Yolk-shell or yolk-in-shell nanocatalysts? A proof-of-concept study

The development of advanced nanocatalysts, especially those integrating high catalytic activity and recyclability, is a rapidly developing field in nanocatalysis and nanomaterials science. Yolk-shell nanostructures comprising a noble metal nanoparticle as the movable core inside a hollow cavity have been proven as promising nanocatalysts towards various catalytic reactions. Herein, we developed a new class of yolk-in-shell nanocatalysts. For the proof-of-concept study, Au@mesoporous carbon (Au@C) yolk-in-shell nanostructures, where a single Au nanoparticle is incorporated into the shell of a mesoporous carbon hollow nanosphere, have been synthesized. In comparison with Au@C yolk-shell nanocatalysts with a single movable Au nanoparticle inside the hollow cavity of mesoporous carbon, Au@C yolk-in-shell nanocatalysts show incredibly improved catalytic activity and recyclability. The concept of developing yolk-in-shell nanocatalysts will be instructive for preparing robust nanocatalysts towards advanced nanocatalysis.