Hydrogen sensing properties of multiple networked Nb2O5/ZnO core-shell nanorod sensors

Abstract

Nb2O5 nanosensors with good sensing properties toward hydrogen and oxygen gases at high temperatures have been reported, but sensing performances of Nb2O5-based gas sensors are still unsatisfactory. This study examined the sensing properties of Nb2O5-core/ZnO-shell nanorod sensors toward H2 gas. The responses of pristine Nb2O5 and Nb2O5-core/ZnO-shell nanorods to 10,000 ppm H2 at 300 °C were ∼250% and ∼586%, respectively. The response and recovery times of Nb2O5-core/ZnO-shell nanorods at 10,000 ppm H2 at 300 °C were 17 and 23 s, respectively, whereas those of pristine Nb2O5 nanorods were 23 and 32 s. The response of the core–shell nanowire sensor to H2 gas showed strong dependence on the shell layer thickness. The strongest response was obtained with a ZnO shell layer thickness of 46 nm, which is equal to the maximum depletion layer width in the shell. The origin of the enhanced sensing properties of Nb2O5-core/ZnO-shell nanorods toward H2 is also discussed.