▎ 摘　　要

In this paper, we demonstrate two novel green synthesis methods for preparing platinum-graphene catalysts for proton exchange membrane fuel cell (PEMFC) applications. Starting from graphite oxide, the platinum precursor is added and the composite is separately subjected to (a) focused solar radiation and (b) hydrogen gas, for carrying out simultaneous reduction of graphite oxide to graphene and platinum complexes to platinum nanoparticles. These co-reduction methods employ a single agent, namely either sunlight or hydrogen gas, to accomplish the reduction process. Both techniques are therefore cost and energy effective and capable of large scale production. Rotating disc electrode (RDE) and PEMFC measurements reveal the high performance of these electrocatalysts as compared to commercial Pt-C electrocatalysts due to high oxygen reduction reaction (ORR) activity. Stability studies show that both catalysts are highly stable under acidic medium. The proposed methods are quite general in their applicability and we believe that these can be extended for synthesizing a wide variety of electrocatalysts such as various metal, metal oxide or metal alloy nanoparticle decorated carbon nanostructures.