Non-enzymatic glucose sensors based on electrodeposited Cu_xO–ZnO composite nanostructures

The present study investigates the non-enzymatic glucose sensing properties of Cu\(_x\)O–ZnO (x = 1,2) composite nanostructures that have been fabricated using a simple and fast co-electrodeposition (CED) method. Two concentrations of Cu\(^{2+}\) were used and interestingly, for the lower concentration, the fabricated (C\(_2\)) nanostructures are of Cu\(_2\)O–ZnO type while for the higher concentration (C\(_{50}\)), nanostructures show a mixed Cu\(_x\)O–ZnO (x = 1,2) nature. Although both the samples exhibit a good catalytic response for non-enzymatic glucose sensing, the C\(_{50}\) sample shows a far superior response. Along with a high sensitivity of 384.6 µA mM\(^{-1}\) cm\(^{-2}\), a large linear range of 0.03–3 mM, and a low least detection limit (LOD) of 0.7  µM, C\(_{50}\) also demonstrates a good long-term stability, good reproducibility, and good selectivity toward glucose detection, even in the presence of interfering species. The synergistic effect of Cu\(_x\)O–ZnO composite nanostructures and their semiconducting nature may be contributing to the good response of C\(_{50}\) as a glucose sensor. The results presented here demonstrate that C\(_{50}\) can be an excellent non-enzymetic glucose sensor for measuring glucose in blood and food samples.