Flexible N-Doped reduced graphene oxide/carbon Nanotube-MnO2 film as a Multifunctional Material for High-Performance supercapacitors, catalysts and sensors

A flexible 3D N-doped reduced graphene oxide (N-RGO)/carbon nanotube (CNT)MnO2 hybrid film was constructed with outstanding supercapacitor, excellent oxygen reduction reaction (ORR) and good sensing performances. The resultant hybrid film possessed large specific capacitances of 418 F g−1 and 209 mF cm−2 in aqueous and solid electrolytes, and outstanding capacitance retentions of 95% and 94% were obtained for both electrolytes after experiencing 5000 cycles. A simple supercapacitor based on the resultant flexible hybrid film was further fabricated with a much smaller time constant τ0 (0.38 s) than that of typical activated-carbon supercapacitors, suggesting a quick response frequency. Moreover, the assembled supercapacitor device showed high energy densities of 45.72 and 92.13 Wh kg−1 and simultaneously sustained large power densities of 12,526 and 15873 W kg−1 under a scan rate of 50 mV s−1 in aqueous and solid electrolytes, respectively. Furthermore, the resultant flexible film showed excellent performance in the ORR and can also be used to assemble a strain sensor with an excellent sensing performance for bending strain.