Mِssbauer evidence for fast electron hopping between Fe(II) and Fe(III) in iron hydroxide/molybdenum disulfide lamellar nanocomposite

Nanocomposite compounds with iron hydroxide and molybdenum disulfide alternating layers have been studied using 57Fe Mössbauer spectroscopy. Evidence is given of the presence of two oxidation states for iron (Fe(II)/Fe(III)≈1.9). In the temperature range 60–160 K thermal evolution of the absorption areas obeys Debye’s model, with the lattice temperature ΘM equal to 275 and 320 K for Fe(II) and Fe(III), respectively. At higher temperature (T≥180 K), a new iron state is observed, which can be related to fast electron hopping between certain heterovalent iron ions. Tin-doping enhances this process which can already be detected at 140 K.