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 NiWO 4 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 NiWO 4 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–NiWO 4 chain-like aggregates were elaborated. The potential of the NiWO 4 chain-like aggregates was tested in catalytic reaction and in electrochemical supercapacitor studies. Catalysis study revealed that the NiWO 4 aggregated structure acts as a suitable catalyst for the conversion of K 3 [Fe(CN) 6 ] to K 4 [Fe(CN) 6 ] in the presence of Na 2 S 2 O 3 under UV-light illumination within a short time. Supercapacitor study signified that different morphologies of NiWO 4 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.