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

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