▎ 摘　　要

This work reports the design and development of iron oxide (Fe3O4)/graphene nanocomposite for the highly sensitive and selective electrochemical detection of dopamine (DA). The decoration of graphene sheets with Fe3O4 nanostructures was achieved by a simple process of one-step chemical reaction strategy. The morphological studies revealed the six petalled Watsonia meriana flower like Fe3O4 nanostructures and the average length of each petal ranging from the centre is found to be 1.23 mu m and the average diameter of nanoparticles that constitutes the petal is 30 nm and the plausible growth mechanism of above nanostructures was analyzed in detail. The cubic inverse spinel structure of prepared Fe3O4 nanomaterials was confirmed from the diffraction patterns and the morphology, size, and structure of bare Fe3O4 nanomaterials were not altered even after the composite formation with graphene. The catalytic activity of prepared nanostructures toward DA oxidation was investigated by the electrochemical techniques and Fe3O4/rGO nanocomposite exhibited an excellent electrocatalytic oxidation of DA with the amperometric current - time response of 5 s, a wide linear range between 0.010 and 0.270 mu M, high sensitivity of 19.75 mu A/mu M.cm(2) and a lower detection limit of 5 nM. The sensor has proven its superior selectivity toward the detection of DA even under the presence of biologically co-active interfering species and the application of constructed sensor in human urine sample was also successfully demonstrated, which guaranteed the real sample analysis of fabricated sensor with the high accuracy. (C) 2016 Elsevier B.V. All rights reserved.