Cobalt Oxide-Supported Pt Electrocatalysts: Intimate Correlation between Particle Size, Electronic Metal-Support Interaction and Stability
Abstract
Oxide supports can modify and stabilize platinum nanoparticles (NPs) in electrocatalytic materials. We studied related phenomena on model systems consisting of Pt NPs on atomically defined Co3O4(111) thin films.
Chemical states and dissolution behavior of model catalysts were investigated as a function of the particle size and the electrochemical potential by ex situ emersion synchrotron radiation photoelectron spectroscopy and by online inductively coupled plasma mass spectrometry. Electronic metal-support interaction (EMSI) yields partially oxidized Pt delta+ species at the metal/support interface of metallic nanometersized Pt NPs.
In contrast, subnanometer particles form Pt delta+ aggregates that are exclusively accompanied by subsurface Pt4+ species. Dissolution of Cox+ ions is strongly coupled to the presence of Ptd(delta+) and the reduction of subsurface Pt4+ species.
Our findings suggest that EMSI directly affects the integrity of oxide-based electrocatalysts and may be employed to stabilize Pt NPs against sintering and dissolution.