Solid-state chemical synthesis and xylene-sensing properties of α-MoO3 arrays assembled by nanoplates

The special α-MoO3 arrays constructed from nanoplates were synthesized using a simple solid-state chemical reaction. The obtained products were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy and Brunauer-Emmett-Teller analysis. Gas-sensing characteristics of the products toward noxious gases were investigated. The α-MoO3 arrays with high consistency were self-assembled in-situ by two-dimensional nanoplates due to the crystal face preferred orientation and the appropriate protection for specific crystal surface. The arrays exhibited good response to xylene in a wide range of concentrations, and the response value to 100 ppm xylene reached 19.2 at the optimum operation temperature of 370 °C, which is three times higher than that of unassembled α-MoO3 nanoplates. The good xylene response was attributed to the preferential exposure of the active crystal faces with high reactivity and the relatively large specific surface area of arrays, which provided more active sites and adsorbed more oxygen molecules for reaction with xylene molecules. The excellent response properties of the α-MoO3 nanoplates arrays make it a good candidate as a gas-sensing material for xylene detection.