Synthesis Of FeS2 Research Articles

Facile synthesis of FeS2/PVP composite as high-performance electrodes for supercapacitors

Abstract Polyvinyl pyrrolidone (PVP) and iron pyrite (FeS2) films are good to enhance the electrochromic devices as they serve as a surface stabilizer, nanoparticle dispersant, growth modifier, and reducing agent. The synthesis of FeS2 with PVP provides an easy pathway for electrolyte penetration which can improve the electrochemical performances in supercapacitor applications. In this work, we report a facile single-step chemical bath deposition technique to synthesis the FeS2/PVP on Ni foam for the first time. The broad bean-like nanostructure of FeS2 is fully covered with PVP nanoparticles and formed like a coagulation nanostructure on Ni foam. The FeS2/PVP/NF composite was evaluated as an efficient electrode for supercapacitor in 3 M KOH solution, exhibited a greater specific capacitance of 526.08 F g−1 at 1 A g−1, high cyclic stability, remain 91.2% of the initial capacitance after 3000 cycles and high rate capability which is higher compared to bare FeS2/NF electrode (434.9 F g−1 at 1 A g−1 and cyclic stability of 76.7%). The remarkable electrochemical performance of FeS2/PVP/NF composite is attributed to its enhanced electroactive sites, higher surface area, fast electron, and ion transport pathway and most importantly for its facile electrolyte infiltration into the FeS2/PVP/NF.

Synthesis of FeS2 (pyrite) nanotube through sulfuration of Fe2O3 nanotube

Pyrite (FeS2) has been widely used in the photovoltaic field due to its various advantages. In this study, FeS2 nanotube arrays were successfully synthesized by sulfuration of the precursor Fe2O3 nanotube arrays. The microstructure, crystalline phase and optical characteristics of FeS2 nanotube arrays were investigated. It was found that the precursor with tubular nano-topography could effectively accelerate the diffusion rate of sulfur atoms and make the sulfuration more complete. The structure of FeS2 nanotube could enlarge the optical absorption area and enhance the scattering of incident light which would extend the travel path of photon in the nanotube coating and ultimately promoted the optical absorption. The bandgap of FeS2 nanotube arrays was 1.24eV.

Iron Pyrite Nanocrystal Inks: Solvothermal Synthesis, Digestive Ripening, and Reaction Mechanism

Colloidal iron pyrite nanocrystals (or FeS2 NC inks) are desirable as active materials in lithium ion batteries and photovoltaics and are particularly suitable for large-scale, roll-to-roll deposition or inkjet printing. However, to date, FeS2 NC inks have only been synthesized using the hot-injection technique, which requires air-free conditions and may not be desirable at an industrial scale. Here, we report the synthesis of monodisperse, colloidal, spherical, and phase-pure FeS2 NCs of 5.5 ± 0.3 nm in diameter via a scalable solvothermal method using iron diethyldithiocarbamate as the precursor, combined with a postdigestive ripening process. The phase purity and crystallinity are determined using X-ray diffraction, transmission electron microscopy, far-infrared spectroscopy, and Raman spectroscopy techniques. Through this study, a hypothesis has been verified that solvothermal syntheses can also produce FeS2 NC inks by incorporating three experimental conditions: high solubility of the precursor, efficient mass transport, and sufficient stabilizing ligands. The addition of ligands and stirring decrease the NC size and led to a narrow size distribution. Moreover, using density functional theory calculations, we have identified an acid-mediated decomposition of the precursor as the initial and critical step in the synthesis of FeS2 from iron diethyldithiocarbamate.

Formation mechanisms of pyrite (FeS2) nano-crystals synthesized by colloidal route in sulfur abundant environment

Pyrite (FeS2) nano-crystals (NCs) were synthesized in an excess sulfur environment using a colloidal hot-injection method, and the phase change behavior of the iron sulfide compounds was investigated. As the growth time increased, the phase of the iron sulfide NCs transformed from mackinawite (FeS) via greigite (Fe3S4) to pyrite (FeS2). Thus, Fe3S4 phases was considered as intermediate precursors on the pathway of FeS2 phases in the reaction between FeS phases and excess sulfur. The elemental ratio of [S/Fe] increased from 1.1 to 2.1 during the phase change, and the shape of the NCs changed from a hexagonal nano-sheet (Fe3S4), via cubic (FeS2), to a cubic-hedral structure (FeS2). Strong absorption peaks in the UV–Vis spectra were observed in the FeS2 phase, and its optical band gap was estimated to be ∼0.9 eV, indicating the semiconducting nature of pyrite. Consequently, the synthesis of FeS2 in sulfur abundant environment was suitable method to acquire a pure semiconducting FeS2 phases. The reason was thought that the depletion of Fe-element after the formation of FeS2 phases led to the decrease of intermediate phases and the gradual changes from intermediate phases to FeS2 resulted in pure phases.

Electrolytic synthesis of FeS2 for thin-layer lithium battery

Purposeful synthesis of iron sulfide FeS2 films for a lithium battery were purposefully synthesized on a 18N12Kh9T steel cathode from a solution containing Mohr’s salt and Na2S2O3. Various aspects of synthesis were studied. Thin-film Fe-sulfide synthesis products were tested in a prototype lithium battery and also in a lithium-ion system. The synthesized electrolytic iron sulfide FeS2 with a marcasite structure is capable of reversible electrochemical transformation with output of 390 mA h g−1 in negative electrodes of the lithium-ion system with a LiMn2O4 counter electrode.

Synthesis of FeS2 and Co-doped FeS2 films with the aid of supercritical carbon dioxide and their photoelectrochemical properties

The prepared FeS2 and Co-doped FeS2 films revealed better properties in photocurrent response and photocatalysis of water photolysis under simulated sunlight. The films were synthesized on iron substrates with the aid of supercritical carbon dioxide. The experimental results demonstrated that the supercritical carbon dioxide could play an important role in evolution of phases and morphologies during the reaction process. Moreover, the prepared films were characterized by XRD, SEM, TEM and EDS. The UV-vis absorption spectroscopy indicated that the absorption edge has obvious blue shift compared with bulk FeS2. Interestingly, characteristics of photoelectric response and water photolysis were shown by photoelectrochemical experiments under sunlight. Therefore, the prepared films would have an advantage in water photolysis utilizing sunlight.