A study of the gas sensitivity of α-Fe_2O_3 sensors to CO and CH_4

摘要

Haematite, a-Fe2O3, prepared from a solution of iron sulphate or by chemical precipitation from mixed solutions containing quadrivalent metal ions such as Zr, Ti and Sn, has been found to be gas sensitive to combustible gases including CH4, H2 and CO [1-5]. Its gas sensitivity has also been found to decrease as the content of SO42~ decreases, so it is considered that the SO42~ cluster remaining in a-Fe2O3 accounts for its gas sensitivity [1-4,6]. Therefore, understanding the influence of ion clusters in a-Fe2O3 on its gas sensitivity is essential to the successful development of a-Fe2O3-based sensors for various applications [7]. This communication is to show that the gas sensitivity and selectivity to CO and CH4 can be improved simply by controlling the pH value of the precipitating solutions with which to make a-Fe2O3 sensors.