Transmission electron microscopy finds plenty of room on the surface

The atomic features of materials' surfaces have fundamental importance for applications in numerous fields, such as heterogeneous catalysis, energy conversion and thin-film growth. Now transmission electron microscopy (TEM) and affiliated techniques have thoroughly revolutionized many disciplines of natural sciences, and are becoming some of the best solutions for surface exploration. In this Perspective, we try to summarise the important progress in surface elucidation by applying the state-of-the-art TEM, which covers (1) from the essential features of oxides to their dynamic behaviors, and the interactions between surfaces and gases; (2) the visualization of emerging materials from zero-dimensional single atoms to two-dimensional materials, and the development towards an ultimate integration of three-dimensional surfaces. Plenty of room has been made for TEM exploration of a material's surface, and the surface-integral frontiers are being pushed further.