Lanthanide-Coordinated Black Phosphorus

Black phosphorus (BP) possesses unique physical properties and, owing to its intrinsic instability, the proper surface and chemical coordination is the key point in many applications. Herein, a facile and efficient surface lanthanide-coordination strategy based on lanthanide (Ln) sulfonate complexes is designed to passivate and functionalize different BP-based nanostructures including quantum dots, nanosheets, and microflakes. By means of Ln–P coordination, the lone-pair electrons of phosphorus are occupied, thus preventing oxidation of BP, and the LnL₃@BP exhibits excellent stability in both air and water. Furthermore, accompanied by the original photothermal performance of BP nanostructures, the Gd-coordinated BP has high R₁ relativities in magnetic resonance (MR) imaging, and other Ln (Tb, Eu, and Nd) coordinated BP structures exhibit fluorescence spanning the visible to near-infrared regions. Not only is LnL₃ surface passivation an efficient method to enhance the stability of BP, but also the MR or fluorescence derived from lanthanide ions extends the application of BP to optoelectronics and biomedical engineering.