Role of solution pH and SDS on shape evolution of PbS hexagonal disk and star/flower shaped nanocrystals in aqueous media

• SDS adsorption at energetic {1 1 1} facets via Pb-SDS complexation effectively retards growth along 〈1 1 1〉 directions.
• Presence of SDS ensures growth in 〈1 0 0〉 directions and evolution of six pods star/flower shaped PbS structures.
• OH− mediated surface energy perturbation facilitates both {1 1 1} and {1 0 0} facets composed hexagonal disk like PbS structures.
• (I (1 1 1)/I (2 0 0)) in XRD pattern indicates that major fraction of the disk is covered by {1 1 1} facets.

PbS nanoparticles (NPs) with varieties of shapes, including flowers, stars, spheres and hexagonal disk have been synthesised in aqueous phase at mild temperature 90 °C, and effect of solution pH and added surfactant SDS, on morphology of products has been investigated. It has been observed that in the basic medium, OH− ions interaction and SDS adsorption through headgroup on energetic crystallographic faces direct the shape evolution of NPs. It is supposed that initially nucleated truncated octahedron seeds having {1 1 1} and {1 0 0} facets are responsible for transformation of shape into different nanostructures during growth process in the various reaction conditions. The products obtained in the different reactions were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) to derive crystallinity, phase, composition, size and morphology of the products. Fourier transform infrared spectral analysis (FTIR) was used to observe SDS adsorption at NPs surface. UV–Vis spectral analysis was carried out to determine the optical properties of the PbS materials.

SDS adsorption at {1 1 1} facets ensures evolution of six podal PbS stars/flowers, while OH− mediated surface energy perturbation facilitates evolution of {1 1 1} and {1 0 0} facets composed hexagonal PbS disks .Figure optionsDownload as PowerPoint slide