The ultra-high NO2 response of ultra-thin WS2 nanosheets synthesized by hydrothermal and calcination processes

Ultra-thin WS2 nanosheets with a thickness of about 5 nm were synthesized by an economical hydrothermal method and the following calcination process. A three dimensional wall-like structure was formed by the interconnecting WS2 nanosheets. The growth mechanism of as-prepared WS2 nanosheets was discussed, and it was deduced that mesolamellar tungsten sulfide (WS-L) with intercalated CTA+ cations was formed by co-condensation reaction of WS42− and CTAB in the hydrothermal process. The resistive gas sensors based on as-prepared WS2 nanosheets showed a p-type character, achieved a superior response of 9.3% to 0.1 ppm NO2 gas at room temperature (25 °C) and a good stability in low and moderate humidity. The excellent NO2 sensing properties can be attributed to the ultra-thin nanostructure of the WS2 nanosheets.