Synthesis and characterization of DNA fenced, self-assembled SnO2 nano-assemblies for supercapacitor applications

Abstract

Self-assembled, aggregated, chain-like SnO₂ nano-assemblies were synthesized at room temperature by a simple wet chemical route within an hour in the presence of DNA as a scaffold. The average size of the SnO₂ particles and the chain diameter were controlled by tuning the DNA to Sn(II) molar ratio and altering the other reaction parameters. A formation and growth mechanism of the SnO₂ NPs on DNA is discussed. The SnO₂ chain-like assemblies were utilized as potential anode materials in an electrochemical supercapacitor. From the supercapacitor study, it was found that the SnO₂ nanomaterials showed different specific capacitance (C_s) values depending on varying chain-like morphologies and the order of C_s values was: chain-like (small size) > chain-like (large size). The highest C_s of 209 F g⁻¹ at a scan rate of 5 mV s⁻¹ was observed for SnO₂ nano-assemblies having chain-like structure with a smaller size. The long term cycling stability study of a chain-like SnO₂ electrode was found to be stable and retained ca. 71% of the initial specific capacitance, even after 5000 cycles. A supercapacitor study revealed that both morphologies can be used as a potential anode material and the best efficiency was observed for small sized chain-like morphology which is due to their higher BET surface area and specific structural orientation. The proposed route, by virtue of its simplicity and being environmentally benign, might become a future promising candidate for further processing, assembly, and practical application of other oxide based nanostructure materials.