Curvature-induced metal-support interaction of an islands-by-islands composite of platinum catalyst and carbon nano-onion for durable oxygen reduction

Abstract

Platinum nanoparticles supported by carbon (Pt/C) have been the most popular catalysts for cathodes of fuel cells. Du-rable operation of fuel cells based on Pt/C suffers from (1) loss of active Pt mass caused by carbon corrosion and (2) Pt particle agglomeration during operation. To address the issues of the conventional carbon supports, here we present carbon nano-onion (CNO), a new class of carbon allotrope, as a support for Pt catalysts. CNO had the spherical shape with 3 to 5 nm in diameter consisting of ~5 concentric graphitic layers. Superior durability of catalytic oxygen reduc-tion reaction (ORR) was guaranteed by Pt supported by CNO (Pt/CNO) due to: (1) the islands-by-islands configuration of the Pt/CNO composites (c.f. islands-on-a-particle configuration for Pt/C) to isolate each Pt nanoparticle from its neighbors by the same-size CNO particles and to suppress Ostwald ripening by highly tortuous void structure; (2) the curvature-induced strong interaction between CNO and Pt; and (3) the graphite-like concentric layers guaranteeing corrosion resistivity.