2025 AIChE Annual Meeting

(252h) In Situ Measurement of Nanoparticle-Support Interactions in Supported Bimetallic Catalysts

Authors

Götz Veser - Presenter, University of Pittsburgh
Andrew Baker, University of Pittsburgh
Sai Vishnubohtla, University of Pittsburgh
Sanjana Karpe, UNIVERSITY OF PITTSBURGH
Yahui Yang, University of Pittsburgh
Tevis Jacobs, University of Pittsburgh
Metal-support interactions (MSI) are pivotal for properties and performance of functional nanomaterials. In heterogeneous catalysis, where supported metal nanoparticles play a central role, MSI directly affect catalyst properties such as metal dispersion, nanoparticle adhesion, and catalyst stability, and hence control catalytic performance and lifetime. While a fundamental understanding of these interactions is therefore essential, only a single experimental technique exists to-date that can directly measure nanoparticle adhesion. However, this technique is inherently limited to monometallic systems. Multimetallic nanoparticles have so far eluded direct experimental measurement and hence remain poorly understood.

Here, we present a novel technique for the measurement of nanoparticle adhesion via in-situ measurement of nanoparticle-support interactions [1]. The technique couples the spatial resolution of transmission electron microscopy (TEM) with the force resolution of atomic-force-microscopy (AFM), enabling direct measurement of the force of adhesion via probing in situ the formation and separation of an interface between an individual metal nanoparticle and an oxide-coated AFM probe.

The technique was first validated by measuring the work of adhesion for monometallic supported nanoparticles (Pt, Pd, Au, and Ag on CeO2, TiO2, and MgO) and verifying the results against reported trends. We then applied the technique to three ceria-supported bimetallic nanoparticle systems (AuPt, AuPd, and AuAg; each 0 – 100% Au) and found complex, non-monotonic relationships between adhesion and composition. An analytical model of interfacial bonding was able to accurately reproduce the observed behavior, suggesting that adhesion between bimetallic particles and oxide supports is primarily governed by charge transfer between the constituent metals.

We expect that this new ability to probe the impact of alloying on nanoscale adhesion will advance fundamental understanding of heterogeneous catalysis by multimetallic nanoparticles.

[1] Baker et al., “In Situ Measurement of Adhesion for Multimetallic Nanoparticles”, Nanoletters (2025) in print. DOI: 10.1021/acs.nanolett.5c00076