Hydrogen Storage in Novel Carbon-Based Nanostructured Materials

2006 ◽  
Vol 927 ◽  
Author(s):  
Erin S. Whitney ◽  
Calvin J. Curtis ◽  
Chaiwat Engtrakul ◽  
Mark F. Davis ◽  
Tining Su ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Binding Sites ◽  
Temperature Programmed Desorption ◽  
Binding Energies ◽  
Paramagnetic Resonance ◽  
Adsorption Sites ◽  
Wet Chemical ◽  
Temperature Programmed ◽  
Further Development ◽  
Electron Paramagnetic

ABSTRACTExperimental wet chemical approaches to complex an iron atom with two C60 fullerenes, representing a new molecule, dubbed a “bucky dumbbell,” have been demonstrated. The structure of this molecule has been determined by 13C solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR). Furthermore, this structure has been shown to have unique binding sites for dihydrogen molecules with the technique of temperature programmed desorption (TPD). The new adsorption sites have binding energies that are stronger than that observed for hydrogen physisorbed on planar graphite, but significantly weaker than a chemical C-H bond. Further development of these molecules could make them ideal candidates for onboard vehicular hydrogen storage.

Novel Organometallic Fullerene Complexes for Vehicular Hydrogen Storage

2007 ◽  
Vol 1041 ◽  
Author(s):  
Erin Whitney ◽  
Anne C. Dillon ◽  
Calvin Curtis ◽  
Chaiwat Engtrakul ◽  
Kevin O'Neill ◽  
...  
Keyword(s):  
Surface Area ◽  
Hydrogen Adsorption ◽  
Binding Energies ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Adsorption Sites ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Temperature Programmed

AbstractExperimental wet chemical approaches have been demonstrated in the synthesis of a new chainlike (C60-Fe-C60-Fe)n complex. This structure has been proposed based on 13C solid-state nuclear magnetic resonance, electron paramagnetic resonance, high-resolution transmission electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. Furthermore, this structure has been shown to have unique binding sites for dihydrogen molecules with the technique of temperature-programmed desorption. The new adsorption sites have binding energies that are stronger than that observed for hydrogen physisorbed on planar graphite, but significantly weaker than a chemical C-H bond. Volumetric measurements at 77 K and 2 bar show a hydrogen adsorption capacity of 0.5 wt%. Interestingly, the BET surface area is ∼31 m2/g after degassing, which is approximately an order of magnitude less than expected given the measured experimental hydrogen capacity. Nitrogen and hydrogen isotherms performed at 75 K also show a marked selectivity for hydrogen over nitrogen for this complex, indicating hidden surface area for hydrogen adsorption.

scholarly journals Active Site of O2 and Its Improvement Mechanism over Ce-Ti Catalyst for NH3-SCR Reaction

Catalysts ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 336 ◽  
Author(s):  
Dong Jiang ◽  
Shule Zhang ◽  
Yiqing Zeng ◽  
Pengfei Wang ◽  
Qin Zhong
Keyword(s):  
Active Site ◽  
Photoelectron Spectroscopy ◽  
Oxygen Vacancies ◽  
Catalytic Reduction ◽  
Supported Catalyst ◽  
Temperature Programmed Desorption ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Adsorption Sites ◽  
Temperature Programmed

The current study on Ce-Ti catalyst was mainly focused on the function of NH3 and NO adsorption sites. In our study, by comparing Ce-Ti (doped catalyst) to Ce/Ti (supported catalyst), the active site of O2 and its improvement mechanism over Ce-Ti catalyst for NH3-Selective catalytic reduction (SCR) reactions were investigated. For Ce-Ti catalyst, a cerium atom was confirmed entering a TiO2 crystal lattice by X-ray diffraction (XRD) and Raman; the structure of Ce-□-Ti (□ represents oxygen vacancy) in Ce-Ti catalyst was confirmed by X-ray photoelectron spectroscopy (XPS) and Photoluminescence spectra (PL spectra). The nature of this structure was characterized by electron paramagnetic resonance (EPR), Ammonia temperature-programmed desorption (NH3-TPD), hydrogen temperature-programmed reduction (H2-TPR), Nitric oxide temperature-programmed desorption (NO-TPD) and In situ DRIFT. The results indicated that oxygen vacancies had a promotive effect on the adsorption and activation of oxygen, and oxygen was converted to superoxide ions in large quantities. Also, because of adsorption and activation of NO and NH3, electrons were transferred to adsorbed oxygen via oxygen vacancies, which also promoted the formation of superoxide ions. We expected that our study could promote understanding of the active site of O2 and its improvement mechanism for doped catalyst.

scholarly journals The interaction of size-selected Ru3 clusters with RF-deposited TiO2: probing Ru-CO binding sites with CO-Temperature Programmed Desorption

2021 ◽  
Author(s):  
Liam Howard-Fabretto ◽  
Timothy Gorey ◽  
Guangjing Li ◽  
Siriluck Tesana ◽  
Gregory F Metha ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Chemical Reactions ◽  
Binding Sites ◽  
Co Hydrogenation ◽  
Temperature Programmed Desorption ◽  
Temperature Programmed

Small Ru clusters are efficient catalysts for chemical reactions such as CO hydrogenation. In this study 3-atom Ru3 clusters were deposited onto radio frequency (RF)-deposited TiO2 which is an inexpensive,...

scholarly journals DFT Protocol for EPR Prediction of Paramagnetic Cu(II) Complexes and Application to Protein Binding Sites

2018 ◽  
Vol 4 (4) ◽  
pp. 55 ◽  
Author(s):  
Giuseppe Sciortino ◽  
Giuseppe Lubinu ◽  
Jean-Didier Maréchal ◽  
Eugenio Garribba
Keyword(s):  
Binding Sites ◽  
Density Functional ◽  
Computational Procedure ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Protein Binding Sites ◽  
The Mean ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

With the aim to provide a general protocol to interpret electron paramagnetic resonance (EPR) spectra of paramagnetic copper(II) coordination compounds, density functional theory (DFT) calculations of spin Hamiltonian parameters g and A for fourteen Cu(II) complexes with different charges, donor sets, and geometry were carried out using ORCA software. The performance of eleven functionals was tested, and on the basis of the mean absolute percent deviation (MAPD) and standard deviation (SD), the ranking of the functionals for Az is: B3LYP > B3PW91 ~ B3P86 > PBE0 > CAM-B3LYP > TPSSh > BH and HLYP > B2PLYP > MPW1PW91 > ω-B97x-D >> M06; and for gz is: PBE0 > BH and HLYP > B2PLYP > ω-B97x-D > B3PW91~B3LYP~B3P86 > CAM-B3LYP > TPSSh~MPW1PW91 >> M06. With B3LYP the MAPD with respect to A z exp t l is 8.6% with a SD of 4.2%, while with PBE0 the MAPD with respect to g z exp t l is 2.9% with a SD of 1.1%. The results of the validation confirm the fundamental role of the second order spin-orbit contribution to Az. The computational procedure was applied to predict the values of gz and Az of the adducts formed by Cu(II) with albumin and two fragments of prion protein, 106–126 and 180–193.

scholarly journals Spectroscopic studies on the interaction of hypocrellin A with myoglobin

2007 ◽  
Vol 21 (4) ◽  
pp. 235-243 ◽  
Author(s):  
J. H. Zhou ◽  
X. H. Wu ◽  
C. Yang ◽  
X. T. Gu ◽  
L. Zhou ◽  
...  
Keyword(s):  
Binding Sites ◽  
Spectroscopic Analysis ◽  
Spectroscopic Studies ◽  
Interaction Process ◽  
Quenching Mechanism ◽  
Visible Absorption ◽  
Paramagnetic Resonance ◽  
Hypocrellin A ◽  
Uv Visible ◽  
Electron Paramagnetic

Experimental results of UV-visible absorption spectroscopy and fluorescence spectroscopy indicate that hypocrellin A, which has been studied in photodynamic therapy, can interact with the surface of myoglobin through hydrophobic forces, and form a complex. Based on the Stern–Volmer equation, the quenching constants of the process can be calculated to be 4.81×1012L mol−1s−1(t=25°C) and 4.54×1012L mol−1s−1(t=42°C) respectively, and the binding constant is 5.53×104M−1(t=25°C), while the binding sites is 0.94 (t=25°C). In addition, Electron paramagnetic resonance and fluorescence spectroscopic analysis suggests that that the quenching mechanism of the interaction process occurs through the electron transfer between hypocrellin A and myoglobin.

scholarly journals The cytochromes of anaerobically grown Escherichia coli. An electron-paramagnetic-resonance study of the cytochrome bd complex in situ

1989 ◽  
Vol 261 (2) ◽  
pp. 437-443 ◽  
Author(s):  
R A Rothery ◽  
W J Ingledew
Keyword(s):  
Escherichia Coli ◽  
High Spin ◽  
Binding Sites ◽  
Electron Paramagnetic Resonance Study ◽  
Paramagnetic Resonance ◽  
Cytochrome Bd ◽  
Ligand Binding Sites ◽  
Electron Paramagnetic ◽  
Spin Species

The e.p.r. signals attributable to a cytochrome bd-type ubiquinol: O2 oxidoreductase (cytochrome b-558-b-595-d) were studied in a cytoplasmic membrane preparation of Escherichia coli that had been grown on glycerol with fumarate as respiratory-chain oxidant. Two major high-spin ferric haem signals were resolved on the basis of their potentiometric behaviour: a rhombic high-spin species (gx = 6.25, gy = 5.54) was assigned to haem b-595, and an axial high-spin (gx = 5.97, gy = 5.96) species was assigned to the haem d. These signals titrated with Em.7 values of 154 and 261 mV respectively, corresponding closely to optically determined values for haem b-595 and haem d. At high potentials (greater than 300 mV) the rhombic species attributable to haem b-595 underwent a partial transition to a second rhombic species with g-values of 6.24 (gx) and 5.67 (gy). The high-spin ferric haem spectra were affected by O2, CO, cyanide and pH. A low-spin ferric haem signal was observed at g = 3.3 (gz), which titrated with an Em.7 of 226 mV, and this was assigned to haem b-558. The data support a model for cytochrome bd with two ligand-binding sites, a single haem d and a single haem b-595.

Chemisorption of CO on Au/TiOx/Pt(111) Model Catalysts with Different Stoichiometry and Defectivity

2008 ◽  
Vol 8 (7) ◽  
pp. 3595-3602 ◽  
Author(s):  
Luca Artiglia ◽  
Gian Andrea Rizzi ◽  
Francesco Sedona ◽  
Stefano Agnoli ◽  
Gaetano Granozzi
Keyword(s):  
Ultrathin Films ◽  
Au Nanoparticles ◽  
Temperature Programmed Desorption ◽  
Model Catalysts ◽  
Desorption Peak ◽  
Adsorption Sites ◽  
Ordered Array ◽  
Temperature Programmed ◽  
A Minor ◽  
Minor Extent

Au/TiOx/Pt(111) model catalysts were prepared starting from well characterized TiOx/Pt(111) ultrathin films, according to an established procedure consisting in a reactive evaporation of Ti, subsequent thermal treatment in O2 or in UHV, and final deposition of submonolayer quantities of Au. Temperature Programmed Desorption measurements were performed to compare the interaction of CO in the case of two reduced TiOx/Pt(111) substrates (indicated as w-TiOx and w′-TiOx, being the former characterized by an ordered array of defects that can act as template for the deposition of a stable array of Au nanoparticles), with the case of a stoichiometric rect′-TiO2/Pt(111) substrate. It was found that in all cases CO is molecularly adsorbed and two different desorption peaks are detected: one at ≈140 K corresponding to CO desorption from less active adsorption sites (terraces) of the Au nanoparticles and one at ≈200 K corresponding to CO desorption from Au nanoparticles step sites. After annealing at 770 K, the high temperature CO desorption peak is still present in the case of the defective reduced w-TiOx phase, supporting the good templating and stabilizing effect of such phase. On the rect′-TiO2 stoichiometric phase, the CO uptake decreases after annealing but only to a minor extent.

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