We report on the surface, sub-surface (top few nanometers) and bulk properties of hydrothermally grown zinc oxide (ZnO) nanorods (NRs) prior to and after hydrogen treatment. Upon treating with atomic hydrogen (H*), upward and downward band bending is observed depending on the availability of molecular H2O within the structure of the NRs. In the absence of H2O, the H* treatment demonstrated a cleaning effect of the nanorods, leading to a 0.51 eV upward band bending. In addition, enhancement in the intensity of room temperature photoluminescence (PL) signals due to the creation of new surface defects could be observed. The defects enhanced the visible light activity of the ZnO NRs which were subsequently used to photocatalytically degrade aqueous phenol under simulated sunlight. On the contrary, in the presence of H2O, H* treatment created an electronic accumulation layer inducing downward band bending of 0.45 eV (~1/7th of the bulk ZnO band gap) along with the weakening of the defect signals as observed from room temperature photoluminescence spectra. The results suggest a plausible way of tailoring the band bending and defects of the ZnO NRs through control of H2O/H* species.
Nanoparticles Fe (x wt. %)-doped Zn-TiO 2 rutile powders, with x between 0 an 10 wt. %, were prepared using a solution chemistry route based on the wet-gel stirring method. Using the TEM images we found that the powder samples exhibit nanorods and nanosheets with nanorods oriented in different directions and accompanied by an amorphous Zn on the surface. The average length of these nanorods is about 60 nm and they have an average diameter of 7 nm. The x-ray diffraction patterns revealed the formation of the nanocrystalline particles with the rutile phase, which is characterized by the (101) diffraction peak. The magnetic properties of the samples were studied using a vibrating sample magnetometer (VSM) in magnetic filed up to 13.5 kOe and in the temperature range of 100 K to 300 K. We found that the magnetization of the samples does not saturate in the maximum available field. The magnetization (M) at an applied magnetic field of 13.5 kOe is found to increase with increasing the Fe percentage at room temperature and at 100 K. TEM measurements and atomic-force microscopy (AFM) were used to image the samples.
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