Simple and versatile one-step synthesis of FeS2 nanoparticles by ultrasonic irradiation

The synthesis of stable pyrite nanocrystals (NCs) in a simple way is very difficult. A facile and single-stage ultrasonic synthesis route has been successfully developed for the preparation of pyrite (FeS2) NCs in 10min and 70°C. In this study, the influences of reaction time, temperature, and acoustic power on the formation of the target compound were considered. In addition, a comparison was made of the synthesis of pyrite NCs by sonication with 20kHz apparatus and by the classical method (without ultrasound). The as-prepared pyrite was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), Raman spectrophotometry and energy-dispersive X-ray spectroscopy (EDS). The XRD of the sample prepared by classical method indicated a typical cubic FeS2 with space group Pa3 and the average size of 16nm. Sulfur as an impurity in the sample was verified by XRD analysis. The sample prepared by ultrasound showed two phases of pyrite, cubic and marcasite structures. The space groups were pa3 and pnnm, respectively and the average size was 28.8nm. According to the SEM images, the morphology of the synthesized pyrite using the two methods are closely the same. The FT-IR and Raman spectra presented the FeS, FeS and SS functional groups. In addition, the sono-synthesis of pyrite was done under milder conditions and in shorter time with better features than classical method.