A solid-state sensor for continuous monitoring of hydrogen using silver sulfide.

Abstract

A new sensor for continuous monitoring of hydrogen was developed by using a silver sulfide and silver iodide solid electrolyte. The sensor is expressed as Pt/Ag2S/Ag2S+AgI/AgI/Ag, and can be formed easily into a form of small disk with a die and press. Silver powder, silver iodide, mixture of silver sulfide and silver iodide, silver sulfide and a platinum gauze were placed in layers in the die, and 600kg/cm2 of pressure was applied. The diameter and thickness of the disk were 13mm and 2.1mm, respectively. The cell was then transferred in a heating air bath held at 350°C, and a constant voltage of 3μV was applied.When the sample gas containing hydrogen was impinged on the platinum anode of the sensor, an electrolytic current flowed through the external circuit of the sensor. The current was proportional to the concentration of hydrogen at a constant bath temperature and constant flow rate of the gas. The calibration curve for hydrogen was rectilinear between 1001000ppm, and the relative standard deviation in this range was within 5.0%. The detection limits of hydrogen at the flow rate of 50cm3/min was 50ppm, and the response time was about 13min for 500ppm hydrogen. When hydrogen (500ppm H2/N2) was impinged on the sensor for about 6h/d, the sensitivity after 33 days exposure decreased to about 80% of the original value.