Stabilizing black phosphorus nanosheets via edge-selective bonding of sacrificial C molecules.

Few-layer black phosphorus (BP) with an anisotropic two-dimensional (2D)-layered structure shows potential applications in photoelectric conversion and photocatalysis, but is easily oxidized under ambient condition preferentially at its edge sites. Improving the ambient stability of BP nanosheets has been fulfilled by chemical functionalization, however this functionalization is typically non-selective. Here we show that edge-selective functionalization of BP nanosheets by covalently bonding stable C molecules leads to its significant stability improvement. Owing to the high stability of the hydrophobic C molecule, C functions as a sacrificial shield and effectively protects BP nanosheets from oxidation under ambient condition. C bonding leads to a rapid photoinduced electron transfer from BP to C, affording enhanced photoelectrochemical and photocatalytic activities. The selective passivation of the reactive edge sites of BP nanosheets by sacrificial C molecules paves the way toward ambient processing and applications of BP.