Strong response of Pt clusters to the environment and conditions, formation of metastable states, and simple methods to trace the reversible changes. Issue 39 (4th October 2021)

• Record Type: Journal Article
• Authors: Lisitsyn, Alexander S.; Kadtsyna, Anastasiya S.
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 39(2021)
• Page Start: 22718
• Page End: 22732
• Publication Date: 2021-10-04
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp01484f
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Pt/γ-Al2 O3 manifests itself as a self-organizing system, which reacts actively to conditions but can retain memory, a short or long, of its treatment history. Abstract : Subnanometric metal particles, the so-called "clusters", are known to be responsive to their surroundings, but the detection of occurring changes, understanding the causes, and predicting the consequences are still extremely difficult for such small particles. Our study was aimed at estimating the potential of adsorption-based methods for these purposes. Using carbon monoxide as a probing molecule, which readily adsorbs on both bare and H-covered Pt surface, we have probed the adsorption properties of highly dispersed Pt/γ-Al2 O3 samples after treatments under different atmospheres and temperatures (H2 or inert gas, 25–500 °C). The combined results of CO-chemisorption measurements, CO TPD, CO TPO, H2 -by-CO displacement, and H2 TPD suggest that the system shuttles between two states: one with oxygen vacancies in the support and the other one with redox-active oxygen near the Pt clusters. These extreme states can be reversibly created and deleted, giving rise to innumerable intermediate structures that differ in the amount, binding strength, and/or reactivity of adsorbed species. Two adsorbates could act cooperatively, resulting in hydrogen spillover onto the support and making the adsorbate–metal–support interactions even more complex. Implications for better understanding the dynamic behavior of oxide-supported clusters and nanoparticles are discussed.