Hydrogen Gas Promoted Self-Limiting Copper Monolayer Deposition on Platinum

Abstract

A hydrogen gas promoted approach to achieve copper underpotential deposition (UPD) on platinum surfaces was developed to form a copper monolayer on polycrystalline platinum and carbon supported platinum catalysts (Pt/C) in a Cu2+-containing electrolyte, serving as alternative to the commonly used electrochemical deposition methods that require external potential control. Initially, the amount of deposited copper in the presence of dissolved hydrogen was determined via fast stripping voltammetry. Subsequently, by monitoring the open circuit potential drop of Pt disk and Pt/C thin-film electrodes upon exposure of an air saturated electrolyte to H2 containing gas, it could be shown that self-limiting Cu coverages of essentially one monolayer can reliably be obtained for 0.1% and 3% H2/Ar mixtures. In a second part, a cell was designed aiming to facilitate the gram-scale preparation of CuUPDPt/C catalysts by the H2 gas promoted approach. The formation of a Cu UPD layer on the Pt nanoparticles supported on carbon with a coverage slightly higher than a monolayer was successfully validated. However, the reaction cell introduced non-idealities at the solution/gas interface, which would need to be optimized to achieve a perfectly self-limiting Cu monolayer on the Pt nanoparticles by the H2 promoted deposition.