Phosphorene is a single atomic layer of black phosphorus (BP) with a puckered honeycomb structure. It has desirable properties such as a band gap of 1.5 eV, high tensile strain tolerance, potential for superconductivity through doping or strain, and ability to be an effective gas sensor. Phosphorene nanosheets can be exfoliated from BP using liquid-based exfoliation methods involving solvents like NMP under sonication or mechanical exfoliation using scotch tape.

1. Phosphorene
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2. Introduction
● Phosphorene is a single atomic layer of BP
● Black Phosphorus is comprised of 2D sheets that are vertically stacked with
respect to one another
● In-plane bonding in BP is due to sp3 hybridization, Due to the sp3
hybridization, phosphorene does not form atomically flat sheets like graphene
● They form a puckered honeycomb-structured layers. These layers are stacked
together by weak van der Waals forces.

3. ● The electronic band gap of phosphorene has been predicted to be 1.5 eV
● which is much higher than the 0.3 eV value of bulk BP
Structure of phosphorene: (a,b) side views from the zigzag and the armchair direction

4. (c) top view,
and (d) zoomed-in local atomic structure of the P-P bonding configuration

6. Liquid-based Exfoliation of BP
● Dispersion of BP in a preferable solvent followed by sonication
● The exfoliated nanosheets are collected by the centrifugation (about 30 mins)
method
● At the time of sonication, due to the fluctuations and shear forces, micro-and
nano-sized bubbles are produced.
● The solvent molecules, such as N-methyl pyrrolidone (NMP), intercalate
between the layers of BP and disperse the nanosheets within it.
● Large-scale exfoliation of phosphorene nanosheets should be anhydrous and
free of oxygen because of the chemisorption of O-atoms by P-atoms present
on the surface of BP nanosheets

7. Schematic representation showing the exfoliation of BP nanosheets.

8. Mechanical exfoliation (the Scotch tape
method)
● First a single layer BP nanosheet with a thickness of 0.85 nm is created with
the help of the scotch tape
● These nanosheets of BP are then transferred onto a Si/SiO2 substrate
● Then substrate is washed with acetone, isopropyl alcohol, and methanol in
order to remove the scotch tape residue
● The remaining part is treated thermally at 180℃ until the removal of the
solvent residues
● Finally, the required nanosheets are obtained
● Disadvantage: Low Yield

9. Atomic force microscopy image of a
monolayer phosphorene
Scotch Tape

10. Properties
● Desirable band gap
● Phosphorene-based thermoelectric devices can reach an energy conversion
efficiency of 15-20%
● Phosphorene can sustain tensile strains up to 27% and 30% in the zigzag and
armchair directions, respectively
● Phosphorene has been predicted to become superconducting with an
estimated transition temperature of 3-16 K driven by doping and biaxial strain
● It is also suggested to be a superior gas sensor due to its adsorption sensitive
surface

12. Refrences
● https://www.nature.com/articles/s41699-017-0007-5#Sec6
● https://pubs.rsc.org/en/content/articlelanding/2022/ma/d1ma01101d
● https://www.osti.gov/servlets/purl/1332445#:~:text=Phosphorene%20disting
uishes%20itself%20from%20other,1b).

13. THANK YOU!