Creating Faradaic Carbon Nanotube Electrodes with Mild Chemical Oxidation

Abstract The development of new materials to improve interfacial charge transfer characteristics will drastically improve energy storage, heterogeneous catalysis, and many other electrochemical applications. Here, we report a simple procedure 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 “unzip” the MWNTs and expose the redox‐active iron nanoparticles to the electrolyte. 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⁻¹) relative to purified MWNT electrodes (70 F g⁻¹). 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.