General application of ＂greener methods＂ to the synthesis of monodisperse colloidal nanocrystals introduces impurities, including metal carboxylate precursors, non-volatile solvents, free ligands, and non-nanocrysta...General application of ＂greener methods＂ to the synthesis of monodisperse colloidal nanocrystals introduces impurities, including metal carboxylate precursors, non-volatile solvents, free ligands, and non-nanocrystalline side products. These impurities seriously diminish the solution processability and potential applications of colloidal nanocrystals. A protocol was established for evaluating purification schemes. The results revealed that commonly applied purification schemes and their variants do not exhibit a high level of performance and may degrade the ligand surface coverage. A new scheme involving chloroformacetonitrile precipitation quantitatively removed all impurities from colloidal solutions of CdSe and CdS nanocrystals coated with a variety of carboxylate ligands. The new scheme was benign to the surface structure of nanocrystaMigands complexes and resulted in each nanocrystal bearing a close-packed monolayer of carboxylate ligands.展开更多
基金This work was supported by the National Natural Science Foundation of China （Nos. 21233005 and 91433204） and Fundamental Research Funds for the Central Universities （No. 2014FZA3006）.
文摘General application of ＂greener methods＂ to the synthesis of monodisperse colloidal nanocrystals introduces impurities, including metal carboxylate precursors, non-volatile solvents, free ligands, and non-nanocrystalline side products. These impurities seriously diminish the solution processability and potential applications of colloidal nanocrystals. A protocol was established for evaluating purification schemes. The results revealed that commonly applied purification schemes and their variants do not exhibit a high level of performance and may degrade the ligand surface coverage. A new scheme involving chloroformacetonitrile precipitation quantitatively removed all impurities from colloidal solutions of CdSe and CdS nanocrystals coated with a variety of carboxylate ligands. The new scheme was benign to the surface structure of nanocrystaMigands complexes and resulted in each nanocrystal bearing a close-packed monolayer of carboxylate ligands.
