Two Freigeist Fellows interweave their research at HZB
Fabian Weber (right) is investigating the dynamics of electron processes within graphene-oxide quantum dots as a member of the team headed by Dr. Annika Bande (left). Quantum dots like these as catalysts could help make solar water splitting more efficient. Using Weber’s theoretical model, a much greater amount of information can be obtained from the empirical data gathered by the group headed by Dr. Tristan Petit. © HZB
Initial calculations show how the electron density changes over a graphene oxide nanoparticle in solution. The electron density is below average in the areas shown in red, while it is above average in the blue areas. The graphene particle is made of carbon atoms (black) that bind in some places to the oxygen (red) , or in some to the hydrogen (white). © Fabian Weber
Two Freigeist Fellows are conducting research at the HZB Institute for Methods of Material Development through support received from the Volkswagen Foundation. Theoretical chemist Dr. Annika Bande is modelling fast electron processes, while Dr. Tristan Petit is investigating carbon nanoparticles. Annika Bande has now been awarded an ancillary grant of an additional 150,000 Euros from the Volkswagen Foundation to fund another doctoral student position for three years. The doctoral research will connect the two Freigeist research projects with one another.
Doctoral student Fabian Weber is working in Bande’s theory group and will be carrying out electron transfer calculations in a material system being investigated by Petit and his team. “We are concentrating on a special class of what are known as quantum dots, made of graphene oxide nanoparticles”, explains Weber. The group headed by Petit will be analysing nano-graphene oxide using various spectroscopic methods.
Catalyst for solar hydrogen
This is because graphene-oxide nanoparticles are good catalysts, as well for splitting water using solar energy and generating hydrogen. Hydrogen is a versatile energy medium that can be utilised as fuel or to generate environmentally friendly electric power in a fuel cell.
Understanding the system
With the help of theoretical modelling, the empirical data obtained on nanoparticles of graphene oxides can yield considerably more information and also new insights into the ultrafast dynamics of hydrogen bonding. “We start with existing theories and see how we can use them to model exactly what happens with the transfer of electrons during a catalytic reaction”, explains Annika Bande. “We are able to compare our ideas directly with the empirical results in this research project and really come to better understand the system. In addition, the topic is extremely important – not just for purposes of pure research, but also for ensuring society’s energy supply.”
- Metallic nanocatalysts: what really happens during catalysisUsing a combination of spectromicroscopy at BESSY II and microscopic analyses at DESY's NanoLab, a team has gained new insights into the chemical behaviour of nanocatalysts during catalysis. The nanoparticles consisted of a platinum core with a rhodium shell. This configuration allows a better understanding of structural changes in, for example, rhodium-platinum catalysts for emission control. The results show that under typical catalytic conditions, some of the rhodium in the shell can diffuse into the interior of the nanoparticles. However, most of it remains on the surface and oxidises. This process is strongly dependent on the surface orientation of the nanoparticle facets.
- KlarText Prize for Hanna TrzesniowskiThe chemist has been awarded the prestigious KlarText Prize for Science Communication by the Klaus Tschira Foundation.
- Shedding light on insulators: how light pulses unfreeze electronsMetal oxides are abundant in nature and central to technologies such as photocatalysis and photovoltaics. Yet, many suffer from poor electrical conduction, caused by strong repulsion between electrons in neighboring metal atoms. Researchers at HZB and partner institutions have shown that light pulses can temporarily weaken these repulsive forces, lowering the energy required for electrons mobility, inducing a metal-like behavior. This discovery offers a new way to manipulate material properties with light, with high potential to more efficient light-based devices.