  Only a few of the vast range of potential two-dimensional materials have been
isolated or synthesised to date. Typically, 2D materials are discovered by
mechanically exfoliating naturally occurring bulk crystals to produce
atomically thin layers, after which a material-specific vapour synthesis method
must be developed to grow interesting candidates in a scalable manner. Here we
show a general approach for synthesising thin layers of two-dimensional binary
compounds. We apply the method to obtain high quality, epitaxial MoS2 films,
and extend the principle to the synthesis of a wide range of other materials -
both well-known and never-before isolated - including transition metal
sulphides, selenides, tellurides, and nitrides. This approach greatly
simplifies the synthesis of currently known materials, and provides a general
framework for synthesising both predicted and unexpected new 2D compounds.
