Abstract
STM studies of chemically impregnated model Pt catalysts supported on HOPG substrate reveal the dynamics of morphological transformation from catalyst-intermediate to metal crystallites of near-equilibrium shape. Both the morphology and aspect ratio distribution of the crystallites undergo significant changes for catalysts reduced for 0.5, 2, and 60 h at similar pretreatment conditions. The aspect ratio distribution shows that majority (60–70%) of the crystallites have metastable shapes. Another model Pt catalyst was prepared by vacuum deposition of Pt metals onto the graphite substrate. Prior to H2 pretreatment, the Pt particles have random, irregular morphologies which transform to regular spherical shapes after H2 treatment at 250 °C for 30 min.
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Yeung, K.L., Wolf, E.E. STM studies of the effect of pretreatment on the morphology and aspect ratio distribution of crystallites on Pt/HOPG. Catal Lett 12, 213–225 (1992). https://doi.org/10.1007/BF00767203
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DOI: https://doi.org/10.1007/BF00767203