Two-dimensional coupling effects: From local electron density lowering to overall passivation of black phosphorous

Unravelling the mechanism of electronic state evolution is ultimately important when attempting to functionalize two dimensional (2D) materials through electronic state regulation. However, there is still a lack of understanding in how the individual local functionalized regions could influence the entire 2D-layered property. Herein, we report the observation of surface electronic behavior during these functionalization process when utilizing the electron-deficient aluminium ion (Al 3+ ) to passivate 2D black phosphorus (BP). Interestingly, the local electron density change in response to a certain functionalization can induce the periodic electron density gradient via inductive integration effect and spread over the entire 2D surface layer. Such 2D coupling effect is evidently supported by the combined investigation of in-situ / ex-situ experimental analysis and theoretical calculation, upon the model Al 3+ -BP modulating process. This work discloses the electron-level relationship between the individual and the whole during the functionalization process and therefore provides a direction for precise manipulation of electronic behavior in functionalized 2D materials.