Durability and Activity Study of Single-Walled, Double-Walled and Multi-Walled Carbon Nanotubes Supported Pt Catalyst for PEMFCs

Pt nanoparticles (2-3 nm) supported on carbon black (C), single-walled carbon nanotubes (SWNT), double-walled carbon nanotubes (DWNT) and multi-walled carbon nanotubes (MWNT) are prepared by an ethylene glycol reduction method. The catalytic activity towards the oxygen reduction reaction (ORR) and the durability of the catalysts are evaluated under condition simulating the environment of proton exchange membrane fuel cell (PEMFCs). The Pt electrochemical surface area (ECSA) of Pt/DWNT and Pt/MWNT degrade 32% after accelerated durability test (ADT), compared with 38% for Pt/SWNT and 48% for Pt/C. The degradation rate of Pt/C is about 1.5 times higher than that of Pt/DWNT. The typical ORR polarization curves of Pt/C, Pt/SWNT, Pt/DWNT and Pt/MWNT obtained before and after ADT are also examined. Before ADT, Pt/DWNT shows the highest catalytic activity towards ORR, followed by Pt/MWNT, Pt/C, and Pt/SWNT in that order. After ADT, the sequence of ORR activity of Pt/C and Pt/SWNT has changed and the overall order is: Pt/DWNT > Pt/MWNT > Pt/SWNT > Pt/C. The Pt/DWNT catalyst shows the highest catalytic activity and the best durability for ORR among the C and CNT supported Pt catalysts.