Patent ID: 7312174
Filing Date: 2007-12-25
Classification: C23C,H01M,Y02E

Abstract:
1. A method for preparing particles of a platinum metal element on a carbon substrate that comprises the steps of: (a) contacting a carbon substrate having a surface area of about 100 to about 2500 m.sup.2/g with an aqueous solution of a dissolved platinum metal element complex present at a pH value of about 2 to about 4 where said platinum metal element is present as an anionic complex and at a pH value of about 10.5 to about 13 where said platinum metal element is present as a cationic complex, whereby said carbon substrate has a higher PZC value at said low pH values or said carbon substrate has a lower PZC at said high pH values provides greater adsorption of said platinum metal element complex than the reverse usage; (b) maintaining said contact at said pH value for a time period sufficient for said platinum metal element complex to adsorb onto said substrate to form a platinum metal complex-loaded substrate; (c) heating said platinum metal complex-loaded substrate under reducing conditions to form particles of a platinum metal element on said carbon substrate.