Co-Pt alloys were studied in detail by a corrosion test under phosphoric acid fuel cell (PAFC) conditions on the well-defined crystallographic structures for a typical combination of the alloy catalysts used in PAFCs, examining the long-life stabilities of the structures and the catalytic activities for O2 electroreduction. The ordered (O) and disordered (D) alloys at the same particle sizes can be obtained by heat-treating the mother alloy in different temperature sequences. The O-alloy exhibits a specific activity, an electrocatalytic activity based on the catalyst surface area, L35 times higher than the D-alloy before the corrosion test, but shows less activity (0.73 times) after the corrosion test, due to a higher degradation (47%) in the O-alloy activity as compared with that of the D-alloy (1%). It was found that the Co atoms on particle surfaces of both alloys dissolve easily in the acid. This is followed by a second slow dissolution from inside the alloy particles probably due to the protective action by a monolayer thickness of Pt remaining on the alloy surfaces, but the loss of Co in the second stage dissolution for the O-alloy is higher by several percentage points compared to that of the D-alloy. It was also found that the Pt content does not change on the catalyst support even after 50 h of corrosion test, but the pure Pt phase is formed in the corrosion product, where the phase for the O-alloy grows faster than that for the D-alloy with corrosion time. Based on these results, obtained by chemical, x-ray diffraction, and transmission electron microscopy with energy dispersive spectroscopy analyses, the corrosion for Pt alloy catalysts is clearly explained, i.e., after the dissolution

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A new AB‐type monomer, N,N‐bistrimethylsilylated p‐aminobenz‐aldehyde diethyl acetal was prepared via three steps from p‐bromoaniline as a starting material. The two‐stage polymerization involving a soluble precursor polymer process gave a poly(p‐phenylenevinylene)‐type polyazomethine, poly(1,4‐phenylene‐nitrilomethylidyne). The first stage of polymerization was carried out in tetrahydrofuran or hexamethylphosphoramide containing water at room temperature. In the second stage, the polymer was thermally converted into the final polyazomethine by heating over 300°C to form a free‐standing film. The film was reddish brown and insoluble in common organic solvents. The investigation of the first‐stage products by means of MALDI‐TOF mass spectroscopy proved the oligomers with 4‐11 repeating units per molecule. From the 1H‐NMR analysis of the model reaction, the polymerization mechanism was found to be a stepwise polycondensation of 4‐diethoxymethylaniline which was formed by removal of two silyl groups of the monomer.

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