EQCM Study on Pulse Current Pt Electrodeposition

Abstract

Electrochemical Quartz Crystal Microbalance (EQCM) was used to investigate the events occurring during current-on (T-on) and current-off (T-off) for pulse current electrodeposition of Pt in both air and Ar atmospheres. The EQCM profiles indicated a transient mass loss when the current was turned on, followed by a linear mass gain associated with the Pt electrodeposition from the H2PtCl6 plating bath. During the T-off, the mass revealed a steady increase until it leveled off after 10 sec. The minute transient mass loss during the initial stage of T-on was attributed to the reduction of the adsorbed PtCl62- whereas the mass gain during the T-off was due to the absorption of PtCl62- onto the freshly-deposited Pt surface. In air atmosphere, the parasitic oxygen reduction reaction consumed part of the reduction current and thus, reduced the Pt plating efficiency by 6%. In addition, smaller mass gains during T-off and T-on were observed for the Pt plating in air atmosphere.