Diverse Adsorption/Desorption Abilities Originating from the Nanostructural Morphology of VOC Gas Sensing Devices Based on Molybdenum Trioxide Nanorod Arrays

Nanorod arrays gas sensors are attracting much scientific and engineering interest because of their excellent sensing performance arising from their unique nanostructures. In this work, large-scale random 3D networks of ultrafine single-crystal alpha-MoO3 nanorod arrays are applied as gas sensors. The arrays are spontaneously grown by a simple single-step solution route. A prompt response and obvious discrimination of ethanol, methanol, isopropanol, and acetone vapors at 573 K are investigated via the modulation of the resistance of the gas sensors. The sensitivity, response time, and recovery time of the sensors strongly depend on the specific morphologies of the nanorod arrays, such as length, number, and coverage of nanorods in the 3D network. A reaction mechanism in which the 3D-network nanorod arrays adsorb and react with the target molecules more readily than the seed layer is proposed to explain the different response and recovery times of the sensors. These random 3D-network nanorod arrays with functionally tunable morphology are promising for universal application as gas sensors for detecting various vapors, and provide valuable insights for the production of fast, large-scale, low-cost, and simple synthesis of sensing devices.