Rational design of hierarchically porous birnessite-type manganese dioxides nanosheets on different one-dimensional titania-based nanowires for high performance supercapacitors

A facile and large-scale strategy of mesoporous birnessite-type manganese dioxide (MnO2) nanosheets on one-dimension (1D) H2Ti3O7 and anatase/TiO2 (B) nanowires (NWs) is developed for high performance supercapacitors. The morphological characteristics of MnO2 nanoflakes on H2Ti3O7 and anatase/TiO2 (B) NWs could be rationally designed with various characteristics (e.g., the sheet thickness, surface area). Interestingly, the MnO2/TiO2 NWs exhibit a more optimized electrochemical performance with specific capacitance of 120 F g(-1) at current density of 0.1 A g(-1) (based on MnO2 + TiO2) than MnO2/H2Ti3O7 NWs. An asymmetric supercapacitor of MnO2/TiO2//activated graphene (AG) yields a better energy density of 29.8 Wh kg(-1) than MnO2/H2Ti3O7//AG asymmetric supercapacitor, while maintaining desirable cycling stability. Indeed, the pseudocapacitive difference is related to the substrates, unique structure and surface area. Especially, the anatase/TiO2 (B) mixed-phase system can provide good electronic conductivity and high utilization of MnO2 nanosheets. (C) 2014 Elsevier B.V. All rights reserved.