A Microelectrode Modified with Co-electrodeposited Carboxyl Graphene and AuNPs: Characterization and Application in Water Quality Detection

摘要

A microelectrode modified with carboxyl graphene and Au nanoparticles (AuNPs) was developed, andthe application of the microelectrode in water quality detection was studied. The microelectrode wasfabricated by Micro-Electro-Mechanical System (MEMS) techniques to accurately control the shapeand the dimensions. Carboxyl graphene and AuNPs were co-electrodeposited on the microelectrodethrough chronoamperometry. Scanning electron microscope (SEM), cyclic voltammetry (CV),electrochemical impedance spectroscopy (EIS) and Raman spectroscopy were employed to investigatethe modification process. The co-electrodeposited microelectrode displays better conductivity andmore uniform distribution than individually modified electrodes due to the synergistic interaction ofcarboxyl graphene and AuNPs. By combining the advantages of co-electrodeposition andmicroelectrodes, sensitive and rapid detection can be achieved. The modified electrode showed asensitivity of -75.23 nA·(mg/L)-1 for dissolved oxygen detection, which is approximately five timesthat of a bare electrode. The carboxyl functional groups on deposited carboxyl graphene can provideimmobilization sites for subsequent biochemical materials, which extends the application of themodified electrode. As an example, by further immobilization of microorganisms, the modifiedelectrode offered a fast detection method for biochemical oxygen demand. The proposed modifiedelectrode is promising for rapid and sensitive water quality detection.