Carbonization over PFA-protected dispersed PtRu: The CPDM route to synthesize high performance electrocatalysts on mesoporous support

Abstract

Ordered mesoporous carbons have been widely investigated as supports for fuel cell catalysts. These structures are synthesized via carbonization of mesoporous silica templates. Loading Pt and PtRu into the high surface area mesoporous carbon supports faces problems of clustering metal nanoparticles, loss of Pt from precursor, and uneven composition of Pt:Ru. An alternative route of synthesizing mesoporous carbon supported Pt nanoparticles has been proposed[1] to overcome these problems. In reverse order to the conventional route of ethylene glycol method, carbonization occurs after dispersion of platinum. H2PtCl6 acts as a Pt source and serves as a catalyst for the polymerization of furfuryl alcohol (FA). The polymerized FA functions as a protecting agent and prevents the growth of Pt nanoparticles in the later high temperature carbonization step. The resulting Pt nanoparticles are highly dispersed and give much higher methanol oxidation current. We report the extension of the method to synthesize CMK-3 supported PtRu nanoparticles. We denote this 'carbonization over PFA-protected dispersed metal' (CPDM) method. High dispersion with uniform Pt:Ru have been achieved. Fig. 1(b) sees the localization of PtRu nanoparticles near the surface of a CMK-3 particle, as synthesized via the EG route. The PtRu/CMK-3 electrocatalysts synthesized via the proposed CPDM route show uniform dispersion in Fig. 1(c). Higher and more sustained activity towards methanol oxidation is observed.[p][1] Fujun Li, Kwong-Yu Chan* and Hoi Yung, J. Mater. Chem. 2011 , 21, 12139.