Silica@Carbon mesoporous nanorattle structures synthesised by means of a selective etching strategy

A facile route for the fabrication of nanorattles composed of tunable silica spherical nanoparticles confined inside mesoporous carbon shells is presented. The synthetic strategy involves several steps: i) the synthesis of solid core/mesoporous shell silica microspheres, ii) the infiltration of the mesoporous shell with a carbon precursor and its conversion to carbon through a carbonization process and iii) the controlled dissolution of the silica by means of a soft etching agent (NaOH 1.5 M). Following this procedure, a variety of Silica@Carbon nanorattles of diameter ∼ 430 nm is produced. The diameter of the silica core can be uniformly tuned between 330 nm and 160 nm by varying the etching time in a range of 2 h–44 h. The rate constant for the dissolution process of the silica core was estimated to be k ≈ 1.2 × 10− 10 g cm− 2 s− 1. These nanorattles have a high BET surface area and a large pore volume, depending on the amount of silica in the composite.