3D-(p/p/n) NiO/NiWO4/WO3 heterostructures for the selective detection of ozone

Abstract

We propose 3D branched-like NiO/NiWO₄/WO₃ nano-heterostructures for the selective detection of ozone (O₃) at ppb levels, which is crucial for environmental and public health protection. These complex nano-heterostructures were fabricated using a combination of the vapor–liquid–solid and vapor–solid mechanisms, during which the reaction between NiO and WO₃ leads to the formation of an intermediate seed, i.e., NiWO₄. By controlling the charge transport within the nano-heterostructure through modulation of the operating temperature, sensors demonstrated highly selective sensing performances toward O₃ compared to NiO and WO₃ nanowire sensors. At 300 °C, a response as high as 4709 ± 9 was observed for 300 ppb of O₃ gas. In fact, we were able to achieve high selectivity toward O₃ compared to other highly reactive oxidizing compounds such as NO₂. Due to their remarkable sensing performance, these heterostructures are leading candidates for the fabrication of future-generation miniaturized sensing devices for environmental and/or health monitoring.