Inorganic/polymer-graphene hybrid gel as versatile electrochemical platform for electrochemical capacitor and biosensor

Abstract

In this work, we reported the design and synthesis of a new type of polymer-graphene hybrid material by supramolecular self-assembly of polyacrylic acid (PAA) and graphene to form a robust sponge-like PAA-graphene gel (PAA-GG) with internally well-defined porous structure, followed by electrodepositon of high-density and well-dispersed MnO2 nanowires on outer and inner surface of PAA-GG scaffold. The as-obtained MnO2/PAA-GG uniquely combines a series of structural and electrochemical characteristics of its precursors, including large surface area, improved capacitive properties and enhanced electrocatalytic activities, fostering versatile applications as electrochemical capacitor and biosensor. Our results show that the symmetric capacitor assembled by MnO2/PAA-GG electrode presents a specific capacitance of 123 F g−1 under a current density of 0.5 A g−1, and its specific capacitance only loss 13.8% after 5000 cycles. For potential application as electrochemical biosensor, MnO2/PAA-GG exhibits high sensitivity and selectivity in nonenzymatic detection of H2O2. The linear range is between 0.05 mM and 50 mM with a low detection limit down to 10 μM, which enables it to be used for real-time tracking of H2O2 secretion in live cells. These promising features make the inorganic/polymer-graphene hybrid gel attractive for a wide spectrum of applications in energy, electrocatalysis and bioanalytical areas.