Low-temperature and dual-sensing NO2/dimethylamine sensor based on single-crystal WO3 nanoparticles-supported sheets synthesized by simple pyrolysis of spoiled WCl6 powder

Herein, nanoparticle-supported WO3 sheets were simply prepared by direct pyrolysis of spoiled WCl6 powder. The influence of calcination temperature on their composition and morphology transformation was explored through the characterizations of powder X-ray diffractometer, X-ray photoelectron spectrometer, scanning and transmission electron microscope. Amongst, the W-600 sheet-like structure obtained by calcination at 873 K is cross-linked by homogeneous nanoparticles, and has meso/macro-pore distribution, single-crystal nature and relatively small band gap. These favorable factors promote rapid gas diffusion, increase the electron migration rate, as well as expose more active sites for surface chemical reaction. Especially, under the synergism of surface unsaturated W6+ Lewis acid, the fabricated W-600 sensor achieves dual-sensing to dimethylamine (DMA) and NO2 for the first time. It exhibits a good response (S = 35.3) to 100 ppm DMA at 298 K, and also presents a high response (S = 125) to 1 ppm NO2 at 323 K. The actual detection limit can be as low as 1 ppm (DMA) and 10 ppb (NO2). Meanwhile, this sensor still has reversible response-recovery characteristics, satisfactory stability and moisture resistance. Furthermore, the dual-functional sensing mechanism was also explored in detail.