Study Of Sensing Performance Based On Nano-Structured Black Phosphorus

As a new single element two-dimensional?2D?layered material,black phosphorus?BP?has the properties of direct band gap,high hole mobility,and tunable band gap with the number of layers,making it widely used in optoelectronics,energy,sensors and other fields.Black phosphorus nanosheets and black phosphorus quantum dots are two nanostructures of black phosphorus.Nanosheets and quantum dots have quantum confinement effects and edge effects,making black phosphorus nanosheets and quantum dots promising to have superior performance to bulk black phosphorus us materials.Therefore,the rapid preparation of black phosphorus nanosheets and stable black phosphorus quantum dot materials to construct sensors has raised wide attention of researchers.In this paper,black phosphorus nanosheets and their quantum dots are main research objects,the two kinds of nanomaterials are synthesized by supercritical and passivation methods.Properties and structure of the samples were characterized by scanning electron microscopy?SEM?,atomic force microscopy?AFM?,transmission electron microscopy?TEM?,X-ray diffraction?XRD?,and X-ray photoelectron spectroscopy?XPS?,Raman spectrum.Experiments of sensor fabricated by these materials were further operated.The detailed research results are as follows:First,a thin layer of BP using supercritical carbon dioxide assisted ultrasonic rapid synthesis?5hours,typically 12 hours in the literature?has a size of a few microns and a thickness of a few nanometers.And for the first time,the sensing performance of black phosphorus nanosheets in liquid environment was studied.The non-enzymatic hydrogen peroxide?H₂O₂?based on few layer black phosphorus nanosheets was constructed by using the characteristics of black phosphorus nanosheets being oxidized by hydrogen peroxide.The sensor,which is one order of magnitude lower than the lower limit of detection of existing electrochemical sensors,reaches 1 x 10^-7M.Next,black phosphorus quantum dots?BPQDs?were prepared,and then stabilized BPQDs in solution by passivation with 4-nitrobenzene-diazonium?4-NBD?.The crystal structure,morphology and optical properties of stable BPQDs were investigated by TEM,AFM and Raman.The UV-visible?UV-Vis?absorption spectroscopy was used to study the pH sensing performance of stable BPQDs.The results show that the stable BPQDs can be used as sensors in alkaline solution,which exhibits excellent pH sensing performance.Our work broadens the way for new applications of BPQDs in aqueous solutions.Finally,black phosphorus quantum dots?BPQDs?dopamine sensors were constructed by UV-Vis spectroscopy.After the addition of dopamine?DA?,the initial UV-Vis absorption peak of BPQDs in aqueous solution was effectively quenched.The intensity of the absorption peak is proportional to the DA concentration,and the linear range is 1⁷0 nM or 1¹250 nM(the lowest concentration of human dopamine in urine and blood(5.7×10^-7 M and 1.6×10^-5 M)).The lower limit of detection of the sensor is 0.33 nM?pH 5⁹?.The black phosphorus quantum dot optical sensor has the advantages of high sensitivity,high selectivity,good stability,low cost,no toxicity,and can be used for highly sensitive detection of dopamine in human body.In summary,the black phosphorus nanosensor has excellent sensing performance for the objects in the above solution.These sensors have the advantages of wide linear detection range,high sensitivity,and ultra-low detection limit.Our work shows that black phosphorus nanostructured materials can be used as a high performance,simple and fast,ultra-sensitive sensor material?especially to detect substances in solution?,we believe that black phosphorus nanomaterial sensor can be further applied to human disease detection for people's lives,and technical support for people's health.