Structural and gas sensing properties of greigite (Fe3S4) and pyrrhotite (Fe1-xS) nanoparticles

Abstract

Iron sulfide nanoparticles Fe3S4 and Fe1-xS were synthesized via solvothermal decomposition of piperidine iron(III) dithiocarbamate complex in oleylamine. At a reaction temperature of 230 °C, the cubic Fe3S4 phase (greigite) was obtained whereas at 300 °C, monoclinic Fe1-xS (pyrrhotite) was obtained. In both cases, hexagonal sheet like structures with sizes ranging from 50 to 200 nm were obtained. Powder X-ray diffraction studies reveal that the temperature plays a significant role in determining the crystalline structure and chemical composition of the as-synthesized nanoparticles (NPs). Gas sensing applications further reveal activities which are phase-dependent. The greigite has a higher response to humidity but saturates faster than the pyrrhotite. The pyrrhotite phase however outwits the greigite on response to H2, NO2, NH3 and CH4. In these gases, the greigite displays early saturation as well as noisy and uncoordinated signals.