Nickel Cobalt Oxide Nanoneedles for Electrochromic Glucose Sensors

Uniform nanoneedles of binary oxide (Ni and Co) were synthesized on appropriate conducting substrates [fluorine-doped tin oxide (FTO) coated glass and carbon cloth (CC)] and investigated for dual application in electrochromism and glucose sensing. The prepared samples were characterized using electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy to reveal the presence of a NiCo2O4 phase. Porosity analysis was carried to assign the microporous nature of the prepared sample. Detailed electrochemical and in situ bias-dependent optical spectroscopy studies were carried out to understand various aspects related to electrochromism and glucose sensing. A low-operating-voltage (similar to 2 V) color modulation with 50% contrast between the whitish translucent and dark-brown colors was achieved from the nanoneedle grown on a transparent FTO substrate. Furthermore, additionally, NiCo2O4 nanoneedles grown on a CC substrate, with an enhanced exposed surface area, showed selective glucose-sensing properties with a very high sensitivity of 3000 mu A/mM/cm(2) as revealed using detailed electrochemical and impedance spectroscopic measurements.

Automated summary

Uniform nanoneedles of binary oxide (Ni and Co) were synthesized on conducting substrates and investigated for dual application in electrochromism and glucose sensing. Detailed characterization and analysis revealed the presence of NiCo2O4 phase and microporous nature of the prepared samples. The nanoneedles grown on transparent FTO substrate achieved low-operating-voltage color modulation, while those grown on CC substrate exhibited high sensitivity in glucose sensing.