Enhanced catalytic and supercapacitor activities\ud of DNA encapsulated b-MnO2 nanomaterials

摘要

A new approach is developed for the aqueous phase formation of flake-like and wire-like b-MnO2\udnanomaterials on a DNA scaffold at room temperature (RT) within a shorter time scale. The b-MnO2\udnanomaterials having a band gap energy B3.54 eV are synthesized by the reaction of Mn(II) salt with\udNaOH in the presence of DNA under continuous stirring. The eventual diameter of the MnO2 particles in the\udwire-like and flake-like morphology and their nominal length can be tuned by changing the DNA to Mn(II) salt\udmolar ratio and by controlling other reaction parameters. The synthesized b-MnO2 nanomaterials exhibit\udpronounced catalytic activity in organic catalysis reaction for the spontaneous polymerization of aniline\udhydrochloride to emeraldine salt (polyaniline) at RT and act as a suitable electrode material in electrochemical\udsupercapacitor applications. From the electrochemical experiment, it was observed that the b-MnO2\udnanomaterials showed different specific capacitance (Cs) values for the flake-like and wire-like structures. The\udCs value of 112 F g�1 at 5 mV s�1 was observed for the flake-like structure, which is higher compared to that\udof the wire-like structure. The flake-like MnO2 nanostructure exhibited an excellent long-term stability,\udretaining 81% of initial capacitance even after 4000 cycles, whereas for the wire-like MnO2 nanostructure,\udcapacitance decreased and the retention value was only 70% over 4000 cycles. In the future, the present\udapproach can be extended for the formation of other oxide-based materials using DNA as a promising\udscaffold for different applications such as homogeneous and heterogeneous organic catalysis reactions,\udLi-ion battery materials or for the fabrication of other high performance energy storage devices