Research | The Domke Group

Electrocatalytic surface reactivity

To rationally design electrocatalysts, detailed understanding of the interrelation between the electronic structure of specific surface sites and their reactivity is required. For example, the influence of domain boundaries between different catalytic materials or the importance of step edges in contrast to terraces has to be further elucidated on the (sub-)nanometer level. We employ EC-TERS to characterize the electro-active surface sites and the site-specific and potential-dependent pathways of electrocatalytic processes to further understand the development of improved electrocatalysts. Reactivity mapping of nanoscale defect chemistry under electrochemical reaction conditions
J. Pfisterer, M. Baghernejad, G. Giuzio, K.F. Domke*
Nature Communications 2019, 10, 5702.
Unfolding the versatile potential of EC-TERS for electrocatalysis
J. Pfisterer, K.F. Domke*
Current Opinion in Electrochemistry 2018, 8, 96-102.

Biophysical energy conversion in metalloproteins

Many vital functions of living organisms like respiration, photosynthesis or nitrogen fixation rely on the ability of complex metal-ion containing molecules called metalloproteins to induce and sustain finely tuned sequences of chemical processes by exchanging electrons with fellow molecules. We aim to employ EC-TERS to obtain a quasi-atomistic picture of metalloprotein redox behaviour to improve our understanding, for example, of the (mal)functioning of metalloproteins in relation to physiological diseases or biophysical processes. (Funded through the Boehringer Ingelheim Foundation Plus 3 Programme.) Electrochemical TERS elucidates potential-induced molecular reorientation of adenine/Au(111)
N. Martín Sabanés , T. Ohto , D. Andrienko, Y. Nagata, K.F. Domke*
Angewandte Chemie International Edition 2017, 56, 9796-9801 (VIP paper).

Water in proton or anion exchange membranes

The organization of water in proton or anion exchange membranes determines to a large extent the performance of fuel cells, affecting both ion transport and catalytic efficiency. Thus, establishing the molecular properties, such as spatial arrangement and chemical interactions, of water in fuel cell membranes provides a physico-chemical basis for an improved understanding of device performance. With help of coherent anti-Stokes Raman spectroscopy (CARS), we want to quantify the water content inside the membrane and visualize its distribution in 3D with (sub)micrometer resolution. The high sensitivity of CARS provides millisecond temporal resolution and thus allows us to directly monitor how membrane flooding and dehydration processes proceed. Correlated interfacial water transport and protonconductivity in perfluorosulfonic acid membranes
X. Ling, M. Bonn, S.H. Parekh, K.F. Domke*
Proceedings of the National Academy of Sciences 2019, 116, 8715-8720.
Nanoscale distribution of sulfonic acid groups determines structure and binding of water in Nafion membranes
X. Ling, M. Bonn, S.H. Parekh*, K.F. Domke*
Angewandte Chemie International Edition 2016, 55, 4011-4015.

Metal-organic framework electrosynthesis

Metal-organic frameworks (MOFs) constitute an important class of complex functional materials relevant, amongst others, for sensing, catalysis, optoelectronics and energy storage and conversion applications. However, the growth process, particularly the nucleation phase and the early growth stages that govern the final material properties, are not fully understood yet. Such knowledge is crucial for the design of tailored bottom-up MOF fabrication protocols. We characterize the initial stages of potential-controlled MOF growth as a function of applied substrate potential, electrolyte composition, substrate morphology and functional ligands in situ with unprecedented molecular topographic and chemical resolution. Based on the detailed mechanistic insight into the molecular interactions underlying (early stage) MOF growth thus gained, we can rationally design improved preparation protocols for MOFs with desired properties. Trimesic acid on Cu in ethanol: potential-dependent transition from 2D adsorbate to 3D metal-organic framework
P. Schäfer, A. Lalitha, P. Sebastian, S. Kumar Meena, J.M. Feliu, M. Sulpizi, M.A. van der Veen, K.F. Domke*
Journal of Electroanalytical Chemistry 2017, 793, 226-234.
Unraveling a two-step oxidation mechanism in electrochemical Cu-MOF synthesis
P. Schäfer, M.A. Van der Veen*, K.F. Domke*
Chemical Communications 2016, 52, 4722-4725.

Chemical and optical properties of solar cell surfaces

In view of depleting fossil energy resources, the development of cheap and flexible alternative energy conversion concepts is vital. Photovoltaic materials, like dye- or quantum-dot sensitized surfaces, or perovskites, that transform sunlight into electricity are a prime example of such alternative concepts. To improve solar cell devices and further the technology toward large-scale application, molecular-scale insight into the physico-chemical properties of the complex sensitizer/electrode/electrolyte system is required. Our research aims to shed light on solar cell interfacial processes on the nanoscale under operando conditions to help answer key questions in solar cell development: What is the nature of sensitizer-electrode-electrolyte interactions and their relation to surface morphology? Can device activity be controlled through the presence of defect sites and performance-enhancing molecules or particles? What is the chemical origin of device degradation upon UV irradiation and/or in the presence of oxygen or water? Correlating known macroscopic device behaviour to molecular-level processes under realistic working conditions enables performance evaluation of solar cell surfaces in an unprecedented detailed manner and paves the way for rational device design. The SERS signature of PbS quantum dot oxidation
K. Stadelmann, A. Elizabeth, N. Martín Sabanés, K.F. Domke*
Vibrational Spectroscopy 2017, 91, 157-162.
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