a b s t r a c tTiO 2 -graphene nanocomposite was prepared by hydrolysis of titanium isopropoxide in colloidal suspension of graphene oxide and in situ hydrothermal treatment. It provides an efficient and facile approach to yield nanocomposite with TiO 2 nanoparticles uniformly embedded on graphene substrate. The electrochemical behavior of adenine and guanine at the TiO 2 -graphene nanocomposite modified glassy carbon electrode was investigated. The results show that the incorporation of TiO 2 nanoparticles with graphene significantly improved the electrocatalytic activity and voltammetric response towards these species comparing with that at the graphene film. The TiO 2 -graphene based electrochemical sensor exhibits wide linear range of 0.5-200 M with detection limit of 0.10 and 0.15 M for adenine and guanine detection, respectively. The excellent performance of this electrochemical sensor can be attributed to the high adsorptivity and conductivity of TiO 2 -graphene nanocomposite, which provides an efficient microenvironment for electrochemical reaction of these purine bases.

An electrochemical sensor based on graphene-polyaniline (GR-PANI) nanocomposite for voltammetric determination of 4-aminophenol (4-AP) is presented. The electrochemical behavior of 4-AP at the GR-PANI composite film modified glassy carbon electrode (GCE) was investigated by cyclic voltammetry. 4-AP exhibits enhanced voltammetric response at GR-PANI modified GCE. This electrochemical sensor shows a favorable analytical performance for 4-AP detection with a detection limit of 6.5 × 10 −8 M and high sensitivity of 604.2 A mM −1. Moreover, 4-AP and paracetamol can be detected simultaneously without interference of each other in a large dynamic range.

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