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This paper presents a microsensor chip integrated with a gold nanoparticles-modified ultramicroelectrode array (UMEA) as the working electrode for the detection of copper ions in water. The microsensor chip was fabricated with Micro-Electromechanical System technique. Gold nanoparticles were electrodeposited onto the surface of UMEA at a constant potential of −0.3 V. The ratio d/ Rb of interelectrode spacing ( d) over the individual electrode's radius ( Rb) was investigated to improve the electrochemical performance. The UMEA with a d/ Rb of 20 showed the best hemispherical diffusion mode, resulted in fast response time and high current response. The gold nanoparticles increased the active surface area of UMEA by not changing the geometries of UMEA, and the current response was increased further. Incorporating the optimized characteristic of UMEA and gold nanoparticles, the microsensor showed a good linear range from 0.5 to 200 µg L−1 of copper ions in the acetate buffer solutions with the method of square wave stripping voltammetry. Compared with the gold nanoparticles-modified disk electrode, the gold nanoparticles-modified UMEA showed higher sensitivity (0.024 µA mm−2 µg−1 L) and lower limit of detection (0.2 µg L−1). Water samples from river water and tap water were analyzed by the microsensor chip with recovery ranging from 100.7 % to 107.8 %. [ABSTRACT FROM AUTHOR]

In this work, three heavy metals (Cu(II), Pb(II) and Zn(II)) in wide potential window were simultaneously detected on tin film/gold nanoparticles/gold microelectrode (Sn/GNPs/gold microelectrode) by the method of square wave stripping voltammetry. The Sn/GNPs/gold microelectrode was fabricated by in situ plating of a Sn film on a gold nanoparticles (GNPs) modified gold microelectrode. The influence of hydrogen overflow on stripping of Zn(II) on the gold microelectrode was reduced by modification of GNPs, which made the stripping potential of target metals shift positively. The interference of sulfhydryl groups was reduced and the selectivity of the microelectrode was improved due to the addition of Sn in the detection solution. After accumulation at −1.4 V for 300 s in acetate buffer solution (0.1 mol L−1, pH 4.5), the Sn/GNPs/gold microelectrode revealed a good linear behavior in the examined concentration ranges from 5 to 500 µg L−1 for Cu(II) and Pb(II), and from 10 to 500 µg L−1 for Zn(II), with a limit of detection of 2 µg L−1 for Cu(II), 3 µg L−1 for Pb(II) and 5 µg L−1 for Zn(II) ( S/ N=3). When compared with a Sb/GNPs/gold microelectrode and a Bi/GNPs/gold microelectrode, the Sn/GNPs/gold microelectrode showed the best stripping performance to Cu(II), Pb(II) and Zn(II). As a new type of environment-friendly electrode, the Sn/GNPs/gold microelectrode has potential applications for detection of heavy metals. [ABSTRACT FROM AUTHOR]

A 3D dendritic nanostructure of silver-array (DSA) was prepared via electrodeposition on an interdigitated array (IDA) microelectrode. For preparation of this nanostructure, the optimal parameters such as deposition potential, deposition time, the electrode bandwidth and gap size were systematically investigated. It was found that the edge effect of the IDA microelectrode is a key factor for controlling the 3D dendritic growth of silver. Furthermore, the formation of the 3D dendritic morphology was discussed from the aspect of electrochemical nucleation theory and nonequilibrium growth dynamics to give a deep understanding of its growth mechanism. For its potential practical application, we showed that the as-prepared 3D DSA nanomaterial exhibited high electrocatalytic reduction ability to nitrate in neutral solution and excellent performance for nitrate determination. An amperometric nitrate microsensor based on the 3D DSA was obtained. [ABSTRACT FROM AUTHOR]