Method for producing alloy catalyst for fuel cells using silica coating

A method for producing an alloy catalyst supported on carbon, comprising the steps of:

• (1) dispersing ahoy particles, having a size of 2-10 nm, into a mixed solution of water with alcohol, introducing a silica precursor thereto, carrying out sol-gel reaction in the presence of a basic catalyst to obtain silica-coated ahoy particles,
• the silica precursor is selected from TEOS (tetraethyl orthosilicate), TMOS (tetramethyl orthosilicate), TBOS (tetrabutyl orthosilicate) and a mixture thereof,
• the basic catalyst in the sol-gel reaction is selected from aqueous ammonia, sodium hydroxide and potassium hydroxide,
• the sol-gel reaction is carried out at 10-50° C. for 3-48 hours under agitation;
• (2) recovering the silica-coated ahoy particles;
• (3) supporting the recovered silica-coated alloy particles onto a carbon carrier to obtain silica-coated alloy particles supported on carbon;
• wherein the silica coating has a thickness of 3-50 nm;
• (4) heat treating the silica-coated alloy particles supported on carbon to increase the alloying degree, wherein the alloy particles retain the size of 2-10 nm;
• and
• (5) removing the silica coating from the silica-coated alloy particles by using either (i) aqueous hydrofluoric acid (HF) solution and a surfactant or (ii) inorganic base solution and a surfactant;
• wherein the surfactant is a non-ionic surfactant selected from polyoxyethylene glycol sorbitan fatty acid esters, sorbitan fatty acid esters, and polyoxyethylene alkyl ethers;
• wherein the heat treatment in step (4) is carried out under inert gas atmosphere of argon or nitrogen, or mixed gas atmosphere of argon or nitrogen with hydrogen at 400-1000° C. for 2-4 hours to increase the alloying degree.