Last modified: 2014-10-08
Abstract
Nitrogen-doped CNTs directly grown on a carbon cloth (CNT/CC) hybrid with polybenzimidazole (PBI) are utilized as hybrid electrodes for high-temperature proton exchange membrane fuel cells (HT-PEMFCs). The use of rotation holder for Pt nanoparticles (NPs) deposition on CNTs electrode has been developed. The electrochemical surface area of Pt NPs/CNTs is about 161cm2 mg-1 and its grain size is about 8~9 nm. Comparative study of 0.14 mg cm-2 Pt NPs on a PBI–CNT (Pt/PBI–CNT) electrode and 0.8 mg cm-2 Pt NPs on PBI–carbon black (Pt/PBI–CB) for oxygen reduction in the cathode has been performed. In H2/O2 HT-PEMFC single cell tests, the low Pt-loaded (0.14 mg cm-2) Pt/PBI–CNT/CC electrode outperforms the high Pt-loaded (0.8 mg cm-2) Pt/PBI–CB/CC electrode with maximum power densities of 620 mW cm-2 and 468 mW cm-2, respectively, at 160 C. The enhancement is attributed to good interfacial continuity between the PBI membrane and the carbon cloth and the uniform dispersion of the catalyst on the PBI–CNT surface, leading to the formation of three-phase contacts, which is essential for the activity of the catalyst.