The authors report that CuOx/NiOy hollow nanocomposites are an effective bifunctional catalyst capable of oxidizing glucose and reducing hydrogen peroxide. Synthesis is based on a solvothermal process and subsequent thermal treatment. The structure can be controlled by adjusting the amounts of added NiCl2 during the solvothermal etching process, and core-shell, yolk-shell or hollow structures can be obtained. The porous hollow structure composite of type CuO30/NiO90 was used to modify a glassy carbon electrode. It exhibits excellent electrocatalytic activity towards glucose oxidation in solution of pH 13, typically at a working potential of +0.60 V (vs. Ag/AgCl). This enables voltammetric sensing of glucose with (a) a low limit of detection (0.08 μM, at S/N = 3), (b) over a wide linear range (0.20 μM - 2.5 mM), and (c) high sensitivity (2043 μA·mM-1·cm-2). The sensor is reproducible, selective and stable. It can be used to detect glucose in spiked human serum. The CuO30/NiO90 composite also displays good electrocatalytic activity towards reduction of H2O2 in neutral aqueous medium, typically at an applied potential of -0.35 V. It has a detection limit of 90 nM, a sensitivity of 271.1 μA·mM-1·cm-2, and a linear detection range that extends from 0.30 μM to 9.0 mM. Graphical abstract CuOx/NiOy nanocomposites with three different structures were synthesized by coordinated etching precipitation method. The hollow structure CuO30/NiO90 was coated on the surface of glassy carbon electrode for the amperometric determination of glucose and hydrogen peroxide.
Keywords: Bifunctional electrocatalysts; Bimetal oxide; Controllable etching; Cu2O template; Electrochemical sensor; Glucose electro-oxidation; Hollow structure; Human serum; Mesoporous material; Solvothermal method.