Application of Polypyrrole Film Substrates for Characterization of Metallic Electrodeposits by Transmission Electron Microscopy and Electron Diffraction

Abstract

The utility of polypyrrole is demonstrated as a substrate for characterization of metallic electrodeposits by transmission electron microscopy and electron diffraction. Copper and nickel crystallites are electrodeposited onto a polypyrrole film at a potential negative of the film undoping potential at which counterions are expelled and the film becomes an insulator (i.e., vs. ). The relatively slow process of undoping the counterions in the polypyrrole film at negative potentials enables the electrodeposition of thin samples of metals before the film becomes an insulator. Hence, both copper and nickel crystallites can be deposited in the first 30 s following the application of the cathodic potential. The insulating transition of the polypyrrole also insures that electrodeposits will be sufficiently thin for investigation by transmission electron microscopy (TEM). Conventional TEM using a 120 keV electron beam was used to study the morphological characteristics of the electrodeposits supported on a 110 nm thick polypyrrole film. The techniques of selected area electron diffraction (SAED) and energy dispersive x‐ray analysis were also used in conjunction with the TEM to confirm the structural and chemical identity of deposited structures as small as in dimension. The polypyrrole film serves as an acceptable substrate for electrodeposition and TEM characterization because of its mechanical stability, electrical conductivity, and electron transparency. Furthermore, the film can also be used for the TEM characterization of electrolessly deposited cadmium sulfide.