Shell-adjustable hollow ‘soft’ silica spheres as a support for gold nanoparticles

Hollow silica spheres composed of a 'soft' nanosheet network exhibit a large surface area and pore volume and are used here as a support for gold nanoparticles. The nanosheet morphology changes upon binding of gold nanoparticles and facilitates their fixation in the shell. The gold nanoparticles remain well dispersed in the shell even after heat treatment at 500 °C. It is also possible to control easily the loading ratio of gold in the flake-shell sphere by varying the quantity of chloroauric acid added during the preparation. The stably confined but accessible gold nanoparticles in the flake-shell sphere show high performance for the catalytic reduction of nitrophenols with high conversion and good reusability. This new composite structure could also be useful for various other catalytic processes.