Synthetic strategies for hollow particles with open holes on their surfaces

Hollow particles with open holes on their surfaces, which refer to hollow micro/nano spheres with open structures such as single holes or multi-holes on their surfaces, have attracted increasing interest over the past two decades. The strategies used to prepare these particles can be roughly classified into hard-templating, soft-templating and self-templating methods, according to the formation mechanisms of the hollow structures. Based on these categories, this review summarizes the strategies used for the preparation of such particles with a focus on the formation mechanisms of the open structures, followed by a brief discussion on their applications and future developments.