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ZnO nanowires (ZnO-NWs) were adhesively grown on multiwalled carbon nanotubes (MWCNTs) arrays by a hydrothermal process. Electrochemical properties of the electrode based on the ZnO-NWs/MWCNTs nanocomposite were investigated by electrochemical impedance spectroscopy and cyclic voltammetry. The photoelectrochemical responses of the ZnO-NWs/MWCNTs nanocomposite electrode were further studied by linear sweep voltammetry and amperometry under sunlight or UV light irradiation. Compared with pure ZnO-NWs on tantalum substrate, the charge transfer rate of the ZnO-NWs/MWCNTs nanocomposite was remarkably increased because of the MWCNTs. A Mott−Schottky plot displayed a high donor density of 3.9 × 1019 cm−3, a flat band potential of −0.8 V, and a space charge layer of 7 nm. In addition, the ZnO-NWs/MWCNTs nanocomposite yielded higher photocurrent than pure ZnO-NWs. The decay constant of the ZnO-NWs/MWCNTs nanocomposite was also lower than that of its pure counterpart. The recombination of photoinduced electron−hole pairs in the ZnO-NWs/MWCNTs heterojunction was hindered, thus enhancing the photoelectrical conversion efficiency. The heterojunction of ZnO-NWs/MWCNTs provides potential applications in the field of photocatalysis and photoelectrical devices.

In this work, an amperometric H 2 O 2 sensor based on TiO 2 /MWCNTs electrode is reported. TiO 2 nanoparticles were synthesized on vertically aligned multiwalled carbon nanotube (MWCNT) arrays by electrodeposition. The morphology of the TiO 2 /MWCNTs was characterized by scanning electron microscopy (SEM). The electrochemical performance of the TiO 2 /MWCNTs electrode for detection of H 2 O 2 was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry. The TiO 2 /MWCNTs electrode displays high electrocatalytic activity towards oxidation of H 2 O 2 in 0.1 M phosphate buffer solution (PBS, pH 7.4). At an applied potential of þ 0.40 V, the TiO 2 /MWCNTs electrode exhibits a linear dependence (R ¼ 0.998) in the H 2 O 2 concentration up to 15.0 Â 10 À3 M with a sensitivity of 13.4 mA mM À1 and detection limit of 4.0 Â 10 À7 M with signal/noise ¼ 3. The optimal response time is less than 5 s with addition of 1 mM H 2 O 2 . The TiO 2 /MWCNTs electrode presents stable, high sensitivity and also exhibits fast amperometric response to the detection of H 2 O 2 , which is promising for the development of H 2 O 2 sensor.