Science

My interests in science center around the structure and dynamics of novel materials. I have published in the arenas of fullerenes, nanotubes, inorganic polymers and various forms of hydrogen related to storage, taking data from numerous large-scale facilities including ESRF, PSI, ISIS, SNS, LANL, SNLS, ILL and NCNR.

The hydrogen work has really been quite a productive aspect of the overall chemi/physi-sorption efforts. The goals have been stipulated by the DoE and for the case of physisorption the main stumbling blocks are the low-ish volumetric capacities and the need to use cryogenic temperatures. There are a number of mechanisms we are pursuing to increase the operating temperature, from strong-binding (less than 'Kubas' though), engineered nanospaces, spillover mechanisms, and substitution of hetero-atoms in carbon frameworks. The porous frameworks lend themselves to many more applications and uses, however, and here are a few highlights from our efforts.

Adsorption of two gas molecules at a single metal site in a metal–organic framework



Adsorption of Two Gas Molecules at a Single Metal Site in a Metal-Organic Framework, T. Runcevski, M.T. Kapelewski, R.M. Torres-Gavosto, J.D. Tarver, C.M. Brown, J.R. Long, Chem. Comm. 2016.

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A flexible metal–organic framework with record usable methane storage



Methane storage in flexible metal-organic frameworks with intrinsic thermal management, J.A. Mason, J. Oktawiec, M.K. Taylor, M.R. Hudson, J. Rodriguez, J.E. Bachman, M.I. Gonzalez, A. Cervellino, A. Guagliardi, C.M. Brown, P.L. Llewellyn, N. Masciocchi, J.R. Long, Nature 2016.

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An outlook on hydrogen storage



Outlook and challenges for hydrogen storage in nanoporous materials, D.P. Broom, C.J. Webb, K.E. Hurst, P.A. Parilla, T. Gennett, C. M. Brown, R. Zacharia, E. Tylianakis, E. Klontzas, G.E. Froudakis, Th.A. Steriotis, P.N. Trikalitis, D.L. Anton, B. Hardy, D. Tamburello, C. Corgnale, B.A. van Hassel, D. Cossement, R. Chahine, M. Hirscher, J. Appl. Phys. A 2016.

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Why is Cu-BTC (HKUST-1) so good at storing methane?



Critical Factors Driving the High Volumetric Uptake of Methane in Cu₃ (btc)₂, Z. Hulvey, B. Vlaisavljevich, J.A. Mason, E. Tsivion, T.P. Dougherty, E.D. Bloch, M. Head-Gordon, B. Smit, J.R. Long, C.M. Brown, JACS 2015.

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Stuffing the hydrogen in to a larger MOF-74



Hydrogen Storage in the Expanded Pore Metal-Organic Frameworks M₂(dobpdc) (M = Mg, Mn, Fe, Co, Ni, Zn), D. Gygi, E.D. Bloch, J.A. Mason, M.R. Hudson, M.I. Gonzalez, R.L. Siegelman, T.A. Darwish, W.L. Queen, C.M. Brown, J.R. Long, Chem. Mater. 2016.

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Another flexible MOF for CO2 capture



Flexible metal-organic framework compounds: In situ studies for selective CO₂ capture, A.J. Allen , L. Espinal, W. Wong-Ng, W.L. Queen, C.M. Brown, S.R. Kline, K.L. Kauffman, J.T. Culp, C. Matranga, J. Al Comm. 2015.

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Reversible binding of CO to M-dobdc MOFs



Reversible CO Binding Enables Tunable CO/H₂ and CO/N₂ Separations in Metal-Organic Frameworks with Exposed Divalent Metal Cations, E.D. Bloch, M.R. Hudson, J.A. Mason, W.L. Queen, J.M. Zadrozny, S. Chavan, S. Bordiga, C.M. Brown, J.R. Long, JACS, 2014.

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Exhaustive study of CO₂ in M-dobdc MOFs



Comprehensive study of carbon dioxide adsorption in the metal-organic frameworks M₂(dobdc) (M = Mg, Mn, Fe, Co, Ni, Cu, Zn), W.L. Queen, M.R. Hudson, E.D. Bloch, J.A. Mason, M.l Gonzalez, J.S. Lee, D. Gygi, J.D. Howe, K. Lee, T.A. Darwish, M. James, V.K. Peterson, S.J. Teat, B. Smit, J.B. Neaton, J.R. Long, and C.M. Brown, Chem. Sci, 2014.

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A twist to a ligand leads to stronger binding of H₂



M₂(m-dobdc) (M = Mg, Mn, Fe, Co, Ni) Metal-Organic Frameworks Exhibiting Increased Charge Density and Enhanced H₂, M. Kapelewski, S. Geier, M.R. Hudson, D. Stuck, J. Mason, J. Nelson, D. Xiao, Z. Hulvey, E. Gilmour, S. Fitzgerald, M. Head-Gordon, C.M. Brown, J.R. Long, JACS, 2014.

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Determining the route for catalytic oxidation of ethane to ethanol



Oxidation of ethane to ethanol by N₂O in a metal–organic framework with coordinatively unsaturated iron(II) sites, D.J. Xiao, E.D. Bloch, J.A. Mason, W.L. Queen, M.R. Hudson, N. Planas, J. Borycz, A.L. Dzubak, P. Verma, K. Lee, F. Bonino, V. Crocella, J. Yano, S. Bordiga, D.G. Truhlar, L. Gagliardi, C.M. Brown, J.R. Long, Nature Chem., 2014.

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Evaluation of Cation-Exchanged Zeolite Adsorbents for Post-Combustion Carbon Dioxide Capture



Evaluation of Cation-Exchanged Zeolite Adsorbents for Post-Combustion Carbon Dioxide Capture, T.-H. Bae, M.R Hudson, J. Mason,W. L. Queen, J. Dutton, K. Sumida, K. Micklash, S. Kaye, C. M. Brown, J. R. Long, Energy Environ. Sci., 2013.

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Efficient seperations of natural gas components makes it to SCIENCE!



Hydrocarbon Separations in a Metal-Organic Framework with Open Iron(II) Coordination Sites, E.D. Bloch, W.L. Queen, R. Krishna, J.M. Zadrozny, C.M. Brown, J.R. Long, Science, 2012

Press releases through U.C. Berkeley and NIST Techbeat

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CO₂/N₂ separations in Zeolites reveals new binding mechanism



Unconventional and Highly Selective CO2 Adsorption in Zeolite SSZ-13, M.R. Hudson, W.L. Queen, J.A. Mason, D.W. Fickel, R.F. Lobo, C.M. Brown. JACS 2012

Press release picked up through NIST Techbeat

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A new, unique, redox-active framework that separates gases!



Selective Binding of O2 over N2 in a RedoxÐActive MetalÐOrganic Framework with Open Iron(II) Coordination Sites, E.D. Bloch, L.J. Murray, W.L. Queen, S, Chavan, S.N. Maximoff, J.P. Bigi, R. Krishna, V.K. Peterson, F. Grandjean, G.J. Long, B. Smit, S. Bordiga, C.M. Brown, and J.R. Long. JACS 2011

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Associating binding sites with increased enthalpy of adsorption

Refining the models from our earlier observations in this new redox-active framework



Hydrogen Adsorption in the Metal-Organic Frameworks Fe2(dobdc) and Fe2(O2)(dobdc), W.L. Queen, E.D. Bloch, C.M. Brown, M.R. Hudson, J.A. Mason, L.J. Murray, A.J. Ramirez-Cuesta, V.K. Peterson, J.R. Long. dalton Trans. 2012

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Associating binding sites with increased enthalpy of adsorption

A couple of our early papers really pin-pointed the increased enthalpy of adsorption in certain types of coordination-polymers (metal-organic frameworks - MOFs) being due to hydrogen interaction with unsaturated metal sites. Our most recent work on the Fe-BTT compound has given us remarkable clarity on the adsorption sites, and lead to the shortest M-D₂. interaction distance so-far determined.



Hydrogen Storage and Carbon Dioxide Capture in an Iron-Based Sodalite-Type Metal-Organic Framework (Fe-BTT) Discovered via High-Throughput Methods, K. Sumida, S. Horike, S. S. Kaye, Z. R. Herm, W. L. Queen, C. M. Brown, F. Grandjean, G. J. Long, A. Dailly and J. R. Long, J. Chemical Science, 2010
Hydrogen Storage in a microporous metal-organic framework with exposed Mn2+ coordination sites, M. Dinca, W. S. Han, Y. Liu, A. Dailly, C. M. Brown, and J. R. Long, J. Am. Chem. Soc., 2006, 128, 51, 16876.
Observation of CuII-H2 interactions in a fully-desolvated, sodalite-type metal-organic framework, M. Dinca, A. Dailly, Y. Liu, C. M. Brown, D. A. Neumann and J. R. Long, Angewandte Chemie, 2007, 46, 1419.
Neutron powder diffraction study of D2 sorption in Cu3(1,3,5-benzenetricarboxylate)2, V. K. Peterson, Y. Liu, C. M. Brown and Cameron Kepert, J. Am. Chem. Soc., 2006, 128, 15578.

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Increasing the density of adsorbed hydrogen

It turns out that not only do the unsaturated metals in MOFs increase the enthalpy of adsorption, but can increase the packing density of the H₂ as well!



Increasing the density of adsorbed hydrogen with coordinately unsaturated metal centers in metal-organic frameworks, Y. Liu, H. Kabbour, C. M. Brown, D. A. Neumann, and C. C. Ahn, Langmuir, 2008, 24, 4772.

Press release through NIST Techbeat

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Breathing MOFs are cool...

We figured out that MIL-53 changes it's pore size just on cooling (it was known to respond to solvents by the Ferey group). This is a bit of a problem when you do hydrogen isotherm measurements at 77 K, but need to reference the helium volume from room temp! We are working on getting the response with hydrogen in publishable form, should be out soon.



A reversible structural transition of MIL-53 with temperature hysteresis, Y. Liu, J.-H. Her, A. Dailly, A. J. Ramirez-Cuesta, D. A. Neumann and C. M. Brown, J. Am. Chem. Soc. 2008, 130, 11813.

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Understanding Inelastic Neutron Scattering Spectra (INS) of hydrogen in materials

We know that hydrogen has quantum rotational levels that are barely perturbed when adsorbed on various carbons, but the levels are razed with stronger interactions. There is some assumption in the literature that the measured energy levels are related to the enthalpy of adsorption. The most commonly cited relationship is the lower the vibrational frequency the higher the enthalpy of adsorption - something that I really doubt in the cases of H₂-MOFs. For instance, take HKUST-1. It has available copper ions when activated, but the adsorption enthalpy is not much better than a good carbon. Working with Taner Yildrim for bit more of a theoretical basis on this we can easily explain the INS at low coverages and attribute most of the interaction of Cu-H₂ as Coulombic interactions and observe no H--H elongation.



The nature of adsorbed hydrogen in HKUST-1: a Combined Inelastic Neutron Scattering and First-Principles Study, C. M. Brown, Y. Liu, T. Yildirim, V. K. Peterson, and C. J. Kepert, Nanotechnology, 2009, 20, 4025.

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Spillover hydrogen of Pd-nanofibers

Turns out that it is pretty hard to find solid signatures of atomic species in carbon materials. We have had some mild success using an indirect observation or the reduction in the hydrogen rotational line and some increase in the higher energy densities of states for Pd/carbon nanofiber materials with ORNL researchers.



Detection of Hydrogen Spillover in Palladium-Modified Activated Carbon Fibers During Hydrogen Adsorption,, C. I. Contescu, C. M. Brown, Y. Liu, V. V. Bhat and C. Gallego, J. Phys. Chem. 2009, 113, 5886.

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Past Highlights from the NCNR Annual Report

2014 (Cover, page 18-19) Oxidation of ethane to ethanol by N₂O in an iron(II) metal-organic framework
2014 (page 12-13) Tunable CO/H₂ and CO/N₂ separations in metal-organic frameworks with exposed divalent metal cations via reversible CO binding
2013 (page 14-15) More efficient petroleum refining using a highly hexane-selective Metal-Organic Framework
2012 (Cover, page 16-17) Powder neutron diffraction reveals new CO₂ adsorption interactions in chabazite zeolites
2011 (page 34-35) Nature of CO₂ adsorption in Mg-MOF 74: A combined neutron diffraction and first- principles study
2010 (page 28-29) Coordinatively-unsaturated metal-organic frameworks for hydrogen storage
2009 (page 30-31 ) Toward an Improved Understanding of Hydrogen Interactions with Coordinated Metals
2008 (page 35-36) Dense hydrogen upon adsorption in MOF-74
2006 (page 12-13) Hydrogen adsorption in Mn based MOF
2001, Phonon softening in alpha-Uranium
2000, Ligand dynamics in Metal-organic framework
2000, Molten globule-native protein dynamics

Collaborators

A lot of the work we do at the NCNR occurs because of our close ties to various other facilities and universities. Here are some links to a few of these collaborators:

Jeff Long, Berkeley
Mircea Dinca, MIT
Raul Lobo, Delaware
Tom Gennett, NREL
Hiroshi Kageyama, NREL

NCNR homepage