Long-term can-sealing protection: a stable black phosphorus nanoassembly achieved through heterogeneous hydrophobic functionalization.

Black phosphorus (BP), a promising 2D material, has sparked a research boom in various areas, while its fatal atmospheric instability seriously obstructs the progress of most practical applications. To realize the novel scalable concept of can-sealing protection, the selective deposition of a series of hydrophobically- or hydrophilically-functionalized Al2O3 nanostructured capping layers has been successfully achieved to seal the top surface of the exfoliated BP flake assemblies on Ag-patterned substrates. The hydrophobic Al2O3 columnar capping is evidenced as the most promising candidate to provide comprehensive protection against the severe rapid degradation of pristine BP even under a very high-humidity environment (RH = 85%) for a long period of time. The present work provides valuable insight into the distinct anisotropic degradation of the sealed BP flake assemblies evidently induced by the deposited hydrophobically- or hydrophilically-functionalized Al2O3 capping.