title: Influence of Atomic Hydrogen, Band Bending, and Defects in the Top Few Nanometers of Hydrothermally Prepared Zinc Oxide Nanorods.
abstract: 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.
authors.affiliation: Department of Physics, Sultan Qaboos University, PO Box 36, Al Khoudh, 123, Muscat, Oman.
authors.forename: Mubarak J
authors.initials: MJ
authors.lastname: Al-Saadi
authors.affiliation: Department of Physics, Sultan Qaboos University, PO Box 36, Al Khoudh, 123, Muscat, Oman. salim1@squ.edu.om.
authors.forename: Salim H
authors.initials: SH
authors.lastname: Al-Harthi
authors.affiliation: Department of Physics, Sultan Qaboos University, PO Box 36, Al Khoudh, 123, Muscat, Oman.
authors.forename: Htet H
authors.initials: HH
authors.lastname: Kyaw
authors.affiliation: Department of Physics, Sultan Qaboos University, PO Box 36, Al Khoudh, 123, Muscat, Oman.
authors.forename: Myo T Z
authors.initials: MTZ
authors.lastname: Myint
authors.affiliation: Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, PO Box 17, Al Khoudh, 123, Muscat, Oman.
authors.forename: Tanujjal
authors.initials: T
authors.lastname: Bora
authors.affiliation: Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, PO Box 17, Al Khoudh, 123, Muscat, Oman.
authors.forename: Karthik
authors.initials: K
authors.lastname: Laxman
authors.affiliation: Department of Chemistry, Sultan Qaboos University, PO Box 36, Al Khoudh, 123, Muscat, Oman.
authors.forename: Ashraf
authors.initials: A
authors.lastname: Al-Hinai
authors.affiliation: Functional Materials Division, Materials and Nanophysics, ICT School, KTH Royal Institute of Technology, Isafjordsgatan 22, SE-164 40, Kista, Stockholm, Sweden.
authors.forename: Joydeep
authors.initials: J
authors.lastname: Dutta
keywords: Band bending; Hydrogen treatment; Surface defects; Visible light photocatalysis; ZnO