Understanding\nthe Growth of Electrodeposited PtNi\nNanoparticle Films Using Correlated <i>In Situ</i> Liquid\nCell Transmission Electron Microscopy and Synchrotron Radiation

Electrodeposition is a versatile method for synthesizing\nnanostructured\nfilms, but controlling the morphology of films containing two or more\nelements requires a detailed understanding of the deposition process.\nWe used liquid cell transmission electron microscopy to follow the\nelectrodeposition of PtNi nanoparticle films on a carbon electrode\nduring cyclic voltammetry. These <i>in situ</i> observations\nshow that the film thickness increases with each cycle, and by the\nfourth cycle, branched and porous structures could be deposited. Synchrotron\nstudies using <i>in situ</i> transmission X-ray microscopy\nfurther revealed that Ni was deposited in the oxide phase. <i>Ex situ</i> studies of bulk electrodeposited PtNi nanoparticle\nfilms indicated the number of cycles and the scanning rate were the\nmost influential parameters, resulting in a different thickness, a\ndifferent homogeneity, a different nanoparticle size, and a different\nsurface structure, while the precursor concentration did not have\na significant influence. By varying the potential range, we were able\nto obtain films with different elemental compositions.