Bromide (Br−) ion-mediated synthesis of anisotropic palladium nanocrystals by laser ablation

[Display omitted] •Anisotropic Pd nanoparticles were synthesized by pulsed laser ablation.•Growth of Pd nanocrystals were controlled by varying ambient surrounding in laser ablation.•Role of bromide ion in anisotropic growth of Pd is studied.•In situ addition of KBr provided better control over shape than ex situ addition.•Size and shape control of Pd nanocrystal is achieved by employing combination of electrolyte and surfactant. Anisotropic growth of Pd nanoparticles in bromine (Br) containing solution has been studied by pulsed laser ablation. For size and shape control different solutions like water, sodium dodecyl sulphate (SDS) (anionic surfactant), and (Br−) ion containing cetyltrimethylammonium bromide (CTAB) (cationic surfactant) and electrolyte (KBr) were used. In laser ablation surrounding liquid plays a dominant role in controlling size and directional growth. Absorption spectra of as-generated Pd nanoparticles undergo modification with time in different solutions due to Br− ion-mediated directional growth. In water and SDS quasi-spherical and spherical Pd nanoparticles with mean size of 14 and 8nm, respectively, and in CTAB decahedron and icosahedron shape Pd nanocrystals with mean size 65nm were observed. When strong Br− ion source KBr was used sharp edged cuboid shaped large Pd nanoparticles were observed. Surface energy modification due to preferential chemisorption of Br− ions onto {100} planes of Pd resulted in formation anisotropic Pd nanostructures enclosed with {100} planes. The nanocubes exhibit broad plasmon resonance around 250–280nm. Further, size of nanocuboids were controlled by using mixed solutions of KBr with SDS and CTAB for tunable plasmon resonance wavelength from 230 to 550nm.