▎ 摘　　要

In the present work, transition metal oxides decorated graphene (GR) have been fabricated for simultaneous determination of dopamine (DA), acetaminophen (AC) and tryptophan (Trp) using square wave voltammetry. Electro-deposition is a facile preparation strategy for the synthesis of nickel oxide (NiO) and copper oxide (CuO) nanoparticles. GR can be modified by using citric acid to produce more functional groups, which is conducive to the deposition of dispersed metal particles. The morphologies and interface properties of the obtained NiO-CuO/GR nanocomposite were examined by scanning electron microscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy. Moreover, the electrochemical performances of the composite film were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode exhibited that the linear response ranges for detecting DA, AC and Trp were 0.5-20 mu M, 4-400 mu M and 0.3-40 mu M, respectively, and the detection limits were 0.17 mu M, 1.33 mu M and 0.1 mu M (S/N=3). Under optimal conditions, the sensor displayed high sensitivity, excellent stability and satisfactory results in real samples analysis. (C) 2015 Elsevier B.V. All rights reserved.