(460f) Harnessing the Intrinsic Synthesis Catalysts to Create Faradaic Carbon Nanotube Composites

The development of new materials to improve interfacial charge transfer characteristics will drastically enhance energy storage, heterogeneous catalysis, and many other electrochemical applications. Here we report two simple procedures that can harness the Faradaic nature of residual iron nanoparticle catalysts that endure within Multi-walled Carbon Nanotubes (MWNT) post-synthesis, thereby alleviating the challenges associated with forging hybrid nanocomposite electrodes. Non-purified MWNTs, undergo a chemical oxidation process in acidic conditions with KMnO4 to partially “upzip” the MWNTs and exposes the redox-active iron nanoparticles to the bulk liquid. Electrochemical activation of these non-purified MWNTs is also possible by exposing the tubes to high voltages in acidic conditions causing the tubes to rupture partially and permitting the interaction between the catalysts and the electrolytes. In both cases a stable redox peak associated with the Fe^2+/3+ transition is achieved during the MWNT oxidation process yielding a ~350% increase in capacitance (>300 F/g) relative to purified MWNT electrodes (70 F/g). While these materials solely may be pragmatic as energy storage electrodes, the integration of redox species within an inert carbon electrode will also provide new opportunities to accelerate heterogeneous charge transfer reactions.