A Highly-Durable CO-Tolerant Poly(vinylphosphonic acid)-Coated Electrocatalyst Supported on a Nanoporous Carbon

For direct methanol fuel cells (DMFCs) to be commercialized, the durability of the anodic electrocatalyst needs to be highly considered, especially under high temperature and methanol concentration conditions. Low durability caused by carbon corrosion as well as carbon monoxide (CO) poisoning of the platinum nanoparticles (Pt-NP) leads to a decrease in active Pt-NPs and increases inactive Pt-NPs covered by CO species. In this study, we deposited Pt-NPs on poly[2,2'-(2,6-pyridine)-5,5'-bibenzimidazole] (PyPBI)-wrapped nanoporous carbon (NanoPC) and coated the as-synthesized electrocatalyst with poly(vinylphosphonic acid) (PVPA). The durability of the as-synthesized NanoPC/PyPBI/Pt/PVPA was tested in 0.1 M HClO4 electrolyte at 60 °C by cycling the potential from 1.0 to 1.5 V relative to RHE, and the results indicated that NanoPC/PyPBI/Pt/PVPA showed ∼5 times better durability relative to that of the commercial CB/Pt. The methanol oxidation reaction (MOR) of the electrocatalyst was tested before and after the potential cycling in the presence of 4 or 8 M methanol at 60 °C and found that the CO tolerance of the electrocatalyst was ∼3 times higher than that of the commercial CB/Pt. Such a higher CO tolerance is due to the coating of the PVPA, which was proven by an EDX mapping measurement. The NanoPC/PyPBI/Pt/PVPA showed a high durability and CO tolerance under high temperature and high methanol concentration conditions, indicating that the electrocatalyst could be used in real fuel applications.