Fabrication of the Ni-based composite wires for electrochemical detection of copper(â ¡) ions.

Copper ions (Cu2+) pollution in the water environment poses a great threat to the health function of life-sustaining metabolic activities. However, the current detection methods need relatively expensive instruments, complex operation procedures and long time, so a facile and direct detection method is desired to be developed. In this work, the Ni-based composite wires with p-n junction (the Ni/NiO/ZnO/Chitosan wire) and Schottky junction (the Ni/NiO/Au/Chitosan wire) were fabricated, and the barrier driven electrochemical sensing mechanism was studied. The direct and facile detection of Cu2+ was achieved with a wide linear range (0-6000 nM) and a low LOD (0.81 nM). The excellent stability and recovery in real water samples made the Ni-based composite wires a promising candidate for the practical application. The interfacial barriers of semiconductor can be used as a special sensing factor to develop novel sensors.

Preparation of NiMn2O4/C necklace-like microspheres as oxidase mimetic for colorimetric determination of ascorbic acid.

The NiMn2O4/C necklace-like microspheres (NLM) were successfully prepared by hydrothermal method and oil bath. This unique necklace-like structure makes them exhibit the enhanced intrinsic oxidase-like activity, as the special interface can help capture electrons from 3,3',5,5'-tetramethylbenzidine. The fabricated NiMn2O4/C NLM were successfully used as the high-performance oxidase mimetic to catalyze the oxidation of TMB directly for the color reaction. A simple colorimetric method for detection of ascorbic acid by fading was developed, and the high sensitivity with the low detection limit (0.047 µM) was achieved. It is a facile route to fabricate the NiMn2O4/C NLM as the high-performance oxidase mimetic for colorimetric biosensing.

Using the interfacial barrier effects of p-n junction on electrochemistry for detection of phosphate.

A novel type of electrochemical sensor for detection of phosphate in water environment was developed by combining the interfacial barrier of p-n junction with the adsorption of phosphate. The electrochemical response was produced by the induced change of the barrier height, which was only caused by the specific adsorption of phosphate. Two linear concentration ranges (0-0.045 mg L-1 and 0.045-0.090 mg L-1) with two sensitivities (4.98 µA (µg L-1)-1 and 1.28 µA (µg L-1)-1) were found. The good performance made the sensor meet the requirements of the World Health Organization for drinking water (1 mg L-1 of phosphate). It is an approach to develop electrochemical sensors by employing the interfacial barrier effects on electrochemistry.