WO3/Pt/PEG/SiO2 porous film for hydrogen sensing by the sol-gel method

Tungsten oxide (WO 3 ) has been widely used in hydrogen sensing due to its stable chemical properties and high oxygen vacancy diffusion coefficient. However, the response of pure WO 3 to hydrogen is slow, and doping is an effective way to improve the hydrogen sensing performance of WO 3 materials. In this paper, WO 3 /Pt/PEG/SiO 2 porous film was prepared by the sol-gel method using tungsten powder, H 2 O 2 and C 2 H 5 OH as precursors, polyethylene glycol (PEG) as the pore-forming agent, and tetraethyl orthosilicate (TEOS) as the SiO 2 source material. The sensing properties of the WO 3 composite for hydrogen were characterized by a transmission optical fiber hydrogen sensing system made at home. The process parameters such as water bath time, aging time, W:PEG ratio, and W:TEOS ratio were optimized to improve the sensitivity and response time of the sensing film. The experimental results indicate that the sensitivity is 15.68%, the average response time is 45 s, and the repeatability is up to 98.74% in 16 consecutive tests. The linearity index R 2 is 0.9946 within the hydrogen concentration range of 5000 ppm to 50,000 ppm. The film responds only to H 2 when the concentration of interfering gases (CH 4 , CO, CO 2 ) is 2000 ppm. The hydrogen sensing performance of the optimized film is significantly improved compared with that of the undoped film.