The microwave assisted synthesis nowadays attracts a great deal of attention. Monoclinic phase VO2 (M) was prepared from NH4VO3 and H2C2O4 · 2H2O by a rapid microwave assisted technique. The synthesis parameters, microwave irradiation time, microwave power, and calcinations temperature were systematically varied and their influences on the structure and morphology were evaluated. The microwave power level has been carried out in range 180–600 W. TEM analysis demonstrated nanosized samples. The structural and morphological properties were measured using XRD, TEM, and thermal analyses. The variations of vanadium phase led to thermochromic properties.

Mo-doped vanadium dioxide particles were produced by simple solution-based, rapid microwave assisted, and calcination in an inert gas method respectively. The precursors and the heat-treated final powders were characterized by X-ray diffractometer (XRD), differential scanning calorimeter (DSC), scanning electron microscope (SEM), and transmission electron microscope (TEM). The Mo dopant influenced the crystal structure and phase transition of VO2 (M) particles. The XRD pattern indicated that all Mo-doped VO2 particles were monoclinic crystal. The DSC results showed that phase transformation temperature of VO2 from monoclinic to tetragonal or rutile, which normally occurred at 67-68 oC was reduced to 43.18 oC, whereas over doping of Mo led to the increased transition temperature. The results suggested a significant effect of Mo doping content on the transition temperature of VO2. Doping with an optimum amount of Mo into VO2 structure can achieve the lowest phase transformation temperature of VO2 powders.

TiO2nanorod arrays (TNRs) films were fabricated on the polished Ti substrates using hydrothermal and then annealed for 2 h in air at 300°-500°C. The films were characterized by XRD and FESEM. The photocatalytic activities to degrade methylene blue (MB) in solution were determined, expecting these activities to correlate with the hydrophobic property. The experiment showed that rutile peaks recrystallized at the annealing temperature, with the crystallinity increase with increasing annealing temperatures. The TNRs films annealed at 500 oC had a comparatively high crystallinity of rutile phase as well as the highest photocatalytic activity of the films prepared. Surface wettability was studied by measuring the contact angle of the liquid interface which showed hydrophobic nature as water contact angles were greater than 120°. The results can be concluded that as-prepared TNRs film was annealed at 500 oC exhibits excellent hydrophobicity for water molecules and the highest photocatalytic activity on the degradation of MB under UV irradiation.

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