Carbon aerogels, nanofoams, and related ultraporous nanoarchitectures are attractive electrode materials for electrochemical power-source applications due to their inherent characteristics of high surface areas, through-connected networks of porosity with tunable pore sizes, and a highly conductive carbon framework.  These conductive nanoarchitectures serve as effective three-dimensional electrochemical interfaces, and enhance the performance of rate-critical devices, such as electrochemical capacitors and fuel cells.  The principal limitation of such carbon nanoarchitectures is their lack of the electrochemical functionalities that are beneficial for faradaic charge-storage and electrocatalysis.  To address this issue, we modify carbon nanoarchitectures to incorporate such functionalities as electroactive and ion-conducting polymers, mixed-conducting metal oxides, and specifically adsorbed noble-metal nanoparticles.  For example, we recently demonstrated a simple self-limiting electroless deposition process that yields conformal 10- to 20-nm-thick MnO₂ coatings that extend throughout the 170-mm thickness of carbon-paper-supported nanofoam structures [1].  The redox reactions of the nanoscopic MnO₂ phase boosts the energy density of the resulting hybrid nanoarchitectures for electrochemical capacitor applications, and also facilitates oxygen reduction when used as the air-breathing cathode in metal-air battery cells.  In a related approach to electrocatalytic nanoarchitectures, carbon aerogels/nanofoams derivatized with thiophene functionalities readily adsorb pre-formed metal nanoparticles (e.g., Pt, Pd, Ag), resulting in an ultraporous electrode structure for fuel-cell applications [2].

1.  Fischer, A.E.; Pettigrew, K.A.; Stroud, R.M.; Rolison, D.R.; Long, J.W. Nano Lett. 2007, 7, 281.

2.  Baker, W.S.; Long, J.W.; Stroud, R.M.; Rolison, D.R. J. Non-Cryst. Solids 2004, 350, 80.