Waterproof molecular monolayers stabilize 2D materials.
basic_science · Level V
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- Record sourced from PubMed, PMID 31575741.
- Also identified by DOI 10.1073/pnas.1909500116 and PMC identifier 6800348.
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Abstract
Two-dimensional van der Waals materials have rich and unique functional properties, but many are susceptible to corrosion under ambient conditions. Here we show that linear alkylamines <i>n</i>-C <sub><i>m</i></sub> H<sub>2<i>m</i>+1</sub>NH<sub>2</sub>, with <i>m</i> = 4 through 11, are highly effective in protecting the optoelectronic properties of these materials, such as black phosphorus (BP) and transition-metal dichalcogenides (TMDs: WS<sub>2</sub>, 1T'-MoTe<sub>2</sub>, WTe<sub>2</sub>, WSe<sub>2</sub>, TaS<sub>2</sub>, and NbSe<sub>2</sub>). As a representative example, <i>n</i>-hexylamine (<i>m</i> = 6) can be applied in the form of thin molecular monolayers on BP flakes with less than 2-nm thickness and can prolong BP's lifetime from a few hours to several weeks and even months in ambient environments. Characterizations combined with our theoretical analysis show that the thin monolayers selectively sift out water molecules, forming a drying layer to achieve the passivation of the protected 2D materials. The monolayer coating is also stable in air, H<sub>2</sub> annealing, and organic solvents, but can be removed by certain organic acids.