Effect of doping mediated oxygen vacancies on the charge transfer ability of zinc oxide nanosheets for electrochemical glucose sensing

Abstract

We reported on hydrothermally synthesized zinc oxide (ZnO) nanosheets modified by doping with silver (Ag: 1, 2, 3, 4, and 5%) to improve their electrochemical properties for glucose sensing with and without an enzyme. SEM, XRD, EDX, and FTIR were used to investigate the microstructural, chemical, and optical properties of pristine ZnO and Ag-doped ZnO. XPS confirms that silver acts as an effective oxygen vacancy suppressor. Cyclic voltammetry studies revealed that the 5% Ag-doped ZnO electrode has a higher anodic current than the pristine ZnO and Ag (1, 2, 3, 4%)-doped ZnO electrodes. Because of the higher anodic current, the 5% Ag-doped ZnO electrode was used for sensing glucose with and without an enzyme. The 5% Ag-doped ZnO nanosheet-based electrode without an enzyme exhibited enhanced sensitivity (∼104.7 μA mM⁻¹ cm⁻²), lower detection limits (∼0.06 mM), higher selectivity, practical repeatability & reproducibility, and good stability compared to the 5% Ag-doped ZnO nanosheet-based electrode with an enzyme (sensitivity ∼98.3 μA mM⁻¹ cm⁻² and LOD ∼0.098 mM), with each having a response time of ∼5 s.