So, it can be envisioned that a hierarchical porous NiCo2O4 material could combine the merits of not only hierarchical nanostructures, but also porous morphologies.It is well known that three dimensional (3D) hybrid nanostructures with large surface area and short diffusion path for electrons and ions are promising electrode architectures for high-performance sensor devices. The fabrication of fast, sensitive and selective glucose sensors are in high demand, because glucose detection is very important for patients suffering from diabetes. There are mainly two types of glucose sensors, one is the glucose oxidase-based sensor and other is the non-enzymatic glucose sensor.

The glucose oxidase-based sensors are popular due to their high sensitivity and selectivity towards glucose detection and high stability over a wide range of pH, thus different amperometric and potentiometric glucose biosensors have been constructed [11,12]. Amperometric glucose sensors have been developed without the use of enzyme, but potentiometric glucose sensors without the use of enzyme are difficult to construct. The potentiometric technique is simple for measuring glucose level on spot and applicable to quantify the glucose level inside the cell [13]. By exploiting the redox property of binary metal oxides like NiCo2O4 for the oxidation of glucose molecules, a biosensor is proposed in the present work. Beside this, this study may shed some light on simple and cost effective preparation of hierarchical porous nanostructures and the development of materials with advanced functions for sensor devices.

The crystalline NiCo2O4 nanostructures synthesized by using hydrothermal method on nickel foam substrate were used as the backbone to support and provide reliable electrical connections to the CoxNi1?x DHs coatings with surface areas accessible to electrolyte, enabling full utilization of the CoxNi1?x DHs and fast electronic and ionic conduction through the electrode. The nickel cobalt GSK-3 oxide nanostructures were characterized by the scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy techniques. Further these nanostructures were utilized to develop a sensitive, stable and selective glucose sensor using the potentiometric method.2.?Experimental SectionCobalt chloride hexahydrate (CoCl2?6H2O), Nickel chloride hexahydrate (NiCl2?6H2O), urea (CH4N2O), D-glucose, glucose oxidase, ascorbic acid, uric acid, dopamine, sodium hydrogen phosphate, potassium hydrogen phosphate, sodium chloride and potassium chloride were purchased from Sigma-Aldrich (Stockholm, Sweden) and used without any further purification.