▎ 摘　　要

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