“…[6,7] In the field of heterogeneous catalysis, the superior performance of the catalysts with yolk-shell structures is believed to be highly associated with the freely movable core catalysts, and the hollow space between the core and shell, which provides a good environment for the catalytic reaction. [8] Various methods have been developed to prepare yolk-shell structured materials, including selective etching or dissolution, Ostwald ripening, the ship-in-bottle method, soft template assembly, galvanic replacement and the Kirkendall diffusion. [9][10][11] However, many steps are involved in most of these methods, which make them timeconsuming, tedious, and/or costly.…”