Self-assembled NiWO₄ nanoparticles into chain-like aggregates on DNA scaffold with pronounced catalytic and supercapacitor activities

We report a new route for the self-assembled NiWO₄ nanoparticles (NPs) in chain-like aggregates on a DNA scaffold by the reaction of nickel(II) acetate with sodium tungstate under continuous stirring and heating at 60 °C within 90 min of reaction. The size of the individual NiWO₄ particles was found to be ∼20-30 nm and the diameter of the aggregates was in the ∼220 ± 30 nm range. The probable growth mechanisms of DNA-NiWO₄ chain-like aggregates were elaborated. The potential of the NiWO₄ chain-like aggregates was tested in catalytic reaction and in electrochemical supercapacitor studies. Catalysis study revealed that the NiWO₄ aggregated structure acts as a suitable catalyst for the conversion of K₃[Fe(CN)₆] to K₄[Fe(CN)₆] in the presence of Na₂S₂O₃ under UV-light illumination within a short time. Supercapacitor study signified that different morphologies of NiWO₄ show different specific capacitance (C) values, and the highest C value of 173 F g^-1 at a scan rate of 5 mV s^-1 was observed while chain diameter was less. The supercapacitor study also revealed an excellent long cycle life along with 90% retention of C value even after 1000 consecutive times of cycling. The exploitation for the synthesis of mixed metal oxide on DNA scaffold might generate a new avenue for the successful formation of other oxides and can be useful for organic catalysis reactions and in future energy storage devices.