ZnO Nanostructure Synthesized by Hydrothermal Method for Butane Gas Sensor

Abstract

Zinc oxide (ZnO) nanostructure was successfully synthesized on an alumina substrate by the hydrothermal method. The hydrothermal method consists of two stages: the preparation of seeding layers and the growth of ZnO nanostructures. 0.4 M Zinc Acetate Dihydrate (Zn(CH3COO)2·2H2O) and 3 M Sodium Hydroxide (NaOH) were used as precursors. The hydrothermal process was carried out at 90 °C for 4 hours. Morphological characterization of ZnO nanostructures was conducted by using Scanning Electron Microscope (SEM). The result produces a diameter of 60-80 nm and a length of 600-800 nm in the form of nanoflowers. The crystal and crystalline structure were studied with XRD, and it was shown that the ZnO nanostructure is a wurtzite structure in the form of a hexagonal shape and has a crystallite size of 59 nm. After conducting electrical characterization, it was shown that the current is directly proportional to the voltage, forming an ohmic contact curve. ZnO nanostructures have the potential to be applied as a gas sensor since the good response indicated the presence of butane gas. It is clarified that the nanostructure with a flow rate of 200 mL/min has a change in resistance of 0.17 MΩ/s with a recovery time of 30 seconds when it is exposed to butane gas for one minute. ZnO nanostructures also have a sensitivity change of 0.000495 MΩ/mL in the gas flow rate range of 50-250 mL/min.