Dynamics of Metallic Catalysts Under Reactive Conditions

Palestrante:  Profa. Dra. Hazar Guesmi (Université de Montpellier, CNRS, ENSCM, França)

Abstract: Since several decades, chemists and physicists have been dedicated to researching increasingly efficient heterogeneous catalysts. During catalytic reactions, the catalyst, in the form of supported metallic particles (isolated atoms, clusters, and/or nanoparticles), interacts with reactants at operating temperatures. Reactants can adsorb on the particle surfaces, modifying their geometric and electronic structures, thus forming the true active phase, which can differ from the initial material introduced into the reactor. To control and optimize catalyst performance, it is essential to understand, at the atomic scale, the interactions between particles, oxide support, and reactants. Given the computational cost of theoretical methods such as DFT, catalytic surfaces are often modeled as rigid surfaces interacting with isolated molecules. This approach ignores the structural dynamics and chemical order changes induced by the reactive environment, even though these variations play a crucial role in catalytic processes. Today, the major challenge is to predict and describe the composition and structure of catalyst surfaces and their evolution over time to correctly identify active sites and control the reaction’s elementary steps. In this presentation, I will outline the state-of-the-art methods for modeling the structural dynamics of catalysts and present results from several studies on the structural dynamics of supported nanoparticles in the presence of reactive gases. I will show surface changes and their impact on reactivity, demonstrating how this knowledge can improve catalyst design.

Hazar Guesmi is a French researcher at the CNRS (Centre National de la Recherche Scientifique) and an expert in theory and numerical simulation. Her research is centered on describing the nanometric structure of catalytic materials and surface chemical reactivity. She is particularly interested in interfacial dynamics, including environmental effects such as pressure and temperature. Recently, her work has expanded to explore solid/liquid transitions in catalytic materials, as well as nanostructure restructuring phenomena in electrochemical environments, specifically considering the effects of electric fields and solvents (with two ongoing ANR-funded projects). Hazar Guesmi’s research has led to 70 scientific publications, including 66 peer-reviewed journal articles (h-index = 24). She has delivered 14 invited lectures (9 international, including 3 keynotes, and 5 national) and has (co-)supervised 7 PhD theses, 4 postdoctoral researchers, and over a dozen doctoral (visiting) and Master’s (I/II) internships. Additionally, she has served on several national and international committees and taught various courses on materials modeling at workshops and specialized schools, including international sessions in Shanghai, Tunis, Benin, and Brussels.

Prof. Responsável: Pablo Sebastián Fernández