阅读说明：本技术 一种Pt电极颗粒及其应用 (Pt electrode particle and application thereof ) 是由 贺泽龙 陈孔发 白继元 于 2020-11-02 设计创作，主要内容包括：本发明公开了一种Pt电极颗粒及其应用,采用如下方法获得：(1)将Pt电极浆料涂覆在电解质的一侧表面上,随后在一定温度下退火一段时间,得到Pt电极；(2)将步骤(1)得到的Pt电极在一定温度和一定电流密度的条件下进行极化处理。本发明通过对制备得到的Pt电极在运行温度下进行阴极极化处理,使覆盖在电解质表面的Pt颗粒粒径出现了明显的减小,颗粒数量增加,这使得Pt颗粒与电解质的接触位点增多,从而达到增加三相界面的长度,能够有效提高电极的电催化活性。本发明对Pt电极颗粒进行细化的方法操作简单,整个反应过程较为温和,能够有效提高电极的电催化活性,适用于工业化生产。(The invention discloses a Pt electrode particle and application thereof, which are obtained by adopting the following method: (1) coating the Pt electrode slurry on the surface of one side of an electrolyte, and then annealing for a period of time at a certain temperature to obtain a Pt electrode; (2) and (2) carrying out polarization treatment on the Pt electrode obtained in the step (1) under the conditions of a certain temperature and a certain current density. According to the invention, the prepared Pt electrode is subjected to cathode polarization treatment at the operating temperature, so that the grain diameter of Pt particles covered on the surface of an electrolyte is obviously reduced, the number of the particles is increased, and the contact sites of the Pt particles and the electrolyte are increased, thereby increasing the length of a three-phase interface and effectively improving the electrocatalytic activity of the electrode. The method for refining the Pt electrode particles is simple to operate, the whole reaction process is mild, the electrocatalytic activity of the electrode can be effectively improved, and the method is suitable for industrial production.)

1. A Pt electrode particle characterized by being obtained by a method comprising:

(1) coating the Pt electrode slurry on the surface of one side of an electrolyte, and then annealing for a period of time at a certain temperature to obtain a Pt electrode;

(2) and (2) carrying out polarization treatment on the Pt electrode obtained in the step (1) under the conditions of a certain temperature and a certain current density.

2. The Pt electrode particle according to claim 1, wherein the electrolyte material in step (1) is 8mol% Y₂O₃Doped ZrO₂（YSZ）。

3. The Pt electrode particle according to claim 1, wherein the annealing temperature in the step (1) is 800 to 1400 ℃.

4. The Pt electrode particle according to claim 1, wherein the annealing time in the step (1) is 0.1 to 10 hours.

5. The Pt electrode particle according to claim 1, wherein the temperature of the polarization in the step (2) is 500 to 1000 ℃.

6. The Pt electrode particle according to claim 1, wherein the polarized current density in the step (2) is 1 to 2000 mA/cm²The time for the polarization treatment was 12 hours.

7. The Pt electrode particle of any one of claims 1 to 6, wherein the Pt particle has a particle size of less than 100 nm.

8. Use of the Pt electrode particles as defined in claim 7 for an electrode material of a solid oxide fuel cell.

Technical Field

The invention relates to the technical field of preparation of fuel cell catalytic materials, in particular to Pt electrode particles and application thereof.

Background

A fuel cell is a chemical device that directly converts chemical energy of fuel into electrical energy, and is also called an electrochemical generator. It is a fourth power generation technology following hydroelectric power generation, thermal power generation and atomic power generation. The fuel cell converts the Gibbs free energy in the chemical energy of the fuel into electric energy through electrochemical reaction, and is not limited by the Carnot cycle effect, so the efficiency is high; in addition, the fuel cell uses fuel and oxygen as raw materials, and has no mechanical transmission part, so that the fuel cell has no noise pollution and discharges extremely little harmful gas. It follows that fuel cells are the most promising power generation technology from the viewpoint of energy conservation and ecological environment conservation.

Solid Oxide Fuel Cells (SOFC) belong to the third generation fuel cells, have a wide range of fuel applications, and can use hydrogen, syngas, methane, and the like as fuel. SOFC single cells comprise three parts, a cathode, an anode and an electrolyte. During the electrochemical reaction, the cathode undergoes a reduction reaction of oxygen and the anode undergoes an oxidation reaction of the fuel. The region of the cathode where the oxygen reduction reaction occurs can receive electrons and oxygen from the outside and can also transport the generated oxygen ions to the anode through the electrolyte, so that the three-phase boundary of the electron-conducting phase, the gas phase and the ion-conducting phase is called a three-phase interface. Similarly, the anode region where the fuel oxidation reaction is carried out can receive the transported oxygen ions and fuel and can conduct the generated electrons to an external circuit, and the region is also the three-phase boundary of the electron-conducting phase, the gas phase and the ion-conducting phase. Therefore, the length of the three-phase reaction interface is an important factor affecting the electrochemical performance of the SOFC.

Pt is a good electrocatalytic material, and in the prior art, when Pt is applied to an SOFC, the Pt is covered on an electrolyte only through coating and annealing treatment, but because Pt only has electronic conduction capacity, the three-phase reaction interface length of a Pt electrode is limited and can only be limited at an electrode/electrolyte interface. Therefore, how to increase the length of the three-phase interface of the Pt electrode and improve the electrocatalytic activity of the electrode is a problem to be solved by those skilled in the art.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide Pt electrode particles and application thereof, so as to solve the problems that the three-phase reaction interface length of a Pt electrode is limited and the electrocatalytic activity of the electrode is limited in the prior art.

A Pt electrode particle obtained by the method of:

(1) coating the Pt electrode slurry on the surface of one side of an electrolyte, and then annealing for a period of time at a certain temperature to obtain a Pt electrode;

(2) and (2) carrying out polarization treatment on the Pt electrode obtained in the step (1) under the conditions of a certain temperature and a certain current density.

Preferably, the electrolyte material in step (1) is 8mol% Y₂O₃Doped ZrO₂（YSZ）。

Preferably, the annealing temperature in the step (1) is 800-1400 ℃.

Preferably, the annealing time in the step (1) is 0.1-10 h.

Preferably, the temperature for polarization in the step (2) is 500-1000 ℃.

Preferably, the current density of the polarization in the step (2) is 1-2000 mA/cm²The time for the polarization treatment was 12 hours.

A Pt electrode particle according to the present invention, wherein the Pt particle has a particle size of less than 100 nm.

The invention relates to application of Pt electrode particles, in particular to the application of the refined Pt electrode particles in the electrode material of a solid oxide fuel cell.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, after the prepared Pt electrode is heated and electrified, the grain size of Pt particles covering the surface of the electrolyte is obviously reduced, so that more Pt particles can cover a three-phase reaction interface, and pores between the Pt electrode and the electrolyte interface are filled as much as possible, thus the length of the three-phase interface is increased, and the electrocatalytic activity of the electrode can be effectively improved.

2. The particle size of the Pt particles is less than 100nm, the surface area of the electrode is large, and the active sites in contact with the electrolyte are more, so that the electrocatalytic activity is obviously increased, and the Pt particles applied to the catalytic material of the solid oxide fuel cell have the characteristics of small polarization resistance and good stability.

3. The preparation method of the Pt electrode particles is simple to operate, the whole reaction process is mild, the electrocatalytic activity of the electrode can be effectively improved, and the preparation method is suitable for industrial production.

Drawings

FIG. 1 is a surface SEM topography of a Pt electrode of comparative example 1 annealed at 1100 deg.C for 2 h.

Fig. 2 is an SEM image of the interface-refined Pt particles obtained in example 1.

Fig. 3 is a graph showing internal resistance of the Pt electrode obtained in example 1 during anodic polarization.

Fig. 4 is an SEM image of the interface-refined Pt particles obtained in example 2.

Fig. 5 is a graph showing the internal resistance of the Pt electrode obtained in example 2 during the anodic polarization.

Fig. 6 is a graph of internal resistance of the Pt electrode in comparative example 2 under an open-circuit condition.

Detailed Description

The invention will be further explained with reference to the drawings and the embodiments.

A Pt electrode particle is obtained by adopting the following method:

(1) and coating the Pt electrode slurry on one side surface of the electrolyte, and then heating the electrolyte coated with the Pt electrode slurry to 800-1400 ℃, preferably 1100 ℃, and carrying out annealing treatment for 0.1-10 h, preferably 2h to obtain the Pt electrode.

Wherein the electrolyte material is 8mol% of Y₂O₃Doped ZrO₂（YSZ）。

(2) Heating the Pt electrode obtained in the step (1) to 500-1000 ℃ for anode polarization treatment, preferably 800 ℃, and introducing a polarization current with the current density of 1-2000 mA/cm²And the polarization time is 12h, and the treated Pt electrode is finally obtained. The particle size of the Pt electrode particles obtained by the above method is less than 100 nm.

When Pt is applied to a fuel cell, it is found that although Pt is a good electrocatalytic material, electrocatalysis limited to the interface where the Pt electrode contacts the electrolyte, that is, the three-phase interface, and if the electrocatalytic activity of the electrode is to be improved, it is necessary to increase the length of the three-phase reaction interface. When the fuel cell length is fixed, it becomes a problem how to attach as many Pt particles as possible to the electrolyte interface. When the three-electrode method is used for detecting the Pt electrode, the fact that if the temperature of the environment where the Pt electrode is located is changed and anode polarization current is introduced at the same time is found out unexpectedly, detection data show that the polarization resistance Rp of the Pt electrode can be changed. Intensive research shows that when anode polarization current is applied to the Pt electrode under a heating condition, the polarization resistance Rp of the Pt electrode is continuously reduced, so that the electrocatalytic activity of the Pt electrode is continuously improved. Further observing the Pt electrodes before and after polarization treatment, the Pt particles attached to the electrolyte surface have larger particle size after the Pt is coated on the electrolyte surface and annealed by the prior art, and the Pt particles attached to the electrolyte surface of the Pt electrode treated by the method have smaller particle size, so that under the condition of the same geometric dimension of the fuel cell, more Pt particles can be attached to the electrolyte interface obtained by the method, more Pt particles participate in the electrochemical reaction process, the length of a three-phase reaction interface is effectively increased, and the electrocatalytic activity of the electrode is improved.

Second, examples and comparative examples

TABLE 1

Examples	Electrolyte material	Annealing temperature (. degree.C.)	Annealing time (h)	Polarization current density (mA/cm)2）	Polarization temperature (. degree.C.)	Polarization time (h)
							1	YSZ	1100	2	500	800	12
2	YSZ	1100	2	200	800	12
							Comparative example 1	YSZ	1100	2	--	--	--
Comparative example 2	YSZ	1100	2	0	800	40

Note: - -indicates that the operation was not performed.

Scanning electron microscope observation of the Pt electrodes obtained in examples 1-2 and comparative example 1 revealed that the particle size of Pt particles on the Pt electrode changed, FIG. 1 is an SEM surface morphology of a Pt electrode obtained by annealing treatment in comparative example 1, wherein the Pt electrode forms a large sintered region with large particles having an average grain size of about 1.9 μm, and the size of the Pt electrode particles begins to change as polarization progresses, as can be observed by comparing fig. 1 and 2, the Pt particles of example 1 were refined after polarization treatment, wherein the average particle size of Pt particles dispersed on the surface of the electrolyte is less than 50nm (see upper right corner of FIG. 2), the average particle size of the remaining larger clusters is less than 100nm (see lower right corner of FIG. 2), fig. 4 also demonstrates that the Pt particles at the Pt electrode interface obtained in example 2 are also refined.

The polarization process of the embodiment 1-2 is detected by adopting a three-electrode method to obtain figures 3 and 5, and it can be seen from the two figures that the polarization resistance Rp of the battery is continuously reduced along with the progress of the polarization process, which proves that the electrocatalytic activity of the electrode is continuously improved, so that the polarization treatment process can effectively reduce the particle size of Pt particles, and more Pt particles can be covered between the electrode/electrolyte interface on the Pt electrode, thereby increasing the length of a three-phase interface and improving the electrocatalytic activity of the electrode. After the Pt electrode prepared in comparative example 2 is subjected to resistance detection, referring to fig. 6, since comparative example 2 is not treated by the method of the present invention, the polarization resistance Rp of the Pt electrode increases with time when the stability test is performed under the condition of no applied current, which also proves that the Pt electrode treated by the method of the present invention has the advantages of good electrochemical activity and high stability.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the technical solutions, and those skilled in the art should understand that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all that should be covered by the claims of the present invention.