Fabrication of Symmetric Hierarchical Hollow PbS Microcrystals via a Facile Solvothermal Process

Template-free syntheses of hierarchical PbS microstructures using a new sulphur source and their time-dependent morphological evolution and photocatalytic properties

Template-free PbS microstructures composed of nanocrystals exhibiting time-dependent morphological evolution from cubes to dendrites were synthesised by one-pot solvothermal route using DBDS as a new temperature controlled in situ source of S²⁻ ions.

Coordination polymers for catalysis: enhancement of catalytic activity through hierarchical structuring

Hierarchical Prussian white (PW) crystals were synthesized by using a self-aggregation and etching strategy. The crystals exhibit superior catalytic activity in degradation of methylene blue to the non-hierarchical PW crystals.

Unknown aspects of self-assembly of PbS microscale superstructures

A lot of interesting and sophisticated examples of nanoparticle (NP) self-assembly (SA) are known. From both fundamental and technological standpoints, this field requires advancements in three principle directions: (a) understanding the mechanism and driving forces of three-dimensional (3D) SA with both nano- and microlevels of organization; (b) understanding disassembly/deconstruction processes; and (c) finding synthetic methods of assembly into continuous superstructures without insulating barriers. From this perspective, we investigated the formation of well-known star-like PbS superstructures and found a number of previously unknown or overlooked aspects that can advance the knowledge of NP self-assembly in these three directions. The primary one is that the formation of large seemingly monocrystalline PbS superstructures with multiple levels of octahedral symmetry can be explained only by SA of small octahedral NPs. We found five distinct periods in the formation PbS hyperbranched stars: (1) nucleation of early PbS NPs with an average diameter of 31 nm; (2) assembly into 100-500 nm octahedral mesocrystals; (3) assembly into 1000-2500 nm hyperbranched stars; (4) assembly and ionic recrystallization into six-arm rods accompanied by disappearance of fine nanoscale structure; (5) deconstruction into rods and cuboctahedral NPs. The switches in assembly patterns between the periods occur due to variable dominance of pattern-determining forces that include van der Waals and electrostatic (charge-charge, dipole-dipole, and polarization) interactions. The superstructure deconstruction is triggered by chemical changes in the deep eutectic solvent (DES) used as the media. PbS superstructures can be excellent models for fundamental studies of nanoscale organization and SA manufacturing of (opto)electronics and energy-harvesting devices which require organization of PbS components at multiple scales.

High yield synthesis of matchstick-like PbS nanocrystals using mesoporous organosilica as template

A simple hard template method has been developed to prepare uniform matchstick-like PbS nanocrystals. The approach combines functionalization of the mesoporous walls and channel surface with thioether groups, adsorption of Pb2+, and heating in an N2 atmosphere at high temperature. The structure, morphology and composition of the nanocrystals have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The optical properties of the matchstick-like PbS nanocrystals have been systematically investigated by Raman spectroscopy, UV-visible absorption spectroscopy (UV-vis), and photoluminescence spectroscopy (PL). These results demonstrate that these matchstick-like PbS nanocrystals are single crystals and possess novel optical properties, suggesting that they may have many potential applications. A large blue shift is observed in the photoluminescence spectrum, and this clearly shows the quantum size effects of the matchstick-like PbS . Furthermore, a growth mechanism of the PbS heteronanostructure is proposed.