α-MoO3/TiO2 core/shell nanorods: Controlled-synthesis and low-temperature gas sensing properties

Crystalline α-MoO3/TiO2 core/shell nanorods are fabricated by a hydrothermal method and subsequent annealing processes under H2/Ar flow and in the ambient atmosphere. The shell layer is composed of crystalline TiO2 particles with a diameter of 2–6 nm, and its thickness can be easily controlled in the range of 15–45 nm. The core/shell nanorods show enhanced sensing properties to ethanol vapor compared to bare α-MoO3 nanorods. The sensing mechanism is different from that of other one-dimensional metal oxide core/shell nanostructures due to very weak response of TiO2 nanoparticles to ethanol. The enhanced sensing properties can be explained by the change of type II heterojunction barrier formed at the interface between α-MoO3 and TiO2 in the different gas atmosphere. The present results demonstrate a novel sensing mechanism available for gas sensors with high performance.