A voltammetric and nanogravimetric study of Te underpotential deposition on Pt in perchloric acid medium

This work describes the study of Te underpotential deposition on Pt in acid media using cyclic voltammetry, rotating ring-disc electrode and electrochemical quartz crystal microbalance techniques. The voltammetric results indicate the presence of two dissolution peaks in the positive scan with a total charge density of 420 μC cm⁻². These phenomena are attributed to the deposition of one Te monolayer with the occupancy of two active Pt sites by each ad-atom. This is confirmed by rotating ring-disc electrode results. The electrochemical quartz crystal microbalance (EQCM) experiments yielded the small mass variation of −32 ng cm⁻² (while the theoretical one is −140.4 ng cm⁻² for a complete Te monolayer). This low value can be attributed to the simultaneous adsorption of water, perchlorate anions and the formation of platinum oxide.