Modification And Application Of A New Two-dimensional Material Black Phosphorus

Following the discovery of the extraordinary properties of graphene,a tremendous interest has grown towards other layered two-dimension materials.Black phosphorus?BP?is a new“star”two dimensional material.Black phosphorus has been extensively studied,due to its unique optoelectronic properties such as the tunable direct bandgap?change from 0.3 eV to 2.0 eV as the thickness becomes thinner?,response to near infrared light,excellent saturation absorption performance,high carrier mobility,high biocompatibility.The research shows that it has great potential for research and application in the fields of nonlinear optics,flexible intelligent optoelectronic devices,photoelectric detection and biomedicine.Although black phosphorus has many excellent properties,it is very active and easily degrades once it exposed into ambient condition.The research and application of black phosphorus often encounter complex environment,which restricts the study of black phosphorus to a great extent.Therefore,it is particularly important to achieve the stable presence of black phosphorus in the environment.In order to solve this problem,the main way is to modify black phosphorus,so that the black phosphorus is"passivating"so as to improve its stability.Around the modification of black phosphorus,the main contents of this paper include the following aspects:1.We reported on the synthesis of high quality bulk selenium?Se?-doped black phosphorus?BP?crystals using a mineralizer assisted gas-phase transformation in a mild growth condition and employed a liquid phase exfoliation approach to obtain few-layer?FL?Se-doped BP nano-sheets from the bulk counterpart.We experimentally found that FL Se-doped BP shows enhanced optical saturable absorption with longterm stability.We also studied the transistor performance of few-layer BP FET.2.Micromechanical cleavage was employed to achieve the few-layer BP.the use of metal-ion modification to enhance both the stability and transistor performance of BP sheets is described.Ag+spontaneously adsorbed on the BP surface via cation–?interactions passivates the lone-pair electrons of P thereby rendering BP more stable in air.Consequently,the Ag+-modified BP FET shows greatly enhanced hole mobility from 796 to 1666 cm² V^-1 s^-1 and ON/OFF ratio from 5.9×10⁴ to 2.6×10⁶.3.Small interfering RNA?siRNA?nanocarriers system was constructed with black phosphorus quantum dots?BPQDs?for the first time.we reported the engineering of polyelectrolyte polymers coated BPQDs-based nanocarriers to deliver siRNA into human ovarian teratocarcinoma PA-1 cells.Compared to the commercial delivery reagents,superior transfection efficiency of BP-QD?92.7%?was detected.The expression of the LSD1?lysine-specific demethylase 1?mRNA in PA-1 cells was significantly suppressed by BP-QDs-LSD1 siRNA complex.The combination treatment of BP nanodots-LSD1 siRNA complex with NIR light could inhibit the cell growth rate by more than 80%.