Room temperature ammonia sensing properties of W18O49 nanowires

This paper describes the room temperature ammonia sensing properties of ultra-thin W18O49 nanowire (diameter less than 5 nm) bundles prepared by a solvothermal technique. The W18O49 nanowires of high surface areas exhibit a concentration-dependent response when exposed to ammonia. An abnormal behavior of resistance increases first and followed by a decrease was observed when ammonia concentration is above 1 ppm. The response of W18O49 nanowires to ammonia transited from n-type to p-type when the concentration decreased to sub-ppm level. The W18O49 nanowires are highly sensitive to sub-ppm and ppb level ammonia at room temperature, which is attributed to the small diameters, high surface areas and non-stoichiometric crystal structure.