Composite particles of core-shell structure including metal oxide particle core and platinum-group transition metal shell, and electrochemical reaction electrode material including same

1 . Composite particles of a core-shell structure, comprising:

a core containing a metal oxide; and

a shell containing a platinum-group transition metal surrounding the metal oxide,

wherein the metal oxide has a maximum absorption wavelength at 250 to 550 nm, and

wherein the shell has a thickness of 3 to 50 nm.

2 . The composite particles of a core-shell structure of claim 1 , wherein the metal oxide is niobium oxide.

3 . The composite particles of a core-shell structure of claim 1 , wherein the platinum-group transition metal is platinum (Pt).

4 . The composite particles of a core-shell structure of claim 1 , wherein primary particles of the metal oxide have a diameter of 3 to 1,000 nm.

5 . The composite particles of a core-shell structure of claim 1 , wherein the platinum-group transition metal of the shell is prepared from a photoreduction reaction of a platinum-group transition metal precursor.

6 . The composite particles of a core-shell structure of claim 1 , wherein the metal oxide is a catalyst support for platinum-group transition metal-based electrochemical reactions including an oxygen reduction reaction.

7 . A catalyst for platinum-group transition metal-based electrochemical reactions including an oxygen reduction reaction, containing the composite particles of a core-shell structure of claim 1 .

8 . The catalyst of claim 7 , wherein the catalyst for platinum-group transition metal-based electrochemical reactions including an oxygen reduction reaction includes a plurality of composite particles of a core-shell structure, wherein the plurality of composite particles aggregate with each other to form an aggregate and to make an electrically-conductive contact to each other.

9 . The catalyst of claim 7 , wherein the catalyst for platinum-group transition metal-based electrochemical reactions including the oxygen reduction reaction includes 5% by weight or less of carbon.

10 . An electrode comprising the composite particles of a core-shell structure of claim 1 .

11 . A platinum-group transition metal-based electrochemical conversion device, comprising the composite particles of a core-shell structure of claim 1 .

12 . A fuel cell comprising:

an anode;

an electrolyte membrane; and

a cathode including the composite particles having a core-shell structure of claim 1 applied to one side of the electrolyte membrane.

13 . A fuel cell of claim 12 , wherein the cathode includes 5% by weight or less of carbon.

14 . A method for preparing the composite particles of a core-shell structure, comprising:

(a) preparing a dispersion by dispersing metal oxide particles having a maximum absorption wavelength at 250 to 550 nm in an alcohol solution;

(b) preparing a mixed solution by mixing an aqueous solution of a platinum-group transition metal precursor with the dispersion; and

(c) preparing composite particles of a core-shell structure comprising a shell having a thickness of 3 to 50 nm by irradiating the mixed solution with light.

15 . The method of claim 14 , wherein the platinum-group transition metal precursor is a water-soluble platinum-group transition metal precursor.

16 . The method of claim 14 , wherein the metal oxide particles have a band gap of 2.0 eV or more.

17 . The method of claim 14 , wherein the metal oxide particles in step (a) are prepared from:

preparing a metal oxide solution dissolved in hydrofluoric acid;

preparing a diluted solution by mixing the metal oxide solution with water;

preparing a precipitate by mixing the diluted solution with a reducing agent to adjust a pH to basic; and

performing heat treatment on the precipitate.