A high performance polybenzimidazole–CNT hybrid electrode for high-temperature proton exchange membrane fuel cells

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). Pt nanoparticles (NPs) of typically 2.5 nm diameter have been deposited uniformly on the electrode composed of either CNT/CC or carbon black on carbon cloth (CB/CC). Comparative study of 0.1 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 (0.1 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 643 mW cm−2 and 468 mW cm−2, respectively, at 160 °C. Notably, the Pt-loading of a Pt/PBI–CNT/CC cell is one eighth of that of the Pt/PBI–CB/CC cell, while the former outperforms the latter by approximately 38%. 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.