Asymmetry is a key structural feature in natural systems and allows for self-organization and unidirectionality of chemical transformations. JANUS BI aims at developing an innovative protocol for the production of 2D materials bearing different functionalities on the two opposite sides. The challenge is to implement the full process in the liquid phase and thus not resorting to solid phase transfer techniques, which is the current state-of-the-art. With this new method, Janus 2D material colloidal inks can be directly produced and used as they are, or for further solution processing of thin-films and/or more complex architectures. The core of the project is the challenging protocol proposed, which rely on the versatility of liquid phase exfoliation (LPE) of 3D crystalline powders of intrinsically layered species to produce 2D material inks and on the large availability of chemical functionalization approaches for 2D materials, both aspects being soundly mastered by the PI of JANUS BI. A first exfoliation produces quasi-2D nanosheets, which are a-selectively functionalized with bulky groups so as to completely cover the exposed faces. The functionalized quasi-2D objects are then subjected to further LPE, providing single-faced functionalized 2D materials. A second functionalization step is forced to happen on the un-covered face, due to the steric hindrance of the pendant functionalities present on the other. The setting-up of a similar protocol requires a tight control over the nanochemistry and nanomorphology of the substrates employed, resulting in a substantial gain of knowledge in controlled functionalization processes for 2D colloids. Once the guidelines for its successful implementation are identified, the development of a whole library of Janus 2D inks is enabled and many further goals can be targeted, which are here exemplified by the construction of self-assembling superstructures/interfaces and of photoactive and photocatalytic nanosystems.