Två katalysseminarier

Sammanfattningar:

Catalytic Activation of Small Molecules on Single-Atom Alloys: Theory-Experiment Synergy for Understanding and Design

Michail Stamatakis, Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford

In the search for more active, stable and selective catalysts, alloy structures have emerged as highly promising. Single atom alloys (SAAs) constitute a special type of such materials, synthesised by combining a host metal with a dopant metal at ultra-high dilutions, so that the dopant remains atomically dispersed. The dopant atoms therein are subject to electronic and geometric effects, giving rise to catalytic sites with unique properties, not exhibited by either component of the alloy in a pure state. This behaviour generates novel opportunities for designing catalysts for industrially relevant chemistries, such as hydrogenation reactions or alkane activation. A fundamental understanding of the properties of SAAs would be indispensable in formulating principles that would aid catalyst design efforts. Motivated by these opportunities, we have studied SAAs in detail in the past decade and have revealed their reactivity trends as well as their ability to escape traditional Brønsted-Evans-Polanyi relations, thereby providing opportunities for designing superior catalysts. In this talk, we will showcase highlights from this research in the context of alkane valorisation, encompassing conversions such as methane to higher hydrocarbons, and propane to propylene. We will further discuss our latest efforts in building a general theory of SAA reactivity, based on analysing the physics and chemistry of the interactions between SAA sites and species adsorbed thereon. 

Revealing Atomic-Scale Mechanisms at Electrocatalytic Interfaces Using Grand-Canonical DFT

Karoliina Honkala, Department of Chemistry, University of Jyväskylä 

Electrocatalytic systems are central to renewable energy technologies, and improving their efficiency, stability, and cost-effectiveness requires an atomic-level understanding of the electrocatalyst–electrolyte interface. The properties of this interface—and thus overall performance—depend strongly on the solvent environment and electrode potential. 
Grand-canonical ensemble (GCE) DFT provides a powerful framework for modeling electrochemical interfaces and reactions at fixed electrode potentials. In this presentation, I will demonstrate how GCE-DFT can be used to construct Pourbaix diagrams and explore complex reaction networks. I will also introduce the constant inner potential approach, a recent development that extends GCE-DFT to systems previously inaccessible with standard methods, illustrated through applications to the hydrogen evolution reaction on TiO₂ surfaces.