Nitrogen-Doped Carbon Nanosphere Supports for Platinum-Decorated Oxygen Reduction Reaction Catalysts

Abstract

Carbonaceous materials are widely used as supports for platinum-based oxygen reduction reaction (ORR) catalysts that are prevalent in proton exchange membrane fuel cells (PEMFC). In particular, a variety of carbon blacks are popular due to factors such as commercial availability and high surface area. However, as applications of PEMFCs shift towards heavy-duty vehicle deployment, durability of the supports has become an important criterion when evaluating materials. Carbon support corrosion can lead to Pt nanoparticle detachment and agglomeration, both of which decrease the electrochemically active surface area of the catalyst. Recently, nitrogen-doping of carbon supports has shown promising results towards improving stability in fuel cell operating conditions 1 . Graphitization is another strategy that mitigates carbon corrosion, as graphitic carbon is more resistant to oxidation than amorphous carbon 2 . In this work, we present a set of nitrogen-doped carbon nanosphere supports obtained via a one-pot colloidal synthesis and then decorated with Pt nanoparticles for ORR catalysis (Pt/NCS). The nitrogen-doped supports are monodispersed, contain a mesoporous pore structure, and show a higher level of bulk graphitization than commercial carbon blacks. Our work also elucidates how differences in certain nitrogen moieties on the carbon support’s surface impact catalytic activity. The Pt/NCS catalysts exhibit similar mass activity and improved specific activity in rotating disk electrode measurements compared to a commercial Pt/C catalyst at similar Pt weight loadings. (1) Ott, S.; Orfanidi, A.; Schmies, H.; Anke, B.; Nong, H. N.; Hübner, J.; Gernert, U.; Gliech, M.; Lerch, M.; Strasser, P. Ionomer Distribution Control in Porous Carbon-Supported Catalyst Layers for High-Power and Low Pt-Loaded Proton Exchange Membrane Fuel Cells. Nat. Mater. 2020 , 19 (1), 77–85. (2) Yu, P. T.; Gu, W.; Zhang, J.; Makharia, R.; Wagner, F. T.; Gasteiger, H. A. Carbon-Support Requirements for Highly Durable Fuel Cell Operation. In Polymer Electrolyte Fuel Cell Durability ; Büchi, F. N., Inaba, M., Schmidt, T. J., Eds.; Springer New York: New York, NY, 2009; pp 29–53.