Mechanistic Insight into the Conversion Chemistry between Au-CuO Heterostructured Nanocrystals Confined inside SiO2 Nanospheres

Abstract

By taking advantage of a nanospace-confined nanocrystal conversion protocol via high-temperature solid-state reaction within the SiO2 nanosphere, an in-depth study was conducted into the unique transformation behavior of the Au-CuO heterostructured nanocrystals (HNCs), which was discovered during the oxidative annealing of the embedded AuCu alloy nanocrystal (NC). The type of heterojuction structure of the oxidized AuCu NCs, between core@shell and heterodimer, could be determined by modulating either the annealing temperature (Tann) or Cu contents (Pcu) in AuCu NCs; Au@CuO was generated only either at low temperature (Tann ≤ 250 °C) or with very low Cu contents (Pcu = 2.1), whereas the Au/CuO heterodimer was obtained as a major product in most of the cases at relatively high heat treatment (>250 °C). The systematic investigation of the conversion between HNCs could elucidate the distinct evolution pathway of the Au/CuO heterodimer via the kinetically accessed Au@CuO, revealing the escaping motion of the e...