SUPPORTED NOBLE METAL CATALYST, PREPARATION METHOD THEREFOR AND USE THEREOF

Abstract

A method for preparing a supported noble metal catalyst, comprising: i) melting a noble metal sponge, a peroxide, and a support and/or a support precursor together; ii) dispersing the molten mixture in water; and iii) adjusting the pH to 4 to 10, thereby obtaining a supported noble metal catalyst. The method uses a noble metal sponge rather than an intermediate noble metal precursor, such as a noble metal nitrate salt, a noble metal halide salt, a halogenated noble metal acid, or a salt of the halogenated noble metal acid, for example, H.sub.3IrCl.sub.6, H.sub.2IrCl.sub.6, or IrCl.sub.3. The method does not produce any intermediate product, and does not use any chlorine-containing material, thereby avoiding contamination of the final catalyst by chlorine. The catalyst produced by the present invention has high activity, high surface area, and the RDE OER overpotential is less than 230 mV (at 10 mA cm.sup.2).

Claims

1. A supported noble metal catalyst, comprising a support and a noble metal supported on the support, wherein the content of the noble metal is from 10 wt % to 65 wt %, preferably from 35 wt % to 65 wt %, based on the total weight of the supported noble metal catalyst, and the catalyst has an RDE OER overpotential below 230 mV at 10 mA cm.sup.?2.

2. The supported noble metal catalyst according to claim 1, wherein the noble metal is a platinum group metal, preferably Ru, Rh, Pd, Pt, Os, or Ir, more preferably Ru, Pt, or Ir, and most preferably Ir.

3. The supported noble metal catalyst according to claim 1, wherein in the supported noble metal catalyst, the noble metal is in the form of a metal and/or an oxide thereof, preferably in a mixed form of a metal and an oxide thereof.

4. The supported noble metal catalyst according to claim 1, wherein the supported noble metal catalyst has a surface area higher than 100 m.sup.2/g, preferably from 105 m.sup.2/g to 500 m.sup.2/g, as measured by means of nitrogen adsorption according to a BET method.

5. The supported noble metal catalyst according to claim 1, wherein the support is an oxide of Si, Ti, Al, Sn, Ta, Mg, or a rare earth metal, and/or a mixture of the oxides, preferably an oxide of Ti, Si, or Al, and/or a mixture of the oxides.

6. A method for preparing the supported noble metal catalyst according to claim 1, comprising the following steps: i) melting a noble metal sponge, a peroxide, and a support and/or a support precursor together; ii) dispersing the molten mixture in water; and iii) adjusting the pH to 4 to 10, thereby obtaining a supported noble metal catalyst.

7. A method for preparing a supported noble metal catalyst, comprising the following steps: i) melting a noble metal sponge, a peroxide, and a support and/or a support precursor together; ii) dispersing the molten mixture in water; and iii) adjusting the pH to 4 to 10, thereby obtaining a supported noble metal catalyst.

8. The method according to claim 6, wherein the melting in step i) is performed at a temperature between 300? C. to 1000? C., preferably between 500? C. to 700? C. and/or the melting time is from 1 h to 12 h, preferably from 2 h to 7 h.

9. The method according to claim 6, wherein the water used in step ii) is ultrapure water or deionized water, preferably deionized water, the water having a temperature of below 100? C., preferably between 20? C. to 40? C.

10. The method according to claim 6, wherein in step iii), the pH is adjusted to 6 to 8.

11. The method according to claim 10, wherein the pH adjustment is performed using an acid, preferably using a chlorine-free acid, and more preferably an inorganic acid or organic acid, e.g., HNO.sub.3, HNO.sub.2, H.sub.2SO.sub.4, or CH.sub.3COOH.

12. The method according to claim 6, wherein step iii) is performed under heating, preferably at a temperature between 60? C. to 110? C., and more preferably between 90? C. to 110? C.

13. The method according to claim 6, wherein after step iii), a precipitate of the obtained supported noble metal catalyst is filtered, washed, and dried.

14. The method according to claim 6, further comprising the following steps performed after step iii): iv) filtering and calcining; v) washing the calcination product with water until the conductivity of the water is less than 100 s cm.sup.?1; and vi) drying the washed product.

15. Use of the supported noble metal catalyst according to claim 1 in an electrolysis device or a fuel cell.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0080] FIG. 1 shows an XRD spectrum of the supported IrOx catalyst obtained in Example 1. In addition, FIG. 1 also shows XRD spectrums of Ir, IrO.sub.2, and TiO.sub.2.

[0081] FIG. 2 is a graph of an RDE test of the supported IrOx catalyst obtained in Example 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0082] The present invention will be described below with reference to examples, but the scope of the present invention is not limited thereto.

Measurement Methods

[0083] XRD was measured using a Empyrean X-ray diffractometer obtained from Malvern Panalytical (Netherlands) to perform sample testing in a 20 range of 5? to 90? at a rate of 2?/min.

[0084] The overpotential of the oxygen evolution reaction in a rotating disk electrode measurement setup (RDE OER) was measured according to the following method: using a 0.1 mol/L perchloric acid solution as an electrolyte; in a three-electrode system of a PINE rotating disk electrode and an electrochemical workstation, using a saturated Ag/AgCl electrode as a reference electrode; and introducing nitrogen first to perform cyclic voltammetry (CV) activation, then introducing oxygen until saturation, and performing an OER test.

[0085] The BET specific surface area was measured using a Belsorp-mini X physical adsorption tester obtained from MicrotracBEL (Japan), wherein the specific surface area of the sample was measured using a static volume method.

EXAMPLES

Example 1

[0086] 1 g SiO.sub.2 powder, 2 g TiO.sub.2 powder, 3 g iridium sponge and 30 g sodium peroxide powder were mixed homogeneously. The mixture was loaded in a crucible and heat-treated in a muffle furnace at 600? C. for 3 h and was cooled to room temperature and removed. Then, deionized water was added and the pH was adjusted to 7 by the addition of nitric acid. The solution was then heated to 95? C. until a precipitate was formed. The solids were filtered, placed in the crucible again and heat-treated in the muffle furnace at 400? C. for 3 h, and cooled to room temperature and removed. Finally, the resulting solid powder was washed with deionized water until the conductivity of the water was 8 s cm.sup.1, and drying was performed to obtain the finished product.

Example 2

[0087] 1 g SiO.sub.2 powder, 1 g TiO.sub.2 powder, 3 g iridium sponge, and 30 g sodium peroxide powder were mixed homogeneously. The mixture was loaded in a crucible and heat-treated in a muffle furnace at 600? C. for 3 h, and was cooled to room temperature and removed. Then, deionized water was added and the pH was adjusted to 7 by the addition of nitric acid. The solution was then heated to 95? C. until a precipitate was formed. The solids were filtered, then placed in the crucible again and heat-treated in the muffle furnace at 300? C. for 4 h, and cooled to room temperature and removed. Finally, the resulting solid powder was washed with deionized water until the conductivity of the water was 6 ?s.Math.cm.sup.?1, and drying was performed to obtain the finished product.

Example 3

[0088] 1.5 g SiO.sub.2 powder, 0.5 g Al.sub.2O.sub.3 powder, 4 g iridium sponge, and 30 g sodium peroxide powder were mixed homogeneously. The mixture was loaded in a crucible and heat-treated in a muffle furnace at 600? C. for 3 h, and was cooled to room temperature and removed. Then, deionized water was added and the pH was adjusted to 6.5 by the addition of nitric acid. The solution was then heated to 95? C. until a precipitate was formed. The solids were filtered, then placed in the crucible again and heat-treated in the muffle furnace at 300? C. for 3 h, and cooled to room temperature and removed. Finally, the resulting solid powder was washed with deionized water until the conductivity of the water was 5 ?s.Math.cm.sup.?1, and drying was performed to obtain the finished product.

[0089] The performance of the supported IrOx catalysts obtained is shown in Table 1.

TABLE-US-00001 TABLE 1 Iridium content BET (N.sub.2, m.sup.2/g) OER overpotential (mV) Example 1 42% 175 205 Example 2 48% 233 205 Example 3 57% 111 215