PNNL

Abstract

Hydrogen sensing is a critical component of safety to address wide spread public perceptions of the hazards of production, storage, transportation and use of hydrogen in proposed future automobiles and in various other applications. A nanoscale magnetic hydrogen sensor is proposed based on the experimental observation of systematically varying the saturation magnetization and remanence of nanoscale antiferromagnetic hematite with hydrogen flow. The saturation magnetization and remanence of the nanoscale hematite sample showed an increase of one to two orders of magnitude in the presence of flowing hydrogen gas at concentrations in the 1 to 10% range and at 575 K, suggesting that a practical magnetic hydrogen sensor could be developed using this material and the novel magnetic sensing method. Thermogravimetric analysis of the hematite sample shows significant mass loss when hydrogen gas is introduced. Xray diffraction and x-ray photoelectron spectroscopy studies ruled out any impurity phase formation as a result of gas-sample interaction. This work thus facilitates the use of the magnetic properties of an antiferromagnetic material as gas sensing parameters, thus exploring the concept of ‘magnetic gas sensing’.