A team from the East China University of Science and Technology in Shanghai reports in a paper accepted for publication in the RSC journal Chemical Communications that platinum (Pt) supported on graphene sheets showed excellent durability as a catalyst for the oxygen reduction reaction (ORR) in fuel cells. Further, they found that their GNS, when used as a metal-free catalyst for ORR, showed a performance even better than a commercial Pt/C catalyst from Johnson Matthey.
They synthesized the graphene sheets (GNS) continuously by spray pyrolysis of iron carbonyl and pyridine. They then prepared Pt/GNS catalysts and Pt-free GNS catalysts; the Pt loading on GNS was ~25 wt.%
They then electrochemically tested Pt/GNS in 0.5M H2SO4 and GNS Pt-free catalyst in 0.1 M KOH.
To prepare the Pt/GNS electrode, they dispersed Pt/GNS catalyst in a mixture of methanol and 5 wt.% Nafion solution with a weight ratio of 50:1. The mixture was agitated by ultrasonication for 30 minutes to form an ink. A given amount of this ink was then dropped on the electrode and dried to yield a thin-film electrode. The Pt loading on the RDE was ~23 μg cm-2.
To prepare the platinum-free electrode, they dispersed mg of GNS in a mixture of methanol and 5 wt.% Nafion solution with a weight ratio of 50:1. The mixture was agitated by ultrasonication for 30 min to form an ink. Then a given amount of this ink was dropped on the electrode and dried to form a thin-film electrode. The GNS loading on the RDE was controlled to be 0.71 mg cm-2.
Jian Nong Wang, Biao Zou, Xiao Xia Wang and Xin Xin Huang (2014) “Continuous synthesis of graphene sheets by spray pyrolysis and their uses as catalysts for fuel cells”, Chemical Communications doi: 10.1039/C4CC08197H