Facile and fast decoration of SnO2 nanowires with Pd embedded SnO2-x nanoparticles for selective NO2 gas sensing

The typical methods used to improve the sensing properties of metal oxide nanowire-based gas sensors include decoration of a metal catalyst on the surface of nanowires or generation of surface defects. In this study, we suggest a process for preparing a Pd metal catalyst surrounded in SnO2-x with a large number of structural defects on the surface of SnO2 nanowires for gas sensing applications. Initially, SnO2 nanowires were prepared using a simple vapor-liquid-solid method and Pd-embedded SnO2-x-decoration was achieved by flame chemical vapor deposition. Gas sensing studies demonstrated the promising effects of Pd-embedded SnO2-x-decoration. The underlying sensing mechanism was studied in detail and explained in terms of generation of oxygen defects, catalytic activity of Pd, and formation of heterojunctions in the sensing material. The results of the present study clearly demonstrate the usefulness of this simple and fast approach to significantly enhance the gas sensing properties of metal oxide nanowires.