A5101512634- High voltage insulation and dielectric phenomena
- Power Transformer Diagnostics and Insulation
- Advanced Photocatalysis Techniques
- Lightning and Electromagnetic Phenomena
- Electrocatalysts for Energy Conversion
- Electrohydrodynamics and Fluid Dynamics
- Copper-based nanomaterials and applications
- Analytical chemistry methods development
- Advanced Chemical Physics Studies
- Thermal Analysis in Power Transmission
- X-ray Spectroscopy and Fluorescence Analysis
- X-ray Diffraction in Crystallography
- Electrostatic Discharge in Electronics
- Electrochemical Analysis and Applications
- Aerosol Filtration and Electrostatic Precipitation
- Advanced battery technologies research
- Electrical Fault Detection and Protection
- Catalytic Processes in Materials Science
- Fluorine in Organic Chemistry
- Crystallization and Solubility Studies
- Non-Destructive Testing Techniques
- Petroleum Processing and Analysis
- TiO2 Photocatalysis and Solar Cells
- Water Systems and Optimization
- Mercury impact and mitigation studies
Stanford Synchrotron Radiation Lightsource
2020-2025
SLAC National Accelerator Laboratory
2020-2025
Stanford University
2020-2025
Menlo School
2020-2023
Polytechnic University of Turin
2022
King Abdullah University of Science and Technology
2016-2021
King Saud University
1993-2019
University of Oregon
2019
Massachusetts Institute of Technology
2019
COMSATS University Islamabad
2017
Heterogeneous photocatalysis is a potentially competitive solution for the direct production of solar fuels. This research field has seen tremendous growth over last five decades, and with such an exciting topic, it seen—and will continue to see—an increasing number papers being published in variety journals. However, becoming increasingly difficult compare efficiencies heterogeneous photocatalyst powders, because different researchers report their results ways. Efforts have been made create...
Abstract The effect of residual Pd on hydrogen evolution activity in conjugated polymer photocatalytic systems is systematically investigated using colloidal poly(9,9‐dioctylfluorene‐alt‐benzothiadiazole) (F8BT) nanoparticles as a model system. Residual Pd, originating from the synthesis F8BT via catalyzed polycondensation polymerization, observed form homogeneously distributed within polymer. essential for any to be this polymer, and very low concentrations (<40 ppm) are sufficient have...
The present work compares the oxygen evolution reaction (OER) in electrocatalysis and photocatalysis aqueous solutions using nanostructured NiFeOx as catalysts. impacts of pH temperature on electrocatalytic photocatalytic OER kinetics were investigated. For electrocatalysis, a catalyst was hydrothermally decorated Ni foam. In 1 M KOH solution, electrocatalyst achieved 10 mA cm–2 at an overpotential 260 mV. same surface Ta3N5 photocatalyst powder. conducted presence 0.1 Na2S2O8 strong...
Abstract For overall water‐splitting systems, it is essential to establish O 2 ‐insensitive cathodes that allow cogeneration of H and . An acid‐tolerant electrocatalyst described, which employs a Mo‐coating on metal surface achieve selective evolution in the presence In operando X‐ray absorption spectroscopy identified reduced Pt covered with an amorphous molybdenum oxyhydroxide hydrate local structural order composed polyanionic trimeric units molybdenum(IV). The Mo layer likely hinders gas...
The metal cluster size in supported catalysts impacts the oxidation state of atoms, coordination capability, and finally catalytic activity—especially when number atoms becomes countable. correlation between its consequences for ultrafine Pt was studied photocatalytic overall water splitting using a Pt/SrTiO3 (photo)catalyst. A distinctive change behavior observed below 100 Pt-atom clusters at ∼2 nm. Combining density functional theory (DFT) experimental characterizations including X-ray...
Successful conversion of renewable energy to useful chemicals requires efficient devices that can electrocatalyze or photocatalyze redox reactions, e.g., overall water splitting. Excellent electrocatalysts for the hydrogen evolution reaction (HER), such as Pt, also cause other side-reactions, including water-forming back-reaction from H2 and O2 products. A Cr-based amorphous layer coated on catalysts work a successful surface modifier avoids back-reaction, but its capabilities limitations...
Understanding photophysical and electrocatalytic processes during photocatalysis in a powder suspension system is crucial for developing efficient solar energy conversion systems. We report substantial enhancement by factor of 3 photocatalytic efficiency the oxygen evolution reaction (OER) adding trace amounts (∼0.05 wt %) noble metals (Rh Ru) to 2 % cobalt oxide modified Ta3N5 photocatalyst particulate. The optimized exhibited high quantum efficiencies (QEs) up 28 8.4% at 500 600 nm 0.1 M...
The field of heterogeneous photoredox catalysis has grown substantially and impacted organic synthesis because the affordability reusability catalysts. This study reports radical trifluoromethylation with Cd–chalcogenide semiconductors. Cd semiconductors, particularly CdSe, are readily available, commercial, visible-light-responsive, photocatalysts. potential available is confirmed by their increased photocatalytic activity toward various substrates, such as (hetero)arenes vinylic...
Nowadays, zirconium metal–organic frameworks attract more attention because of their robustness and easier predictability in terms topology. Herein, we have been able to control synthetic parameters order construct two new 2D MOFs with the same sql Both materials, ACM-10 ACM-11, characterized by single-crystal X-ray diffraction, thermogravimetric analysis, UV–vis spectroscopy. Their textural, electrochemical, conductivity properties are presented along opportunities that these topologically...
Platinum single atoms are grafted by SOMC on morphology-controlled TiO<sub>2</sub>. Their structure is characterized EXAFS and other techniques, their activity stability in HER backwards reaction studied compared to Pt nanoparticles.
The causative agent of Covid-19 is the SARS-CoV-2 virus. Initiation cell entry by critically dependent upon binding spike protein to angiotensin-converting enzyme 2 (ACE2, EC 3.4.17.23). mechanism receptor domain ACE2 among most intensively studied infection mechanisms any pathogen, including a very large number structural studies. membrane-associated zinc carboxypeptidase, comprising three domains, protease domain, neck and membrane-spanning α-helical domain. In addition its role as also...
Sulfur Kβ non-resonant X-ray emission spectroscopy complements sulfur K-edge absorption in providing information on chemical speciation and electronic structure.
Metallo dithiolene complexes with biological and catalytic relevance are well-known for having strong metal-ligand covalency, which dictates their valence electronic structures. We present the resonant sulfur Kβ (1s3p) X-ray emission spectroscopy (XES) a series of Ni Cu bis(dithiolene) to reveal ligand contributions both occupied unoccupied orbitals. While S K-edge absorption played critical role in identifying covalency orbitals metal dithiolenes, focus on XES explores density states. For [Cu(mnt)
Reliably identifying short-lived chemical reaction intermediates is crucial to elucidate mechanisms but becomes particularly challenging when multiple transient species occur simultaneously. Here, we report a femtosecond x-ray emission spectroscopy and scattering study of the aqueous ferricyanide photochemistry, utilizing combined Fe Kβ main valence-to-core lines. Following UV-excitation, observe ligand-to-metal charge transfer excited state that decays within 0.5 ps. On this timescale, also...
Accelerated aging of two types commercially produced medium voltage XLPE insulated cables was carried out under the combined stresses three consisting ionic aqueous species, elevated electrical stress and temperature cycling. After 1000 h aging, water tree parameters were evaluated. Results show that external species exert profound impact on generation bow tie vented trees, while impurities inherently present in cable components also contribute significantly. Temperature cycling increases...
Quantitative description of electrolyte impact is established for nanoscale water electrolysis prevalent during photocatalytic overall splitting.
Mercury is in some sense an enigmatic element. The element and of its compounds are a natural part the biogeochemical cycle; while many these can be deadly poisons at higher levels, environmental levels absence anthropogenic contributions would generally below threshold for concern. However, mercury pollution, particularly from burning fossil fuels such as coal, providing dramatic increasing emissions into environment. Because this, chemistry toxicology growing importance, with fate being...
The sulfones are a widespread group of organo-sulfur compounds, which contain the sulfonyl SO2 attached to two carbons and have formal sulfur oxidation state +2. We examined K near-edge X-ray absorption spectroscopy (XAS) range different find substantial spectroscopic variability depending upon nature coordination group. also Kβ emission (XES) selected representative sulfones. Density functional theory simulations show satisfactory reproduction both spectra while enabling assignment various...
The authors review the important parameters of particles which are present in environment when sand/dust storms occur. Basic features experimental system summarized. Extensive measurements breakdown voltages and times to carried out under clean polluted conditions using rod-plane sphere-plane gaps. It is shown that positive lightning impulse applied asymmetrical gaps from 5 cm 2 m, presence contamination can cause a voltage reduction. However, greatly affect characteristics negative...
Crosslinked polyethylene (XLPE) insulated power cables are used for transmission and distribution of electrical power. Such subjected to extensive high voltage testing performance evaluation quality control purposes. During such testing, the cable ends have be prepared carefully make a proper end termination. Usually deionized water terminations this purpose. Alternatively conductive paint is prepare This paper presents method calculating across resistive termination when AC testing. The...
For overall water-splitting systems, it is essential to establish O2-insensitive cathodes that allow cogeneration of H2 and O2. An acid-tolerant electrocatalyst described, which employs a Mo-coating on metal surface achieve selective evolution in the presence In operando X-ray absorption spectroscopy identified reduced Pt covered with an amorphous molybdenum oxyhydroxide hydrate local structural order composed polyanionic trimeric units molybdenum(IV). The Mo layer likely hinders O2 gas...
This paper describes HV laboratory tests to study the surface leakage current performance of desert-exposed insulators. It was found that inland desert meteorological conditions and contamination vary considerably from coastal areas. Leakage studies on simulated desert-polluted insulators exhibit some interesting manifestations which may have strong effects in processes leading voltage flashover field. A technique is described for testing rapidly behavior contaminating salts. Interesting...
Investigations have been made to evaluate the performance of rod-rod gaps two different shapes in presence simulated dust storms. Breakdown voltages and time lags determined for a range gap spacings from 5 cm 125 standard lightning impulses. It was found: that influence particles >or=50 is small not much practical importance, but <50 these marked effect as positive breakdown voltage values are considerably reduced. An anomalous condition reported under negative polarity which 50% lower than...