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

TLDR

These nanostructures hold strong potential for blue‑light emitting devices, environmental remediation, drug delivery, energy storage and conversion, and sensors. The study proposes a weak‑acid selective etching strategy to fabricate oxide‑based hollow nanoparticles using core/shell metal/oxide templates. The method employs core/shell nanostructures of active metal/oxide nanoparticles as sacrificial templates for the etching process. The authors achieved ZnO‑based hollow nanoparticles with diameters below 50 nm and shell thicknesses under 6 nm, tunable crystal sizes, controllable elimination and reconstruction of internal metal‑semiconductor interfaces, and dramatic performance gains, including over 3‑order‑of‑magnitude blue luminescence enhancement for pure ZnO HNPs and markedly improved photocatalytic activity for noble‑metal/ZnO HNPs.

Abstract

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.