Different conditions, different composition: investigation on a bimetallic alloy surface
|Besides being cheaper, platinum alloys with 3d transition metals show superior activities in many catalytic reactions when compared to pure platinum, due to their modified electronic structure. However, as complex multi-component systems, bimetallic catalysts suffer from surface structural reorganization under operating conditions (such as gas pressure, temperature and the nature of reaction), that may affect their performance.
In this framework, Assoc. Prof. Ivan Khalakhan and colleagues of the Nanomaterials group (Charles University of Prague) have performed a combined in situ electrochemical and spectroscopic study of surface structural changes in platinum-nickel catalyst during altering oxidation and reduction cycles, carried out at different conditions: electrified liquid and gaseous environments. To monitor possible restructuring of the alloy surface, scientists used cyclic voltammetry and Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) available at the Czech CERIC Partner Facility in Prague (at Charles University).
Scientists discovered that, regardless of the operational environment, the platinum-nickel bimetallic alloy undergoes a significant change in its compositional profile as a result of altering oxidation and reduction cycles. Specifically, this change is manifested in nickel enrichment, that may lead to catalyst deactivation. These finding can have an impact on the development of active and stable catalysts for many reactions by its compositional engineering.
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