Neutron Scattering to Characterize Cu/Mg(Li) Destabilized Hydrogen Storage Materials

Cu-Li-Mg-(H,D) was studied as an example of destabilizer of the Ti-(H,D) system. A Cu-Li-Mg alloy was prepared resulting in the formation of a system with 60.5 at% of CuLi0.08Mg1.92, 23.9 at% of CuMg 2 and 15.6 at% of Cu2Mg. Titanium was added to a fraction of this mixture so that 68.2 at% (47.3 wt%) of the final mixture was Ti. The mixture was ground and kept at 200 °C/473 K for 7h under H2 or 9h under D2 at P = 34 bar. Under those conditions, neutron powder diffraction shows the formation of TiD2, as well as of the deuteride of CuLi0.08Mg1.92. Similarly inelastic neutron scattering shows that at 10 K TiH2 is present in the sample, together with the hydride of CuLi0.08Mg1.92. Interestingly, at 10 K TiH 2 is very clearly detected and at 300 K TiH2 is still clearly present as indicated by the neutron vibrational spectrum, but CuLi 0.08Mg1.92-H is not detected anymore. These results indicate that Ti(H,D)2 is possibly formed by diffusion of hydrogen from the Cu-Li-Mg-(H,D) alloys. This is an intriguing result since TiH 2 is normally synthesized from the metal at T > 400°C/673 K (and most commonly at T ∼ 700 °C/973 K). In the presence of CuLi 0.08Mg1.92, TiH2 forms at a temperature that is 300 - 400 K lower than that needed to synthesize it just from the elements

Governance Beyond the Nation-State : Transnationalization and Europeanization of the Baltic Sea Region

After the end of the Cold War, the Baltic Sea Region (BSR) developed into a highly dynamic area of cross-border cooperation and transnational networking. Four types of governance beyond the nation-state are discussed here: (1) international regimes, such as the Helsinki Convention for the Protection of the Baltic Sea; (2) transnational policy networks, such as Baltic 21, the world’s first regional Agenda 21; (3) transnational networks, such as the Union of the Baltic Cities (UBC); and (4) the European Union with approaches such as the “Northern Dimension” for the development of the Baltic Sea Region. Governance towards sustainable development of the Baltic Sea Region undoubtedly requires a combination of national governance with these governance types beyond the nation-state. In this respect, transnational (policy) networks and the European Union provide promising new approaches that can complement the traditional forms of international and intergovernmental cooperation between nation-states. These new governance types represent two parallel trends: a development towards (1) transnationalization and (2) the Europeanization of the Baltic Sea Region.Nach dem Ende des Kalten Krieges entwickelte sich die Ostseeregion zu einem außerordentlich dynamischen Raum der grenzüberschreitenden Kooperation und der transnationalen Netzwerkbildung. In dem vorliegenden Artikel werden vier Typen der Governance jenseits des Nationalstaates diskutiert: (1) internationale Regime wie die Helsinki-Konvention zum Schutz der Ostsee; (2) transnationale Politiknetzwerke wie die Baltic 21, die weltweit erste regionale Agenda 21; (3) transnationale Netzwerke wie die „Union of the Baltic Cities“ (UBC); und (4) die Europäische Union mit Ansätzen wie der „Northern Dimension“ zur Entwicklung der Ostseeregion. Governance in Richtung auf eine nachhaltige Entwicklung des Osteseeraums erfordert zweifelsohne eine Kombination aus nationaler Governance mit diesen Governance-Typen jenseits des Nationalstaats. In dieser Hinsicht liefern transnationale (Politik-)Netzwerke und die Europäische Union viel versprechende neue Ansätze, welche die traditionellen Formen der internationalen und intergouvernementalen Kooperation zwischen Nationalstaaten ergänzen können. Diese neuen Governance-Typen repräsentieren zwei parallele Trends in Richtung auf (1) die Transnationalisierung und (2) die Europäisierung der Ostseeregion

Neutron Scattering to Characterize Cu/Mg(Li) Destabilized Hydrogen Storage Materials

Cu-Li-Mg-(H,D) was studied as an example of destabilizer of the Ti-(H,D) system. A Cu-Li-Mg alloy was prepared resulting in the formation of a system with 60.5 at% of CuLi0.08Mg1.92, 23.9 at% of CuMg 2 and 15.6 at% of Cu2Mg. Titanium was added to a fraction of this mixture so that 68.2 at% (47.3 wt%) of the final mixture was Ti. The mixture was ground and kept at 200 °C/473 K for 7h under H2 or 9h under D2 at P = 34 bar. Under those conditions, neutron powder diffraction shows the formation of TiD2, as well as of the deuteride of CuLi0.08Mg1.92. Similarly inelastic neutron scattering shows that at 10 K TiH2 is present in the sample, together with the hydride of CuLi0.08Mg1.92. Interestingly, at 10 K TiH 2 is very clearly detected and at 300 K TiH2 is still clearly present as indicated by the neutron vibrational spectrum, but CuLi 0.08Mg1.92-H is not detected anymore. These results indicate that Ti(H,D)2 is possibly formed by diffusion of hydrogen from the Cu-Li-Mg-(H,D) alloys. This is an intriguing result since TiH 2 is normally synthesized from the metal at T > 400°C/673 K (and most commonly at T ∼ 700 °C/973 K). In the presence of CuLi 0.08Mg1.92, TiH2 forms at a temperature that is 300 - 400 K lower than that needed to synthesize it just from the elements

Zr-Porphyrin Metal–Organic Framework as nanoreactor for boosting the formation of hydrogen clathrates

We report the first experimental evidence for rapid formation of hydrogen clathrates under mild pressure and temperature conditions within the cavities of a zirconium-metalloporphyrin framework, specifically PCN-222. PCN-222 has been selected for its 1D mesoporous channels, high water-stability, and proper hydrophilic behavior. Firstly, we optimize a microwave (MW)-assisted method for the synthesis of nanosized PCN-222 particles with precise structure control (exceptional homogeneity in morphology and crystalline phase purity), taking advantage of MW in terms of rapid/homogeneous heating, time and energy savings, as well as potential scalability of the synthetic method. Second, we explore the relevance of the large mesoporous 1D open channels within the PCN-222 to promote the nucleation and growth of confined hydrogen clathrates. Experimental results show that PCN-222 drives the nucleation process at a lower pressure than the bulk system (1.35 kbar vs 2 kbar), with fast kinetics (minutes), using pure water, and with a nearly complete water-to-hydrate conversion. Unfortunately, PCN-222 cannot withstand these high pressures, which lead to a significant alteration of the mesoporous structure while the microporous network remains mainly unchanged.Authors would like to acknowledge financial support from Ministerio de Ciencia e Innovación (Project PID2019-108453GB-C21 and PID2022-141034OB-C22), Consejo Superior de Investigaciones Científicas (CSIC) for internal funds (Intramural project, 202280I170), and Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital (Project CIPROM/2021/022). A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory (project IPTS-29742.1)

Freezing/melting of water in the confined nanospace of carbon materials: Effect of an external stimulus

Freezing/melting behavior of water confined in the nanopores of activated carbon materials has been evaluated using differential scanning calorimetry (DSC) at different water loadings, and after the application of an external stimulus. Under atmospheric pressure conditions, the DSC scans show a depression in the freezing/melting point of confined water compared to the bulk system. Interestingly, water confined in narrow micropores (pores below 0.7 nm) does not exhibit any phase transition, i.e. it is non-freezable water. Inelastic neutron scattering (INS) data confirm the presence of a distorted molecular assembly in narrow micropores, whereas synchrotron X-ray powder diffraction data (SXRPD) demonstrate the non-freezable nature of the water confined in these narrow-constrictions. Similar experiments under high-pressure CH4 give rise to a completely different scenario. Under high-pressure conditions methane hydrates are formed with a water-to-hydrate yield of 100% for the under-saturated and saturated samples, i.e. in the presence of an external stimulus even water in narrow micropores is prone to experience a liquid-to-solid phase transition. These results confirm the beneficial role of carbon as a host structure to promote nucleation and growth of methane hydrates with faster kinetics and a higher yield compared to the bulk system and to other porous materials.The authors would like to acknowledge financial support from the MINECO (MAT2016-80285-p), Generalitat Valenciana (PROMETEOII/2014/004), H2020 (MSCA-RISE-2016/NanoMed Project), Spanish ALBA synchrotron (Projects 2018022707 & 2019023322) and Oak Ridge beam time availability (Project IPTS-20843.1)

Gate-opening effect in ZIF-8: the first experimental proof using inelastic neutron scattering

The gate-opening phenomenon in ZIFs is of paramount importance to understand their behavior in industrial molecular separations. Here we show for the first time using in situ inelastic neutron scattering (INS) the swinging of the –CH3 groups and the imidazolate linkers in the prototypical ZIF-8 and ZIF-8@AC hybrid materials upon exposure to mild N2 pressure.The authors acknowledge financial support from MINECO projects: MAT2013-45008-p and CONCERT Project-NASEMS (PCIN-2013-057). EVRF gratefully acknowledge support from MINECO (Spain) for his Ramón y Cajal grant (RyC-2012-11427). DFJ thanks the Royal Society (UK) for funding through a University Research Fellowship and Dr Axel Zeitler for interesting discussions. This research benefited from the use of the VISION beamline (IPTS-13608) at ONRL’s Spallation Neutron Source and the VirtuES (Virtual Experiments in Spectroscopy) project, (LDRD 7739), which are supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy, under Contract No. DE-AC0500OR22725 with UT Battelle, LLC

New insights into the breathing phenomenon in ZIF-4

Structural changes in ZIFs upon adsorption remain a paradigm due to the sensitivity of the adsorption mechanism to the nature of the organic ligands and gas probe molecules. Synchrotron X-ray diffraction under operando conditions clearly demonstrates for the first time that ZIF-4 exhibits a structural reorientation from a narrow-pore (np) to a new expanded-pore (ep) structure upon N2 adsorption, while it does not do so for CO2 adsorption. The existence of an expanded-pore structure of ZIF-4 has also been predicted by molecular simulations. In simulations the expanded structure was stabilized by entropy at high temperatures and by strong adsorption of N2 at low temperatures. These results are in perfect agreement with manometric adsorption measurements for N2 at 77 K that show the threshold pressure for breathing at ∼30 kPa. Inelastic neutron scattering (INS) measurements show that CO2 is also able to promote structural changes but, in this specific case, only at cryogenic temperatures (5 K).The authors would like to acknowledge financial support from the MINECO (MAT2016-80285-p), Generalitat Valenciana (PROMETEOII/2014/004), H2020 (MSCA-RISE-2016/NanoMed Project), Spanish ALBA synchrotron (Projects AV-2017021985 and IH-2018012591) and Oak Ridge beam time availability (Project IPTS-20843.1). JSA and JGL acknowledge financial support from UA (ACIE17-15) to cover all the expenses for INS measurements at Oak Ridge. JGL acknowledges GV (GRISOLIAP/2016/089) for the research contract

Rapid and efficient hydrogen clathrate hydrate formation in confined nanospace

Clathrate hydrates are crystalline solids characterized by their ability to accommodate large quantities of guest molecules. Although CH4 and CO2 are the traditional guests found in natural systems, incorporating smaller molecules (e.g., H2) is challenging due to the need to apply higher pressures to stabilize the hydrogen-bonded network. Another critical limitation of hydrates is the slow nucleation and growth kinetics. Here, we show that specially designed activated carbon materials can surpass these obstacles by acting as nanoreactors promoting the nucleation and growth of H2 hydrates. The confinement effects in the inner cavities promote the massive growth of hydrogen hydrates at moderate temperatures, using pure water, with extremely fast kinetics and much lower pressures than the bulk system.We would like to acknowledge financial support from Ministerio de Ciencia e Innovación (Project PID2019-108453GB-C21), MCIN/AEI/10.13039/501100011033 and EU “NextGeneration/PRTR” (Project PCI2020-111968 /3D-Photocat) – JSA. Neutron scattering experiments were performed at ORNL’s Spallation Neutron Source, IPTS-27062, supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, US DOE, under Contract No. DE-AC0500OR22725 with UT Battelle, LLC—J.S.A., Y.Q.C., L.D., A.J.R.C.. We gratefully acknowledge research support from the Hydrogen Materials—Advanced Research Consortium (HyMARC), established as part of the Energy Materials Network under the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technology Office, under Contract Number DE-AC05-00OR22725—R.B.-X. This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The publisher acknowledges the US government license to provide public access under the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan)

Thermal Expansion in 3d-Metal Prussian Blue Analogs - A Survey Study

We present a comprehensive study of the structural properties and the thermal expansion behavior of 17 different Prussian Blue Analogs (PBAs) with compositions MII3[(M')III(CN)6]2.nH2O and MII2[FeII(CN)6].nH2O, where MII = Mn, Fe, Co, Ni, Cu and Zn, (M')III = Co, Fe and n is the number of water molecules, which range from 5 to 18 for these compounds. The PBAs were synthesized via standard chemical precipitation methods, and temperature-dependent X-ray diffraction studies were performed in the temperature range between -150oC (123 K) and room-temperature. The vast majority of the studied PBAs were found to crystallize in cubic structures of space groups, and . The temperature dependence of the lattice parameters was taken to compute an average coefficient of linear thermal expansion in the studied temperature range. Of the 17 compounds, 9 display negative values for the average coefficient of linear thermal expansion, which can be as large as 39.7 x 10-6 K-1 for Co3[Co(CN)6]2.12H2O. All of the MII3[CoIII(CN)6]2.nH2O compounds show negative thermal expansion behavior, which correlates with the Irving-Williams series for metal complex stability. The thermal expansion behavior for the PBAs of the MII3[FeIII(CN)6]2.nH2O family are found to switch between positive (for M = Mn, Co, Ni) and negative (M = Cu, Zn) behavior, depending on the choice of the metal cation (M). On the other hand, all of the MII2[FeII(CN)6].nH2O compounds show positive thermal expansion behavior.Comment: Submitted, 32 pages, 3 tables, 10 figure