Stable Aqueous Dispersions of Optically and Electronically Active Phosphorene

A method of preparing few-layer phosphorene, said method comprising:

• providing a composition comprising a black phosphorus starting material, at least one amphiphilic surface active component and deoxygenated water;
• sonicating said composition to provide a deoxygenated aqueous medium comprising exfoliated phosphorous nanomaterials;
• centrifuging said aqueous medium to provide a supernatant component comprising a polydisperse population of planar few-layer phosphorene nanomaterials comprising mono-, bi-, and n-layer few-layer phosphorene nanosheets, wherein n is an integer selected from 3- about 6;
• and
• separating said few-layer nanomaterials into two or more separation fractions comprising a subpopulation of few-layer phosphorene nanosheets comprising a surface area, each said fraction comprising monolayer phosphorene nanosheets, bilayer phosphorene nanosheets and trilayer phosphorene nanosheets, or combinations thereof, said separation comprising centrifuging said few-layer phosphorene nanomaterials in a deoxygenated fluid medium comprising a density gradient for at least one of a time and at a rotational rate sufficient to provide said separation fractions.