A5015488907- Catalytic Processes in Materials Science
- Advanced Photocatalysis Techniques
- Covalent Organic Framework Applications
- Catalysis and Oxidation Reactions
- Electrochemical Analysis and Applications
- 2D Materials and Applications
- Electronic and Structural Properties of Oxides
- Graphene research and applications
- Spectroscopy and Quantum Chemical Studies
- Metal-Organic Frameworks: Synthesis and Applications
- Radioactive element chemistry and processing
- Transition Metal Oxide Nanomaterials
- Quantum and electron transport phenomena
- Electrocatalysts for Energy Conversion
- Nuclear Materials and Properties
- Luminescence Properties of Advanced Materials
- Gas Sensing Nanomaterials and Sensors
- TiO2 Photocatalysis and Solar Cells
- Analytical Chemistry and Sensors
- Quantum Dots Synthesis And Properties
- Copper-based nanomaterials and applications
- Electrostatics and Colloid Interactions
- Advanced Chemical Physics Studies
- Boron and Carbon Nanomaterials Research
- Magnetic and transport properties of perovskites and related materials
University of Potsdam
2021-2025
University College London
2020-2024
London Centre for Nanotechnology
2020-2024
Humboldt-Universität zu Berlin
2013-2020
Thomas Young Centre
2020
Abstract Covalent organic frameworks (COFs) have emerged as an important class of semiconductors and photocatalysts for the hydrogen evolution reaction (HER)from water. To optimize their photocatalytic activity, typically moieties constituting are considered most suitable combinations them searched for. However, effect covalent linkage between these on performance has rarely been studied. Herein, we demonstrate that donor‐acceptor (D‐A) type imine‐linked COFs can produce with a rate high...
When new covalent organic frameworks (COFs) are designed, the main efforts typically focused on selecting specific building blocks with certain geometries and properties to control structure function of final COFs. The nature linkage (imine, boroxine, vinyl, etc.) between these naturally also defines their properties. However, besides type, orientation, i.e., constitutional isomerism linkages, has rarely been considered so far as an essential aspect. In this work, three pairs...
We examine (VO)k and (VO2)k (k = 1, 2, 3) species supported on CeO2(111) by periodic density functional theory as models for ceria-supported vanadia catalysts. use the PBE correct onsite Coulomb correlation (PBE+U). As reactivity descriptors, we calculate oxygen defect formation hydrogenation energies. In agreement with experiment, our results suggest that vanadyl-terminated monomers, is, VO2, represent most active species. This system has a remarkably low energy of 0.84 eV (clean surface:...
The role of surface and subsurface O vacancies for gold adsorption on crystalline CeO2(111) films has been investigated by scanning tunneling microscopy density functional theory. Whereas serve as deep traps the Au atoms, defects promote formation characteristic pairs with a mean atom distance two ceria lattice constants (7.6 Å). Hybrid theory calculations reveal that pair arises from titration Ce3+ ions generated single vacancy. Au-Ce3+ bond forms due to strain effect, associated charge...
The reduced dimensionality of thin transition metal dihalide films on single-crystal surfaces unlocks a diverse range magnetic and electronic properties. However, achieving stoichiometric monolayer islands requires precise control over the growth conditions. In this study, we employ scanning probe microscopy to investigate MnI2 Ag(111) via single-crucible evaporation. catalytic properties surface facilitate dehalogenation, leading formation reconstructed iodine adlayer that acts as buffer...
The solvation of ions at interfaces is important to areas as diverse atmospheric sciences, energy materials, and biology. Despite the significance, fundamental understanding, particularly molecular level, remains incomplete. Here, we probe initial two singly charged but differently sized (Li Cs) on a Au(111) by combining low-temperature scanning tunneling microscopy with density functional theory. Real-space scale information reveals that water–ion interactions dominate Li−water system,...
Abstract Covalent organic frameworks (COFs) have emerged as an important class of semiconductors and photocatalysts for the hydrogen evolution reaction (HER)from water. To optimize their photocatalytic activity, typically moieties constituting are considered most suitable combinations them searched for. However, effect covalent linkage between these on performance has rarely been studied. Herein, we demonstrate that donor‐acceptor (D‐A) type imine‐linked COFs can produce with a rate high...
The multicomponent approach allows to incorporate several functionalities into a single covalent organic framework (COF) and consequently the construction of bifunctional materials for cooperative catalysis. well-defined structure such COFs is furthermore ideally suited structure-activity relationship studies. We report series that contain acridine- 2,2'-bipyridine linkers connected through 1,3,5-benzenetrialdehyde derivatives. acridine motif responsible broad light absorption, while...
Understanding the molecular and electronic structure of solvated ions at surfaces requires an analysis interactions between surface, ions, solvent environment on equal footing. Here, we tackle this challenge by exploring initial stages Cs^{+} hydration a Cu(111) surface combining experiment theory. Remarkably, observe "inside-out" solvation i.e., their preferential location perimeter water clusters metal surface. In addition, water-Cs complexes containing multiple are observed to form these...
In nature, organic molecules play a vital role in light harvesting and photosynthesis. However, regarding artificial water splitting, the research focus is primarily on inorganic semiconductors. Although photocatalysts have high structural variability, they tend to exhibit lower quantum efficiencies for splitting than their counterparts. Multicomponent reactions (MCRs) offer an attractive route introduce different functional units into covalent frameworks (COFs) enable semiconducting...
By virtue of periodic density functional theory, we investigate structure and thermodynamic stability (VO)k (VO2)k (k = 1, 2, 3) clusters deposited on the CeO2(111) surface, which serve as models for very active sub-monolayer vanadia catalyst a ceria support. We find V always completely oxidized (oxidation state +5) coordinated to four O atoms. As consequence, Ce4+ is (partially) reduced Ce3+. Thus, localized Ce-4f states are populated, requires an onsite U-term (PBE+U) avoid...
Structures and stabilities of vanadium oxide oligomers as well two candidate structures for a monolayer on the CeO2(111) surface have been studied by density functional theory, employing genetic algorithm to determine global energy minimum structures. These ceria-supported predominantly 4-fold coordinated V5+ ions with V═O groups in common. The agglomeration VO2 clusters deposited is strongly exothermic process, particularly when ring three or six units are formed that commensurate...
Polarons are ubiquitous in many semiconductors and have been linked with conductivity optical response of materials for photovoltaics heterogeneous catalysis, yet how surface polarons influence adsorption remains unclear. Here, by modelling the rutile titania using density functional theory, we reveal effect small on water adsorption, dissociation, hydrogen bonding. On one hand presence such significantly suppresses dissociation molecules that bonded directly to polaronic sites. other hand,...
Recently we showed that Au atoms may titrate Ce3+ ions in near-surface layers of reduced CeO2(111). This surface contained oxygen vacancies subsurface position within the topmost O–Ce–O trilayer [Pan et al., Phys. Rev. Lett., 2013, 111, 206101.]. The present work builds upon these findings and discusses additional results obtained using PBE+U hybrid functionals. These approaches do not predict same relative stabilities for various adsorption sites a single adatom at an O-defect concentration...
Metal-oxide aqueous interfaces are important in areas as varied photocatalysis and mineral reforming. Crucial to the chemistry at these is structure of electrical double layer formed when anions or cations compensate for charge arising from adsorbed H+ OH–. This has proven extremely challenging determine atomic level. In this work, we use a surface science approach, involving level characterization, pH-dependent model electrified TiO2(110) with HCl NaOH using X-ray diffraction (SXRD). A...
The vibrational dynamics and (time-dependent) vSFG spectra of deuterated water molecules at g-C 3 N 4 C 2 surfaces have been studied using DFT-based AIMD simulations.
Graphene is well-known for its unique combination of electrical and mechanical properties. However, vanishing band gap limits the use graphene in microelectronics. Covalent functionalization has been a common approach to address this critical issue introduce gap. In Article, we systematically analyze single-layer (SLG) bilayer (BLG) with methyl (CH3) using periodic density functional theory (DFT) at PBE+D3 level theory. We also include comparison methylated graphene, as well discussion...
Hydrogen bonding is essential in electron-transfer processes at water–electrode interfaces. We study the impact of H-bonding water as a solvent molecule on real-time dynamics across Cs+–Cu(111) ion–metal interface using femtosecond time-resolved two-photon photoelectron spectroscopy. distinguish formed water–alkali aggregates two regimes below and above molecules per ion. Upon crossing boundary these regimes, lifetime excess electron localized transiently Cs+ ion increases from 40 to 60 fs,...
The effect of protonation, constitutional isomerism, and solvation on the water splitting reaction at imine-linked covalent organic frameworks is investigated by density functional theory calculations.
In this work, the vibrational dynamics and spectroscopy of deuterated water molecules (D$_{2}$O) mimicking dense layers at room temperature on surfaces two different C/N based materials with N content pore size, namely graphitic C$_{3}$N$_{4}$ (g-C$_{3}$N$_{4}$) C$_{2}$N are studied using Ab Initio Molecular Dynamics (AIMD). particular, Time-Dependent Sum-Frequency Generation spectra (TD-vSFG) OD modes also time-averaged vSFG frequency distributions computed.
Covalent organic frameworks (COFs) are a promising class of metal- free catalysts, offering high structural and functional variety. Here, we systematically study imine-linked COFs with donor (D) ac- ceptor (A) groups using density theory (DFT). Using water splitting as model reaction, analyze the effects protonation catalyst, orientation imine linkage leading to differ- ent constitutional isomers, solvation. In agreement experi- mental results, show that decreases band gap. addition, in...