Cobalt encapsulated in the nitrogen and sulfur co-doped carbon nanotube supported platinum for the oxygen reduction reaction catalyst

Abstract

In this paper, cobalt encapsulated in nitrogen and sulfur co-doped carbon nanotube (Co-NST) was synthesized through a simple pyrolysis method to impregnate platinum (Pt) nanoparticles. The Co-NST presented a bamboo-like morphology with the high degree of graphitization. Owing to the dual heteroatoms co-doped in the carbon matrix, the Pt supported on the Co-NST (Pt/Co-NST) showed the well-dispersed morphology of the Pt nanoparticles. In addition, the synergistic effect between the Co-NST support and the Pt nanoparticle was observed from the physicochemical characterizations. As a result, the Pt/Co-NST presented improved oxygen reduction reaction (ORR) activity and stability compared to the commercial Pt/C. The mass activity and specific activity of the Pt/Co-NST presented 508.48 mA mg(pt)(-1) and 723.93 mu A cm(pt)(-2), respectively, which exhibited more than 3 times higher compared to those of the commercial Pt/C. After repeating 5000 potential cycles, the Pt/Co-NST showed improved stability with 29 mV loss in half-wave potential, while the half-wave potential of the commercial Pt/C was severely decreased by 118 mV.