Facile Fabrication of Pt, Pd and Pt−Pd Alloy Films on Si with Tunable Infrared Internal Reflection Absorption and Synergetic Electrocatalysis

A new facile fabrication of Pt, Pd and their alloy films on Si, intended mainly for in situ ATR surface infrared spectroscopy and electrocatalysis study, has been achieved through an alternate electroless deposition approach from very simple acidic baths with hydrazine dihydrochloride as the reducing agent. Compositional analyses reveal that Pt and Pd elemental ratios in the alloy films are close to those in the plating baths, and higher in skin layers compared to those of bulk films. Electrochemical and IR spectroscopic characterizations suggest the Pt−Pd alloy films may exhibit synergetic effects in surface electrochemistry toward oxidation of CO adlayer and formic acid. Of particular interest is the reproducible control of internal reflection absorption responses through adjusting Pt and Pd compositions in the films. More enhanced surface IR absorption with normal band shape and direction was observed for surface species at Pt and Pd electrodes. For the as-deposited Pt−Pd alloys, in addition to less enhanced IR absorption intensity, bipolar and totally inverted bands may appear for different alloy films.