  Two-dimensional (2D) materials family with its many members and different
properties has recently drawn great attention. Thanks to their atomic thickness
and smooth surface, 2D materials can be constructed into heterostructures or
homostructures in the fashion of out-of-plane perpendicular stacking or
in-plane lateral stitching, resulting in unexpected physical and chemical
properties and applications in many areas. In particular, 2D
metal-semiconductor heterostructures or homostructures (MSHSs) which integrate
2D metals and 2D semiconductors, have shown great promise in future integrated
electronics and energy-related applications. In this review, MSHSs with
different structures and dimensionalities are first introduced, followed by
several ways to prepare them. Their applications in electronics and
optoelectronics, energy storage and conversion, and their use as platforms to
exploit new physics are then discussed. Finally, we give our perspectives about
the challenges and future research directions in this emerging field.
