A5087057269- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Semiconductor materials and devices
- Advanced Chemical Physics Studies
- CO2 Reduction Techniques and Catalysts
- Electrocatalysts for Energy Conversion
- Catalytic Processes in Materials Science
- Molecular Junctions and Nanostructures
- Electronic and Structural Properties of Oxides
- Ammonia Synthesis and Nitrogen Reduction
- Machine Learning in Materials Science
- Electrochemical Analysis and Applications
- Carbon dioxide utilization in catalysis
- Hydrogen Storage and Materials
- Advanced battery technologies research
- Organometallic Complex Synthesis and Catalysis
- Asymmetric Hydrogenation and Catalysis
- Semiconductor materials and interfaces
- Ferroelectric and Negative Capacitance Devices
- Ionic liquids properties and applications
- Silicon Nanostructures and Photoluminescence
- Catalytic C–H Functionalization Methods
- Catalytic Cross-Coupling Reactions
- Advanced Polymer Synthesis and Characterization
- Copper Interconnects and Reliability
University of Colorado System
2010-2025
California Institute of Technology
1991-2025
University of Colorado Boulder
2014-2025
Northwestern University
2024-2025
University of Utah
2025
nLIGHT (United States)
2023
University of Guelph
2023
Stanford University
2001-2010
Hanyang University
2008
Agilent Technologies (United States)
2008
We report how closely the Kohn-Sham highest occupied molecular orbital (HOMO) and lowest unoccupied (LUMO) eigenvalues of 11 density functional theory (DFT) functionals, respectively, correspond to negative ionization potentials (-IPs) electron affinities (EAs) a test set molecules. also accurately HOMO-LUMO gaps these methods predict excitation energies using both time-independent time-dependent DFT (TD-DFT). The functionals include local spin approximation (LSDA), five generalized gradient...
Precise control from a metal-free catalyst Polymerization can be rather dangerous free for all, with molecules joining randomly in chains at chaotic pace. One of modern chemistry's great accomplishments has been the development methods to assemble polymers steady, orderly steps. However, order comes price, and often it's need metal catalysts that are hard remove plastic product. Theriot et al. used theory guide design light-activated offers precise atom transfer radical polymerization,...
Solar thermal water-splitting (STWS) cycles have long been recognized as a desirable means of generating hydrogen gas (H2) from water and sunlight. Two-step, metal oxide-based STWS generate H2 by sequential high-temperature reduction reoxidation oxide. The temperature swings between oxidation steps thought necessary for stifled STWS's overall efficiency because time losses that occur during the frequent heating cooling We show these are unnecessary isothermal splitting (ITWS) at 1350°C using...
N-Aryl phenoxazines have been synthesized and introduced as strongly reducing metal-free photoredox catalysts in organocatalyzed atom transfer radical polymerization for the synthesis of well-defined polymers. Experiments confirmed quantum chemical predictions that, like their dihydrophenazine analogs, photoexcited states phenoxazine are achieve superior performance when they possess charge character. We compare to previously reported dihydrophenazines phenothiazines gain insight into these...
Abstract Support-induced strain engineering is useful for modulating the properties of two-dimensional materials. However, controlling planar molecules technically challenging due to their sub-2 nm lateral size. Additionally, effect on molecular remains poorly understood. Here we show that carbon nanotubes (CNTs) are ideal substrates inducing optimum through curvature. In a tandem-flow electrolyser with monodispersed cobalt phthalocyanine (CoPc) single-walled CNTs (CoPc/SWCNTs) CO 2...
Fe-N-C materials are emerging catalysts for replacing precious platinum in the oxygen reduction reaction (ORR) renewable energy conversion. However, their potential is hindered by sluggish ORR kinetics, leading to a high overpotential and impeding efficient Using iron phthalocyanine (FePc) as model catalyst, we elucidate how local strain can enhance performance of Fe-N-Cs. We use density functional theory predict mechanism four-electron water. Several key differences between mechanisms...
Not a bit like his brother: DFT studies show that ammonia–borane dehydrogenations by iridium pincer complexes occur concerted hydride and proton transfer from to the catalyst, not through BH activation subsequent β-hydride elimination nitrogen end, as had been suggested. Such dehydrogenation pathway does exist for ethane, which is isoelectronic with ammonia–borane. Supporting information this article available on WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z702886_s.pdf or...
The atomic layer deposition of alumina using water and trimethylaluminum is investigated the density functional theory. atomistic mechanisms two half-cycles on Al–CH3* Al–OH* surface sites are investigated. Both half-cycle reactions proceed through formation an Al–O Lewis acid-base complex followed by CH4 formation. complexes relatively stable, with energies between 0.57 0.74 eV. activation range from 0.52 to 0.91 eV both exothermic overall enthalpies reaction 1.30 1.70
First-principles quantum simulations complemented with kinetic Monte Carlo calculations were performed to gain insight into the oxygen vacancy diffusion mechanism and explain effect of dopant composition on ionic conductivity in yttria-stabilized zirconia (YSZ). Density-functional theory (DFT) within local-density approximation gradient correction was used calculate a set energy barriers that ions encounter during migration YSZ by mechanism. Kinetic then using Boltzmann probabilities based...
Despite the fundamental role oxygen vacancy formation energies play in a broad range of important energy applications, their relationships with intrinsic bulk properties solid oxides remain elusive. Our study La1−xSrxBO3 perovskites (BCr, Mn, Fe, Co, and Ni) conducted using modern, electronic structure theory solid-state defect models demonstrates that combination two materials properties, oxide enthalpy minimum band gap energy, accurately correlate energies. The to form single, neutral...
Reactions of HF with uncoated and Al Zn oxide-coated surfaces LiCoO2 cathodes were studied using density functional theory. Cathode degradation caused by reaction the hydroxylated (101̅4) surface is dominated formation H2O a LiF precipitate via barrierless that exothermic 1.53 eV. We present detailed mechanism where reacts at alumina coating to create partially fluorinated rather than forming AlF3 thus films reduce cathode scavenging avoiding formation. In contrast, we find etches monolayer...
In the (salen)Co(III)-catalyzed hydrolytic kinetic resolution (HKR) of terminal epoxides, rate- and stereoselectivity-determining epoxide ring-opening step occurs by a cooperative bimetallic mechanism with one Co(III) complex acting as Lewis acid another serving to deliver hydroxide nucleophile. this paper, we analyze basis for extraordinarily high stereoselectivity broad substrate scope observed in HKR. We demonstrate that stereochemistry each two (salen)Co(III) complexes rate-determining...
The dynamic exchange of thiols and thioesters in organic media was explored, leading to room temperature plasticity crosslinked polymers.
High-performance lithium-ion batteries require electrolytes that are stable over wide operating voltages. We used density functional theory to investigate the degradation of ethylene carbonate (EC) activated by interactions with LiCoO2 cathode surfaces and PF5 species in electrolyte. report detailed mechanisms for activation EC ring-opening reactions Lewis acids form CO2, organics, or organofluorines. find acid-base complexation between either weakens C-O bonds ring consequently lowers...
The hydrodynamics of electrochemical CO2 reduction (CO2R) systems is an insufficiently investigated area research that has broad implications on catalyst activity and selectivity. While most previous reports are limited to laminar CO2-sparged systems, herein we address a wide range via electrolyte recirculation systems. We find increased at the electrode surface results directly in changes ethylene methane Tafel slopes, demonstrating mass transport equal footing with active sites determining...
We present a new hybrid density-functional method which predicts transition state barriers with the same accuracy as CBS-APNO, and enthalpies of reaction smaller errors than B3LYP, BHandHLYP, G2. The is demonstrated on 132 energies, including 74 58 reaction. For 40 reactions reliable experimental barriers, absolute mean deviations are 0.9, 1.0, 3.1, 3.5, 3.6 kcal/mol for G2, BHandHLYP methods, respectively. 38 1.2, 1.4, 3.0, 5.9 maximum 2.6 5.6 kcal/mol, In addition, we simple scheme...
The concept of proton affinity on semiconductor surfaces has been explored through an investigation the chemistry amines Ge(100)-2 x 1, Si(100)-2 and C(100)-2 1 surfaces. Multiple internal reflection Fourier transform infrared (MIR-FTIR) spectroscopy, temperature programmed desorption (TPD), density functional theory (DFT) calculations were used in studies. We find that methylamine, dimethylamine, trimethylamine undergo molecular chemisorption surface formation Ge-N dative bonds. In...
Enders' N-heterocyclic carbene (NHC) dehydrogenates ammonia-borane with a relatively low barrier, producing NH(2)BH(2) and NHC-(H)(2). The nickel NHC catalyst present in the reaction media can activate NHC-(H)(2) produced to regenerate free release H(2). of enables further dehydrogenation ammonia-borane.
The reactivity of NH(2)BH(2) in the presence ammonia-borane (AB) is investigated using ab initio CCSD(T) simulations to answer following three questions: How do AB and react? aminoborane species oligomerize apart from catalytic centers? Can formation experimentally observed products, especially cyclic N(2)B(2)H(7)-NH(2)BH(3), be explained through kinetics oligomerization AB? shown react with by addition NH(3)-BH(3) across N=B double bond, generating linear NH(3)BH(2)NH(2)BH(3). This...
We report a trinuclear copper(II) complex, [(DAM)Cu3(μ3-O)][Cl]4 (1, DAM = dodecaaza macrotetracycle), as homogeneous electrocatalyst for water oxidation to dioxygen in phosphate-buffered solutions at pH 7.0, 8.1, and 11.5. Electrocatalytic 7 occurs an overpotential of 550 mV with turnover frequency ∼19 s–1 1.5 V vs NHE. Controlled potential electrolysis (CPE) experiments 11.5 over 3 h 1.2 8.1 40 min 1.37 NHE confirm the evolution Faradaic efficiencies 81% 45%, respectively. Rinse tests...
The decatungstate anion, [W10O32]4– or DT, is a useful photocatalyst for organic transformations involving C–H functionalization. Herein, we leverage the unique photoredox properties of DT to generate chlorine radical from chloride ion photochemical partial oxidation methane. Under optimized conditions, DT–chloride–iodine ensemble achieves methane methyl trifluoroacetate conversion with >350 turnovers at ∼60% yield based on in trifluoroacetic acid solvent. Methyl exhibits excellent stability...
We investigate the mechanism of NH3 adsorption and initial decomposition on (2×1) reconstructed Si(100) surface using B3LYP density functional theory. The Si(100)-(2×1) is described cluster approximation. Ammonia found to adsorb “down” atom buckled silicon dimer with no activation barrier. also find that only half atoms are active sites for ammonia adsorption. exothermic an energy 29 kcal/mol. Dissociation adsorbed form NH2(a) H(a) proceeds a low 5 kcal/mol below NH3(g) bare energy. Our...