Ultra-Thin Platinum Deposits by Surface-Limited Redox Replacement of Tellurium

Abstract

Platinum is the most employed electrocatalyst for the reactions taking place in energy converters, such as the oxygen reduction reaction in proton exchange membrane fuel cells, despite being a very low abundant element in the earth’s crust and thus extremely expensive. The search for more active electrocatalysts with ultra-low Pt loading is thus a very active field of investigation. Here, surface-limited redox replacement (SLRR) that utilizes the monolayer-limited nature of underpotential deposition (UPD) was used to prepare ultrathin deposits of Pt, using Te as sacrificial metal. Cyclic voltammetry and anodic potentiodynamic scanning experiments have been performed to determine the optimal deposition conditions. Physicochemical and electrochemical characterization of the deposited Pt was carried out. The deposit comprises a series of contiguous Pt islands that form along the grain interfaces of the Au substrate. The electrochemical surface area (ECSA) of the Pt deposit obtained after 5 replacements, estimated to be 18 m2/g, is in agreement with the ECSA of extended surface catalysts on flat surfaces.

Electrodeposition of Ternary BiTePd Nanofilm Electrocatalyst Using Surface-Limited Reaction for Direct Ethanol Fuel Cell

“…However, compared to bare Au, Te-UPD 1 shows a minor positive (0.13 V) shift, ascribed to Te's greater interaction with pre-deposited Pd on Au. 35 As a result, the Te-UPD potential is slightly higher than that of plain Au equivalents. The redox characteristics are consistent with the tellurium electrodeposition reaction in acidic conditions, as indicated by the reduction reaction mechanism below.…”