Abstract
ZnO has been widely investigated for its unique properties and versatile applications. This study focuses on the controlled growth and the properties of Al-doped ZnO nanowalls prepared by aqueous chemical solution method. Large area, well aligned Al-doped ZnO nanowalls were synthesized. The Al atoms are uniformly doped into ZnO nanowalls to an atomic concentration of about 14 % after 400 ℃ annealing for 2 hr. The unique nanowalls structure was only found on Al substrates. The height of the nanowalls can be controlled by adjusting the reaction time and the amount of Al source. The density was influenced by the growth temperature or the ratio and the concentration of the reactants. As a result, the surface area can be well controlled. The influences on the growth of Al-doped ZnO nanowalls at different annealing temperature and time were investigated. Al atoms in ZnO nanowalls become uniformly doped in the nanowalls with an increasing grain size after the heat treatment. The gas sensing properties to NO2 were demonstrated in this work. A higher sensitivity for the denser structure was observed. A mixed structure of Al-doped ZnO nanowalls and pure ZnO nanorods was found to possess a lower detection limit than nanowalls and higher sensitivity than nanorods. In addition, the mixed structure was not saturated for absorption for 10 min in 100 ppm NO2 environment.