A Novel Nonenzymatic Hydrogen Peroxide Sensor Based on Magnetic Core-Shell Fe₃O₄@C/Au Nanoparticle Nanocomposite

Fe₃O₄@C/Au nanoparticle (AuNP) nanocomposites were prepared through electrostatic adsorption of AuNPs onto PDDA-functionalized core/shell Fe₃O₄@C magnetic nanospheres, which had been synthesized by a facile solvothermal method. The morphology and composition of the nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), etc. Moreover, highly electrocatalytic activity to the reduction of hydrogen peroxide (H₂O₂) was also exhibited on the Fe₃O₄@C/AuNP-modified indium tin oxide (ITO) electrode. The effect of solution pH and the modification amount of Fe₃O₄@C/AuNPs on the performance of electrocatalytic H₂O₂ reduction was investigated. Under the optimal conditions, the catalytic current showed a linear relationship with the increase of H₂O₂ concentration in the range of 0.007-15 mM and a detection limit of 5 μM. The H₂O₂ sensor showed high selectivity for H₂O₂ detection, which could effectively resist the interference of ascorbic acid (AA), uric acid (UA), and citric acid (CA). Finally, the H₂O₂ sensor was used in the real fetal bovine serum to detect H₂O₂ and obtained satisfactory results with the recovery values ranging from 95.14 to 103.6%.