Shape and Thermodynamic Stability of Pyrite FeS₂ Nanocrystals and Nanorods

Abstract

The pyrite polymorph of iron disulfide (FeS 2 ) has been attracting considerable attention, as it shows promise for solar energy conversion devices, solid-state batteries, and catalysis. As-prepared FeS 2 powders naturally displayed rod-like morphologies, but if tailor-made pyrite nanocrystals and nanorods are to be reliably exploited in future devices, it is desirable to be able to predict and precisely control the shape (and aspect ratio) of FeS 2 , and to understand the morphological stability under various conditions. Therefore, we have begun by investigating the relationship between size, shape, axial orientations, and aspect ratio of unpassivated FeS 2 nanostructures, using a thermodynamic model and energetic parameters calculated from first principles. The results show that the unusual morphologies such as the decahedral pyritohedron are less likely at the nanoscale than they are macroscopically, and that the preferred orientation of 1-D FeS 2 nanostructures is likely to be defined by kinetics, irrespective of aspect ratio.

Enhanced electrochemical performance of FeS2 synthesized by hydrothermal method for lithium ion batteries

“…Therefore, {111} faces expansion at the expense of {100} faces. The surface energy of pyrite {111} is higher than that of {100} faces, thus crystals form skeleton spheres via self-organization to minimize the total surface energy [33]. Then the sphere-like morphology with sawtooth-like surface is formed.…”

Microwave-hydrothermal synthesis of Co-doped FeS2 as a visible-light photocatalyst

“…Among them, the polymorph pyrite of iron disulfide (FeS 2 ) is of great interest owing to its potential as a useful material for solar-energy applications [5][6][7] and as the cathode for high-energy density batteries [8][9][10]. Previous research has proved that pyrite exhibits a very high absorption coefficient (C5 9 10 5 cm -1 , k B 700 nm) and has a comparable energy band gap (E g & 0.95 eV) [4].…”

The Renaissance of Iron Pyrite Photovoltaics: Progress, Challenges, and Perspectives

“…It is necessary to first note that pyrite crystal surface energies are an enigma compared to normal crystal theory. It has been shown that the {100} face is lower in surface energy than the {111} energy, which is the opposite of normal theory [26]. This leads to many different observables in synthesis, which will be discussed later.…”