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TiO 2 nanotube arrays (TiO 2 NTAs) were firstly used as photoanode in methylammonium lead iodide (CH 3 NH 3 PbI 3 ) perovskite/TiO 2 NTAs heterojunction solar cell, where CH 3 NH 3 PbI 3 functions as both light absorber and hole conductor. The composition, structure and photoelectrochemical properties of the as-prepared samples were characterized by x-ray diffractometer (XRD), field-emission scanning electron microscope (FE-SEM), ultraviolet-visible (UV–vis) spectrophotometer and electrochemical workstation. The results indicate that the as-prepared CH 3 NH 3 PbI 3 belongs to the cubic crystal system, and TiO 2 NTAs sensitized by 0.3 M CH 3 NH 3 I and PbI 2 exhibit the best photoelectrochemical properties with an open-circuit voltage of 0.422 V and a short-circuit current density of 173.4 μA cm −2 . The EIS result shows that the extremely large resistance at CH 3 NH 3 PbI 3 /FTO interface contributes to the low current density of the perovskite solar cell. [ABSTRACT FROM AUTHOR]

A nearly 100% filling of PEDOT in TiO 2 nanotube array (NTA) was successfully prepared by a simple electropolymerization method at a constant potential of 1.8 V, which was demonstrated by field emission scanning electron microscopy (FESEM). UV–vis diffusion reflection spectroscopy (DRS) revealed that the filling of PEDOT in TiO 2 NTA can dramatically improve the visible-light and near-infra-red absorption property of the TiO 2 NTA, which is especially useful for the application of solar cells. Cyclic voltammetry experiments indicate that the PEDOT–TiO 2 NTA hybrid material is electrochemically more active than the TiO 2 NTA and has excellent redox reversibility. [ABSTRACT FROM AUTHOR]

The capacitance of MnO2 supercapacitors (SCs) is not high as expected due to its low conductivity of MnO2. The synergistic effects of MnO2 with high theoretical specific capacitance and TiN with high theoretical conductivity can extremely enhance the electrochemical performance of the MnO2-TiN electrode material. In this work, we synthesized different nanostructured and crystalline-structured MnO2 modified TiN nanotube arrays electrode materials by hydrothermal method and explained the formation mechanism of different nanostructured and crystalline-structured MnO2. The influences of MnO2 nanostructures and crystalline-structures on the electrochemical performance has been contrasted and discussed. The specific capacitance of δ-MnO2 nanosheets-TiN nanotube arrays can reach 689.88 F g−1, the highest value among these samples TN-MO-SS, TN-MO-S, TN-MO-SR, TN-MO-RS, and TN-MO-R. The reason is explained based on MnO2 nanostructure and crystalline-structure and electron/ion transport properties. The specific capacitance retention rates are 97.2% and 82.4% of initial capacitance after 100 and 500 cycles, respectively, indicating an excellent charging-discharging cycle stability. [ABSTRACT FROM AUTHOR]