Engineered macroporosity in single-wall carbon nanotube films.

A key advantage of bulk nanoscale materials in applications ranging from energy storage to chemical catalysis is their inherent high surface area. Single-wall carbon nanotube films possess the additional advantages of high electrical conductivity and robust mechanical integrity. Nevertheless the flexibility of the individual nanotubes and their affinity for each other conspire to obstruct the porosity in such films limiting the perfusion rate of liquids and gases, restricting the accessible surface area and thereby limiting their utility in important applications. Here we demonstrate a simple, effective means to engineer controlled porosity into the nanotube films. The newly incorporated porosity modifies the film electrolytic capacitance and comparative perfusion rates. Pseudocapacitive RuO(2) electrodeposited onto the highest porosity films exhibits a specific capacitance of 1084 F/g. Knowledge of the underlying nanotube capacitance and mass permits extraction of the deposited RuO(2) specific capacitance of 1715 F/g, which closely approaches the predicted theoretical maximum RuO(2) capacitance of 2000 F/g.