title: Enhanced catalytic and supercapacitor activities of DNA encapsulated β-MnO₂ nanomaterials.
abstract: A new approach is developed for the aqueous phase formation of flake-like and wire-like β-MnO2 nanomaterials on a DNA scaffold at room temperature (RT) within a shorter time scale. The β-MnO2 nanomaterials having a band gap energy ∼3.54 eV are synthesized by the reaction of Mn(II) salt with NaOH in the presence of DNA under continuous stirring. The eventual diameter of the MnO2 particles in the wire-like and flake-like morphology and their nominal length can be tuned by changing the DNA to Mn(ii) salt molar ratio and by controlling other reaction parameters. The synthesized β-MnO2 nanomaterials exhibit pronounced catalytic activity in organic catalysis reaction for the spontaneous polymerization of aniline hydrochloride to emeraldine salt (polyaniline) at RT and act as a suitable electrode material in electrochemical supercapacitor applications. From the electrochemical experiment, it was observed that the β-MnO2 nanomaterials showed different specific capacitance (Cs) values for the flake-like and wire-like structures. The Cs value of 112 F g(-1) at 5 mV s(-1) was observed for the flake-like structure, which is higher compared to that of the wire-like structure. The flake-like MnO2 nanostructure exhibited an excellent long-term stability, retaining 81% of initial capacitance even after 4000 cycles, whereas for the wire-like MnO2 nanostructure, capacitance decreased and the retention value was only 70% over 4000 cycles. In the future, the present approach can be extended for the formation of other oxide-based materials using DNA as a promising scaffold for different applications such as homogeneous and heterogeneous organic catalysis reactions, Li-ion battery materials or for the fabrication of other high performance energy storage devices.
authors.affiliation: Electrochemical Materials Science (ECMS) Division, CSIR-Central Electrochemical Research Institute (CECRI), Karaikudi-630006, Tamil Nadu, India. skundu@cecri.res.in kundu.subrata@gmail.com.
authors.forename: Sivasankara Rao
authors.initials: SR
authors.lastname: Ede
authors.forename: Ananthakumar
authors.initials: A
authors.lastname: Ramadoss
authors.forename: S
authors.initials: S
authors.lastname: Anantharaj
authors.forename: U
authors.initials: U
authors.lastname: Nithiyanantham
authors.forename: Subrata
authors.initials: S
authors.lastname: Kundu
mesh_terms: D002384:Catalysis; D004247:DNA / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D017895:Manganese Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D013696:Temperature
chemical_list: D017895:Manganese Compounds; D010087:Oxides; C027424:manganese oxide; D004247:DNA