A carbon modified MnO2nanosheet array as a stable high-capacitance supercapacitor electrode

Abstract

A carbon-modified manganese dioxide (MnO₂@C) nanosheet array has been synthesized on a titanium foil current collector via a facile hydrothermal method followed by carbonization of glucose pre-adsorbed onto the nanosheets. The direct growth of MnO₂@C nanosheets on a current collector leads to enhanced electron transport/collection and more sufficient ion adsorption–desorption. Carbon modification proves to enhance the electrical conductivity of MnO₂. With the elegant combination of ordered array electrode architecture with conductive carbon, our MnO₂@C nanosheet array displays well-defined capacitive features with both high gravimetric and areal capacitances (∼622 F g⁻¹ and 143 mF cm⁻²; much higher than those of our pristine MnO₂ film and other reported MnO₂ electrodes), good rate capability and outstanding cycling stability up to 4000 times (only 5.9% loss). The present study provides an alternative way to design a high-performance MnO₂-based supercapacitor electrode and the concept is extendable to other pseudocapacitive electrodes.