Phase Pure Pyrite FeS₂ Nanocubes Synthesized Using Oleylamine as Ligand, Solvent, and Reductant

Abstract

Pyrite (FeS2) nanocrystals with a narrow size distribution and optical absorption from 1600 to 380 nm were synthesized in a single stage by reacting ferrous chloride with elemental sulfur in oleylamine (OAm) without an additional ligand. X-ray diffraction, Raman, and scanning electron microscopy showed that pyrite cubes with dimensions of 88 ± 14 nm formed at 200 °C, an S to Fe ratio of 6, and 1 h reaction time in OAm. The time required to form phase pure pyrite depended on the S to Fe ratio. Phase purity was obtained in less than 1 h at a ratio of 6, but times as long as 24 h were necessary at a ratio of 2.75. The rate of pyrite formation increased with higher sulfur concentrations, which shows that molecules containing sulfur are involved in the rate-determining step. Both H2S and polysulfides of the form S n 2– are known to form in oleylamine. The slow step is the reaction between FeS and these molecules. Fe2+S2– undergoes nucleophilic attack by H2S and S n 2–; S2– converts to S– and sulfur is transferred forming pyrite Fe2+S2 2–.

Achieving electroreduction of CO2to CH3OH with high selectivity using a pyrite–nickel sulfide nanocomposite

“…The binding energy at 706.8 and 719.5 eV are conformed to the Fe 2p 3/2 and Fe 2p 1/2 which are characterized of pyrite. 36 The Ni 2p 3/2 and Ni 2p 1/2 peaks are observed at 853.6 and 871.8 eV, exist two satellite peaks at 858.7 and 878.1 eV respectively, 32 indicating that the nickel existed in bivalent states. There are four peaks in the high resolution XPS spectra of S. The S 2p 3/2 and S 2p 1/2 peaks located at 161.9 and 162.8 eV are consistent with S 2À , 31 while the peaks at 162.5 and 163.7 eV are identied with the S 2p 3/2 and S 2p 1/2 of S 2 2À .…”

Nanocrystalline Pyrite for Photovoltaic Applications

“…Recently, FeS 2 nanocrystals (average edge length=37 ± 11 nm) and FeS 2 cubes (88 ± 14 nm) synthesised in oleylamine (OLA) with sulfur to iron ratio 6. The higher sulfur concentration favours higher FeS 2 formation rate that is the rate‐determining step . A very recent investigation of growth mechanism of FeS 2 NCs by Zhu et al .…”

Origin of Ferromagnetism in Pure and Ion Doped Pyrite FeS2 Nanoparticles

“…There are some investigations about different sulfur to iron ratios in FeS 2 NP where a randomly distribution of those ions has to be considered. Because the inclusion of a distribution of ions is beyond the scope of our approach we will shift the discussion to a forthcoming paper.…”

“…Sulfur dimer vacancies support the building of a cubic FeS structure. Jiang et al have investigated the sulfur‐iron ratio in FeS 2 nanocubes. Krishnamoorthy et al employ density functional theory to study the formation energetics and electronic structure of intrinsic Fe and S vacancies in bulk pyrite (FeS 2 ) and on the pyrite (100) surface.…”