Surface compositional dynamics in a PtNi bimetallic alloy under simulated operational conditions: Electrochemical and NAP-XPS Study
Abstrakt
Platinum-based bimetallic alloys possess unique activities exceeding those of pure platinum. Nevertheless, as complex multi-component systems, they suffer from surface structural reorganization under operating condi-tions, strongly affecting their lifetime performance.
This work reports an in situ electrochemical and spectro-scopic study of surface compositional changes in a PtNi catalyst during repetitive oxidation/reduction cycles, simulating inherent working conditions for numerous redox reactions. Using cyclic voltammetry and near -ambient pressure X-ray photoelectron spectroscopy, quantitative surface characterization under realistic elec-trified liquid and gaseous environments are obtained and correlated.
We show that regardless of the operating environment, PtNi undergoes a significant and irreversible change in compositional profile reflected in surface nickel enrichment and consequent catalyst deactivation, exemplary confirmed using a methanol electrooxidation reaction.