Iron pyrite: Phase and shape control by facile hot injection method

Pure phases of cubic and spherical FeS2 nanocrystals (NCs) with the mean size of 80 nm and 30 nm, respectively, were obtained using trioctylamine and oleylamine as the solvents to dissolve the sulfur source via a facile and efficient hot injection method. The pure phase formation and shape control were strongly dependent on the concentration of active sulfur source (H2S) that could be formed by the reaction between the elemental sulfur and a primary amine. The chemically active sulfur source could facilitate the formation of a pure FeS2 phase from a FeS phase via a Fe3S4 phase. In addition, the active sulfur concentration is believed to be the main factor to drive the orientation attachment to obtain different shapes of FeS2 NCs. The obtained FeS2 pyrite NCs with excellent phase purity and good optical properties are believed to have potential applications to various energy devices including low-cost photovoltaics.