Synthesis and characterization of graphene and ordered mesoporous TiO2 as electrocatalyst for the determination of azo colorants

Abstract

Ordered mesoporous TiO2, synthesized by soft template method, coupled with graphene was used to modify a carbon paste electrode. The graphene layer was very thin and the mesoporous TiO2 particles were nano-scale, as confirmed by scanning electron microscopy and transmission electron microscopy. Graphene and mesoporous TiO2 displayed remarkable enhancement effect and greatly increased the oxidation signals of two azo colorants, i.e., Ponceau 4R and Allura Red. The influence of electrolyte, scan rate, amount of graphene and mesoporous TiO2, accumulation potential, and time on the signal enhancement of Ponceau 4R and Allura Red was discussed, and therefore, a novel and sensitive electrochemical method was developed for the detection of Ponceau 4R and Allura Red. The linear range was wider than two order of magnitude for both of Ponceau 4R and Allura Red. The limit of detection for Ponceau 4R and Allura Red was 1.35 and 0.34 nM, respectively. Finally, this method was successfully applied in soft drink and sausage samples, which was confirmed by high-performance liquid chromatography technique.