An Electrocatalyst Based on Carbon Nanotubes Coated with Poly(vinylpyrrolidone) Shows a High Tolerance to Carbon Monoxide in a Direct Methanol Fuel Cell

We describe a facile method to enhance the CO tolerance of a fuel-cell electrocatalyst dramatically based on carbon nanotubes. The electrocatalyst is composed of Pt deposited on carbon nanotubes wrapped in poly[2,2′-(2,6-pyridine)-5,5′-bibenzimidazole] (PyPBI) further covered by poly(vinylpyrrolidone) (PVP) through multipoint hydrogen bonding interactions between the PyPBI and PVP. The PVP-coated electrocatalyst showed a ∼10times higher CO tolerance compared to the non-PVP-coated electrocatalyst under a high (4 m) methanol concentration. Additionally, the PVP-coated electrocatalyst showed an enhancement in the Pt stability because of the stabilization of the Pt-NP by the PyPBI and PVP. After the durability test, the PVP-coated electrocatalyst still showed ∼8times higher CO tolerance because of the presence of the PVP bound stably with PyPBI. This study provides useful information for the design and fabrication of a state-of-the-art anodic electrocatalyst for direct methanol fuel cells.