Vx-Na2TiOSiO4 MWNTs: Reduction of V5+ by electronegative oxygen and doping mechanism of V4+, formation and its hydrogen uptake

Hydrogen is nowadays in focus as an energy carrier that is locally emission free. Especially in combination with fuel-cells, hydrogen offers the possibility of a CO2 neutral mobility, provided that the hydrogen is produced with renewable energy. Structural parts of automotive components are often made of steel, but unfortunately they may show degradation of the mechanical properties when in contact with hydrogen. Under certain service conditions, hydrogen uptake into the applied material can occur. To ensure a safe operation of automotive components, it is therefore necessary to investigate the time, temperature and pressure dependent hydrogen uptake of certain steels, e.g., to deduct suitable testing concepts that also consider a long term service application. To investigate the material dependent hydrogen uptake, a tubular autoclave was set-up. The underlying paper describes the set-up of this autoclave that can be pressurised up to 20 MPa at room temperature and can be heated up to a temperature of 250 °C, due to an externally applied heating sleeve. The second focus of the paper is the investigation of the pressure dependent hydrogen solubility of the martensitic stainless steel 1.4418. The autoclave offers a very fast insertion and exertion of samples and therefore has significant advantages compared to commonly larger autoclaves. Results of hydrogen charging experiments are presented, that were conducted on the Nickel-martensitic stainless steel 1.4418. Cylindrical samples 3 mm in diameter and 10 mm in length were hydrogen charged within the autoclave and subsequently measured using thermal desorption spectroscopy (TDS). The results show how hydrogen sorption curves can be effectively collected to investigate its dependence on time, temperature and hydrogen pressure, thus enabling, e.g., the deduction of hydrogen diffusion coefficients and hydrogen pre-charging concepts for material testing.

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Charge-Transfer Intermediates in the Electrochemical Doping Mechanism of Conjugated Polymers

Journal of the American Chemical Society ◽

10.1021/jacs.0c10692 ◽

2020 ◽

Author(s):

Ilaria Bargigia ◽

Lisa R. Savagian ◽

Anna M. Österholm ◽

John R. Reynolds ◽

Carlos Silva

Keyword(s):

Charge Transfer ◽

Conjugated Polymers ◽

Electrochemical Doping ◽

Doping Mechanism

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Boron from net charge acceptor to donor and its effect on hydrogen uptake by novel Mg-B-electrochemically synthesized reduced graphene oxide

Scientific Reports ◽

10.1038/s41598-021-90531-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Marla V. V. Satya Aditya ◽

Srikanta Panda ◽

Sankara Sarma V. Tatiparti

Keyword(s):

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Incubation Time ◽

Photoelectron Spectroscopy ◽

Weight Ratio ◽

Hydrogen Uptake ◽

Binding Energies ◽

Unit Cell ◽

Net Charge ◽

Reduced Graphene

AbstractHydrogen uptake (H-uptake) is studied in ball milled Mg-B-electrochemically synthesized reduced graphene oxide (erGO) nanocomposites at PH2 ≈ 15 bar, ~ 320 °C. B/C (weight ratio): 0, ~ 0.09, ~ 0.36, ~ 0.90 are synthesized maintaining erGO≈10wt %. B occupies octahedral interstices within Mg unit cell—revealed by electron density maps. Persistent charge donations from Mg and B to C appear as Mg-C (~ 283.2 eV), B-C (~ 283.3–283.9 eV) interactions in C-1s core X-ray photoelectron spectroscopy (XPS) at all B/C. At B/C > 0.09, charge reception by B from Mg yields Mg-B interaction. This net charge acceptor role of B renders it electron-rich and does not alter Mg unit cell size significantly. Despite charge donation to both C and B, the Mg charge is < + 2, resulting in long incubation times (> 5 h) at B/C > 0.09. At B/C≈0.09 the minimal Mg-B interaction renders B a charge donor, resulting in Mg-B repulsion and Mg unit cell expansion. Mg-C peak shift to lower binding energies (C-1s XPS), decreases incubation time to ~ 2.25 h and enhances H-uptake kinetics. Various atomic interactions influence the reduction of incubation time in H-uptake and increase its kinetics in the order: (Mg → C; B → C)B/C≈0.09, B: donor > (Mg → C)B/C=0 > (ternary Mg → B → C)B/C>0.09, B: acceptor.

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Electrolyte-Assisted Hydrogen Cycling in Lithium and Sodium Alanates at Low Pressures and Temperatures

Energies ◽

10.3390/en13225868 ◽

2020 ◽

Vol 13 (22) ◽

pp. 5868

Author(s):

Jason Graetz ◽

John J. Vajo

Keyword(s):

Growth Parameters ◽

Reaction Times ◽

Hydrogen Uptake ◽

Hydrogen Desorption ◽

Reaction Rates ◽

Rate Coefficients ◽

Aluminum Hydrides ◽

Dehydrogenation Reactions ◽

Low Pressures ◽

Sodium Alanates

An investigation of electrolyte-assisted hydrogen storage reactions in complex aluminum hydrides (LiAlH4 and NaAlH4) reveals significantly reduced reaction times for hydrogen desorption and uptake in the presence of an electrolyte. LiAlH4 evolves ~7.8 wt% H2 over ~3 h in the presence of a Li-KBH4 eutectic at 130 °C compared to ~25 h for the same material without the electrolyte. Similarly, NaAlH4 exhibits 4.8 wt% H2 evolution over ~4 h in the presence of a diglyme electrolyte at 150 °C compared to 4.4 wt% in ~15 h for the same material without the electrolyte. These reduced reaction times are composed of two effects, an increase in reaction rates and a change in the reaction kinetics. While typical solid state dehydrogenation reactions exhibit kinetics with rates that continuously decrease with the extent of reaction, we find that the addition of an electrolyte results in rates that are relatively constant over the full desorption window. Fitting the kinetics to an Avrami-Erofe’ev model supports these observations. The desorption rate coefficients increase in the presence of an electrolyte, suggesting an increase in the velocities of the reactant-product interfaces. In addition, including an electrolyte increases the growth parameters, primarily for the second desorption steps, resulting in the observed relatively constant reaction rates. Similar effects occur upon hydrogen uptake in NaH/Al where the presence of an electrolyte enables hydrogenation under more practical low temperature (75 °C) and pressure (50 bar H2) conditions.

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Synthesis and Characterization of CMK Porous Carbons Modified with Metals Applied to Hydrogen Uptake and Storage

Microporous and Mesoporous Materials ◽

10.5772/63710 ◽

2016 ◽

Author(s):

Marcos B. Gómez Costa ◽

Juliana M. Juárez ◽

Oscar A. Anunziata

Keyword(s):

Hydrogen Uptake ◽

Synthesis And Characterization ◽

Porous Carbons ◽

And Storage

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Understanding the mechanism of hydrogen uptake at low pressure in carbon/palladium nanostructured composites

Journal of Materials Chemistry ◽

10.1039/c1jm12939b ◽

2011 ◽

Vol 21 (44) ◽

pp. 17765 ◽

Cited By ~ 41

Author(s):

Camelia Matei Ghimbeu ◽

Claudia Zlotea ◽

Roger Gadiou ◽

Fermin Cuevas ◽

Eric Leroy ◽

...

Keyword(s):

Hydrogen Uptake ◽

Low Pressure ◽

Nanostructured Composites

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Effect of Electrochemical Polarization on Hydrogen Uptake by Titanium in DC1-D2O Solution

Corrosion engineering digest ◽

10.3323/jcorr1954.21.6_256 ◽

1972 ◽

Vol 21 (6) ◽

pp. 256-262

Author(s):

Tadahiko Mizuno ◽

Tatsushi Suzuki ◽

Takashi Morozumi

Keyword(s):

Hydrogen Uptake ◽

Electrochemical Polarization

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Characterization of nitrogen species incorporated into graphite using low energy nitrogen ion sputtering

Physical Chemistry Chemical Physics ◽

10.1039/c5cp02305j ◽

2016 ◽

Vol 18 (1) ◽

pp. 458-465 ◽

Cited By ~ 10

Author(s):

Hisao Kiuchi ◽

Takahiro Kondo ◽

Masataka Sakurai ◽

Donghui Guo ◽

Junji Nakamura ◽

...

Keyword(s):

Low Energy ◽

Nitrogen Species ◽

Ion Sputtering ◽

Zigzag Edge ◽

Nitrogen Doped ◽

Doping Mechanism ◽

Nitrogen Ions ◽

Nitrogen Ion

The well-controlled nitrogen doped graphite with graphitic nitrogen located in the zigzag edge and/or vacancy sites can be realized using the low energy nitrogen sputtering. The doping mechanism of nitrogen ions is also discussed.

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