This paper presents the fabrication procedure and characterization of cobalt nanostructure-based microelectrodes for phosphate detection. Cobalt thin films with different plane, nano-scale structures were obtained on gold microelectrodes by adjusting the parameters of electrodepositing method. The result of the fabrication was examined by XRD and SEM, showing the crystal direction and surface morphology of the electrodeposited cobalt layer. Electrochemical characterization of these microelectrodes was performed. The electrodes deposited under different parameters present a linear response in the range from 10-6mol/L to 10-2mol/L with a slope ranging from -19 to -17.6mV/decade. The potential response becomes stable in 200s after the electrode was put into the phosphate solution. It could be assumed that the difference in surface morphology of the electrode caused by changing depositing parameters may have little affection to the response to phosphate.

A novel micro-sensing chip for detecting total nitrogen (TN) was reported, which was based on 3D bimetallic Ag/Pd nanodendrites for electrocatalystic reduction of nitrate. The 3D structured Ag/Pd nanodendrites were synthesized by electrodepositon of Ag and Pd on gold interdigitated microband array electrode (Au-IDA). Such 3D Ag/Pd bimetallic nanodendrites possess an extremely high electrocatalytic activity for nitrate reduction in alkaline media at pH 12.5 hence realizing an excellent performance of TN determination without pH adjusting. The electrochemical detection limit of TN is 0.1mgL-1 and the measurement results of real water samples showed a relative error of less than 10% with UV spectrophotometric method. The present micro-sensing chip has significant potential for developing of portable and inexpensive TN instrument for on-line environmental measurement.

Cadmium(II) is a common water pollutant with high toxicity. It is of significant importance for detecting aqueous contaminants accurately, as these contaminants are harmful to human health and environment. This paper describes the fabrication, characterization, and application of an environment-friendly graphene (Gr)/l-cysteine/gold electrode to detect trace levels of cadmium (Cd) by differential pulse stripping voltammetry (DPSV). The influence of hydrogen overflow was decreased and the current response was enhanced because the modified graphene extended the potential range of the electrode. The Gr/l-cysteine/gold electrode showed high electrochemical conductivity, producing a marked increase in anodic peak currents (vs. the glass carbon electrode (GCE) and boron-doped diamond (BDD) electrode). The calculated detection limits are 1.15, 0.30, and 1.42 µg/L, and the sensitivities go up to 0.18, 21.69, and 152.0 nA·mm−2·µg−1·L for, respectively, the BDD electrode, the GCE, and the Gr/l-cysteine/gold electrode. It was shown that the Gr/l-cysteine/gold-modified electrode is an effective means for obtaining highly selective and sensitive electrodes to detect trace levels of cadmium.

This work presents a bulk electrode and a microband electrode array for electrochemical nitrate sensing in acidic medium. The microelectrode array is fabricated on silicon wafer by micro electro-mechanical system technique. Electrodepostion was carried out to modify tin onto the bulk palladium electrode and thus formed Pd-Sn bimetallic composite. On the microelectrode array, Pd and Sn were successively deposited to obtain a double-layer composite. The performance of the two kinds of electrodes towards nitrate sensing was investigated and compared. The microelectrode array showed better sensitivity and repeatability than the bulk electrode. The results are consistent with the unique properties of the microelectrode array in electrochemical analysis such as high current density and low background noise.