| Since the unique advantages of upconversion nanoparticles?UCNPs?/semiconductor nanoheterostructures,it is of great significance to develop various strategies to construct UCNPs-based energy transfer system and expand its applications in environmental treatment,energy storage,biomedicine and even more fields.However,it is inevitably happened for the secondary nucleation and growth process of the shell component of UCNPs during the seed-mediated growth process with hot-injection of shell precursor.Moreover,due to the serious lattice mismatch between UCNPs and semiconductor,it is difficult to combine them directly.Thus,it remains a great challenge for the controllable synthesis of UCNPs/semiconductor nanoheterostructures.In this work,an amorphous shell component-crystallization strategy has been firstly developed to realize precise synthesis of monodisperse sub-10 nm NaYF4:Yb/Er@NaGdF4 core-shell nanoparticles with uniform morphology and size.The influence of the size of seed nanocrystals on the nucleation and growth of NaYF4:Yb/Er@NaGdF4 core-shell nanocrystals was investigated by dynamic light scattering?DLS?technique.Based on UCNPs,UCNPs@ZnxCd1-xS/TiO2 composite catalytic nanostructure has been prepared by an AA-[Zn?OH?4]2-amorphous layer conversion strategy combined with hydrothermal ion exchange process.The sample showed good performance of active oxygen production?·OH,1O2,etc.?under the irradiation of near infrared light?NIR?and simulated sunlight.The results of cell experiments indicated that the composites had good biocompatibility and certain killing effect of tumor cells.Interestingly,we found that AA-[Zn?OH?4]2-amorphous composite had high reaction activity on its own,which can be used as a hard template to design AA-[Zn?OH?4]2-/Ag composite nanostructures.The favorable antibacterial effect on Escherichia coli and Staphylococcus aureus showed the great potential of AA-[Zn?OH?4]2-/Ag in antibacterial field. |
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