A5070203543- Advanced Photocatalysis Techniques
- Gas Sensing Nanomaterials and Sensors
- Copper-based nanomaterials and applications
- Electronic and Structural Properties of Oxides
- Advanced Chemical Physics Studies
- Graphene research and applications
- ZnO doping and properties
- Catalytic C–H Functionalization Methods
- Transition Metal Oxide Nanomaterials
- Radical Photochemical Reactions
- Perovskite Materials and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Hormonal Regulation and Hypertension
- Supercapacitor Materials and Fabrication
- Advancements in Battery Materials
- Catalysis and Oxidation Reactions
- Chalcogenide Semiconductor Thin Films
- Organometallic Complex Synthesis and Catalysis
- Oxidative Organic Chemistry Reactions
- Ion-surface interactions and analysis
- Ga2O3 and related materials
- Advanced Optical Sensing Technologies
- MXene and MAX Phase Materials
- Fuel Cells and Related Materials
- Quantum Dots Synthesis And Properties
Paul Scherrer Institute
2022-2024
Koç University
2019-2023
SLAC National Accelerator Laboratory
2023
Pacific Northwest National Laboratory
2023
Bilkent University
2016
Transition metal reactivity toward carbon-hydrogen (C-H) bonds hinges on the interplay of electron donation and withdrawal at center. Manipulating this in a controlled way is difficult because hypothesized metal-alkane charge-transfer interactions are challenging to access experimentally. Using time-resolved x-ray spectroscopy, we track during C-H activation octane by cyclopentadienyl rhodium carbonyl complex. Changes oxidation state as well valence-orbital energies character emerge data...
On the BiVO 4 photoanode surface, oxygen vacancies modified by cobalt incorporation have a remarkable impact on water oxidation activity and charge injection efficiency.
BiVO4 is one of the most promising photoanode candidates to achieve high-efficiency water splitting. However, overwhelming charge recombination at interface limits its oxidation activity. In this study, we show that activity significantly boosted by TiO2 overlayer prepared atomic layer deposition. With a an optimized thickness, photocurrent 1.23 VRHE increased from 0.64 1.1 mA·cm-2 under front illumination corresponding 72% enhancement. We attribute substantial improvement enhanced...
The synthesis and control of properties p-type ZnO is crucial for a variety optoelectronic spintronic applications; however, it remains challenging due to the intrinsic midgap (defect) states. In this study, we demonstrate synthetic route yield colloidal quantum dots (QD) via an enhanced sol–gel process that effectively eliminates residual intermediate reaction molecules, which would otherwise weaken excitonic emission. This supports creation with or compensation inherited n-type defects,...
Abstract A new method for time‐resolved X‐ray absorption near edge structure (XANES) spectroscopy that enables faster data acquisition and requires smaller sample quantities high‐quality data, thus allowing the analysis of more samples in a shorter time is introduced. The uses large bandwidth free electron laser pulses to measure laser‐excited XANES spectra transmission mode. beam‐splitting grating configuration allows simultaneous measurements incoming Free Electron Laser (XFEL) XANES,...
BiVO4 is one of the most promising photoanode materials for water-splitting systems. Nitrogen incorporation into a surface overcomes known bottleneck in its charge-transfer kinetics electrolyte. We explored role nitrogen charge recombination and by employing transient photocurrent spectroscopy at time scale water oxidation kinetics, absorption spectroscopy, X-ray photoelectron spectroscopy. attributed activity enhancement mechanism to accelerated V5+/V4+ redox process, which incorporated...
Postsynthetic treatments of BiVO4 photoanodes have recently shed light on better understanding and improving the for water splitting. We demonstrate that a mild heat treatment under O2 flow at 200 °C improves its oxidation activity. Charge separation charge injection efficiencies increase along with decreased transfer resistances across BiVO4/electrolyte interface. The depletion region width band bending shown to after annealing, while carrier density remains unchanged. Transient...
Photogenerated charge carrier dynamics of BiVO4 have been investigated by ultrafast transient absorption spectroscopy (TAS), and a numerical modeling has applied to reveal the origins dynamical behavior. The model, based on rate equations, presents possibility both photogenerated hole electron below 500 nm, as opposed generally suggested mechanism. investigations done in time regime show that positive peak at 470 nm exhibits inverse behavior compared broad-band feature represented 550 under...
We report on the correlation of atomic concentration profiles diffusing species with blueshift quantum well luminescence from both as-grown and impurity free wells intermixed actual large optical cavity high power laser diode structures. Because it is critical to suppress catastrophic mirror damage, sputtered SiO2 thermally evaporated SrF2 were used enhance intermixing, respectively, in these (Al)GaAs A 55 nm (130 meV) was obtained for samples 400 thick SiO2. These layers generate point...
The reactivity towards C-H bond activation of alkanes with transition metals is determined by the ability metal to donate and withdraw electron density in due proportion. Manipulating this a controlled way difficult, because hypothesized metal-alkane charge-transfer interactions are challenging access experimentally. Using time-resolved X-ray spectroscopy, we track activating Rh complex reveal changes oxidation state as well valence-orbital energies character from femtosecond Rh-alkane...
In this study, we place a strong emphasis on understanding the ultrafast dynamics of carrier recombination pathways in p-type ZnO, especially midgap region. Synthesizing and controlling properties ZnO remains pivotal yet challenging task for numerous optoelectronic spintronic applications due to intrinsic (defect) states. Through an advanced sol-gel process, have successfully produced quantum dots (QD), eliminating unreacted molecules that decrease excitonic emission. This refined method...
Photochemically prepared transition-metal complexes are known to be effective at cleaving the strong C-H bonds of organic molecules in room temperature solutions. There is also ample theoretical evidence that bidirectional charge-transfer between an incoming alkane group and transition metal decisive interaction activation reaction. What missing, however, experimental methods directly probe these interactions order reveal what determines reactivity intermediates rate Here, we propose...
Abstract Understanding the fundamental steps of adsorption and controlled release hydrogen in two-dimensional (2D) materials is relevance for applications nanoelectronics requiring tuning physical properties or functionalization material, storage environmental sensors. Most demand that desorption can be at room temperature. Here we report an element-specific study on hydrogenation dehydrogenation, a low coverage regime, quasi-free standing 2D heterostructure (h-BNG) form coexisting lateral...
Using ultrafast X-ray absorption spectroscopy, we observe how a rhodium carbonyl catalyst is formed on femtosecond timescales and reveal the decisive orbital interactions which facilitate efficient cleavage of an alkane C-H bond from solution.
Manganese doping of ZnO nanoparticles, by introducing midgap states, is a potential solution to overcome the limitations rapid recombination photogenerated carriers. Ultrafast transient anisotropy measurements uncover trapping dynamics upon Mn doping.