Influence of Li-doping on structural characteristics and photocatalytic activity of ZnO nano-powder formed in a novel solution pyro-hydrolysis route

Abstract Different types of Li-doped ZnO (LDZ) (Li = 0–10 wt.%) powders were prepared by following a novel pyro-hydrolysis route at 450 °C, and were thoroughly characterized by means of thermo-gravimetry (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR), Fourier-transform Raman (FT-Raman) spectroscopy, diffuse reflectance spectroscopy (DRS), ultra-violet visible (UV–Vis) spectroscopy, Brunauer–Emmett–Teller (BET) surface area (SA), and zeta potential ( ζ ) measurements. Photocatalytic activity of these powders was evaluated by means of methylene blue (MB) degradation experiments conducted under the irradiation of simulated and natural solar light. Characterization results suggest that both pure ZnO and LDZ powders are quite thermally stable up to a temperature of 700 °C and possess band gap (BG) energies in the range of 3.16–3.2 eV with a direct band to band transition and ζ values of −31.6 mV to −56.4 mV. The properties exhibited by LDZ powders were found to be quite comparable to those exhibited by p -type semi-conducting LDZ powders. In order to study the kinetics of MB degradation reaction under the irradiation of simulated solar light, the Li (0.2–10 wt.%) and Al (0.5 wt.%) co-doped ZnO (0.2LADZ to 10LADZ) powders were also synthesized and employed for this purpose. The photocatalytic degradation of MB over LADZ catalysts followed the Langmuir–Hinshelwood (L–H) first order reaction rate relationship. The 10LDZ catalyst exhibited highest photocatalytic activity among various powders investigated in this study.

[1]  L. J. Mandalapu,et al.  p-type ZnO films with solid-source phosphorus doping by molecular-beam epitaxy , 2006 .

[2]  Yue Zhang,et al.  Ba0.5Sr0.5Co0.8Fe0.2O3 nanopowders prepared by glycine–nitrate process for solid oxide fuel cell cathode , 2008 .

[3]  Ibram Ganesh,et al.  Conversion of Carbon Dioxide to Methanol Using Solar Energy - A Brief Review , 2011 .

[4]  Wenlei Xie,et al.  Catalytic Properties of Lithium-Doped ZnO Catalysts Used for Biodiesel Preparations , 2007 .

[5]  Lin Guo,et al.  Synthesis and red-shifted photoluminescence of single-crystalline ZnO nanowires , 2009 .

[6]  L. J. Mandalapu,et al.  p-type behavior from Sb-doped ZnO heterojunction photodiodes , 2006 .

[7]  M. R. Wagner,et al.  A Systematic Study on Zinc Oxide Materials Containing Group I Metals (Li, Na, K)-Synthesis from Organometallic Precursors, Characterization, and Properties , 2009 .

[8]  P. Banerji,et al.  Effect of Li incorporation on the structural and optical properties of ZnO , 2009 .

[9]  W. D. Kingery,et al.  Introduction to Ceramics , 1976 .

[10]  A. Fujishima,et al.  Photoelectrocatalytic reduction of carbon dioxide in aqueous suspensions of semiconductor powders , 1979, Nature.

[11]  Qingliang Liao,et al.  Doping and defects in the formation of single-crystal ZnO nanodisks , 2006 .

[12]  H. katayama-Yoshida,et al.  Unipolarity of ZnO with a wide-band gap and its solution using codoping method , 2000 .

[13]  S. Jeong,et al.  Study on the doping effect of Li-doped ZnO film , 2008 .

[14]  S. Sasa,et al.  Control of chemical bonding of the ZnO surface grown by molecular beam epitaxy , 2004 .

[15]  P. Raji,et al.  Synthesis and Characterization of Nano Zinc Oxide by Sol Gel Spin Coating , 2011 .

[16]  E. El-Maghraby,et al.  Influence of gamma radiation on the absorption spectra and optical energy gap of Li‐ doped ZnO thin films , 2004 .

[17]  M. Kreft,et al.  Erratum to “Fusion Pore Diameter Regulation by Cations Modulating Local Membrane Anisotropy” , 2012, The Scientific World Journal.

[18]  L. Alexander,et al.  X-Ray diffraction procedures for polycrystalline and amorphous materials , 1974 .

[19]  Yujia Zeng,et al.  Dopant source choice for formation of p-type ZnO: Li acceptor , 2006 .

[20]  J. Tauc,et al.  States in the gap , 1972 .

[21]  Ibram Ganesh,et al.  Preparation and Characterization of Ni-Doped TiO2 Materials for Photocurrent and Photocatalytic Applications , 2012, TheScientificWorldJournal.

[22]  H. Morkoç,et al.  A COMPREHENSIVE REVIEW OF ZNO MATERIALS AND DEVICES , 2005 .

[23]  C. Hogarth,et al.  Optical Absorption in Thin Films of Cerium Dioxide and Cerium Dioxide Containing Silicon Monoxide , 1986 .

[24]  D. Geetha,et al.  HYDROTHERMAL SYNTHESIS OF NANO ZnO STRUCTURES FROM CTAB , 2010 .

[25]  S. Manorama,et al.  Bandgap studies on anatase titanium dioxide nanoparticles , 2003 .

[26]  Charles C. Sorrell,et al.  Photo-electrochemical hydrogen generation from water using solar energy. Materials-related aspects , 2002 .

[27]  David C. Look,et al.  As-doped p-type ZnO produced by an evaporation∕sputtering process , 2004 .

[28]  M. Halmann,et al.  Photoelectrochemical reduction of aqueous carbon dioxide on p-type gallium phosphide in liquid junction solar cells , 1978, Nature.

[29]  Toru Aoki,et al.  ZnO diode fabricated by excimer-laser doping , 2000 .

[30]  Masashi Kawasaki,et al.  Room-temperature ultraviolet laser emission from self-assembled ZnO microcrystallite thin films , 1998 .

[31]  B. P. Saha,et al.  Effect of fuel type on morphology and reactivity of combustion synthesised MgAl2O4 powders , 2002 .

[32]  R. Thangavel,et al.  Micro‐Raman scattering spectroscopy study of Li‐doped and undoped ZnO needle crystals , 2009 .

[33]  Joydeep Dutta,et al.  Photocatalytic degradation of organic dyes with manganese-doped ZnO nanoparticles. , 2008, Journal of hazardous materials.

[34]  Sukchan Lee,et al.  Deposition of aluminum-doped zinc oxide films by RF magnetron sputtering and study of their surface characteristics , 2003 .

[35]  Yujia Zeng,et al.  Influence of post-annealing temperature on properties of ZnO:Li thin films , 2006 .

[36]  T. Moriga,et al.  Properties of ZnO:In film prepared by sputtering of facing ZnO:In and Zn targets , 1998 .

[37]  Ibram Ganesh,et al.  Preparation and characterization of Co-doped TiO2 materials for solar light induced current and photocatalytic applications , 2012 .

[38]  Ibram Ganesh,et al.  Preparation and characterization of Fe-doped TiO2 powders for solar light response and photocatalytic applications , 2012 .

[39]  M. Joseph,et al.  Fabrication of the low-resistive p-type ZnO by codoping method , 2001 .

[40]  Ekoko Bakambo Gracien,et al.  Photocatalytic activity of manganese, chromium and cobalt-doped anatase titanium dioxide nanoporous electrodes produced by re-anodization method , 2007 .

[41]  M. Rashad,et al.  Li-doping effects on the electrical properties of ZnO films prepared by the chemical-bath deposition method , 2005 .

[42]  Bing Wang,et al.  Synthesis and characteristics of Li-doped ZnO powders for p-type ZnO , 2010 .

[43]  Andrew B. Bocarsly,et al.  Selective solar-driven reduction of CO2 to methanol using a catalyzed p-GaP based photoelectrochemical cell. , 2008, Journal of the American Chemical Society.

[44]  M. V. Tkachev,et al.  Raman spectra of oxide zinc powders and single crystals , 1996 .

[45]  R. Reeber Lattice parameters of ZnO from 4.2° to 296°K , 1970 .

[46]  J. Langford X‐ray diffraction procedures for polycrystalline and amorphous materials by H. P. Klug and L. E. Alexander , 1975 .

[47]  R. T. Rajendra Kumar,et al.  Li doped and undoped ZnO nanocrystalline thin films: a comparative study of structural and optical properties , 2007 .

[48]  K. Nakamoto Infrared and Raman Spectra of Inorganic and Coordination Compounds , 1978 .

[49]  Arthur J. Nozik,et al.  p‐n photoelectrolysis cells , 1976 .

[50]  S. Chu,et al.  Li2CO3-doped ZnO films prepared by RF magnetron sputtering technique for acoustic device application , 2002 .