Mechano-thermal synthesis and characterization of nano-structured Fe/FeS for application in photocatalysis

Abstract A novel method was used to prepare a nano-structured 32 wt% Fe/FeS core/shell powder via a mechano-thermal route by 1-h heat treatment of a mechanically activated powder mixture of Fe and S. The structural and microstructural characteristics, formation mechanism, magnetic properties, and photocatalytic activity of the powder were studied by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, surface area analysis, differential scanning calorimetry, vibrating sample magnetometry, and UV–vis spectrophotometry. A detailed study of the mechanism of transformation showed that during the heat treatment process, an FeS2 phase was formed as the intermediate product. In the final product, an FeS shell approximately 2 nm in thickness was formed on the Fe core. In the presence of NaCl as a process control agent, the particle size decreased and the size distribution became more uniform. Mechanical activation and NaCl addition together led to a decrease of the saturation magnetization from 82 to 74 emu/g. The photocatalytic activity of the powder in the degradation of methylene blue was 50%.