Abstract
This paper investigated two different modification methods of graphene (GN) on ultramicroelectrode array (UMEA) and applied the GN modified UMEA for the determination of dissolved oxygen (DO). The UMEAs were fabricated by Micro Electro-Mechanical System (MEMS) technique and the radius of each ultramicroelectrode is 10 μm. GN-NH2 and GN-COOH were modified on UMEA by using self-assembling method. Compared with GN-NH2 modified UMEA, the GN-COOH modified UMEA showed better electrochemical reduction to DO, owing to better dispersing and more active sites. The GN-COOH on UMEA was electroreduced to reduced GN-COOH (rGN-COOH) to increase the conductivity and the catalysis performance. Finally, the palladium nanoparticles/rGN-COOH composite was incorporated into DO microsensor for the detection of DO.
Highlights
Dissolved oxygen (DO) is a vital parameter in water monitoring
The electrolyte pool around the three-electrode system was covered with 0.1 M LiCl solution, and a gas permeable membrane of Teflon was covered on the electrolyte pool
The results showed that the GN-COOH has been reduced to rGN-COOH, which has good conductivity and fast electron transfer
Summary
Dissolved oxygen (DO) is a vital parameter in water monitoring. A number of biological reaction and chemical reaction in water are influenced directly or indirectly by the quantity of DO. Zheng et al [5] investigated a hot electron induced cathodic electrochemiluminescence at a disposable CdS modified screen printed carbon electrodes for the detection of DO. This sensor showed low detection limit, good stability and was satisfactorily reproducible, showing potential application in DO and biochemical oxygen demand detection. UMEA is an important tool in electrochemical sensor fabrication, which possesses high sensitivity, low limit of detection, fast response time and well reproducible geometries [13]. Graphene (GN) has several advantages, such as huge surface area, high conductivity and fast electron transfer [14] These unique characteristics enable it to hold great promise for application in many fields, especially for developing high-performance sensors [15,16]. The GN-COOH modified UMEAs were further electroreduced and modified by palladium nanoparticles (PdNPs) for DO microsensor fabrication
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