Size dependent gas sensing properties of spinel iron oxide nanoparticles

Spinel iron oxide nanoparticles of sizes from 12 to 60 nm have been prepared via a hydrothermal synthesis. Thick films of the Fe(3-x)O(4) nanoparticles deposited on interdigital electrodes were applied as resistive gas sensors. The electrical and gas sensing properties were characterized by impedance spectroscopy using multielectrode substrates. The reducing analytes CH(4), NO, H(2) and NH(3) in N(2) as a reference were applied in order to investigate the sensor response, the selectivity and the recovery behavior at temperature between 50 degrees C and 300 degrees C. The materials exhibit good sensor responses towards NH(3) with low cross sensitivities towards H(2) and NO at 250 degrees C. A linearly increasing sensor response towards NH(3) and H(2) with decreasing particle size was found. (C) 2011 Elsevier B.V. All rights reserved.