Selective Etching Strategy Research Articles

Hollow/Rattle-Type Mesoporous Nanostructures by a Structural Difference-Based Selective Etching Strategy

A novel "structural difference-based selective etching" strategy has been developed to fabricate hollow/rattle-type mesoporous nanostructures, which was achieved by making use of the structural differences, rather than traditional compositional differences, between the core and the shell of a silica core/mesoporous silica shell structure to create hollow interiors. Highly dispersed hollow mesoporous silica spheres with controllable particle/pore sizes could be synthesized by this method, which show high loading capacity (1222 mg/g) for anticancer drug (doxorubicin). Hemolyticity and cytotoxicity assays of hollow mesoporous silica spheres were conducted, and the synthesized hollow mesoporous silica spheres with large pores show ultrafast immobilization of protein-based biomolecules (hemoglobin). On the basis of this strategy, different kinds of heterogeneous rattle-type nanostructures with inorganic nanocrystals, such as Au, Fe(2)O(3), and Fe(3)O(4) nanoparticles, as the core and mesoporous silica as the shell were also prepared. This strategy could be extended as a general approach to synthesize various hollow/rattle-type nanostructures by creating adequate structural differences between cores and shells in core/shell structures in nanoscale.

ZnO-Based Hollow Nanoparticles by Selective Etching: Elimination and Reconstruction of Metal−Semiconductor Interface, Improvement of Blue Emission and Photocatalysis

A weak acid selective etching strategy was put forward to fabricate oxide-based hollow nanoparticles (HNPs) using core/shell nanostructures of active metal/oxide nanoparticles as sacrificial templates. ZnO-based HNPs, including pure ZnO, Au/ZnO, Pt/ZnO, and Au/Pt/ZnO HNPs with diameter below 50 nm and shell thickness below 6 nm has been first achieved at low temperature. The diameter, thickness, and even sizes of ZnO and noble metal ultrafine crystals of HNPs can be well adjusted by the etching process. Synchronous with the formation of HNPs, the internal metal-semiconductor interfaces can be controllably eliminated (Zn-ZnO) and reconstructed (noble metal-ZnO). Excitingly, such microstructure manipulation has endued them with giant improvements in related performances, including the very strong blue luminescence with enhancement over 3 orders of magnitude for the pure ZnO HNPs and the greatly improved photocatalytic activity for the noble metal/ZnO HNPs. These give them strong potentials in relevant applications, such as blue light emitting devices, environment remediation, drug delivery and release, energy storage and conversion, and sensors. The designed fabrication procedure is simple, feasible, and universal for a series of oxide and noble metal/oxide HNPs with controlled microstructure and improved performances.