Materials Science and Engineering Seminar Series: Debra Rolison
Nanoarchitectures: Why more of less is moreEspecially for energy storage and conversion
Naval Research Laboratory
When multifunctionality and molecular transport paths are performance essential, as they are in rate-critical applications such as catalysis, energy storage and conversion, sensing, and fabrication, the challenge is to move beyond the creation of a functional nanoscale object or feature. High performance, large-scale construction, and bridging to the macroscale requires architectural design [1,2,3]. Sol‒gel-derived ultraporous, aperiodic aerogel-like nanofoams unite high surface area for heterogeneous reactions, including post-synthesis modifications, with a continuous, porous network for rapid flux of molecular and nanoscopic reactants. The walls are defined by the nanoscopic, covalently bonded, one-dimensional solid network of the gel―and because the walls are erected by solgel chemistry, the architecture is readily scaled from nanometer to meter length scales. The vast open, interconnected space characteristic of a building is represented by the interpenetrating nanoscopic pore network (3D plumbing). Such nanoarchitectures yield high performance in rate-critical applications; for instance, response times to gas-phase analytes are >10-times faster than those of the same chemistry expressed in typical solgel-derived sensors based on xerogels. As one example of these ideas, we can paint the walls of a conductive nanoarchitecture with conformal nanoscopic coatings of redox-active polymers or oxides in order to produce high performance electrochemical capacitors [2,3,4,5,6]. An architectural viewpoint provides a powerful metaphor to guide the chemist and materials scientist in the design of aperiodic nanoarchitectures and in their physicochemical transformation into multifunctional objects that express high performance.
 D.R. Rolison, Catalytic nanoarchitectures―The importance of nothing and the unimportance of periodicity. Science 2003, 299, 16981701.
 J.W. Long, D.R. Rolison, Architectural design, interior decoration, and three-dimensional plumbing en route to multifunctional nanoarchitectures. Acc. Chem. Res. 2007, 40, 854862.
 D.R. Rolison, J.W. Long, J.C. Lytle, A.E. Fischer, C.P. Rhodes, T.M. McEvoy, M.E. Bourg, A.M. Lubers, Multifunctional 3D nanoarchitectures for energy storage and conversion. Chem. Soc. Rev. 2009, 38, 226252.
 A.E. Fischer, K.A. Pettigrew, D.R. Rolison, R.M. Stroud, J.W. Long, Incorporation of homogeneous, nanoscale MnO2 within ultraporous carbon structures via self-limiting electroless deposition: Implications for electrochemical capacitors. Nano Lett. 2007, 7, 281286.
 J.W. Long, M.B. Sassin, A.E. Fischer, D.R. Rolison, A.N. Mansour, V.S. Johnson, P.E. Stallworth, S.G. Greenbaum, Multifunctional MnO2carbon nanoarchitectures exhibit battery and capacitor characteristics in alkaline electrolytes. J. Phys. Chem. C 2009, 113, 1759517598.
 M.B. Sassin, A.N. Mansour, K.A. Pettigrew, D.R. Rolison, J.W. Long, Electroless deposition of conformal nanoscale iron oxide on carbon nanoarchitectures for electrochemical charge storage. ACS Nano 2010. 4, 45054514.