Influence of Pyridine‐Polybenzimidazole Film Thickness of Carbon Nanotube Supported Platinum on Fuel Cell Applications

Pyridine‐polybenzimidazole (PyPBI) films of different thickness (～1.0–2.4 nm) are wrapped on the surfaces of multi‐walled carbon nanotubes (CNTs). To prepare Pt on PyPBI/CNT (Pt‐PyPBI/CNT) catalysts, Pt⁴⁺ ions are immobilized on these PyPBI wrapped CNTs (PyPBI/CNTs) via Lewis acid‐base coordination between Pt⁴⁺ and :N‐ of imidazole groups, followed by reducing Pt⁴⁺ to Pt nanoparticles. The influence of PyPBI film thickness on the Pt particle size, loading and electrochemical surface area, respectively, of Pt‐PyPBI/CNTs is investigated. Fuel cell performances of the PBI/H₃PO₄ based membrane electrode assemblies (MEAs) prepared from these Pt‐PyPBI/CNT catalysts are also evaluated at 160 °C with unhumidified H₂/O₂ gases. Among the catalysts, the Pt‐PyPBI/CNT catalyst with a PyPBI film thickness of ～1.6 nm (which is around half of the Pt particle size), a Pt loading of ～44 wt.%, and a Pt particle size of ～3.3 nm exhibits the best fuel cell performance.