Optical Signatures of Phosphorene Chemical Evolvement in Liquid Environment

Abstract

Phosphorene possesses a unique combination of physical and chemical properties, including tunable direct bandgap, anisotropic electronic and optical properties. However, application of phosphorene is hampered by its fast degradation under ambient conditions. It is believed that H2O and O2 play key roles in the instability of phosphorene, but their exact contributions have not yet been completely understood in experiment. Herein, a technique of probing the mechanism of phosphorene oxidation through the evolvement of its photoluminescence spectra in a liquid suspension is introduced. With the addition of H2O2, the photoluminescence intensity of the suspension surprisingly increases, indicating a passivation effect due to the formation of phosphorene oxide, which is also verified by Raman spectroscopy. In contrast, direct addition of H2O leads to irreversible and rapid degradation as shown by the quenching of photoluminescence. Furthermore, monolayer phosphorene suspension photoluminescence at 2.17 eV is obtained by completely eliminating effects from contaminations, substrate strain, dielectric substrate, and oxidation of samples. Solvent protection in combination with the optical probing method provides an effective approach in investigating the chemistry of active materials like phosphorene. Phosphorene has great potential in the range of sensing applications including high‐resolution H2O2 and humidity sensors.