We reported an aqueous synthesis of urchin-like gold nanoparticles (NPs) in the presence of hydroquinone through a seed-mediated growth approach. By altering the feed ratio of hydroquinone, seeds, and additional HAuCl4, the diameters of urchin-like NPs were tunable from 55 to 200 nm. Accordingly, the centers of surface plasmon resonance absorption shifted from 555 to 702 nm. Systematical analysis revealed that the generation of urchin-like particles as well as their size evolution strongly depended on the reactivity of gold ions, mainly controlled by the concentration of hydroquinone. At low hydroquinone concentration, only spherical particles were achieved. The increase of the hydroquinone concentration promoted a kinetics-favored deposition of gold atoms on the (111) lattice planes and thereby the growth of branches. Moreover, the as-prepared urchin-like particles possessed good structural stability, which could be kept in the growth solution for more than 10 days without morphology variation.

Whereas organic-inorganic hybrid perovskite nanocrystals (PNCs) have remarkable potential in the development of optoelectronic materials, their relatively poor chemical and colloidal stability undermines their performance in optoelectronic devices. Herein, this issue is addressed by passivating PNCs with a class of chemically addressable ligands. The robust ligands effectively protect the PNC surfaces, enhance PNC solution processability, and can be chemically addressed by thermally induced crosslinking or radical-induced polymerization. This thin polymer shield further enhances the photoluminescence quantum yields by removing surface trap states. Crosslinked methylammonium lead bromide (MAPbBr ) PNCs are applied as active materials to build light-emitting diodes that have low turn-on voltages and achieve a record luminance of over 7000 cd m , around threefold better than previous reported MA-based PNC devices. These results indicate the great potential of this ligand passivation approach for long lifespan, highly efficient PNC light emitters.

Thioglycerol-capped CdTe nanocrystals were used as core template to generate CdTe/CdS core-shell nanocrystals in aqueous solution by means of ultrasonic irradiation. The photoluminescence quantum yields of CdTe/CdS core-shell nanocrystals were up to 20%, larger than the original CdTe nanocrystals by around 10 times. The reaction conditions, such as the concentration, the molar ratio of reactants, and the pH value, were investigated, showing that ultrasonic irradiation controlled the decomposition of thiourea and the formation of a gradient CdS shell around the original CdTe core.