Nanoelectronics based on truly two-dimensional materials has become a reality in the past few years. Due to its extraordinary electronic and mechanical properties, graphene has been investigated as prototype 2D material. However, the absence of a band gap and the difficulty to open a sizable one is defining the limits for the application of graphene as semiconductor substitutes. Alternative 2D materials are required, and available in the much more general class of 2D materials beyond graphene.