A5068167977- Advanced Photocatalysis Techniques
- Surface Chemistry and Catalysis
- Electronic and Structural Properties of Oxides
- Molecular Junctions and Nanostructures
- Semiconductor materials and devices
- 2D Materials and Applications
- MXene and MAX Phase Materials
- Graphene research and applications
- Copper-based nanomaterials and applications
- Quantum Dots Synthesis And Properties
- Perovskite Materials and Applications
- Chalcogenide Semiconductor Thin Films
- Machine Learning in Materials Science
- Electrocatalysts for Energy Conversion
- Electron and X-Ray Spectroscopy Techniques
- ZnO doping and properties
- Covalent Organic Framework Applications
- Gas Sensing Nanomaterials and Sensors
- X-ray Diffraction in Crystallography
- Inorganic Chemistry and Materials
- Crystallization and Solubility Studies
- Advanced Memory and Neural Computing
- CO2 Reduction Techniques and Catalysts
- Surface and Thin Film Phenomena
- Transition Metal Oxide Nanomaterials
Technical University of Munich
2014-2025
Schott (Germany)
2020-2024
Lawrence Berkeley National Laboratory
2017-2022
Joint Center for Artificial Photosynthesis
2018-2022
Max Planck Computing and Data Facility
2018-2021
Berkeley College
2017-2019
Nanosystems Initiative Munich
2016-2018
Center for NanoScience
2014-2018
Deutsches Museum
2011-2018
On-surface Ullmann coupling is a versatile and appropriate approach for the bottom-up fabrication of covalent organic nanostructures. In two-dimensional networks, however, kinetically controlled irreversible leads to high defect densities lack long-range order. To derive general guidelines optimizing reaction parameters, structural quality 2D porous networks was evaluated different preparation protocols. For this purpose, polymerization an iodine- bromine-functionalized precursor studied on...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFundamental Properties of a Synthetic Cation Exchange ResinW. C. Bauman and J. EichhornCite this: Am. Chem. Soc. 1947, 69, 11, 2830–2836Publication Date (Print):November 1, 1947Publication History Published online1 May 2002Published inissue 1 November 1947https://doi.org/10.1021/ja01203a065Request reuse permissionsArticle Views1303Altmetric-Citations134LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum full text article downloads...
The role of organometallic intermediates during on-surface polymerization via Ullmann coupling was studied on Ag(111). progress monitored by X-ray photoelectron spectroscopy (XPS). Scanning Tunneling Microscopy (STM) used to characterize and covalent networks identify the temperature regimes for bond formation.
Understanding the interplay between surface chemistry, electronic structure, and reaction mechanism of catalyst at electrified solid/liquid interface will enable design more efficient materials systems for sustainable energy production.
Solar-driven photocathode converts carbon dioxide to C<sub>2</sub>and C<sub>3</sub>products.
Catalysts for electrochemical carbon dioxide reduction in aqueous electrolytes suffer from high energy input requirements, competition with hydrogen evolution water reduction, and low product selectivity. Theory suggests that plasmonic catalysts can be tuned to selectively lower the barrier a specific reaction set of competitive reactions, but there has been little experimental evidence demonstrating plasmon-driven selectivity complicated multielectron processes. Here, photoactivity at...
We elucidate the role of subsurface oxygen on production C2 products from CO2 reduction over Cu electrocatalysts using newly developed grand canonical potential kinetics density functional theory method, which predicts that rate pure with no O is ∼500 times slower than H2 evolution. In contrast, starting Cu2O, >5,000 faster Cu(111) and comparable to production. To validate these predictions experimentally, we combined time-dependent product detection multiple characterization techniques show...
The instability of perovskite absorbers under various environmental stressors is the most significant obstacle to widespread commercialization solar cells. Herein, we study evolution crystal structure and microstrain present in naked triple-cation mixed CsMAFA-based films heat, UV, visible light (1 Sun) conditions by grazing-incidence wide-angle X-ray scattering (GIWAXS). We find that gradient distributed along surface normal films, decreasing from upper regions deeper within film. Moreover,...
Zinc nitride (Zn3N2) comprises earth-abundant elements, possesses a small direct bandgap, and is characterized by high electron mobility. While these characteristics make the material promising compound semiconductor for various optoelectronic applications, including photovoltaics thin-film transistors, it commonly exhibits unintentional degenerate n-type conductivity. This character has significantly impeded development of Zn3N2 technological applications assumed to arise from incorporation...
The polymerization of 1,4-diethynylbenzene was studied on a Cu(111) surface using scanning tunneling microscopy (STM) under ultra-high vacuum conditions. Thermal activation yielded disordered covalent networks, where distinct basic structural motifs indicate different coupling reactions.
Abstract The performance of energy materials hinges on the presence structural defects and heterogeneity over different length scales. Here we map correlation between morphological functional in bismuth vanadate, a promising metal oxide photoanode for photoelectrochemical water splitting, by photoconductive atomic force microscopy. We demonstrate that contrast mapping electrical conductance depends charge transport limitations, contact at sample/probe interface. Using temperature...
Two-dimensional materials with engineered composition and structure will provide designer beyond conventional semiconductors. However, the potentials of defect engineering remain largely untapped, because it hinges on a precise understanding electronic excitonic properties, which are not yet predictable by theory alone. Here, we utilize correlative, nanoscale photoemission spectroscopy to visualize how local introduction defects modifies properties two-dimensional at nanoscale. As model...
Understanding the chemical and electronic properties of point defects in two-dimensional materials, as well their generation passivation, is essential for development functional systems, spanning from next-generation optoelectronic devices to advanced catalysis. Here, we use synchrotron-based X-ray photoelectron spectroscopy (XPS) with submicron spatial resolution create sulfur vacancies (SVs) monolayer MoS2 monitor situ during defect creation process. irradiation leads emergence a distinct...
We report on covalent two-dimensional phenylene–boroxine hybrid-networks that were synthesized under ultra-high vacuum conditions from doubly functionalized monomers through thermally activated condensation prior to deposition and successive heterogeneously catalyzed radical addition Ag(111). Structural properties characterized in situ by high resolution Scanning-Tunneling-Microscopy (STM).
Self-assembly of 1,3,5-tris(4-mercaptophenyl)benzene (TMB), a 3-fold symmetric, thiol-functionalized aromatic molecule, was studied on Au(111) with the aim realizing extended Au-thiolate-linked molecular architectures. The focus lay resolving thermally activated structural and chemical changes by combination microscopy spectroscopy. Thus, scanning tunneling (STM) provided submolecularly resolved information, while state sulfur assessed X-ray photoelectron spectroscopy (XPS). Directly after...
The on-surface synthesis of covalent organic nanosheets driven by reactive metal surfaces leads to strongly adsorbed nanostructures, which conceals their intrinsic properties. Hence, reducing the electronic coupling between networks and commonly used is an important step towards characterization true material. We demonstrate that post-synthetic exposure iodine vapor intercalation monolayer polyphenylene Ag(111) surfaces. experimentally observed changes from surface-bound detached are...
Crystal orientations are closely related to the behavior of photogenerated charge carriers and vital for controlling optoelectronic properties perovskite solar cells. Herein, we propose a facile approach reveal effect lattice plane orientation distribution on carrier kinetics via constructing CsBr-doped mixed cation phases. With grazing-incidence wide-angle X-ray scattering measurements, investigate crystallographic films at microscopic scale extrinsic CsBr doping stacking planes. Combined...
Abstract While Ta 3 N 5 shows excellent potential as a semiconductor photoanode for solar water splitting, its performance is hindered by poor charge carrier transport and trapping due to native defects that introduce electronic states deep within bandgap. Here, it demonstrated controlled Ti doping of can dramatically reduce the concentration deep‐level enhance photoelectrochemical performance, yielding sevenfold increase in photocurrent density 300 mV cathodic shift onset compared undoped...
Abstract The photoelectrochemical performance of Ta 3 N 5 photoanodes is strongly impacted by the presence shallow and deep defects within bandgap. However, role such states in defining stability under operational conditions not well understood. Here, a highly controllable synthesis approach used to create homogenous thin films with tailored defect concentrations establish relationship between atomic‐scale point macroscale stability. Reduced oxygen contents increase long‐range structural...
The surface chemistry of 1,6-dibromo-3,8-diiodopyrene (Br2I2Py) is comparatively studied on Au(111) versus Ag(111) surfaces under ultrahigh vacuum conditions by a combination high-resolution scanning tunneling microscopy (STM) and X-ray spectroscopy. chemical state the molecular networks, that is, dehalogenation possible formation organometallic intermediates, assessed photoelectron In addition, pyrene tilt angles are quantified carbon K-edge near edge absorption fine structure experiments....
Using polystyrene opal templates, we employ electrodeposition for the synthesis of highly homogeneous, large scale nanoporous (photo)electrocatalytic materials artificial photosynthesis.
The (opto)electronic properties of Ta 3 N 5 photoelectrodes are often dominated by defects, but precise control these defects provides new insight into the electronic structure, photocarrier transport, and photoelectrochemical function.
We report on post-synthetic decoupling of covalent polyphenylene networks from Au(111) by intercalation a chemisorbed iodine monolayer. The were synthesised on-surface Ullmann polymerization 1,3-bis(p-bromophenyl)-5-(p-iodophenyl)benzene precursors under ultra-high vacuum conditions. present study relates to previous work, where successful detachment was demonstrated Ag(111) combination microscopic and spectroscopic techniques. On the more reactive surfaces, readily accomplished exposing...
Artificial photosynthetic approaches require the combination of light absorbers interfaced with overlayers that enhance charge transport and collection to perform catalytic reactions.