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

We propose 3D branched-like NiO/NiWO4/WO3 nano-heterostructures for the selective detection of ozone (O-3) 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 O-3 compared to NiO and WO3 nanowire sensors. At 300 degrees C, a response as high as 4709 +/- 9 was observed for 300 ppb of O-3 gas. In fact, we were able to achieve high selectivity toward O-3 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.