On the preparation methods for carbon nanofiber-supported Pt catalysts

A study of the suitability of different methods for preparing highly loaded, well dispersed carbon nanofiber (CNF) supported Pt catalysts intended for application in fuel cells is reported. Preparation routes that are successfully applied on conventional carbon supports are hampered by the lower surface area and number of surface groups on CNFs. Ion exchange, homogeneous deposition precipitation and impregnation are all techniques that are limited to low metal loading on this CNF support. The most promising methods are the colloidal methods. By the modified polyol method, a Pt-content of 24 wt% with a particle size of 2-4 nm was achieved. CNFs could also be completely covered by 2-3 nm Pt oxide particles by using the metal-oxide colloid route, reaching a Pt-content of 17 wt%. The merits that make these methods more suitable than the other methods and the mechanism for deposition of Pt particles on CNFs are discussed.