Improvement in the Hydrogen-Storage Properties of Mg2Ni by Adding LiBH4

Young Jun Kwak,Myoung Youp Song,Ki-Tae Lee 대한금속·재료학회 2024 대한금속·재료학회지 Vol.62 No.4

To improve the hydrogen-storage properties of Mg2Ni, LiBH4 was added by milling in hydrogenatmosphere (reactive mechanical milling, RMM). Mg2Ni-10LiBH4 was prepared with a composition of 90 wt%Mg2Ni + 10 wt% LiBH4. The quantity of released hydrogen (Hr) versus temperature T curve for Mg2Ni-10LiBH4 was obtained by heating at a rate of 4~5 K in 1.0 bar hydrogen. The hydrogen-storage propertiesof the sample were investigated. The phases formed were examined from the x-ray diffraction (XRD) patternsof the samples after RMM, and after hydrogen-absorption and release cycling. The XRD pattern of Mg2Ni-10LiBH4 showed that this sample contained Mg2Ni, Mg2NiH4, o-LiBH4, h-LiBH4, Ni, and MgH2. The dHr/dTversus T curve exhibited three peaks at 325 K, 563 K, and 600 K, respectively. The peak at 325 K is for thehydrogen release from o-LiBH4 and h-LiBH4. The peak at 563 K is for the hydrogen release from Mg2NiH4and the peak at 600 K is for the hydrogen release from Mg2NiH4 and MgH2. The RMM of Mg2Ni with addedLiBH4 creates defects and cracks. RMM facilitates nucleation, increases reactivity, and shortens the diffusiondistances of hydrogen atoms. Expansion and contraction of lattices due to cycling has effects similar to, butweaker than, the effects of RMM.

기계적 합금화법으로 제조된 Mg2Ni-5mass Nb 복합재료의 수소화 특성평가

석송,조경원,김기배,홍태환,연규붕,김경일,유성웅 한국수소및신에너지학회 2006 한국수소 및 신에너지학회논문집 Vol.17 No.4

Mg and Mg-based alloys are promising hydrogen storage alloys for renewable clean energy applications. It is a lightweight and low cost material with high hydrogen storage capacity. However, commercial applications of the Mg hydride are currently hindered by its high absorption/desorption temperature, and very slow reaction kinetics. In this work, we aim to study the absorption properties of the Mg2Ni-5mass% Nb composite prepared by mechanical alloying under hydrogen. The absorption capacity of the sample is found to be about 3.0 wt.% at T=573 K and P=1.0 MPa. The absorption characteristics observed have been compared with those of the prepared Mg2Ni.

Effect of grain size on the resistance to hydrogen embrittlement of API 2W Grade 60 steels using in situ slow-strain-rate testing

Park, Cheolho,Kang, Namhyun,Liu, Stephen Elsevier 2017 Corrosion science Vol.128 No.-

<P><B>Abstract</B></P> <P>This study investigated the grain size effect on the resistance to hydrogen embrittlement (HE) of API 2W Grade 60 steels using in situ slow-strain-rate testing. Hydrogen was electrochemically charged into specimens and the hydrogen content evolved from diffusible hydrogen-trap sites was measured by thermal desorption spectrometry (TDS). The fine-grained (14μm) steel showed superior HE resistance despite exhibiting higher total hydrogen content than the coarse-grained (35μm) steel. Decreasing grain size resulted in a larger grain boundary area, thereby better reducing the normalized amount of diffusible hydrogen trapped per unit length of grain boundary.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrogen embrittlement resistance increased with grain size refinement. </LI> <LI> Quasi cleavage fracture decreased displacement significantly with increasing grain size. </LI> <LI> The amounts of hydrogen desorbed from lattice sites and grain boundaries increased with decreasing grain size. </LI> <LI> Fine-grained steel exhibited the lowest normalized hydrogen content in a unit grain boundary. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Excited State Dynamics of Curcumin and Solvent Hydrogen Bonding

양일승,진승민,강준희,Venkatnarayan Ramanathan,김형민,서영덕,김성근 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.8

Curcumin is a natural product with antioxidant, anti-inflammatory, antiviral and antifungal functions. As it is known that the excited state intramolecular hydrogen transfer of curcumin are related to its medicinal antioxidant mechanism, we investigated its excited state dynamics by using femtosecond transient absorption spectroscopy in an effort to understand the molecule’s therapeutic effect in terms of its photophysics and photochemistry. We found that stronger intermolecular hydrogen bonding with solvents weakens the intramolecular hydrogen bonding and decelerates the dynamical process of the enolic hydrogen. Exceptions are found in methanol and ethylene glycol due to their nature as simultaneous hydrogen bonding donor-acceptor and high viscosity solvent, respectively.

Excited State Dynamics of Curcumin and Solvent Hydrogen Bonding

Yang, Il-Seung,Jin, Seung-Min,Kang, Jun-Hee,Ramanathan, Venkatnarayan,Kim, Hyung-Min,Suh, Yung-Doug,Kim, Seong-Keun Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.suppl8

Curcumin is a natural product with antioxidant, anti-inflammatory, antiviral and antifungal functions. As it is known that the excited state intramolecular hydrogen transfer of curcumin are related to its medicinal antioxidant mechanism, we investigated its excited state dynamics by using femtosecond transient absorption spectroscopy in an effort to understand the molecule's therapeutic effect in terms of its photophysics and photochemistry. We found that stronger intermolecular hydrogen bonding with solvents weakens the intramolecular hydrogen bonding and decelerates the dynamical process of the enolic hydrogen. Exceptions are found in methanol and ethylene glycol due to their nature as simultaneous hydrogen bonding donor-acceptor and high viscosity solvent, respectively.

Notched-tensile properties under high-pressure gaseous hydrogen: Comparison of pipeline steel X70 and austenitic stainless type 304L, 316L steels

Song, Eun Ju,Baek, Seung-Wook,Nahm, Seung Hoon,Baek, Un Bong Elsevier 2017 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.42 No.12

<P><B>Abstract</B></P> <P>The effect of high-pressure gaseous H<SUB>2</SUB> on the fracture behavior of pipeline steel X70 and austenitic stainless steel type 304L and 316L was investigated by means of notched-tensile tests at 10 MPa H<SUB>2</SUB> gas and various test speed. The notch tensile strength of pipeline X70 steel and austenitic stainless steels were degraded by gaseous H<SUB>2</SUB>, and the deterioration was accompanied by noticeable changes in fracture morphology. The loss of notch tensile strength of type 316L and X70 steels was comparable, but type 304L was more susceptible to hydrogen embrittlement than the others. In the X70 steel, hydrogen embrittlement increased as test speed decreased until the test speed reached 1.2 × 10<SUP>−3</SUP> mm/s, but the effect of test speed was not significant in 304L and 316L steels.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The notch tensile strengths of X70 steel and austenitic stainless steels were degraded by H<SUB>2</SUB>. </LI> <LI> The amount of degradation increased with strain rate in X70 steel. </LI> <LI> X70 and austenitic stainless steels under H<SUB>2</SUB> showed brittle fracture. </LI> </UL> </P>

Pd 박막의 전기저항-수소농도 이력현상

이은송이 ( Eunsongyi Lee ),이준민 ( Jun Min Lee ),전계진 ( Kye Jin Jeon ),이우영 ( Woo Young Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 2009 대한금속·재료학회지 Vol.47 No.6

We report on hysteresis behavior in the electrical resistance-hydrogen concentration of Pd thin films. The variation of the electrical resistance has been investigated during the process of absorption and desorption of hydrogen gas (H2) as a function of thickness of Pd thin films. The hysteresis behavior in the electrical resistance with H2 concentration was found for Pd thin films and consists of α phase, α+β phase, and β phase regions. The sensitivity of Pd thin films with H2 concentration was found to follow Sieverts` law in the α phase region. However, the sensitivity was observed to increase abruptly with H2 concentration in the α+β phase co-exist region. This is because Pd-H interaction is stronger in the β phase than in the α phase and needs a higher concentration gradient as a driving force to desorb. The formation of the β phase also was observed to cause the structural change because of the lattice expansion during absorption. The hysteresis height and the trace of structural change were affected by the thickness of the Pd film. As the film becomes thinner, the hysteresis height becomes lower and the amount of delamination on the surface becomes smaller. For films thinner than 20 nm in thickness, the delamination was not found but electrical resistance hysteresis was still observed. (Received December 22, 2008)

Molecular interaction between a reduced riboflavin derivative and salicylic acid derivatives

Yu, Byung-Sul,Sohn, Dong-Hwan,Sohn, Dong-Hwan The Pharmaceutical Society of Korea 1985 Archives of Pharmacal Research Vol.8 No.3

The interaction of reduced riboflavin 2', 3', 4', 5'-tetrabutyrate with salicylic acid, aspirin, and salicylamide has been spectroscopically investigated to determine the binding mechanism. Hydrogen-1 and carbon-13 unclear magnetic resonance, infrared, and absoption spectra were measured in chloform-d and chloroform. The association of the reduced riboflavin with salicylic acid derivatives is different from that osidizd one. Salicylic acid and the reduced riboflavin form a cyclic hydrogen bounded complex through the imino (3-N, 5-N) protons and the carbonyl (2-C, 4-C) oxygens of the isolloxazine ring of the latter, and the carboxylic hydroxyl proton and carbonyl oxygen of the former. Aspirin and the reduced riboflavin form a complex by the same mode as salicylic acid. Salicylamide forms a cyclic hydrogen bonded complex with the reduced riboflavin through the imino (3-N, 5-N) protons and the carbonyl (2-C, 4-C) oxygens of the isoalloxazine ring, and the amino proton and the carbonyl oxygen of salic aylmide. It appears that both the oxidized and reduced form of riboflavin are associated with salicylic acid derivatives.

Excited state intramolecular proton transfer of 1,2- dihydroxyanthraquinone by femtosecond transient absorption spectroscopy

이세복,이재범,방윤수 한국물리학회 2015 Current Applied Physics Vol.15 No.11

1,2-Dihydroxyanthraquinone (alizarin) shows dual emission bands with a large Stokes shift from a “locally-excited (LE)” and “proton-transferred (PT)” tautomers in the excited state. Excited state intramolecular proton transfer (ESIPT) reaction of alizarin is tunable by changing concentration, solvent polarity, excitation wavelength, and etc. ESIPT reaction of alizarin in the excited state was investigated by steady-state absorption/emission spectroscopy and femtosecond transient absorption spectroscopy. In ethanol solution, the lifetime of PT tautomer of alizarin was measured as 87 ps, in addition to 0.35 and 8.3 ps vibrational cooling dynamics for the LE and PT tautomers of alizarin, respectively. In binary mixtures of ethanol and water, the excited state dynamics became more complicated; the LE and PT tautomers appeared to decay with 8.9 and 30.8 ps lifetimes, which is much shorter compared to the lifetime of the PT tautomer in ethanol. A long-lived nonradiative state in the excited states of alizarin was found as well, which was proposed as a “trapped” state with tightly hydrogen-bonded water molecules. The ESIPT reaction of alizarin was blocked in a 1:1 mixture of ethanol-water due to strong hydrogen bonding between water molecules and alizarin, which was further confirmed by the efficient coupling of alizarin to TiO2 nanoparticles in the 1:1 binary mixture of ethanol-water.

Three-dimensional modeling and simulation of hydrogen absorption in metal hydride hydrogen storage vessels

Nam, Jinmoo,Ko, Johan,Ju, Hyunchul Elsevier 2012 APPLIED ENERGY Vol.89 No.1

<P><B>Highlights</B></P><P>► We newly developed a three-dimensional hydrogen absorption model. ► Equilibrium pressure with the H/M ratio cannot be overlooked during absorption simulations. ► External S/V ratio of a MH vessel is a key factor to control the absorption performance. ► Higher H<SUB>2</SUB> feeding pressure leads to a faster absorption reaction and a shorter charging time.</P> <P><B>Abstract</B></P><P>In this paper, a three-dimensional hydrogen absorption model is developed to precisely study the hydrogen absorption reaction and resultant heat and mass transport phenomena in metal hydride hydrogen storage vessels. The 3D model is first experimentally validated against the temperature evolution data available in the literature. In addition to model validation, the detailed 3D simulation results show that at the initial absorption stage, the vessel temperature and H/M ratio distributions are uniform throughout the entire vessel, indicating that hydrogen absorption is very efficient early during the hydriding process; thus, the local cooling effect is not influential. On the other hand, non-uniform distributions are predicted at the subsequent absorption stage, which is mainly due to differential degrees of cooling between the vessel wall and core regions. In addition, a parametric study is carried out for various designs and hydrogen feed pressures. This numerical study provides a fundamental understanding of the detailed heat and mass transfer phenomena during the hydrogen absorption process and further indicates that efficient design of the storage vessel and cooling system is critical to achieve rapid hydrogen charging performance.</P>