Highly sensitive electrochemical sensor for Sudan I based on graphene decorated with mesoporous TiO2

A sensor for the highly sensitive determination of Sudan I based on the amplified electrochemical response of mesoporous TiO₂-decorated graphene (GN–TiO₂) was fabricated. The nanoparticles of TiO₂ arrayed densely and uniformly on the GN sheets, as confirmed by field emission scanning electron microscopy and transmission electron microscopy images. The electrochemical behavior of Sudan I at this sensor was studied in detail, showing that this sensor exhibited electrocatalytic activity for the oxidation of Sudan I because of the significant peak current enhancement and the lowering of oxidation overpotential. Furthermore, the experimental parameters including supporting electrolyte, volume of GN–TiO₂ suspension on electrode surface, accumulation potential, and time were optimized and the electrochemical reaction mechanism of Sudan I on this sensor was investigated. The linear range is from 3.3 nM to 0.66 μM, and the limit of detection is estimated to be 0.60 nM. At last, the sensor was used to determine Sudan I in food sample extracts, which are in good agreement with the results obtained by chromatographic method.