▎ 摘　　要

This study synthesized Fe3O4 nanoparticles of 30-40 nm by a sonochemical method, and these particles were uniformly dispersed on the reduced graphene oxide sheets (Fe3O4/RGO). The superparamagnetic property of Fe3O4/RGO was evidenced from a saturated magnetization of 30 emu/g tested by a sample-vibrating magnetometer. Based on the testing results, we proposed a mechanism of ultrasonic waves to explain the formation and dispersion of Fe3O4 nanoparticles on RGO. A biosensor was fabricated by modifying a glassy carbon electrode with the combination of Fe3O4/RGO and hemoglobin. The biosensor showed an excellent electrocatalytic reduction toward H2O2 at a wide, linear range from 4 x 10(-6) to 1 x 10(-3) M (R-2 = 0.994) as examined by amperometry, and with a detection limit of 2 x 10(-6) M. The high performance of H2O2 detection is attributed to the synergistic effect of the combination of Fe3O4 nanopartides and RGO, promoting the electron transfer between the peroxide and electrode surface. (C) 2012 Elsevier B.V. All rights reserved.