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A novel nanocomposite was prepared by direct mixing of titania nanoparticles (nano-TiO 2) and gold nanoparticles (nano-Au)-modified carbon nanotubes (CNTs) in a solution of chitosan. The electrochemical performance of a TiO 2 /Au/CNT nanocomposite-modified electrode for hydroquinone detection was investigated. When measured at a scan rate of 50 mV s − 1 , the detected amount of hydroquinone at the TiO 2 / Au/CNT electrode varied linearly with hydroquinone concentration, for concentrations from 1 × 10 − 6 to 1 × 10 − 8 M; the sensitivity was 997 617 μA(mol l − 1) − 1 , and the detection limit was 1 × 10 − 10 M (S/N = 3). In all experiments, TiO 2 /Au/CNT nanocomposites exhibited better electrochemical performance than TiO 2 /CNT composites or CNTs. Enhanced current response can be attributed to the synergic effect of nano-TiO 2 , nano-Au and CNTs.

In this research, Ni/MgO is used as catalyst and CNTs were synthesized by radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD), and then liquid oxidation method was used to purify CNTs. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscope and infrared spectroscopy were used to study the influences of purification time on morphology and microstructure of CNTs. The results show that CNTs synthesized by RF-PECVD contain a great amount of impurities. With the increasing of purification time, the impurities decreased. Meanwhile, carboxyl oxygen-containing groups introduced on the surface of CNTs are also gradually increasing along with purification time. And the crystallization properties of CNTs increased first but decreased then with the introduction of a large amount of oxygen-containing groups. The surface modification of CNTs has very important significance for the applications of CNTs in the field of electrochemical biosensor.