Aerobic and anaerobic H_2 sensing sensors fabricated by diffusion membranes depositing on Pt-ZnO film

摘要

Utilizing sensor to detect H_2 under different oxygen concentrations is essential in monitoring status of nuclear weapon. A membrane covering on a sensing film could influence the diffusion of oxygen, thus changing the sensing performance of a metal oxide (MOX) gas sensor. In this research, silica and alumina (SiO_2/Al_2O_3) composite membranes were deposited in-situ on Pt-modified ZnO by combining chemical vapor deposition (CVD) and ultrasonic spray pyrolysis (USP) methods Through adjusting the ratio of silicon to aluminum (Si/Al), the composition of membranes, the diffusion rate of oxygen and H_2 sensing property under different oxygen concentrations were regulated. With the decrease of the Si/Al ratio, the H_2 responses of the sensors increased first and decreased then under high (10,000 ppm) oxygen concentration. While under low (50 ppm) oxygen concentration, the H_2 responses of the sensors went down first and rose then. The sensors covered with membranes of high Si/Al ratio exhibited aerobic H_2 sensing property. Meanwhile, sensors deposited with membranes of low Si/Al ratio or without membrane showed anaerobic H_2 sensing property. This study contributes to further understanding of the influence of oxygen diffusion on MOX sensing properties.