Large exchange splitting in monolayer graphene magnetized by an antiferromagnet
Not provided.
Engineering↗
SEARCH · Engineering Papers
Results for “Splitting”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
In situ investigation on ultrafast oxygen evolution reactions of water splitting in proton exchange membrane electrolyzer cells
We present that the oxygen evolution reaction (OER) is a half reaction in electrochemical devices, including low-temperature water electrolysis, which is considered as one of the most promising methods to generate hydrogen/oxygen for the storage of energy. It is affected by many factors, and its mechanism is still not completely understood. A proton exchange membrane electrolyzer cell (PEMEC) with optical access to the surface of anode catalyst layer (CL) coupled with a distinguished high-speed and micro-scale visualization system (HMVS) was developed to in situ investigate OERs. It was revealed in real time that OERs only occur on the anode CL adjacent to liquid/gas diffusion layer (LGDL). The CL electrical conductivity plays a crucial role in OERs on CLs. The large in-plane electrical resistance of CLs becomes a threshold of OERs over the entire CL, and causes a lot of catalyst waste in the middle of LGDL pores. Moreover, the oxygen bubble nucleation, growth, and detachment and the effect of current density on those processes were also characterized. Here, this study proposes a new approach for better understanding the mechanisms of OERs and optimizing the design and fabrication of membrane electrode assemblies.
25 ENERGY STORAGE↗
Effects of coordination sphere on unusually large zero field splitting and slow magnetic relaxation in trigonally symmetric molecules
Coordination of a water molecule results in drastic effects on the magnetic behavior of a series of trigonal monopyramidal and bipyramidal compounds.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Precious metal-free solar-to-fuel generation: SSM-DSCs powering water splitting with NanoCOT and NiMoZn electrocatalysts
A precious metal-free sequential series multijunction dye-sensitized solar cell (SSM-DSC)-powered water electrolysis system is shown using NanoCOT and NiMoZn electrodes. Furthermore, a stable 3.9% solar-to-hydrogen (STH) efficiency is achieved using a recently reported black organic dye and graphene electrodes for DSCs.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Computational screening of transition-metal single atom doped C 9 N 4 monolayers as efficient electrocatalysts for water splitting
Ni@C 9 N 4 performs as a promising bifunctional electrocatalyst with N and Ni atoms as the catalytic active sites for HER and OER, with calculated hydrogen adsorption Gibbs free energy (Δ G H* ) of −0.04 eV and OER overpotential ( η OER ) of 0.31 V.
Zhou, Yanan↗
Hierarchical tri-functional electrocatalysts derived from bimetallic–imidazolate framework for overall water splitting and rechargeable zinc–air batteries
There is a growing need for an efficient multi-functional electrocatalyst that can produce industry-level high currents at low overpotentials. In this article, we report a highly efficient, robust tri-functional catalytic electrode that simultaneously catalyzes three different electrochemical reactions: the oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR). The catalytic electrodes with a hierarchical structure are converted from a hierarchical nickel-rich, nickel–cobalt bimetallic–imidazolate framework directly grown onto a nickel foam. Catalytic electrodes composed of bimetallic phosphides exhibit excellent OER and HER catalytic activity (an overpotential of 201/250 mV at 20/100 mA cm -2 for OER and an overpotential of 67/110 mV at 20/100 mA cm -2 for HER), as well as ORR activity with a half-wave potential at 0.82 V vs. RHE. Furthermore, the bimetal–nitrogen–carbon (M–N–C) catalytic electrode also exhibits tunable tri-functional catalytic activity, including excellent ORR activity with a half-wave potential at 0.88 V vs. RHE. Lastly, the high potential of these multi-functional electrocatalysts from single nickel-rich bimetallic–organic complexes is demonstrated by employing them as robust alkaline water electrolyzers, as well as decoupled air electrodes for rechargeable zinc–air batteries (ZABs).
25 ENERGY STORAGE↗
Aliovalent fluorine doping and anodization-induced amorphization enable bifunctional catalysts for efficient water splitting
Abstract not provided
Zhong, Chenglin↗
Effect of charge selective contacts on the quasi Fermi level splitting of CuGa 3 Se 5 thin film photocathodes for hydrogen evolution and methylviologen reduction
The defect-copper chalcopyrite CuGa 3 Se 5 is a promising photocathode material for solar hydrogen generation. Here we assess its performance with photoelectrochemical measurements and vibrating Kelvin probe surface photovoltage spectroscopy.
14 SOLAR ENERGY↗
Modulation of the coordination environment enhances the electrocatalytic efficiency of Mo single atoms toward water splitting
Here, enhancing the catalytic efficiency through engineering active site environments is expected to work pronouncedly for single atom catalysts (SACs) because of intense atomic scale interactions involved between SAs and their coordination environments. Taking Mo SACs for catalyzation of the hydrogen evolution reaction (HER) as an example, three SACs of different coordination environments, namely Mo-O 2 N 2 , Mo-O 2 N 1 C 1 , and Mo-O 2 C 2 , were successfully created for demonstration. The HER performances are in an increasing order of Mo-O 2 N 2 , Mo-O 2 N 1 C 1 , and Mo-O 2 C 2 , exhibiting η 10 of 98, 71, and 61 mV, η 500 of 340, 248, and 200 mV, Tafel slopes of 95.8, 39.6, and 33.8 mV dec -1 , and current density decays of 9, 6, and 6% after a 50 hour operation at an initial current density of 100 mA cm -2 , respectively. Substituting C with N in the coordination environment results in inferior HER catalytic efficiency and stability. Density functional theory calculations reveal that replacing carbon with nitrogen for coordination with the Mo SA on a carbon substrate of a higher N-doping level shifts the d-band center of Mo more negatively from the Fermi level, thereby increasing the hydrogen adsorption energy and thus decelerating the hydrogen desorption kinetics, giving consequent inferior HER activities.
25 ENERGY STORAGE↗
Impact of morphology and oxygen vacancy content in Ni, Fe co-doped ceria for efficient electrocatalyst based water splitting
Schematic presentation of Ni + Fe co-doped CeO 2 mesoporous.
Chemistry↗
Giant Rashba-splitting of one-dimensional metallic states in Bi dimer lines on InAs(100)
Experimental electronic structure and quasi 1D spin texture of Bi dimer lines on InAs(100) displaying giant Rashba parameter.
36 MATERIALS SCIENCE↗
Room temperature crystal field splitting of curium resolved by circularly polarized luminescence spectroscopy
Coordination of Cm(III) with a chiral decadentate ligand N,N,N',N'-tetrakis[(6-carboxypyridin-2-yl)methyl]-1,2-diaminocyclohexane (tpadac) generated complexes with strong luminescence allowing for the unprecedented measurement of well-resolved Cm(III) circularly polarized luminescence spectra. Quantitative resolution of the electronic structure of the [Cm(tpadac)][K] complexes was achieved at room temperature, highlighting the strength of the combination of luminescence and circularly polarized luminescence spectroscopies to unravel the fundamental electronic structure of Cm(III). These results are a clear demonstration that these spectroscopies are powerful yet simple tools for the fundamental understanding of electronic structure, which opens the door to future investigations of other Cm(III) complexes in geometries relevant to nuclear applications, and even other 5f-elements.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Unveiling the photocatalytic potential of two-dimensional ferroelastic LuSX monolayers for efficient water splitting: a first-principles discovery
Two-dimensional ferroelastic materials can be utilized to enhance photocatalytic applications.
Ma, Fengxian [College of Physics, Hebei Key Labora↗
Gaunt and Breit two-electron contributions to mean-field transformations and fine structure splitting
Materials utilized by novel energy systems are often studied using weakly correlated mean-field theories. However, if these systems incorporate heavy elements, relativistic effects must be included. Therefore, a Kramers unrestricted coupled cluster with singles and doubles excitation formalism within a molecular mean-field exact two-component framework (X2C mmf ) using a four-component Dirac–Hartree–Fock (DHF) reference state is presented. The exact X2C mmf transformed normal-order Hamiltonian incorporates all one-electron and two-electron (2e) contributions from the Coulomb, Gaunt, and Breit operators and is used with the equation of motion method to calculate the excitation energies of the alkali group of elements. Using this framework, the effects of 2e Gaunt and Breit integrals are studied. Results demonstrate growing contributions from these integrals to the generated X2C mmf mean-fields and electronic fine structure calculations with increasing atomic number. Overall, this paper outlines the method, its effect within the X2C mmf approach, and lays the foundation for future theoretical development of relativistic calculations within this framework.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Communication: Water activation and splitting by single metal-atom anions
We report experimental and computational results pertaining to the activation of single water molecules by single, atomic Group 10 metal anions. The anion photoelectron spectra of [Pt(H 2 O)] - , [Ni(H 2 O)] - , and [Pd(H 2 O)]- exhibit spectral features that are due both to anion-molecule complexes of the form, M-(H 2 O), where M = Pt, Ni, Pd, and to the formation of HMOH- intermediates. Computations at the CCSD(T) level of theory provide structures and vertical detachment energies of both HMOH- and H 2 MO - intermediates. The calculated vertical detachment energies for HMOH- are in good agreement with the photoelectron spectra and thus supports their identification. The formation of HMOH - intermediates requires that one O-H bond in water be broken; the presence of these species shows that water has been activated. The formation of H 2 MO - intermediates, however, requires that two O-H bonds be broken. While the photoelectron spectra do not exhibit features that can unambiguously be assigned to H 2 MO - , the observation of PtO - suggests the presence of H 2 PtO - .
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Inhomogeneous broadening and splitting of lines in spectra of YAG : Tm
The shape and fine structure of lines due to Tm{sup 3+} f −f electronic transitions in multifunctional Y{sub 3}Al{sub 5}O{sub 12} garnet crystals have been studied by high-resolution spectroscopy. The observed inhomogeneously broadened lines have a Lorentzian shape, suggesting that point defects make a predominant contribution to the inhomogeneous broadening. Moreover, Y{sub Al} antisite defects, which are formed during high-temperature melt growth, produce spectral satellites near the main lines. (paper)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Pseudogap in electron-doped cuprates: Strong correlation leading to band splitting
The pseudogap phenomena have been a long-standing mystery of the cuprate high-temperature superconductors. The pseudogap in the electron-doped cuprates has been attributed to band folding due to antiferromagnetic (AFM) long-range order or short-range correlation. We performed an angle-resolved photoemission spectroscopy study of the electron-doped cuprates Pr 1.3−x La 0.7 Ce x CuO 4 showing spin-glass, disordered AFM behaviors, and superconductivity at low temperatures and, by measurements with fine momentum cuts, found that the gap opens on the unfolded Fermi surface rather than the AFM Brillouin zone boundary. The gap did not show a node, following the full symmetry of the Brillouin zone, and its magnitude decreased from the zone-diagonal to (π,0) directions, opposite to the hole-doped case. These observations were reproduced by cluster dynamical-mean-field-theory calculation, which took into account electron correlation precisely within a (CuO 2 ) 4 cluster. In conclusion, the present experimental and theoretical results are consistent with the mechanism that electron or hole doping into a Mott insulator creates an in-gap band that is separated from the upper or lower Hubbard band by the pseudogap.
74 ATOMIC AND MOLECULAR PHYSICS↗