Iron pyrite: Phase and shape control by facile hot injection method (original) (raw)
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Korean Journal of Chemical Engineering, 2018
Iron pyrite (FeS 2) thin films were fabricated by spin coating the solution of FeS 2 nanocrystals of ~40 nm in size on glass substrates, followed by annealing in a sulfur environment at different temperatures. The effect of sulfurization temperature on the morphology, structural, optical and electrical properties was investigated. With increase of the sulfurization temperature, the grain size and crystallinity of the films was improved, although some cracks and voids were observed on the surface of thin films. The band gap of the FeS 2 films was decreased at higher sulfurization temperature. The electrical properties were also changed, including the increasing in resistivity and the decrease in Hall mobility, with increase of sulfurization temperature. The change in the optical and electrical properties of the FeS 2 thin films was explained based on the changes of phase, morphology, surface, and grain boundary property.
Universal Synthesis of Single-Phase Pyrite FeS 2 Nanoparticles, Nanowires, and Nanosheets
The Journal of Physical Chemistry C, 2013
Nanoscale pyrite FeS 2 is considered to be one of few potentially transformative materials for photovoltaics capable of bridging the cost/performance gap of solar batteries. It also holds promise for energy storage applications as the material for high-performance cathodes. Despite prospects, the synthesis of FeS 2 nanostructures and diversity of their geometries has been hardly studied. Moreover, the state-ofthe-art aqueous dispersions of nanoscale pyrite, which have special significance for solar energetics, are particularly disappointing due to low quality. There are no known methods to produce well-crystallized nanoparticles and other geometries of nanoscale pyrite in water or mixed aqueous solvents. Here, we describe a successful synthesis of single-phase pyrite nanoparticles with a diameter of 2−5 nm in polar solvent and aqueous dispersions. The particles display high uniformity and crystallographic purity. Moreover, the synthetic approach developed for nanoparticles was proven to be quite universal and can be modified to produce both nanowires and nanosheets, which also display high crystallinity. The diameter of the pyrite nanowires was 80−120 nm with the length exceeding 5 μm. The nanosheets displayed lateral dimensions of 100−200 nm with the thickness of 2 nm. Availability of single-phase FeS 2 nanoscale aqueous dispersions is expected to stimulate further studies of these materials in green energy conversion technologies and drug delivery applications.
Universal Synthesis of Single-Phase Pyrite FeS2 Nanoparticles, Nanowires, and Nanosheets jp3111106
Nanoscale pyrite FeS 2 is considered to be one of few potentially transformative materials for photovoltaics capable of bridging the cost/performance gap of solar batteries. It also holds promise for energy storage applications as the material for high-performance cathodes. Despite prospects, the synthesis of FeS 2 nanostructures and diversity of their geometries has been hardly studied. Moreover, the state-ofthe-art aqueous dispersions of nanoscale pyrite, which have special significance for solar energetics, are particularly disappointing due to low quality. There are no known methods to produce well-crystallized nanoparticles and other geometries of nanoscale pyrite in water or mixed aqueous solvents. Here, we describe a successful synthesis of single-phase pyrite nanoparticles with a diameter of 2−5 nm in polar solvent and aqueous dispersions. The particles display high uniformity and crystallographic purity. Moreover, the synthetic approach developed for nanoparticles was proven to be quite universal and can be modified to produce both nanowires and nanosheets, which also display high crystallinity. The diameter of the pyrite nanowires was 80−120 nm with the length exceeding 5 μm. The nanosheets displayed lateral dimensions of 100−200 nm with the thickness of 2 nm. Availability of single-phase FeS 2 nanoscale aqueous dispersions is expected to stimulate further studies of these materials in green energy conversion technologies and drug delivery applications.
J. Mater. Chem. A, 2015
We use a solution-based hot injection method to synthesize stable, phase pure and highly crystalline cubic iron pyrite (FeS 2 ) nanocrystals, with size varying from $70 to 150 nm. We use iron(II) bromide as an iron precursor, elemental sulfur as the sulfur source, trioctylphosphine oxide (TOPO) and 1,2-hexanediol as capping ligands, and oleylamine (OLA) as a non-coordinating solvent during the synthesis. We report on the influence of hydrazine treatment, and of thermal sintering, on the morphological, electronic, optical, and surface chemical properties of FeS 2 films. Four point probe and Hall measurements indicate that these iron pyrite films are highly conductive. Although they are unsuitable as an effective photovoltaic light-absorbing layer, they offer clear potential as a conducting contact layer in photovoltaic and other optoelectronic devices. † Electronic supplementary information (ESI) available: Band gap calculation for FeS 2 NC lm, absorbance before and aer hydrazine treatment, TEM image and size distribution of NCs, characterizations of oleylamine and 1,2-hexanediol capped NCs, SEM images before and aer sintering, grain size calculation based on Scherrer analysis, electrical four point probe measurements and work function calculation of FeS 2 before and aer hydrazine treatment. See
Synthesis and structural characterization of FeS2 nanoparticles using rietveld refinement
AIP Conference Proceedings, 2019
We report the synthesis and characterization of FeS 2 nanoparticles (NPs) in view of their possible applications, which may range from organic and inorganic based hybrid solar cells to the replacements of Lithium Batteries (LIBs). The Polyol method was used to prepare the Iron Pyrite (FeS 2) NPs with reducing reagent Ethylene Glycol (EG) and precursor Thiourea. The crystalline quality and stoichiometry of synthesized FeS 2 NPs were confirmed by X-ray diffraction (XRD) and Raman Spectroscopy, which gave an average crystallite size of 35.4 nm. The Rietveld refinement of the diffraction data revealed the lattice parameters, hkl values, phase, Rp (Profile Factor) etc. of FeS 2 NPs through the profile matching routine of FullProf software. The elemental has been investigation has been performed using Energy-Dispersive X-ray Spectroscopy (EDS), where characteristic emission peaks of Fe and S elements were observed. Further, Raman Spectroscopy experiment provided information on chemical bonding and symmetry of molecules for the device possibilities of surfactant coated FeS 2 NPs.
Chemistry of Materials, 2017
In the colloidal synthesis of iron sulfides, a series of dialkyl disulfides, alkyl thiols, and dialkyl disulfides (allyl, benzyl, tbutyl, and phenyl) were employed as sulfur sources. Their reactivity was found to tune the phase between pyrite (FeS 2), greigite (Fe 3 S 4), and pyrrhotite (Fe 7 S 8). DFT was used to show that sulfur-rich phases were favored when the C-S bond strength was low in the organosulfurs, yet temperature dependent studies and other observations indicated the reasons for phase selectivity was more nuanced; the different precursors decomposed through different reaction mechanisms, some involving the oleylamine solvent. The formation of pyrite from diallyl disulfide was carefully studied as it was the only precursor to yield FeS 2. Raman spectroscopy indicated that FeS 2 forms directly without an FeS intermediate, unlike most synthetic procedures to pyrite. Diallyl disulfide releases persulfide (S-S) 2due to the lower C-S bond strength relative to the S-S bond strength, as well as facile decomposition in the presence of amines through S N 2 ′ mechanisms at elevated temperatures.
Low temperature synthesis of iron pyrite (FeS2) nanospheres as a strong solar absorber material
Phase pure iron pyrite (FeS2) nanosphere morphology was synthesized by a solvothermal route an alternative to colloidal synthesis by utilizing an ethylene glycol and benzylamine as a solvent and structure directing ligand at 160 °C for 12 h in Teflon lined autoclave. The as obtained nanospheres were in average ∼50 nm diameter with a smooth surface and well mono-disperse as observed by the FESEM images. The XRD analysis shows a typical iron pyrite crystal phase with 2θ position at 28.23°, 32.76°, 36.84°, 40.48°, 47.32° and 56.01° without any impurity peaks. The Raman spectra further confirmed the phase pure pyrite structure. The UV-Vis and PL spectra shows excellent solar absorbance with a band gaps of 1.35 eV close to the direct band gap (1.38 eV) of pyrite materials, however the photoluminescence spectra shows a band gap of 1.39 eV close to the direct band gap. The obtained nanosphere morphology was highly promising as an excellent solar absorber material for the photovoltaic application.
Study of Structural and Optical Properties of FeS2 Nanoparticles Prepared by Polyol Method
Journal of Nano- and Electronic Physics, 2020
FeS2 nanoparticles were prepared using a simple and cost-effective Polyol method with ethylene glycol and precursor thiourea as capping reagents. The crystalline structure of FeS2 nanoparticles were confirmed by X-ray diffraction. Dimensions of the unit cell and Pa-3 space group were determined by Rietveld refinement. The average crystallite size was found to be ~ 42.1 nm. The stoichiometry of these nanoparticles were also confirmed by, Raman and Fourier Transform Infrared Spectroscopy. Further, Raman spectroscopy revealed the chemical bonding and symmetry of molecules. FTIR spectroscopy exhibited the presence of functional groups of Fe=S, Fe-S and S-S in the samples. Advanced measurements and analysis towards the applicability of surfactant coated pyrite FeS2 nanoparticles for solar cell etc. applications are in progress.
Materials Characterization, 2005
FeS 2 -thin films with good crystallinity were synthesized by a simple method which consists of sulphuration, under vacuum, of amorphous iron oxide thin films pre-deposited by spray pyrolysis of FeCl 3 d 6H 2 O (0.03 M)-based aqueous solution onto glass substrates heated at 350 8C. At optimum sulphuration temperature (450 8C) and duration (6 h), black green layers having granular structure and high absorption coefficient (~5.10 4 cm À1 ) were obtained. The study of the electrical properties of the asprepared films vs. the temperature variations showed three temperature domain dependence of the conductivity behaviour. The first one corresponds to the high temperature range (330 K-550 K) for which an Arrhenius plot type was obtained. The activation energy value was estimated at about 61.47 meV. The second domain corresponding to the intermediate temperature range (80 K-330 K) showed a variable activation energy between the grain boundaries. The barrier height, q/, was estimated to 27F0.5 meV, and the standard deviation, qr / , was evaluated at about 14F0.5 meV. We found that at lower temperatures (20 K-80 K), the conductivity is governed by two conduction types. The density of localised states, was about 2.45Â10 20 eV À1 cm À3 .