KR20180053088A - Oxygen Electrode For Regenerative Fuel Cell, Regenerative Fuel Cell Including The Same and Method For Preparing The Oxygen Electrode - Google Patents

Abstract

The present invention provides a regenerative fuel cell including a substrate, an iridium oxide layer electroplated on the substrate, and a layer of palladium (Pd) or platinum (Pt) or a platinum and ruthenium mixture (Pt-Ru) formed on the iridium oxide layer, in particular, an oxygen electrode for an unitized regenerative fuel cell (URFC), a regenerative fuel cell including the same, and in particular, an URFC and a method for producing the electrode. The oxygen electrode can exhibit excellent cell performance while lowering the loading amount of noble metal, especially platinum.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen electrode for a regenerative fuel cell, a regenerative fuel cell including the same, and a method of manufacturing the oxygen electrode.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerative fuel cell, in particular, an oxygen electrode for an integral regenerative fuel cell, a regenerative fuel cell including the regenerative fuel cell, and more particularly, Type integrated regenerative fuel cell, an integral regenerative fuel cell including the same, and a method of manufacturing the oxygen electrode.

Renewable fuel cells, particularly unitized regenerative fuel cells (URFC), have been viewed as promising candidates for large area energy storage / conversion devices. This single device not only can produce hydrogen gas from electrical energy, but it can also convert it back into electricity, enabling energy storage in the form of hydrogen fuel.

In addition, URFCs have self-discharge and high theoretical energy density of 3600 Wh kg ^-1 , which is several times higher than conventional batteries.

One of the key challenges in the current URFC technology is designing a highly efficient, stable oxygen electrode that can provide low overvoltage for ORR (oxygen reduction reaction) and OER (oxygen evolution reaction).

For this purpose, research has been conducted to develop effective bifunctional catalysts, corrosion resistant catalyst supports, stable and efficient diffusion layers, and the like.

Nonetheless, current URFC performance is lower than for individual water electrolyzers (WE) or fuel cells (FC).

A notable difference between the URFC and conventional fuel cells is the catalyst support for the oxygen electrode.

Carbon supports have been commonly used in fuel cells, but carbon supports can not be applied directly to water electrolysis devices (WE) or URFCs due to carbon corrosion under severe corrosive conditions during water electrolysis operation. For this reason, iridium or iridium oxide-supported platinum catalysts, non-supported PtIr, film type PtIr catalyst layer, Ti-based catalyst alternatives to the support such that has been proposed for URFC applied, most of them dangyang to be high catalyst in mg / cm ² need.

In these studies, attempts have been made to lower the content of precious metal catalysts because of the high content of platinum catalysts. However, the URFC's electrolytic solution and fuel cell performance are unsatisfactory and still require a high content of noble metal catalyst.

Non-Patent Document 1: B.-S. Lee, S. H. Ahn, H.-Y. Park, I. Choi, S. J. Yoo, H.-J. Kim, D. Henkensmeier, J. Y. Kim, S. Park, S. W. Nam, K.-Y. Lee and J. H. Jang, Appl. Catal. B, 179, 285 (2015). Non-Patent Document 2: B.-S. Lee, H.-Y. Park, I. Choi, M. K. Cho, H.-J. Kim, S. J. Yoo, D. Henkensmeier, J. Y. Kim, S. W. Nam, S. Park, K.-Y. Lee and J. H. Jang, J. Power Sources, 309, 127 (2016). Non-Patent Document 3: B.-S. Lee, H.-Y. Park, M. K. Cho, J. W. Jung, H.-J. Kim, D. Henkensmeier, S. J. Yoo, J. Y. Kim, S. Park, K.-Y. Lee and J. H. Jang, Electrochem. Commun., 64, 14 (2016). Non-Patent Document 4: S. Altmann, T. Kaz and K. A. Friedrich, Electrochim. Acta, 56, 4287 (2011). Non-Patent Document 5: X. Zhuo, S. Sui and J. Zhang, Int. J. Hydrogen Energy, 38, 4792 (2013). Non-Patent Document 6: S. A. Grigoriev, P. Millet, K. A. Dzhus, H. Middleton, T. O. Saetre and V. N. Fateev, Int. J. Hydrogen Energy, 35, 5070 (2010). Non-Patent Document 7: S. Zhigang, Y. Baolian and H. Ming, J. Power Sources, 79, 82 (1999). Non-Patent Document 8: G. Chen, H. Zhang, J. Cheng, Y. Ma and H. Zhong, Electrochem. Commun., 10, 1373 (2008). Non-Patent Document 9: S. Song, H. Zhang, X. Ma, Z.-G. Shao, Y. Zhang and B. Yi, Electrochem. Commun., 8, 399 (2006).

Embodiments of the present invention, in one aspect, provide an improved regenerative fuel cell, particularly a regenerative fuel cell having an efficient structure capable of exhibiting the performance of an integral regenerative fuel cell, especially a single regenerative fuel cell, Electrode, and a regenerative fuel cell including the same, in particular, an integral regenerative fuel cell and a method of manufacturing the oxygen electrode.

In exemplary embodiments of the present invention, a substrate includes a substrate; An iridium oxide layer electroplated on the substrate; And a palladium (Pd) or platinum (Pt) or platinum-ruthenium (Pt-Ru) mixture layer formed on the iridium oxide layer, and particularly to an oxygen electrode for an integrated regenerative fuel cell and a regenerative fuel cell comprising the same, Particularly an integral type regenerative fuel cell.

Exemplary embodiments of the present invention also include a method of fabricating the oxygen electrode, comprising: forming an iridium oxide layer on the substrate by electroplating; And forming a layer of palladium (Pd) or platinum (Pt) or a mixture of platinum and ruthenium (Pt-Ru) on the iridium oxide layer, and a method of manufacturing an oxygen electrode for an integrated regenerative fuel cell do.

According to exemplary embodiments of the present invention, there is provided a regenerative fuel cell having an efficient structure capable of exhibiting noble metals, particularly an excellent regenerative fuel cell while reducing the amount of platinum loading, particularly an integral regenerative fuel cell, Electrode and a regenerative fuel cell including the same, in particular, an integral regenerative fuel cell can be provided.

FIG. 1 is a graph showing the surface morphology and correspondence of (a) Pt / IrO ₂ / CP 1, (b) Pt / IrO ₂ / CP ₂ , and (c) Pt / IrO ₂ / Gt; EDS < / RTI >
Figure 2 according to embodiments of the present invention, Pt / IrO at 80 ℃ of water electrolysis mode _{2 / CP1, Pt / IrO 2} / CP2 and the Pt / IrO ₂ / TP electrode of IV curves (Figure 2a) and 1.6, 1.7, and 1.8 V and the roughness factor of the substrate (FIG. 2B).
Figure 3 according to embodiments of the present _{invention, Pt / IrO 2 / CP1,} Pt / IrO 2 / CP2 and the Pt / IrO ₂ / TP electrode of the IV curve (Figure 3a) in 80 ℃ fuel cell mode and 0.5 , The current density at 0.6, 0.7 V and the roughness factor of the substrate (Fig. 3B).
4 shows the surface morphology and corresponding EDS mapping results of (a) Pd / IrO ₂ / CP1 and (b) Pt-Ru / IrO ₂ / CP1 electrodes in embodiments of the present invention.
5 is a graph showing the relationship between IrO ₂ / CP 1, Pt / IrO ₂ / CP 1, Pd / IrO ₂ / CP 1 and Pt-Ru / IrO ₂ / CP ₁ during 80 ° C water electrolysis mode in Examples and Comparative Examples of the present invention It is the IV curve of the electrode.
FIG. 6 is an IV curve of Pt / IrO ₂ / CP 1, Pd / IrO ₂ / CP 1 and Pt-Ru / IrO ₂ / CP 1 electrodes during the 80 ° C. fuel cell mode in the embodiments of the present invention.
FIG. 7 is a graph showing the relationship between the amount of catalyst loaded on Pt / IrO ₂ / CP 1, Pd / IrO ₂ / CP 1 and Pt-Ru / IrO ₂ / 7A) and the current density at 0.6 V (fuel cell mode) (FIG. 7B). Reference values in the literature are shown as a comparison in Fig.
Figure 8 according to embodiments of the present invention, 0.2 A / cm ² (Fig. 8a) and 0.4 A / cm ² (Fig. 8b) Pt / IrO ₂ / CP1 and Pt-Ru / IrO of ₂ / CP1 Round at trip efficiency. Reference values in the literature are described as a comparison in Fig.

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

The roughness factor in this specification is a value representing an actual surface area per unit area, which means, for example, the total surface area of fibers contained in a substrate of a unit area when the substrate is made of carbon fiber or titanium fiber.

The present inventors have proposed using an electrodeposition (ED) method in forming a catalyst layer to lower the amount of catalyst loading in PEMWE, although the electroplated IrO ₂ film has a very low loading of 0.1 mg / cm ² And exhibited excellent catalytic activity (Non-Patent Documents 1 and 2).

The present inventors have also found that when platinum black formed by spraying carbon paper and bilayers of sprayed Pt black and electrodeposited IrO ₂ are used as the oxygen electrode of the URFC, -trip efficiency and good cycle durability (Non-Patent Document 3).

However, according to the research results of the present inventors, in order to lower the noble metal, especially the platinum loading while maintaining the acceptable cell performance from the practical point of view, still needs research.

On the other hand, the use of a substrate capable of providing a high-density three-phase interface during water electrolysis and fuel cell operation in a regenerative fuel cell (hereinafter RFC), particularly an integral regenerative fuel cell (hereinafter URFC) And is one of the possible ways to lower platinum loading. However, there are currently no studies addressing the effect of a substrate on the performance of RFCs or URFCs.

On the other hand, it is possible to reduce the amount of platinum loading because Ru can have an effective OER performance while having a low cost equivalent to 15% of the platinum cost (see the Johnson Matthey Co. price table), but in the case of Ru alone, Reduction of efficiency during operation is inevitable.

Thus, in exemplary embodiments of the present invention, there is provided a lithographic apparatus comprising: a substrate; An iridium oxide layer formed on the substrate by electroplating; And a mixture (Pt-Ru) layer of palladium (Pd) or platinum (Pt) or platinum and ruthenium formed in the iridium oxide layer, and an RFC, particularly a URFC, comprising the same.

In an exemplary embodiment of the present invention, there is also provided a method of manufacturing the oxygen electrode, comprising: forming an iridium oxide layer on a substrate by electroplating; And forming a layer of palladium (Pd) or platinum (Pt) or a mixture of platinum and ruthenium (Pt-Ru) in the iridium oxide layer.

On a porous substrate material having a porous substrate material, preferably a macropore, an IrO ₂ In particular using a material formed through electrolytic plating, and also using the corresponding IrO ₂ A palladium (Pd) or platinum (Pt) or a platinum-ruthenium (Pt-Ru) by forming a mixture layer, IrO ₂ reduces the loading amount of the noble metal is iridium using line significantly the content, yet improve the oxygen and water mass transfer and high Cell performance (excellent fuel cell performance and water electrolysis performance) can be achieved.

In particular, when a platinum-ruthenium (Pt-Ru) mixture layer is formed, excellent cell performance can be achieved while lowering the amount of platinum loading.

In an exemplary embodiment, the loading amount of platinum or palladium may be from 0.01 to 1 mg cm ^-2 or from 0.1 to 0.3 mg cm ^-2 .

In one exemplary embodiment, the platinum and the mixture (Pt-Ru) of platinum in a weight range of the ruthenium layer is 0.05-0.5 mg / cm ^2, the sum of platinum and ruthenium weight range is 0.1-1.0 mg / cm ^2. If the weight of the platinum falls below 0.05 mg / cm ² , there may be a decrease in performance in the fuel cell mode, and if it exceeds 0.5 mg / cm ² , there may be a decrease in performance in the power dissipation mode. In addition, if the total weight is less than 0.1 mg / cm ² , the performance in the fuel cell mode may be decreased. If the total weight exceeds 1.0 mg / cm ² , the performance in the power failure mode may be decreased.

In an exemplary embodiment, the roughness factor of the substrate is 30-300. In the roughness factor of less than 30, the decrease in the performance due to the reduction of the 3-phase interface is remarkable. In the roughness factor of more than 300, the durability due to the decrease of the carbon fiber thickness of the substrate,

In an exemplary embodiment, the substrate can be a porous material, preferably a hydrophilic porous material.

In an exemplary embodiment, the porous material may be a porous material having macropores by inter-fiber space.

In an exemplary embodiment, the porosity of the substrate is between 30% and 90%. For porosity less than 30%, there may be a decrease in performance due to degradation of mass transfer, and for porosities greater than 90%, there may be a decrease in performance due to the reduction of the 3-phase interface.

In an exemplary embodiment, the substrate is preferably carbon or titanium.

In an exemplary embodiment, the substrate is preferably a titanium paper made of carbon paper or titanium fiber made of carbon fibers.

In one exemplary embodiment, IrO ₂ to a substrate by electrolytic plating Layer is formed, the surface of the substrate is made of IrO ₂ Layer, and the corresponding IrO < _{2 >} Lt; _{RTI ID = 0.0 &} So that the particles have a structure in which they are deposited.

In an exemplary embodiment, IrO ₂ It is preferred that the layer covers the substrate surface, so that the substrate material is not exposed. That is, a preferable structure is that the substrate surface is made of IrO ₂ Layer is covered but the structure is exposed free.

In an exemplary embodiment, IrO ₂ Lt; RTI ID = 0.0 &_gt; IrO2 < / RTI _> The layer preferably has a structure free from cracks. That is, a preferable structure is that the substrate surface is made of IrO ₂ Layer covered with IrO ₂ The layer is a crack free structure.

As in the exemplary embodiments of the present invention, IrO ₂ Lt; _{RTI ID = 0.0} > IrO2 < / _{RTI &} May be formed to have a curved surface in the porous material. For example, carbon or titanium paper made of fibers is coated with IrO ₂ Lt; RTI ID = 0.0 _> IrO2 < / RTI _> / CP or IrO ₂ / Ti has a curved surface. When palladium (Pd), platinum (Pt) or platinum-ruthenium (Pt-Ru) catalyst ink is sprayed thereon and dried by solvent evaporation, for example, palladium (Pd) Palladium (Pd) or platinum (Pt) or platinum-ruthenium (Pt-Ru) layers can be obtained as the shrinkage rate of the platinum (Pt) or platinum- ruthenium .

Thus, in one exemplary embodiment, the oxygen electrode, a carbon material surface IrO ₂ Layer, and the corresponding IrO < _{2 >} Lt; _{RTI ID = 0.0 &} Particles are deposited (or deposited), and the IrO ₂ Layer or IrO ₂ Porous palladium (Pd) or platinum (Pt) or platinum-ruthenium (Pt-Ru) layers are formed on the particles.

The IrO ₂ An electrode structure having a layer of palladium (Pd) or platinum (Pt) or platinum-ruthenium (Pt-Ru) applied to a coated porous material (e.g., IrO ₂ -coated CP or Ti) may have an open structure with a macropore have.

Specifically, the porous structure may be a porous structure having a sub-micrometer size, for example, a macro-pore, which is sub-micrometer-sized pores, which has an open structure in which pores of the electrode can be connected to the interface of the membrane to be. Thereby facilitating the supply of the reactants and the discharge of the products.

In an exemplary embodiment, the macropore may be derived from pores of a porous material. For example, the porous material may be a macropore formed by an inter-fiber space, and the IrO ₂ Layer and a porous palladium (Pd) or platinum (Pt) or platinum-ruthenium (Pt-Ru) layer is formed on a separate strand of fiber, the macropore of the porous material may be retained. In addition, porous palladium (Pd) or platinum (Pt) or platinum-ruthenium (Pt-Ru) layers have smaller micropores.

Accordingly, the oxygen electrode of the exemplary embodiments of the present invention can have macropores by porous materials and micropores by porous palladium (Pd) or platinum (Pt) or platinum-ruthenium (Pt-Ru) layers.

As described above, the macrophore is an open structure that is connected to the interface of the electrochemical catalyst and the membrane. In this exemplary embodiment of the present invention, in such an open structure, the macrophore is hardly disturbed by the ORR catalyst layer having a micropore . The macropore can be connected to the micropore.

Therefore, the oxygen supply and water removal can be smoothly performed through the open structure. The oxygen generated in the IrO ₂ layer is porous palladium (Pd) or platinum (Pt) or a platinum-ruthenium (Pt-Ru) can be easily removed through the layer and to be able not substantially interfere with the OER the IrO ₂ layer.

For example, micropores formed by a porous ORR layer such as palladium (Pd) or platinum (Pt) or platinum-ruthenium (Pt-Ru) layer are used as macropores (for example, pore size of 1 to 100 micrometers) because it is directly connected to, the oxygen generated in the IrO ₂ layer can be easily removed through the porous layer and ORR may not interfere with the substantially OER within the IrO ₂ layer.

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 substrate material The loading amount may be 0.01 to 1.00 mg cm ^-2 or 0.01 to 0.54 mg cm ^-2 .

In an exemplary embodiment, the thickness of the porous palladium (Pd) or platinum (Pt) or platinum-ruthenium (Pt-Ru) layer may be 0.5 to 3 占 퐉.

In an exemplary embodiment, the oxygen electrode is particularly suitable when operated at a low current density of less than 0.3 A / cm < ² >.

Hereinafter, specific embodiments according to exemplary embodiments of the present invention will be described in more detail. It should be understood, however, that the invention is not limited to the embodiments described below, but that various embodiments of the invention may be practiced within the scope of the appended claims, It will be understood that the invention is intended to facilitate the practice of the invention to those skilled in the art.

[ Example ]

Experimental course

Titanium paper was prepared as TP (ST / Ti / 20/600) by using two commercially available carbon paper as CP1 (TGPH-090, Toray) and CP2 (35AA, SGL carbon) / 73, Bekinit). Details of each substrate are shown in Table 1.

CP1 CP2 TP matter carbon carbon titanium Porosity (%) 78 88 73 Roughness factor 35.7 18.6 13.3

The OEL and ORR catalyst layers were formed by electroplating and spraying, respectively.

First, an IrO ₂ film was formed as an OER catalyst. For this, a mixture of 10 mM iridium tetrachloride (IrCl ₄ H ₂ O), 100 mM hydrogen peroxide (H ₂ O ₂ ), 40 mM oxalic acid (COOH ₂ 2H ₂ O, 340 mM) and 0.34 M potassium carbonate (KCO ₃ ) The plating solution was prepared and stored at room temperature for 3 days.

Thereafter, an electrochemical circuit comprising a carbon paper or a titanium paper as an anode, a titanium mesh as a cathode, and a standard calomel electrode as a reference electrode was constructed, followed by immersing it in a plating solution and applying a potential of 0.7 V _SCE to carbon paper for 10 minutes to the IrO ₂ to form the electrode by loading 0.1 mg / cm ^2. At this time, electroplating was performed with an electrostatic charger (potentiostat equipment, AUT302N, AUTO LAB Ltd.).

Next, after the IrO ₂ electroplating, a catalyst ink comprising an ORR catalyst, a 5 wt% naphthene solution (Dupont), isopropyl alcohol (IPA, JT Baker) and deionized water to be described later was sprayed on the substrate.

A 1: 1 mixture of Pt black (Johnson Matthey), Pd black (Alpha aesar), or Pt and Ru (mixture of Pt black and Ru black) (Alpha aesar) was used as the ORR catalyst. The ORR catalyst loading amount was adjusted to 0.3 mg / cm < ^{2 &} gt ;.

The resulting electrode configuration was named ORR catalyst / OER catalyst / substrate.

The surface morphology and composition of the electrodes were analyzed by FESEM (field emission scanning electron microscope, Inspect F50, Field emission Inc.) and electron probe micro analyzer (JXA-8500F, JEOL).

In order to prepare a hydrogen electrode, catalyst ink composed of 46.5 wt% Pt / C, 5 wt% Nafion solution, IPA and deionized water was sprayed on a commercial carbon paper (10BC, SGL carbon).

Nafion content was 30 wt% and platinum content was fixed at 0.4 mg / cm ² . MEAs were prepared by placing oxygen and hydrogen electrodes on a Nafion membrane (NR-212, Dupont) respectively.

For fuel cell (FC) testing, fully humidified H ₂ and O ₂ gases were injected into the hydrogen and oxygen electrodes, respectively, at a flow rate of 100 mL / min. The current density was raised from 0 to 1.2 A / cm < ² > to obtain an IV curve.

For the water electrolysis (WE) test, deionized water was injected into the oxygen electrode at a flow rate of 15 mL / min. The IV curves of the cells were obtained through a multistage chronoamperometry experiment of 1.35 to 1.8 V. The duration of each step was fixed at 60 seconds.

All measurements were performed at 80 ° C using a potentiostat (HCP-803, biologic) equipped with a power booster.

result

As shown in Table 1, both CP1 and CP2 are made of carbon fibers having a thickness of 7 to 8 mu m, but they differ in roughness factor and porosity.

CP2 has a high porosity, so mass transfer of reactants and products is fast, but the roughness factor is low and electrolyte / electrode interface size is small.

TP is composed of Ti fibers with a thickness of 20 ㎛, and both the roughness factor and porosity are low. However, since it has a relatively hydrophilic surface compared to carbon, it can provide a positive effect during water electrolysis operation.

The EMPA results of _{Pt / IrO 2 / CP1, Pt} / IrO 2 / CP2 and the Pt / IrO ₂ / TP if the oxygen electrode morphology and delivered to be the corresponding plating and then sprayed Pt and Ir is illustrated in Figure 1a-c . Specifically, Figure 1 _{(a) Pt / IrO 2 /} CP1, (b) Pt / IrO 2 / CP2, and _{(c) Pt / IrO 2 /} TP represents the surface morphology support and a corresponding EDS mapping results of the electrode will be.

Porous electrodes having submicrometer size pores were observed regardless of the substrate. The EMPA results show that both Pt and IrO ₂ are uniformly distributed and do not result in significant changes in the macropore structure of the carbon and titanium substrates.

2 is at 80 ℃ of water electrolysis (WE) mode Pt / IrO in _{2 / CP1, Pt / IrO 2} / CP2 and the Pt / IrO ₂ / TP electrode IV curve (Fig. 2a) and of 1.6-1.8V (Fig. 2B) showing the correlation between the current density and the roughness factor of the substrate.

The electrode performance was in the order of Pt / IrO ₂ / CP 1> Pt / IrO ₂ / CP ₂ > Pt / IrO ₂ / TP. It is noteworthy that, as shown in Figure 2b, the electrode performance is roughly related to the roughness factor of the electrode.

Specifically, when the roughness factor was reduced from 35.7 (CP1) to 18.6 (CP2), the current density at 1.7 V decreased from 1.56 A / cm ² to 0.85 A / cm ² .

An additional reduction in the roughness factor from 18.6 to 13.3 also resulted in a reduction of the current density from 0.85 A / cm ² to 0.70 A / cm ² .

This performance difference seems to be related to the change in catalyst utilization depending on the roughness factor of the substrate. In general, the area where the reaction takes place is called the three-phase interface, which is directly affected by the contact area between the electrolyte and the electrode when mass transfer of the reactants is fast enough. Thus, an electrode with a high roughness factor provides more three-phase interfaces and, therefore, good electrode performance.

FIG. 3 shows the IV curves (FIG. 3A) of Pt / IrO ₂ / CP 1, Pt / IrO ₂ / CP ₂ and Pt / IrO ₂ / TP electrodes in the fuel cell mode at 80 ° C. and the current density at 0.5, 0.6, And the roughness factor of the substrate (Fig. 3B).

Pt / IrO ₂ / CP ₂ > Pt / IrO ₂ / TP in the order of Pt / IrO ₂ / CP 1> Pt / IrO ₂ / CP ₂ (see FIG. . Figure 3b also shows a linear relationship between roughness factor and electrode performance.

Figures 2 to 3 show that CP1 in the test substrate exhibits the most excellent catalytic activity due to the high roughness factor.

On the CP1 substrate, a mixture layer of Pt and Ru (Pt-Ru) was formed instead as a low-cost ORR catalyst, and the OER and ORR characteristics were evaluated.

FIG. 4A shows Pd / IrO ₂ / CP 1, FIG. 4B shows surface images of Pt-Ru / IrO ₂ / CP 1 oxygen electrodes and their EDS results.

Like the Pt / IrO ₂ / CP 1 electrode, Pd and Pt-Ru of the porous structure were uniformly distributed on the entire surface of CP 1. Figure 4 also shows that the pore size of the Pd and Pt-Ru layers is submicron scale like the Pt layer.

Pd / IrO ₂ / CP 1 and Pt-Ru / IrO ₂ / CP 1 electrodes were measured and shown in FIG.

That is, FIG. 5 is an IV curve of the Pt-Ru / IrO ₂ / CP 1 electrode during the 80 ° C water electrolysis mode in an embodiment of the present invention. Figure 5 also has a Pt / IrO ₂ / CP1 electrode and a comparative example, IrO ₂ / CP1 electrode of the water electrolytic performance is shown together.

As can be seen in FIG. 5, the water electrolysis performance of the Pt / IrO ₂ / CP ₁ electrode was better than that of the IrO ₂ / CP 1 electrode, which is believed to be due to additional catalytic action on the OER of the platinum.

Figure 5 also shows that represents the Pt-Ru / IrO ₂ / CP1 electrode is lower than the over-voltage ₂ / CP electrode Pt / IrO (overvoltage) at all current densities. This shows that Ru and Pd surfaces for OER are more effective catalyst surfaces than Pt.

FIG. 6 is an IV curve of Pt / IrO ₂ / CP 1, Pd / IrO ₂ / CP 1 and Pt-Ru / IrO ₂ / CP 1 electrodes during a fuel cell mode at 80 ° C. in Examples and Comparative Examples of the present invention.

Unlike the water electrolysis mode, both Pd / IrO ₂ / CP 1 and Pt-Ru / IrO ₂ / CP ₁ were much less effective than Pt / IrO ₂ / CP ₁ because of the relatively low catalytic activity of Pd and Ru than platinum for ORR Because.

FIG. 7 is a graph showing the relationship between the amount of catalyst loaded on Pt / IrO ₂ / CP 1, Pd / IrO ₂ / CP 1 and Pt-Ru / IrO ₂ / 7A) and the current density at 0.6 V (fuel cell mode) (FIG. 7B). Reference values in the literature are also shown in Fig. Non-Patent Document 3-9 (Ref. 3-9) used a mixture of Pt and IrO ₂ as an oxygen electrode catalyst.

Non-Patent Document 3 (Ref. 3) [Pt / IrO ₂ / CP1] is a result of research conducted by the present inventors, and Non-Patent Document 4-9 (Ref. 4-9) .

7, despite the low loading of the catalyst (0.4 mg / cm ² ), the Pd / IrO ₂ / CP 1 and Pt-Ru / IrO ₂ / CP 1 electrodes, While showing excellent performance. This seems to be due to the excellent catalytic activity of the electroplated iridium oxide.

In addition, it shows that from Fig. 7, in particular Pt-Ru / IrO ₂ / CP1 electrode can be used for the URFC. The Pt-Ru / IrO Pt-Ru / IrO cycle efficiency (ε _RT) and the literature value of ₂ / CP1 electrode in ₂ / CP1 in order to evaluate the applicability of the electrode, 0.2, 0.4 A / cm ² in FIG. 8 Respectively.

That is, FIG. 8 according to embodiments of the present invention, 0.2 A / cm ² (Fig. 8a) and 0.4 A / cm ² (Fig. 8b) Pt / IrO ₂ / CP1 and Pt-Ru / IrO ₂ / CP1 in Is the round trip efficiency. Reference values in the literature are described as a comparison in Fig.

As shown in Figure _{8, Pt-Ru / IrO 2} / CP1 electrode showed satisfactory ε _RT when the particular current density of 0.2 A / cm ² days.

More specifically, the 竜_RT of the Pt-Ru / IrO ₂ / CP 1 electrode loaded with 0.15 mg / cm ^{2 of} platinum and iridium oxide at a current density of 0.2 A / cm ² was 0.50, and platinum was 0.2 mg / cm ² And 0.48 for the loaded Pt / IrO ₂ / CP1 electrode. These results show that the Pt-Ru / IrO ₂ / CP1 electrode has a higher performance than the Pt / IrO ₂ / CP1 electrode at a current density of 0.2 A / cm ² despite the lower platinum loading. Therefore, it can be seen from the economic point of view that a Pt-Ru / IrO ₂ / CP 1 electrode is preferred, especially for low currents of less than 0.2 A / cm ² .

Claims (13)

Board;
An IrO ₂ layer formed on the substrate by electroplating; And
(Pt) or a mixture of platinum and ruthenium (Pt-Ru) layer formed on the IrO ₂ layer.
The method according to claim 1,
The surface of the porous substrate having the macro pores was treated with IrO ₂ Layer, and the IrO ₂ layer is coated with IrO ₂ Particles are attached,
The IrO ₂ Layer or IrO ₂ (Pd) or platinum (Pt) or a mixture of platinum and ruthenium (Pt-Ru) is formed on the particles,
Wherein said electrode has a micropore formed by a macropore and porous palladium (Pd) or platinum (Pt) or a mixture of platinum and ruthenium (Pt-Ru) layer by a porous substrate material.
3. The method of claim 2,
The porous substrate material has macropores due to the space between the fibers,
Fiber strands of the porous ceramic material surfaces IrO ₂ Layer is covered by, the IrO ₂ Wherein the IrO ₂ particles are adhered to the layer.
The method according to claim 1,
Wherein the weight of the platinum-ruthenium mixture (Pt-Ru) layer is 0.1-1.0 mg / cm ² and the weight of platinum is 0.05-0.5 mg / cm ² .
The method according to claim 1,
Wherein the roughness factor of the substrate is 30-300.
The method according to claim 1,
Wherein the porosity of the substrate is 30% to 90%.
The method according to claim 1,
Wherein the substrate is a hydrophilic substrate.
The method according to claim 1,
Wherein the substrate is carbon or titanium.
The method according to claim 1,
Wherein the substrate is a titanium paper made of carbon paper or titanium fiber made of carbon fibers.
The method according to claim 1,
Wherein said oxygen electrode is used in a regenerative fuel cell operated at a current density of 0.2 A / cm < ² > or less.
A regenerative fuel cell comprising an oxygen electrode according to any one of claims 1 to 10.
12. The method of claim 11,
Wherein the regenerative fuel cell is an integral regenerative fuel cell.
11. A method of manufacturing an oxygen electrode for a regenerative fuel cell according to any one of claims 1 to 10,
Forming an iridium oxide layer on the substrate by electroplating; And
And forming a palladium (Pd) or platinum (Pt) or a mixture of platinum and ruthenium (Pt-Ru) on the iridium oxide layer.

Images