Pyrite nanocrystals: shape-controlled synthesis and tunable optical properties via reversible self-assembly

Abstract

Nanocrystals from non-toxic, earth abundant materials have recently received great interest for their potential large-scale application in photovoltaics and photocatalysis. Here, we report for the first time on the shape-controlled and scalable synthesis of phase-pure pyrite (FeS 2 ) nanocrystals employing the simple, inexpensive, thermal reaction of iron-oleylamine complexes with sulfur in oleylamine. Either dendritic nanocrystals (nanodendrites) or nanocubes are obtained by adjusting the iron-oleylamine concentration and thereby controlling the nucleus concentration and kinetics of the nanocrystal growth. Pyrite nanodendrites are reversibly assembled by washing with toluene and redispersed by adding the ligand oleylamine. The assembly-redispersion-process is accompanied by an increased absorption in the red/near-infrared spectral region for the aggregated state. This increased low-energy absorption is due to interactions between the closed-packed nanocrystals. High-concentration nanodendrite dispersions are used to prepare pyrite thin films with strong broadband extinction in the visible and near-infrared. These films are attractive candidates for light harvesting in all inorganic solar cells based on earth abundant, non-toxic materials as well as for photocatalytic applications.

Stabilized fabrication of anatase-TiO2/FeS2 (pyrite) semiconductor composite nanocrystals for enhanced solar light-mediated photocatalytic degradation of methylene blue

“…These results are very close to our prediction because the thrust of our study was to reduce the bandgap energy of a TiO 2 un-doped system by combining with the FeS 2 nanocrystals. Similarly, a polymer solar cell based on P 3 HT ¼ FeS 2 -NCs was reported 21 and the results showed that a combination of polymer (P 3 HT) and FeS 2 can contribute to an extended photovoltaic response in the red light region similar to literature 36,37 reports that FeS 2 is a narrow bandgap semiconductor (0.95-1.2 eV) showing absorbance across the entire visible region, and presence of sulfur in composite and pure FeS 2 is indicated by a tail broadening of the peak. 25 …”

Low temperature synthesis of iron pyrite nanorods for photovoltaic applications

“…Indirect band gap obtained through the Tauc plot in Fig. 5c, was found to be 1.13 eV and is in accordance with most of the reported values of band gap in pyrite nanomaterials [2,[30][31][32][33][34][35]. The direct band gap may be interpreted from the slope at the absorption edge near 400 nm in the absorption curve to be nearly 2.7 eV.…”

“…The broad, slowly increasing absorption of pyrite NRs reflects the indirect band gap nature of the material [30,31]. Indirect band gap obtained through the Tauc plot in Fig.…”

Morphology controllable syntheses of micro- and nano-iron pyrite mono- and poly-crystals: a review

“…Following injection, the initial iron pyrite monomer concentration is an important role in controlling the shape of iron pyrite. Li et al 67 obtained iron pyrite nanocubes and nanodendrites by adjusting the precursor concentration, which results in different monomer concentration. Ge et al 77 also concluded that increasing the monomer concentration changes the shape of the nal particles from nanocubes to nanoplates and nally to spheres.…”