The Study Of Stability And Corresponding Applications Based On Liquid Exfoliated 2D Black Phosphorus

Black phosphorous(BP)is a unique layered p-type semiconducting material,composed of the picked layers held together via van der Waals interactions.Inspired by successful use of BP nanosheets in field-effect transistors,BP atomic layers have been attracting fast-growing interest in exploration of their novel optical and electronic properties.For mechanical exfoliation,the obtained BP nanosheets with clean surfaces display degradation under ambient exposure owing to reactions with water and/or oxygen,strongly limiting their applications.Considering the fast degradation of mechanical exfoliated BP,we produced the BP nanosheets in large quantities in a series of solvents,the choice of these solvents was based on their different surface tensions.Among the exfoliated BP nanosheets in the used solvents,the BP-GBL(γ-Butyrolactone)nanosheets show the fastest degradation,the BP-ACT(acetone)one displays the slowest degradation,and the BP-IPA(isopropanol)one lies between them.Here,based on the different BP nanosheets,solvent molecule and oxygen functional groups were absorbed on the surfaces of BP nanosheets,we expand the applications of liquid exfoliated BP nanosheets in the fields of supercapacitors,resistive random access memory and microwave absorption.Firstly,similar to the two dimensional restacked nanosheets of graphene and TMDs,restacking of ACT-exfoliated BP nanoflakes as flexible electrodes,efficient adsorption and desorption of ions between restacked BP nanoflakes during charging/discharging process should be expected for enhanced high-performance electrochemical energy storage.The fabricated BP all-solid-state supercapacitors(BP-ASSP)devices have revealed excellent performances,delivers a high stack capacitance up to 13.75 F/cm~3(45.8 F/g),outstanding mechanical flexibility and cycling stability,high energy density of 2.47 mWh/cm~3 and high power density of 8.83 W/cm~3.These results indicate a promise for application of liquid-exfoliated BP nanoflakes as flexible electrodes in high-performance in electrochemical energy storage devices.Secondly,during our investigations on the fabricated BP films with the different solvents exfoliated nanosheets,we noticed the different degree degradation on BP films.Thereby,we have focused our attention to the studies on the resistive switching of degraded BP films and its potential application in resistive random access memory devices.The BP films,show the solvent-dependent degradation upon ambient exposure,inducing the formation of an amorphous top degraded layer(TDL).With the TDL as an insulating barrier just below the Al electrode,the flexible BP memory devices exhibit bipolar resistive switching(BRS)behavior with a low switching voltages of±2 V,a high ON/OFF current ratio up to~3x10~5 and excellent retention ability over 10~5 s.Impressively,even with the BP films after ambient exposure for 3 months,the fabricated memory devices still exhibit excellent memory performance,a high ON/OFF ratio up to 10~4 can be still achieved,showing the environmental stability of the BP memory devices.Finally,we successfully fabricate porous reduced graphene oxide/black phosphorus(rGO/BP)composite aerogel,using a facile self-assembled process.We find that the BP nanosheets homogeneously distribute throughout the rGO 3D framework,and the interfaces between rGO and BP have multiform interconnections.Compared with pure rGO aerogel,the rGO/BP composite aerogel exhibit tremendously enhanced microwave absorption ability,and we get the minimum reflection loss value of-46.9 dB with the sample thickness of 2.53 mm.The superior microwave absorption property is demonstrated to stem from the interfacial polarization loss mechanism in which the multiform interface interactions between rGO skeleton and BP nanosheets play critical roles.