Shape controllable fabrication and characterisation of single crystalline PbS nanosheets and dendritic microcrystals

With the assistance of polyvinylpyrrolidone (PVP), PbS single crystalline nanosheets with large size (5-25 μm in diameter) were synthesised via a hydrothermal route. The nanosheets presented shapes of four-horn, square or rectangle. Nanosheets with a zigzag edge were also found in the products. By adjusting the reaction parameters, dendritic or flower-like PbS microcrystals could be obtained. The formation of nanosheets should be a result of the cooperation effect from PVP, thiourea and solvent. X-ray diffraction, a scanning electron microscope, a transmission electron microscope, high-resolution transmission electron microscopy, selected area electron diffraction and Raman spectra were used to characterise the products. A possible growth mechanism for the microcrystals is also discussed.