Enhanced-electrocatalytic activity of Pt nanoparticles supported on nitrogen-doped carbon for the oxygen reduction reaction

Spillover, a well-known phenomenon in heterogeneous catalysis referring to the transport of the adsorbed intermediates over the catalyst/support interface, could enhance the catalytic performance by providing additional active sites. Here, we report the spillover-promoted electrocatalytic activity of Pt supported on nitrogen-doped carbon black (NCB) for the oxygen reduction reaction (ORR). By treating Vulcan XC-72R carbon black (CB) at 600 degrees C under gaseous NH3, NCB of near 1 at% surface nitrogen content is obtained. The catalyst of Pt supported on NCB (Pt/NCB) exhibits simultaneously smaller particle sizes and higher electrochemical surface area and electrocatalytic activity for the ORR than the catalyst of Pt supported on pristine CB (Pt/CB) prepared with the same impregnation method. Particularly, the activity enhancement of Pt/NCB over Pt/CB surpasses that expected due to the surface area increase, which seems to conflict with the common belief that Pt nanoparticles of smaller sizes would have lower area specific activities for the ORR. Cyclic voltammetric responses of these catalysts implied that the oxygenated adsorbates formed on Pt can transport to surface of the NCB support, which may be responsible for the increased area specific activity of the Pt/NCB catalyst. (C) 2013 Elsevier B.V. All rights reserved.