Coherent Carbon Cryogel – Hydride Nanocomposites for Efficient Hydrogen StorageGuozhong Cao, University of Washington, DMR 0605159

Solid state hydrogen storage offers a solution because it requires essentially no pressure, is inert at typical operating temperatures, and releases hydrogen on demand. This research will utilize advancements in nanotechnology to manipulate and control the performance of solid state hydrogen storage materials – a much needed step towards development of the new American energy economy. Specifically, the research intends to establish the capability of tuning the dehydrogenation temperature, altering the reaction mechanisms and kinetics through confining hydrides inside nanopores of highly porous carbon scaffold that also offer the easy thermal management (as shown in the insert schematics). The success of the project will be a significant step toward the realization of a hydrogen economy and will attain a better fundamental understanding of the physical properties and chemical behavior when matter shrinks to the nanometer scale. This research will expose, educate, and attract graduate and undergraduate students to the field of energy related materials and technology and be environmentally conscious through their thesis research, faculty seminars, workshops, and publications.

While fuel cell technology has rapidly advanced towards application in automobiles, the on-board storage of the hydrogen needed to power a fuel cell has not. For practical applications, hydrogen needs to be stored in the form of either liquid or solid, as gas typically takes 1000 times the space of the equal amount of solid or liquid at ambient. However, pressurized hydrogen storage tanks would require impractically bulky and heavy vessels and liquid hydrogen must be stored at – 251 C making it logistically very difficult. In addition, pressurized or liquidified hydrogen can be a safety concern. AB in THF at RT AB crystallization at RT

Coherent Carbon Cryogel – Hydride Nanocomposites for Efficient Hydrogen Storage

Guozhong Cao, University of Washington, DMR 0605159

This research is to develop novel nanocomposites consisting of a highly porous chemically modified carbon cryogel filled and intimately mixed with hydrides and optionally coated with a porous catalyst oxide layer. The extremely high surface area (>2000 m2/g) and porosity (>95%) of carbon cryogels facilitates an intimate contact between hydrides and the carbon network with possible catalytic effects as well promoting a homogeneous dispersion while trapping hydrides inside the tunable pores ranging from <1 nm to 100 nm in diameter. Such coherently structured nanocomposites have demonstrated to have a tunable dehydrogenation temperature that decreases with reduced pore size (shown on right), much improved kinetics, doubled capacity of dehydrogenation, and total suppression of hazard byproduct. Recent results also demonstrated the significant influence of the surface chemistry of the porous carbon scaffold and offers an extra approach to manipulate and alter the dehydrogenation properties of hydrides. This research has supported three PhD students (two women and one Hispanic) with Aaron Feaver graduated in January 2007, Saghar Sepehri in August 2008, and Betzaida Garcia is scheduled to graduate in Spring 2010. This grant has also supported 5 undergraduate research, and resulted 3 patent applications and 8 journal papers published, 1 submitted to journal for possible publications, 1 book chapter and various conference proceedings. The graduate students and the PI have presented various seminars and invited talks such as in the 2008 TMS annual meeting, 2008 IMRS meeting and 2009 US-China Nano workshop.

• B.B. Garcia, A.M. Feaver, G.T. Seidler, and G.Z. Cao, “Effect of Pore Morphology on Electrochemical Properties of Carbon Cryogel Supercapacitors,” J. Appl. Phys. 104, 014205 (2008).

• S. Sepehri, B.B. Garcia, and G.Z. Cao, “Tuning Dehydrogenation Temperatures of Carbon – Ammonia Borane Nanocomposites,” J. Mater. Chem. 18, 4034-4037 (2008).

• S. Sepehri, B.B. García, and G.Z. Cao, “Influences of Surface Chemistry on Dehydrogenation in Carbon Cryogel - Ammonia Borane Nanocomposites,” Euro. J. Inorg. Chem., 599-603 (2009).

• S. Sepehri, B.B. García, and G.Z. Cao, “Enhanced Electrochemical Properties of Carbon Cryogels by Surface Chemistry Alteration with Boron and Nitrogen,” Carbon 47, 1436-1443 (2009).

• S. Sepehri, B.B. García, and G.Z. Cao, “Boron-Modified Carbon Cryogel – Ammonia Borane Nanocomposites with Enhanced Hydrogen Storage Properties,” ACS Applied Materials and Interfaces.

• S. Sepehri, B.B. Garcia, Q.F. Zhang, and G.Z. Cao, “Influences of Surface Chemistry on Dehydrogenation Kinetics of Ammonia Borane in Porous Carbon Scaffold,” Journal of Materials Chemistry.

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