The Deposition of Pt via Electroless Surface Limited Redox Replacement

Abstract

This work demonstrates the furthering of Electroless Surface Limited Redox Replacement (ESLRR) to the deposition of Pt on polycrystalline Au through the displacement of Pb and Cu. Pb and Cu executive electrodes are initially explored utilizing their respective cations as sacrificial mediators, and a green Pd-H electrode is also explored with Pb 2+ mediation. Mixed potential diagrams are presented in order to predict the potential of each executive electrode, and potential-time curves are presented to demonstrate both the transient and steady-state behavior for each respective electrode. Pb and Cu exhibit expected mixed potential behavior with immediate potential establishment whereas the Pd-H electrode exhibits slow steady-state potential realization. The deposition of Pt on the Pd-H (Pt, Pd-H) electrode improves the kinetics of H absorption and desorption resulting in viability of the electrode. Pt films grown by ESLRR up to 200 replacement events are characterized electrochemically via H UPD. Films deposited via Pb mediation exhibit slow surface area evolution whereas the surface area development is much faster when Cu mediation is used. Morphology characterized by scanning tunneling microscopy, up to 10 displacement events, exhibits uniform nucleation followed by cluster growth, overlapping and eventual merging during subsequent ESLRR cycles.