5 to 2.5 bar) was observed (the embodiment of Experiment 2: indicated as EP in FIG. 9). And, it is manufactured by spraying IrO ₂ / CP anode: ^- was in contrast with (coating weight 2.0 mg cm ²⁾ for employing a PEMWE single cell (comparison of Experiment 2, for example) compared the performance of the 120 ℃, 2.5 bar (Indicated as Spray in FIG. 9).

Generally, as the temperature increases, the Kernetics of OER accelerates and the thermodynamic energy required for the reaction is lowered by the Nernst equation.

9 is a graph showing the high-temperature hydrothermal performance of the Examples and Comparative Examples in Experiment 2. The X axis represents the current density (unit Acm ^{- 2} ) and the Y axis represents the voltage (unit: V).

As can be seen in FIG. 9, when the pressure is increased to 1.5 bar or more to supply water to the liquid, the performance is 1.5 bar to 1.71 A cm ^-2 at 1.6 V, 1.73 A cm ^-2 at 2.0 bar, 1.79 A cm ^-2 , which is superior to the performance at 90 ° C (1.01 A cm ^-2 ). In addition, the results are considerably more coating weight of MEA is manufactured by spraying with an amount of 2.0 mg cm ^{-2 -} exhibited performance similar to (1.86 A cm ^2).

On the other hand, the PEMWE performance of the electrolytically plated IrO ₂ / CP electrode of this example was evaluated at 120 ° C in comparison with the results of the prior art reports on the IrO ₂ , RuO ₂ and RuIrO ₂ anodes 2: performance evaluation of electrolytic solution at 120 캜).

membrane Temperature (℃) Pressure (bar) Loading amount
(mg cm ^-2 ) Current density at 1.6V
(A cm ^-2 ) Non-Patent Document 8: Antonucci et al. Nafion + SiO ₂ 120 3.0 IrO ₂
5.0 0.75 Non-Patent Document 9: Xu et al. Nafion + SiO ₂ 120 3.0 Ru IrO ₂
2.5 1.10 Non-patent document 10: Baglio et al. Nafion + TiO ₂ 120 3.0 IrO ₂
5.0 0.63 Non-Patent Document 11: Skulimowska et al. Aquivion 120 7.0 IrO ₂
2.0 1.24 Non-patent document 12: Aili et al. PA doping
PBI 130 1.0 IrO ₂
4.0 0.30 Non-Patent Document 13: Natarajan et al. PA doping
PBI 120 2.5 RuO ₂
1.5 0.45 Non-Patent Document 14: Hansel et al PA doping
Aquivion 130 1.0 IrO ₂
1.0 0.41 In Experiment 2,
Example Nafion 120 2.5 IrO ₂
0.1 1.82

For reference, FIG. 10 shows graphs of the results of Table 2 in Experiment 2. In FIG. 10, the X axis represents the loading amount (unit: cm cm ^-2 ) and the Y axis represents the current density (unit: A cm ^-2 ) at 1.6 V.

Table 2 and as can be seen from Figure 10, prior art is a high IrO _2, RuO _2, and the loading amount RuIrO ₂ ^- the current density at 1.6V for the case of ^{(1.0 ~ 5.0 mg cm 2)} , 120 ℃ 0.30 to 1.24 A cm ^-2 .

In contrast, according to embodiments of the present invention, IrO ₂ The high PEMWE performance (1.82 A cm ^-2 at 1.6 V, 120 ° C) exhibited by the electrolytically plated IrO ₂ / CP is very good, even though the loading is greatly reduced to 0.1 mg cm ^-2 , which is a promising result. That is, the PEMWE performance achievable in the case of conventional anode loading (> 2.0 mg cm ^{&lt; -2} &gt;) can be achieved at a significantly lower loading level as well as low temperature electrolytic solution will be.

IrO ₂ / CP electrodes were fabricated by anode electroplating for various plating voltages and plating times. Surface morphology and Coulomb effect were analyzed by SEM, ICP, and CV.

In the embodiments of the present invention, the surface of the porous carbon material is coated with IrO ₂ Lt; _{RTI ID = 0.0} &gt; IrO2 Thereby providing a structure in which particles are formed. Cracks were formed at a voltage exceeding a certain range and the plating time to expose the carbon material, but no cracking occurred at a voltage within a certain range and plating time, and no carbon material was exposed. As a result, good catalytic activity can be obtained while preventing carbon corrosion. In addition, the PEMWE cell using the anode provided significantly higher current densities at various temperature conditions, albeit with very low loading, and showed very high activity per mass.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (4)

Polymer Electrolyte Membrane;
A cathode formed on one side of the film;
And an anode formed on the other side of the membrane,
The anode is IrO ₂ on the carbon paper surface hydrophilic porous carbon material As the electrolytically plated,
Wherein the polymer electrolyte membrane is a Nafion membrane, the cathode is Pt / C,
The IrO ₂ of the anode Loading amount is 0.01 ~ 0.54 mg cm ^{- 2} be when, 1.6 V, 90 ℃, from ^{1.0 ~ 700 bar 0.33 A cm -2} ~ 1.6 indicate the current density in A cm ^-2, or
Or an IrO _{2 of the} anode Wherein the polymer electrolyte membrane has a current density of 1.5 A cm ^-2 to 2.5 A cm ^-2 at 1.6 V, 120 ° C, and 1.0 to 700 bar when the loading amount is 0.01 to 0.54 mg cm ^-2 .

Polymer Electrolyte Membrane;
A cathode formed on one side of the film;
And an anode formed on the other side of the membrane,
The anode is IrO ₂ on the carbon paper surface hydrophilic porous carbon material As the electrolytically plated,
Wherein the polymer electrolyte membrane is a Nafion membrane, the cathode is Pt / C,
The IrO ₂ of the anode Exhibits an activity per mass of 74.7 to 0.64 A mg ^-1 at 1.6 V, 90 ° C, 1.0 to 700 bar when the loading amount is 0.01 to 0.54 mg cm ^-2 ,
Or 1.6 V, the anode of the IrO ₂ eseo 120 ℃, 1.0 ~ 700 bar Wherein the polymer has an activity per mass of 3.2 A mg ^-1 to 117 A mg ^-1 when the loading amount is 0.01 to 0.54 mg cm ^-2 .
A polymer electrolytic membrane water electrolysis apparatus comprising the single cell of claim 1 or 2.
A method for electrolyzing a polymer electrolyte membrane according to claim 3, which uses the polymer electrolyte membrane water electrolysis apparatus.

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