Fabrication of Ag-Decorated ZnO Nanorods for Glucose Sensing

A stoichiometric ratio of zinc acetate dihydrate and cyclo-hexamethylenetetramine (HMTA) were taken in 90 mL of deionized water and stirred well for 30 min to complete the synthesis of the reaction solution of ZnO NRs. Then, the solution was transferred to the Teflon-lined autoclave and the substrates were kept inside the solution for the growth of the ZnO NRs. The autoclave was placed in an oven at a temperature of 80 °C for 4 h, and after being reduced to room temperature, the substrates were taken out and cleaned with deionized water. The decoration of the ZnO NRs with Ag nanoparticles was achieved using a simple vacuum sputtering technique under ambient conditions for 5 min, adopting the method followed by Yoon, J. et al. [26 (link)]. The pressure during the sputtering process was maintained at 20 Pa and the current was controlled at 2 mA. The calculated average diameter of the Ag NPs of 15.55 ± 3.71 nm was maintained using the above-mentioned sputtering conditions for all the samples fabricated in this study. The diameter distribution of the Ag NPs decorating the ZnO NRs is included in the supporting information file, Section S2. After Ag decoration, 20 μL of the glucose solutions of different concentrations was filled with ZnO NRs and placed on a heating plate at 80 °C for 1 h and then used for the analysis. The schematic diagram of the synthesis of ZnO, Ag@ZnO, and glucose/Ag@ZnO is shown in Figure 1.