Prussian blue nanospheres synthesized in deep eutectic solvents

A novel route for controlled synthesis of Prussian blue nanospheres (PB NSs) with different sizes by using deep eutectic solvents (DES) as both solvent and template provider was demonstrated. The size-controlled PB NSs were obtained directly by the coordination of Fe(CN)64− ion with Fe3+ ion in the DES. The probable mechanism of formation of PB NSs was discussed based on the characterization results of UV-visible, X-ray diffraction, X-ray photoelectronic spectrum and transfer electron microscopy. Furthermore, the electrochemical and electrocatalytic properties of the synthesized PB NSs were investigated, and it has demonstrated that the PB NSs exhibited excellent catalytic activity for H2O2 reduction, and then extended this strategy to glucose sensing, by detecting H2O2 formed from the enzymatic reaction of glucose oxidase with its substrate glucose. The linear calibration range for glucose was from 0.9 μM to 0.12 mM, with a correlation coefficient of 0.998. The limit of detection was 0.3 μM and the sensitivity was 61.7 A cm−2 M−1. The present study provides a general platform for the controlled synthesis of novel nanomaterials in DES and can be extended to other optical, electronic and magnetic nanocompounds.