氮掺杂二氧化钛纳米棒阵列的制备和光电转化性能表征

In this paper, nitrogen-doped single crystal rutile TiO2 nanorod arrays were prepared on transparent conductive fluorine-doped tin oxide (FTO) substrates through a facile hydrothermal process, using aqueous ammonia as nitrogen source. X-ray photoelectron spectroscopy analysis demonstrates that only a small amount of nitrogen in reactant was added into TiO2, and formed O-Ti-N structure. With the increase of doping concentration, the length of nanorods and the X-ray diffraction intensity of the (002) plane increased, but the optical absorption of the nanorods remained without obvious changes, indicating the doping had little effect on the bandgap position of TiO2. Moreover, photocurrent response and external quantum efficiency of the nanorods were improved obviously via the doping process, and their highest values reached 0.15 mA/cm2 and 3.1%, respectively, which were about 3.8 times those of undoped TiO2. However, over-doped nitrogen can induce the aggregation of TiO2 nanorods, which leads to the recombination of photogenerated charges. Also, excess ammonia directly reacts with the reactants through the hydrolysis, which thus inhibits the growth of the nanorods on FTO substrate. Above all, nitrogen-doping with desirable concentrations can enhance photoelectrical properties of TiO2 nanorods for their applications in solar cells.