Comparative gas-sensing performance of 1D and 2D ZnO nanostructures

In this work we have grown one-dimensional (1D) and two-dimensional (2D) zinc oxide nanostructures. Changing the deposition parameters we were able to obtain ZnO nanowires with an average diameter of 80-250 nm. Nanosheets grown in different conditions show thickness values in the range 70-360 nm. These kinds of nanostructure have been used to fabricate conductometric gas sensors for liquid petroleum gas (LPG) detection. Different sensing parameters are investigated in both cases as a function of the dimensionality and size of the zinc oxide nanostructures. A first approximation of the "depletion layer sensing mechanism" is used to explain how the geometrical factors of one- and two-dimensional nanostructures affect their sensing parameters. The depletion layer affects two dimensions of nanowires and only one of nanosheets. This greatly improves the sensor response of 1D-nanostructures. On the other side two-dimensional nanostructures have a larger cross-section, which increases the base current, thus lowering the limit of detection. At the same operative conditions, nanowires show a better percentage response when compared to similar thickness nanosheets, but 2D nanosheets demonstrate an improved limit of detection (LoD). (C) 2015 Elsevier B.V. All rights reserved.