Rapid microwave assisted synthesis of Zn_1-xIn_xO heterostructured nanotetrapods and their hydrogen sensing properties

Zn_1-xIn_xO nanostructures have been synthesized in large quantity by a microwave-assisted evaporation method. A mixture of high purity zinc and indium metal flakes evaporated under ambient air using a microwave absorber placed in a conventional microwave oven. This is single step, fast and very effective method to produce large quantity (grams) of Zn_1-xIn_xO nanotetrapods. The synthesized nanotetrapods powder was characterized by X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM). The observations and analyses confirmed the formation of high aspect-ratio nanotetrapods and the incorporation of In into the ZnO creating heterostructure. Hydrogen gas sensor made from the nanotetrapods Zn_1-xIn_xO showed reversible response and recovery. The results are consistent with a sensing mechanism controlled by the presence of a space charge region at the surface of the sensor.