BESSY II: Influence of protons on water molecules
The spectral fingerprints of water molecules could be studied at BESSY II. The result: the electronic structure of the three innermost water molecules in an H7O3+ complex is drastically changed by the proton. In addition, the first hydrate shell of five other water molecules around this inner complex also changes, which the proton perceives via its long-range electric field. © MBI
How hydrogen ions or protons interact with their aqueous environment has great practical relevance, whether in fuel cell technology or in the life sciences. Now, a large international consortium at the X-ray source BESSY II has investigated this question experimentally in detail and discovered new phenomena. For example, the presence of a proton changes the electronic structure of the three innermost water molecules, but also has an effect via a long-range field on a hydrate shell of five other water molecules.
Excess protons in water are complex quantum objects with strong interactions with the dynamic hydrogen bond network of the liquid. These interactions are surprisingly difficult to study. Yet so-called proton hydration plays a central role in energy transport in hydrogen fuel cells and in signal transduction in transmembrane proteins. While the geometries and stoichiometries have been extensively studied both in experiments and in theory, the electronic structure of these specific hydrated proton complexes remains a mystery.
A large collaboration of groups from the Max Born Institute, the University of Hamburg, Stockholm University, Ben Gurion University and Uppsala University has now gained new insights into the electronic structure of hydrated proton complexes in solution.
Using the novel flatjet technology, they performed X-ray spectroscopic measurements at BESSY II and combined them with infrared spectral analysis and calculations. This allowed them to distinguish between two main effects: Local orbital interactions determine the covalent bond between the proton and neighbouring water molecules, while orbital energy shifts measure the strength of the proton's extended electric field.
The results suggest a general hierarchy for proton hydration: the proton interacts with three water molecules and forms an H7O3+ complex. The hydrate shell of this complex is influenced by the electric field of the positive charge of the proton.
The new research findings have direct implications for understanding proton hydration from protons in aqueous solution to proton complexes in fuel cells to water structure hydration pockets of proton channels in transmembrane proteins.
Full text of the MBI-Press release >
- How carbonates influence CO2-to-fuel conversionResearchers from the Helmholtz Zentrum Berlin (HZB) and the Fritz Haber Institute of the Max Planck Society (FHI) have uncovered how carbonate molecules affect the conversion of CO2 into valuable fuels on gold electrocatalysts. Their findings reveal key molecular mechanisms in CO2 electrocatalysis and hydrogen evolution, pointing to new strategies for improving energy efficiency and reaction selectivity.
- Peat as a sustainable precursor for fuel cell catalyst materialsIron-nitrogen-carbon catalysts have the potential to replace the more expensive platinum catalysts currently used in fuel cells. This is shown by a study conducted by researchers from the Helmholtz-Zentrum Berlin (HZB), Physikalisch-Technische Bundesanstalt (PTB) and universities in Tartu and Tallinn, Estonia. At BESSY II, the team observed the formation of complex microstructures within various samples. They then analysed which structural parameters were particularly important for fostering the preferred electrochemical reactions. The raw material for such catalysts is well decomposed peat.
- Helmholtz Investigator Group on magnonsDr Hebatalla Elnaggar is setting up a new Helmholtz Investigator Group at HZB. At BESSY II, the materials scientist will investigate so-called magnons in magnetic perovskite thin films. The aim is to lay the foundations for future terahertz magnon technology: magnonic devices operating in the terahertz range could process data using a fraction of the energy required by the most advanced semiconductor devices, and at speeds up to a thousand times faster.