Research

Research Themes

Understanding the Atomic Scale Synergies of Catalytically Active Nanoclusters on Metal Oxide Surfaces (OxideSynergy)

This research theme concerns the application of new experimental methods for atomic-scale characterization of model catalysts based on insulating metal oxides with the goal of exploring the potential for designing new and efficient heterogeneous catalysts by enhanced control of the catalyst structure at the atomic level. This objective will be achieved by a carefully integrated sequence of synthesis, characterization, and reactivity measurements of model catalysts based on the insulating metal oxides used as integral parts of most industrial heterogeneous catalysts. Follow the headline link to read more.

Jensen, T. N.; Meinander, K.; Helveg, S.; Foster, A. S.; Kulju, S.; Musso, T.; Lauritsen, J. V. Atomic Structure of a Spinel-Like Transition Al2O3(100) Surface. Phys. Rev. Lett. 2014, 113, 106103.

 

Non-contact Atomic Force Microscopy studies of insulating surfaces

In this project we develop and optimize atomic force microscopy applied in the highly sensitive non-contact mode (NC-AFM) for atomically resolved AFM imaging of insulator surface. Most surface science techniques do not work well (or at all) on insulating metal oxide supports used in catalysis such as Al2O3, MgAl2O4, MgO, CeO2, ZnO, TiO2 , etc., and a serious gap exists in the atomic and nano-scale knowledge available of insulator surfaces. Even a basic understanding of the atomic-scale structure of most metal oxide surfaces in the clean state has not been achieved. This project aims to use the NC-AFM to close this gap. Follow the headline link to read more. 

 

 

Hydrotreating Catalysis and Metal Sulfide Nanostructures

In the project we study the fundamental properties of metal-sulfide nanocatalyst using the Scanning Tunneling Microscope (STM). The hydrotreating catalyst based on MoS2 is among the most important heterogeneous catalysts used today, since it is used for upgrading crude oil and cleaning up sulphur impurities. However, much better hydrotreating in catalysts will in the future be in high demand due to the dwindling fossil fuel resources and the associated requirement to process crude oil with a higher impurity level. Using the STM, we can successfully use the STM to provide a genuine atomic-scale view of the active MoS2 nanoclusters and follow in atomic detail the key intermediate steps in the desulfurization process, and based on this insight we collaborate with an industry partner to develop new hydrotreating catalyst. Follow the headline link to read more. 

 

 

Earth Abundant Materials for Water Splitting Catalysis

Cobalt oxides are among the best performers as future alternative electrocatalysts for the water splitting reaction with attractive properties in terms of stability, efficiency, abundance and low-cost. However, fundamental understanding of the catalytic properties of CoOx is still limited.To elucidate the fundamental structure, composition and surface chemistry of CoOx based catalysts, we characterize the surface of CoOx nanoislands under ultra-high vacuum conditions by high-resolution Scanning Tunneling Microscopy (STM) and X-Ray Photoelectron and Absorption Spectroscopies (XPS and XAS).

Walton, A. S.; Fester, J.; Bajdich, M.; Arman, M. A.; Osiecki, J.; Knudsen, J.; Vojvodic, A.; Lauritsen, J. V. "Interface controlled oxidation States in layered cobalt oxide nanoislands on gold" ACS Nano 2015, 9, 2445-53.

Monolayer MoS2

Epitaxially grown 2D MoS2 layers

MoS2 is, like graphite, a layered structure which can exist in single layer form. Unlike graphene, single-layer MoS2 has a nonzero bandgap qualifying it for use in 2-dimensional transistors and optoelectronic devices. In these studies we investigate the synthesis and properties of epitaxially grown "perfect" layers of MoS2. The samples allow for example detailed Angle-resolved Photoemission Spectroscopy studies (collaboration with Ph. Hofmann)

Sørensen, S. G.; Füchtbauer, H. G.; Tuxen, A. K.; Walton, A. S.; Lauritsen, J. V. "Structure and Electronic Properties of In Situ Synthesized Single-Layer MoS2 on a Gold Surface". ACS Nano 2014, 8, 6788-6796.