[Study on single-walled carbon nanotube thin film photoelectric device].

The single-walled carbon nanotube film photoelectric device was invented, and it can generate net photocurrent under bias voltage when it is illuminated by the laser. The influences of bias voltage, laser power and illuminating position on the net photocurrent were investigated. The experimental results showed that when the center of the film was illuminated, the photocurrent increased with the applied bias, but tended to saturate as the laser power increased. As the voltage and the laser power reached 0. 2 V and 22. 7 mW respectively, the photocurrent reached 0. 24 µA. When the voltage was removed, the photocurrent varied with the laser illuminating position on the film and its value was distributed symmetrically about the center of the device. The photocurrent reached maximum and almost zero respectively when the laser illuminated on two ends and the center of the film. Analysis proposes that the net photocurrent can be generated due to internal photoelectric effect when the device is under voltage and the laser illuminates on the center of the film. It can be also generated due to photo-thermoelectric effect when the device is under no voltage and the laser illuminates on the film, and the relation between the net photocurrent and the illuminating position was derived according to the nature of thermoelectric power of single-walled carbon nanotubes with the established temperature model, which coincides with experimental result. Two effects are the reasons for the generation and variety of the net photocurrent and they superimpose to form the result of the net photocurrent when the device is under general conditions of voltage and laser illuminating position. The device has potential applications in the areas of photovoltaic device and optical sensor for its characteristic.

[A phase error correction method for the new Fourier transforms spectrometer].

To decrease the distortion of the recovered spectrum, improve the quantity of the recovered spectrum and decrease the influence of the phase error of the new spectrum detection system based on MEMS (micro-electro-mechanical systems) micro-mirrors, a new phase error correction method for this system is proposed in the present paper. The source of phase error of the spectrum detection system based on MEMS micro-mirrors is analyzed firstly. The analyzed result indicated that the phase error of the new spectral Fourier transform detection system is the zero drift of the optical path difference, and the phase error can be corrected by Zero-crossing sampling which is realized by improving the structure of the interferometer system and Mertz product The spectrum detection system is set up and the phase error correction method is verified by this system. The experiment result is show that the quantity of the recovered spectrum of the spectrum detection is improved obviously by using the improved interferometer system and Mertz product, and the recovered spectrum has no negative peaks and the side lobes is suppressed markedly. This correction method can reduce the influence caused by phase error to the system performance well and improve the spectral detection performance effectively. In this paper, the origin of the system phase error based on the new MEMS micromirror Fourier transform spectroscopy detection system is analyzed, and the phase error correction method is proposed. This method can improve the performance of the spectrum detection system.

Engineering hydrogenated manganese dioxide nanostructures for high-performance supercapacitors.

Improving the rate capability of transition metal oxides is of great important for the development of high-performance electrodes for supercapacitors. Here, a novel strategy of hydrogenation to enhance the electron transfer rate of manganese dioxide (MnO2) is proposed. Detailed preparative parameters (i.e. hydrogenation temperature and time) are systematically investigated. The hydrogenated MnO2 (H-MnOx) exhibits modified crystal phase/surface structures and increased electrical conductivity. The prepared H-MnOx exhibits high specific capacitance (640 mF cm-2 at current density of 1 mA cm-2), good rate capability (89.6% of capacitance retained from 1 to 10 mA cm-2), and good cycling stability (84.6% retention after 1000 cycles). The high specific capacitance is ascribed to the unique interconnected ultrathin nanosheets structure, which could not only provide porous channels for electrolyte infiltration to offer sufficient electrode/electrolyte interface, but also shorten the ions diffusion distance inside the active material. The good rate capability could be attributed to the good conductivity of the H-MnOx nanosheets, which was confirmed by the DFT calculation. These results highlight the importance of hydrogenation as a facile yet effective strategy to improve the rate capability of transition metal oxides for supercapacitors.