Alkylaminosilane-assisted simultaneous etching and growth route to synthesise metal nanoparticles encapsulated by silica nanorattles.
An efficient and facile method to synthesise silica nanorattles with multiple noble metal (Au and Pd) cores by a simultaneous etching and growth route has been developed. In this strategy, a dual-functional alkylaminosilane was adopted to form the middle layer of solid organic-inorganic hybrid solid-silica spheres (HSSSs), which enabled the selective etching of the middle hybrid layer of the HSSSs and the in situ growth of metal nanoparticles (NPs) inside the cavity in a one-step hydrothermal reaction. By adjusting the pH values of the reaction system, the metal NPs could be grown exclusively inside the silica nanorattles, resulting in a high atomic utilisation of the noble metals. The size and number of Au cores were tunable by manipulating the initial concentration of HAuCl(4). The prepared silica nanorattles with Au cores were successfully applied to the catalytic reduction of 4-nitrophenol and showed high catalytic activity and cycle stability. Catalysts with multiple gold cores exhibited superior catalytic activity to those with a single gold core, probably because they possess smaller Au cores with greater surface area.