Self-supporting, transparent films (40-micron thick) are obtained upon slowly evaporating an aqueous mixture of synthetic hectorite, Pt(NH_3)_2Cl_2, and polyethylene oxide (PEO). Films containing 2-5 wt percent platinum are then reduced under H_2 at 150 deg C for 2-4 hr, turning black upon reduction. XRD shows development of Pt(O) by the appearance of crystalline peaks upon reduction. A lineshape analysis using the Scherrer equation of the (220) peak shows Pt(O) particles from 3.8 nm to 7.5 nm depending upon processing conditions. These values are confirmed by TEM, and a high dispersion of the metal throughout the matrix is evident.
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