Natural catkins-derived single-crystal WO3 tubes rich in oxygen vacancies for high response and rapid detection of hydrazine at near room temperature

It is urgent to improve the comprehensive detection ability of chemoresistive gas sensors for highly toxic and explosive N2H4 due to less report. To this aim, we simply immersed discarded catkins in ammonium metatungstate aqueous solution to obtain a biotemplate precursor, which was then calcinated in air to controllably replicate two biomorphic WO3 materials by cross-linked nanoparticles. Amongst, single crystal WO3-6 tubes calcinated at 600 °C show good overall sensing performances towards trace N2H4 for the first time. At near room temperature (50 °C), WO3-6 sensor presents large response value (S = 120) and short response time (12 s) to 10 ppm N2H4, along with low practical detection limit (5 ppb). The above four important indexes are significantly better than those of currently reported metal oxide-based sensors. Meanwhile, it also exhibits good selectivity, satisfactory reproducibility, stability and moisture resistance. Such enhanced N2H4 sensing mechanism mainly roots from the synergy of its unique tubular structure (e.g. broad pores, oxygen vacancy defects), catalysis of W6+ ions with dangling bonds, as well as surface adsorbed oxygen species.