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.”
- Battery research: visualisation of aging processes operandoLithium button cells with electrodes made of nickel-manganese-cobalt oxides (NMC) are very powerful. Unfortunately, their capacity decreases over time. Now, for the first time, a team has used a non-destructive method to observe how the elemental composition of the individual layers in a button cell changes during charging cycles. The study, now published in the journal Small, involved teams from the Physikalisch-Technische Bundesanstalt (PTB), the University of Münster, researchers from the SyncLab research group at HZB and the BLiX laboratory at the Technical University of Berlin. Measurements were carried out in the BLiX laboratory and at the BESSY II synchrotron radiation source.
- New instrument at BESSY II: The OÆSE endstation in EMILA new instrument is now available at BESSY II for investigating catalyst materials, battery electrodes and other energy devices under operating conditions: the Operando Absorption and Emission Spectroscopy on EMIL (OÆSE) endstation in the Energy Materials In-situ Laboratory Berlin (EMIL). A team led by Raul Garcia-Diez and Marcus Bär showcases the instrument’s capabilities via a proof-of-concept study on electrodeposited copper.
- Green hydrogen: A cage structured material transforms into a performant catalystClathrates are characterised by a complex cage structure that provides space for guest ions too. Now, for the first time, a team has investigated the suitability of clathrates as catalysts for electrolytic hydrogen production with impressive results: the clathrate sample was even more efficient and robust than currently used nickel-based catalysts. They also found a reason for this enhanced performance. Measurements at BESSY II showed that the clathrates undergo structural changes during the catalytic reaction: the three-dimensional cage structure decays into ultra-thin nanosheets that allow maximum contact with active catalytic centres. The study has been published in the journal ‘Angewandte Chemie’.