Free‐Standing NiO Nanosheets as Non‐Enzymatic Electrochemical Sensors

A simple, rapid and sensitive electrochemical sensor for determination of urea has been developed based on two‐dimensional (2D) Free‐standing NiO nanosheet. High quality, ultrathin two‐dimensional NiO nano‐sheets were synthesized by using graphene oxide paper as sacrificial template. Various techniques such as x‐ray diffraction (XRD), x‐ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to characterize the morphology of the nanostructure. According to TEM image, the average size of the as‐synthesized NiO nanosheets is around 50 nm and with 5–20 nm pores. Electrochemical studies indicate that the 2D NiO papers exhibit excellent stability and high electrocatalytic activity for the oxidation of urea in an alkaline medium, even without any conductive supporting agent, and low oxidation potential (vs SCE), high sensitivity (3.4 A/M cm²) and a low detection limit (2 μM) as a non‐enzymatic sensor for urea.