Enhanced NO2 sensing aptness of ZnO nanowire/CuO nanoparticle heterostructure-based gas sensors. Issue 2 (1st February 2019) - Navale, Y.H.
Abstract: Designing heterostructure materials for better gas sensing performance is a key for obtaining low-temperature gas sensor device technologies. Herein, CuO nanoparticle-ZnO nanowire heterostructure-based gas sensors have been fabricated by thermal evaporation followed by annealing in argon and air atmospheres and named respectively as NWG and NWA sensors. X-ray diffraction demonstrates the monoclinic structure of CuO and hexagonal wurtzite structure of ZnO and, thus, the formation of heterostructure. Morphological analysis confirms the ZnO nanowires (NWs) were well-linked to CuO nanoparticles (NPs). At an optimized temperature of 150 °C, the heterostructure sensor exhibits a maximum response (NWG, 175%) to NO2 over other oxidizing/reducing target gases on the exposure of 100 ppm concentration. This heterostructure sensor, noteworthy, responds to an extremely low exposure of NO2 gas (1 ppm). The interactions of oxidizing NO2 gas with ZnO/CuO heterostructure sensors has effectively been scrutinized using impedance spectroscopy analysis. Graphical abstract: Highlights: Thermal evaporation method was used for the fabrication of ZnO/CuO heterostructures. As-fabricated NWG and NWA ZnO/CuO sensors are highly selective towards NO2 . NWG and NWA ZnO/CuO sensors show response of 175% and 71% to 100 ppm NO2 @ 150 °C. Sensing mechanism of ZnO/CuO sensors with NO2 is discussed through impendence study.