Silica/titania sandwich-like mesoporous nanosheets embedded with metal nanoparticles templated by hyperbranched poly(ether amine) (hPEA)

Abstract

We here demonstrated a novel square silica/titania mesoporous nanosheet which was prepared with hyperbranched poly(ether amine) nanosheets (hPEA-NSs) as a template. TEM and SEM images reveal that the obtained nanosheets possess a large aspect ratio with the average edge length of 1–2 μm and thickness of ∼40 nm, respectively. Various metal nanoparticles such as gold, silver, and platinum can be embedded into these nanosheets with hPEA-NSs decorated with the corresponding nanoparticles as templates. These nanosheets possess a sandwich-like structure, which is comprised of amorphous SiO₂ as the inner layer, and the anatase TiO₂ as the outer layer determined by a cross-sectional STEM image and EDS mapping. Meanwhile, the obtained nanosheets are mesoporous with a high surface area (∼429 m² g⁻¹), and the SiO₂ inner layer can be removed by chemical etching with NaOH solution to obtain anatase TiO₂ nanosheet-like boxes embedded with gold nanoparticles (AuNPs). The photodegradation of Methyl Orange (MO) by the obtained nanosheets can be enhanced by the embedding of AuNPs owing to the localized surface plasmon resonance (LSPR) effect from AuNPs. The preparation of a silica/titania mesoporous nanosheet with hPEA-NSs as template is believed to provide a convenient and general method to produce various square inorganic mesoporous nanosheets with a large aspect ratio between edge length and thickness.