In recent years, nanocrystals of metal sulfide materials have attracted scientific research interest for renewable energy applications due to the abundant choice of materials with easily tunable electronic, optical, physical and chemical properties. Metal sulfides are semiconducting compounds where sulfur is an anion associated with a metal cation; and the metal ions may be in mono-, bi- or multi-form. The diverse range of available metal sulfide materials offers a unique platform to construct a large number of potential materials that demonstrate exotic chemical, physical and electronic phenomena and novel functional properties and applications. To fully exploit the potential of these fascinating materials, scalable methods for the preparation of low-cost metal sulfides, heterostructures, and hybrids of high quality must be developed. This comprehensive review indicates approaches for the controlled fabrication of metal sulfides and subsequently delivers an overview of recent progress in tuning the chemical, physical, optical and nano- and micro-structural properties of metal sulfide nanocrystals using a range of material fabrication methods. For hydrogen energy production, three major approaches are discussed in detail: electrocatalytic hydrogen generation, powder photocatalytic hydrogen generation and photoelectrochemical water splitting. A variety of strategies such as structural tuning, composition control, doping, hybrid structures, heterostructures, defect control, temperature effects and porosity effects on metal sulfide nanocrystals are discussed and how they are exploited to enhance performance and develop future energy materials. From this literature survey, energy conversion currently relies on a limited range of metal sulfides and their composites, and several metal sulfides are immature in terms of their dissolution, photocorrosion and long-term durability in electrolytes during water splitting. Future research directions for innovative metal sulfides should be closely allied to energy and environmental issues, along with their advanced characterization, and developing new classes of metal sulfide materials with well-defined fabrication methods.

Recent advances in metal sulfides: from controlled fabrication to electrocatalytic, photocatalytic and photoelectrochemical water splitting and beyond

Iron disulfide for solar energy conversion

Iron pyrite (FeS2) is a naturally abundant and nontoxic photovoltaic material that can potentially make de- vices as efficient as silicon-based ones; however existing iron pyrite photovoltaic devices contain thermodynamically un- stable FeS2 film surfaces that lead to low open circuit voltages. Wereporttherationalsynthesisofphasepure,highlycrystalline cubic FeS2 nanocrystals (NCs) using a trioctylphosphine oxide (TOPO) assisted hot-injection method. The synthesized pyrite NC films have excellent air stability over one year. In contrast, obvious surface decomposition was observed on the surface of FeS2 NCs synthesized without TOPO. A high carrier mobility of 80 cm 2 /(V s) and a strong photoconductivity were observed for the first time for pyrite films at room temperature. Our results indicate that TOPO passivates both iron and sulfur atoms on FeS2 NC surfaces, efficiently inhibiting surface decomposition.

https://www.unk.edu/academics/chemistry/Miscellaneous-files/Exstrom20_NanoLett2011.pdf

Air stable, photosensitive, phase pure iron pyrite nanocrystal thin films for photovoltaic application.

Iron pyrite (cubic FeS 2 ) is a promising candidate absorber material for earth-abundant thin-fi lm solar cells. In this report, single-phase, large-grain, and uniform polycrystalline pyrite thin fi lms are fabricated on glass and molybdenum-coated glass substrates by atmospheric-pressure chemical vapor deposition (AP-CVD) using the reaction of iron(III) acetylacetonate and tert -butyl disulfi de in argon at 300 ° C, followed by sulfur annealing at 500‐550 ° C to convert marcasite impurities to pyrite. The pyrite-marcasite phase composition depends strongly on the concentration of sodium in the growth substrate and the sulfur partial pressure during annealing. Phase and elemental composition of the fi lms are characterized by X-ray diffraction, Raman spectroscopy, Auger electron spectroscopy, secondary ion mass spectrometry, Rutherford backscattering spectrometry, and X-ray photoelectron spectroscopy. The in-plane electrical properties are surprisingly insensitive to phase and elemental impurities, with all fi lms showing p -type, thermally activated transport with a small activation energy ( ≈ 30 meV), a roomtemperature resistivity of ≈ 1 Ω cm, and low mobility. These ubiquitous electrical properties may result from robust surface effects. These CVD pyrite thin fi lms are well suited to fundamental electrical studies and the fabrication of pyrite photovoltaic device stacks.

/pdf/atmospheric-pressure-chemical-vapor-deposition-of-iron-48rfpfxqo5.pdf

Atmospheric‐Pressure Chemical Vapor Deposition of Iron Pyrite Thin Films

Iron pyrite (cubic FeS2) is a promising candidate absorber material for earth-abundant thin-film solar cells. Here, we report on phase-pure, large-grain, and uniform polycrystalline pyrite films that are fabricated by solution-phase deposition of an iron(III) acetylacetonate molecular ink followed by sequential annealing in air, H2S, and sulfur gas at temperatures up to 550 °C. Phase and elemental compositions of the films are characterized by conventional and synchrotron X-ray diffraction, Raman spectroscopy, Auger electron spectroscopy, secondary ion mass spectrometry, and X-ray photoelectron spectroscopy (XPS). These solution-deposited films have more oxygen and alkalis, less carbon and hydrogen, and smaller optical band gaps (Eg = 0.87 ± 0.05 eV) than similar films made by chemical vapor deposition. XPS is used to assess the chemical composition of the film surface before and after exposure to air and immersion in water to remove surface contaminants. Optical measurements of films rich in marcasite (o...

/pdf/iron-pyrite-thin-films-synthesized-from-an-fe-acac-3-ink-526t69b6pp.pdf

Iron Pyrite Thin Films Synthesized from an Fe(acac)3 Ink

Thin pyrite (FeS2) films prepared by magnetron sputtering

Pyrite films were prepared using the pure elements as source materials: thin iron films were evaporated on quartz substrates and exposed to a sulfur plasma The process was controlled by a transmission measurement X‐ray spectroscopy was used to characterize the films and preliminary optical and electrical measurements were carried out

/pdf/preparation-of-pyrite-films-by-plasma-assisted-sulfurization-2ylalg1rjo.pdf

B. Sailer

Papers

Thin pyrite (FeS2) films prepared by magnetron sputtering

Preparation of pyrite films by plasma‐assisted sulfurization of thin iron films