Light-Induced Molecular Transformations on Cluster-Assembled Materials
This focus group consists of Hans Fischer Senior Fellow Prof. Ib Chorkendorff (Technical University of Denmark) and his hosts Prof. Ulrich Heiz (TUM Department of Chemistry) and Prof. Ian Sharp (TUM Department of Physics). This Focus Group seeks new and efficient catalysts for photoinduced hydrogen and oxygen evolution reactions as well as for the hydrogenation of CO2 by accessing the non-scalable size regime, i.e., the cluster regime and the cluster-nanoparticle transition regime. In most catalytic applications, we are used to working with materials that are scalable. Consider a particle that occupies a certain volume: We would expect that if we double the number of atoms in the particle, then the volume also doubles. We could expect similar effects for a catalytically active surface: Doubling the area should double the number of molecules turned over, if all other parameters remain constant. Nonetheless, this is not the case when the nanoparticles become smaller. Below 2 nm (non-scalable size regime), they also begin to exhibit more molecule-like behavior, with discrete electronic levels. This has strong implications for the reactivity of the individual surface atoms, drastically influencing the overall activity and thus opening up possibilities for tuning reactivity by size.