Multifunctional carbon nano-architectures as designer platforms for electrochemical power sources

Abstract

We use fiber-paper-supported carbon nanofoams as the basis for multifunctional electrode nanoarchitectures in which the nanofoams serve as conductive, ultraporous scaffoldings for subsequent incorporation of electroactive functionalities such as metal oxides, metal nanoparticles, and ultrathin polymers. The resulting functionalized carbon nanofoam papers are designed to serve as plug-and-play electrode structures in electrochemical devices ranging from high-rate Li-ion batteries and electrochemical capacitors to metal-air batteries and fuel cells. Electroless deposition is an attractive approach to functionalize structurally complex substrates, such as carbon nanofoams, and we have recently demonstrated that conformal nanoscopic coatings of manganese oxide (MnO x ) can be generated on the exterior and interior surfaces of pre-formed carbon nanofoam papers via redox reaction with aqueous permanganate (MnO 4 - ). The resulting nanoscale MnO x coatings provide not only faradaic charge-storage functionality to the nanofoam structure, but also enhanced electrocatalytic activity for molecular oxygen reduction. The electrocatalytic functionality of MnO x can now be combined with the desirable structural characteristics of carbon nanofoams (through-connected and size-tunable pore structures, high specific surface areas, and good electrical conductivity) to produce high-performance air-breathing cathodes for metal-air batteries. Herein, we report preliminary results for a particular series of native and MnOx-functionalized carbon nanofoams as examined for their O 2 -reduction activity in a three-electrode testing configuration.