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

Abstract

Tungsten oxide (WO3) has been widely used in hydrogen sensing due to its stable chemical properties and high oxygen vacancy diffusion coefficient. However, the response of pure WO3 to hydrogen is slow, and doping is an effective way to improve the hydrogen sensing performance of WO3 materials. In this paper, WO3/Pt/PEG/SiO2 porous film was prepared by the sol-gel method using tungsten powder, H2O2 and C2H5OH as precursors, polyethylene glycol (PEG) as the pore-forming agent, and tetraethyl orthosilicate (TEOS) as the SiO2 source material. The sensing properties of the WO3 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 R2 is 0.9946 within the hydrogen concentration range of 5000 ppm to 50,000 ppm. The film responds only to H2 when the concentration of interfering gases (CH4, CO, CO2) is 2000 ppm. The hydrogen sensing performance of the optimized film is significantly improved compared with that of the undoped film.