Collaboration between experimentalists and theoreticians is HOT
A recent collaborative paper between researchers from the Theoretical Chemistry & Catalysis and Surface Chemistry groups has been chosen by the renowned Physical Chemistry Chemical Physics journal as a "2018 PCCP HOT article".
Most chemists will confirm that lowering coordination of a catalytically active site often causes an increase in reactivity. In heterogeneous catalysis, molecules from the gas phase react on the surface of metal (or metal oxide) particle. Metallic surface atoms with lower coordination, such as present in edges, would thus be expected to be more active in, e.g., dissociation the H-H bond in molecular hydrogen.
Kun Cao -a PhD student working in the CASC group at the Leiden Institute of Chemisty on experimental determination of the relation between surface structure and catalytic activity- compared the reactivity of the atomically flat Cu(111) surface to the highly stepped Cu(211) surface. Surprisingly, the rougher surface with many low-coordinated Cu atoms proved less reactive toward H2 dissociation.
Gernot Füchsel -a post doc formally working in the THEOR group on theoretical descriptions of gas-surface interactions- unveiled the origin of this behavior. In contrast to common beliefs, 4-fold coordinated Cu atoms in the so-called A-type step show a larger activation barrier toward splitting the bond than Cu atoms that are perfectly surrounded by 6 atoms in the atomically flat plane. The higher barrier hardly changes when neighboring catalytic sites are increasingly covered by H atoms.
The results of the experiments and theoretical studies agree so well on this anomalous behavior that the journal Physical Chemistry Chemical Physics deemed it a 2018 HOT article.