H 2 sensing performance of optical fiber coated with nano-platelet WO 3 film

Abstract

For the first time, we have integrated nano-platelet Pd/WO 3 films, which are formed using an acid etching method, with optical fibers to develop a hydrogen gas (H 2) sensors. The tungsten films were firstly RF sputtered on top of optical fiber tips, and subsequently etched in 1.5 M nitric acid to produce tungstite films. After annealing at 300 and 480 °C, these films were coated with approximately 25 thick Pd layers. The films were characterized using SEM, GADDS, EDX, and both Raman and UV-vis-NIR spectroscopy. H 2 testing measurements were conducted when the sensors were interacting with 0.06-1% H 2 in synthetic air at an optimum temperature of 100°C. It was found that the highly crystalline nano-platelet Pd/WO 3 film based optical fiber H 2 sensors show large reflectance responses in the NIR wavelength of 6% and 12% in the presence of 0.06% and 1% H 2, respectively.