Intelligent metallic micro/nanomotors: From propulsion to application

Synthetic micro/nanomotors (MNMs) are a particular class of micrometer or nanometer scale devices that have controllable motion behavior in solutions through a transfer of various energies (chemical, optical, acoustic, magnetic, electric) into mechanical energy. MNMs are an attractive and cutting-edge research field in nanotechnology. These intelligent MNMs have shown great potential across various multidisciplinary fields due to their tiny size, controllable motion, and diverse functionalization. Over the years, various novel metals have played a significant role in this emerging nanotechnology. In this review, we introduce the fundamental theory of MNMs and the significance of metals in MNMs. Then, we systematically describe the relationship between the metal properties and the propulsion of MNMs, and we clarify the importance of metal in the applications of MNMs. Finally, to promote the development of intelligent and advanced MNMs, outlooks and opportunities of ideal metallic MNMs are further presented after the summary of the advantages and challenges of the current systems.