We report the electrochemical properties and performance of Pt-decorated carbon nanotube (Pt-CNT) catalysts for long-term operation in phosphoric acid fuel cells (PAFCs). Electrochemical measurements of Pt-CNT catalysts including cyclic voltammetry, rotating ring disk electrode voltammetry, and electrochemical impedance spectroscopy were conducted to evaluate the catalyzed oxygen reduction reaction (ORR). Furthermore, we tested the long-term performance of the Pt-CNT catalysts in 2 00 Â 2 00 PAFC cathodes operating at 190°C in 85% H 3 PO 4 for extended periods (up to 240 days). Lifetime studies show that electrodes containing the Pt-CNT catalysts were approximately 20 times more stable than conventional Pt-C catalyst materials, even with a substantially thinner catalyst layer. This finding of the enhanced Pt-CNT catalyst stability bodes well for possible personal electronics or automotive applications, where catalyst longevity is an essential requirement.
We have developed an optimized high-throughput UV Raman spectrometer that utilizes a simple, inexpensive new 224.3 nm hollow cathode laser. This quasi-continuous wave (CW) 224.3 nm laser can be used to detect sub-ppm concentrations of aromatic and polycyclic aromatic hydrocarbons in aqueous solutions. This excitation is also useful for studying aromatic amino acids in proteins. We demonstrate the utility of this spectrometer to study the environments of tyr and trp in horse heart myoglobin.
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