Marta Perxés

Studying restructuring in bimetallic catalysts using in-situ transmission electron microscopy

Bimetallic nanoparticles are gaining attention in the field of catalysis, exhibiting strongly enhanced activity and selectivity compared to their monometallic counterparts. The synergy is achieved by mixing a very active metal (normally Pd or Pt) with a less active metal (Au), that slows the reaction rate and provides selectivity to the system. However, atomic distribution inside a nanoparticle is dynamic and it can drastically change under catalytical reaction conditions, such as high temperatures or exposure to different gases.

In this work, we aim to correlate restructuring in bimetallic nanoparticles with their catalytical performance. For this, we make use of in situ transmission electron microscopy (in situ TEM), which with modified TEM sample holders allows imaging with the presence of gas at atmospheric pressure [1]. Using Energy Dispersive X-Ray Analysis (EDX), we can monitor the position of the elements in a single nanoparticle and determine the redistribution kinetics.

These kinds of studies will help us corroborate structure-function relations in bimetallic catalysts. For example Pd is known to segregate to the surface under an oxidative atmosphere, which increases hydrogenation activity since surface palladium is necessary for H₂ dissociation [2]. Likewise, core shell structures in Au@Pd nanorods have been found to be more active in the butadiene selective hydrogenation than their monometallic counterparts, by having more Pd in the surface [3].

During my PhD, I will be watching atomic restructuring in well-defined bimetallic nanoparticles upon exposure to common reaction gases using in situ TEM. Since the catalytical properties of the particles can vary depending on the surface composition, gaining knowledge on how the surface composition changes upon different gas exposures, will help us to design switchable catalysts that catalyze different reactions depending on the pretreatment they received.

[1]        L. I. van der Wal, S. J. Turner, and J. Zečević, “Developments and advances in in situ transmission electron microscopy for catalysis research,” Catal. Sci. Technol., vol. 11, no. 11, pp. 3634–3658, 2021, doi: 10.1039/D1CY00258A.

[2]        M. Luneau et al., “Enhancing catalytic performance of dilute metal alloy nanomaterials,” Commun. Chem., vol. 3, no. 1, pp. 1–9, 2020, doi: 10.1038/s42004-020-0293-2.

[3]          J. E. S. van der Hoeven et al., “Unlocking synergy in bimetallic catalysts by core–shell design,” Nat. Mater., vol. 20, no. 9, pp. 1216–1220, Sep. 2021, doi: 10.1038/s41563-021-00996-3.

C.V.

2021-present

PhD Candidate in the Materials Chemistry and Catalysis group, Utrecht University. Project under supervision of dr. Jessi van der Hoeven.

2020-2021                           

Master of Multidisciplinary Research on Experimental Sciences. Barcelona Institute for Science and Technology (BIST) & Universitat Pompeu Fabra (UPF).

Master Thesis at the Catalan Institute for Nanoscience and Nanotechnology (ICN2), Novel Energy Oriented Materials group led by Pedro Gómez and with the supervision of Sara Goberna: “Polyoxometalate-protected metal  nanoparticles and composite assembly with nanocarbons: Tricomponent hybrid materials for energy storage”.

Minor project of my Master’s Thesis in Josep Samitier’s group Nanobioengineering at IBEC (Institute for Bioengineering of Catalonia), “Polyoxometalate-protected gold nanoparticles as β-amyloid inhibitors”

2016-2020                

Bachelor of Nanoscience and Nanotechnology, Universitat Autònoma de Barcelona (UAB).

2020                           

Exchange student in the University of Melbourne (UoM). Bachelor thesis in the University of Melbourne, Nanoscience laboratory (Exciton Science), led by Paul Mulvaney. “Synthesis of Silica Coated Magnetic Nanoparticles for Covid-19 detection”.

2019

Summer internship at CIC Biomagune, at Bioplasmonics lab (Luis Liz Marzán). Synthesis of silica coated gold nanotriangles for SERS and MALDI sensing in spheroid culture. Uv-Vis, MALDI and cell culture.

1998

Born in Bordils