Branching TiO2nanowire arrays for enhanced ethanol sensing.

Nanostructure modulation is effective to achieve high performance TiO2-based gas sensors. We herein report a wet-chemistry route to precipitate directly branched TiO2nanowire arrays on alumina tubes for gas sensing applications. The optimized branched TiO2nanowire array exhibits a response of 9.2 towards 100 ppm ethanol; whilst those of the pristine TiO2nanowire array and the branched TiO2nanowire powders randomly distributed are 5.1 and 3.1, respectively. The enhanced response is mainly contributed to the unique porous architecture and quasi-aligned nanostructure, which provide more active sites and also favor gas migration. Phase junctions between the backbone and the branch of the branched TiO2nanowire arrays help the resistance modulation as a result of potential barriers. The facile precipitation of quasi-aligned arrays of branched TiO2nanowires, which arein situgrown on ceramic tubes, thus provides a new economical synthetic route to TiO2-based sensors with excellent properties.