Liquid Phase Preparation Of Black Phosphorus Nanosheets And Its Application In Heavy Metal Ions Detection

Environmental pollution is a serious threat to human health and economic development.The heavy metal pollution of water has attracted more and more attention due to its hazardous and difficult to eliminate features.Traditional methods for detecting heavy metal ions all face the disadvantages of high cost and complicated equipment.The sensor and electrochemical method have attracted significant interest due to low cost,simple and efficient.But both detection methods put forward higher requirements for sensor materials.The emergence of two-dimensional materials provided new directions.In 2014,Prof.Zhang first used black phosphors to prepare FETs.In addition to the large specific surface area and conductivity of traditional two-dimensional materials,black phosphorus also has a direct band gap,which can be used directly in the field of semiconductor manufacturing.Our study also found that black phosphorus does not degrade under the ambient of water,which has prompted us to apply black phosphorus to the field of heavy metal detection.The following research is done in this paper:First,the nanoscale films with large transverse size and thickness were prepared by the liquid shear peeling method.The morphology of the nanoscale films at different preparation time,different solvents and different centrifugal rates was investigated.The Raman,scanning electron microscopy,and transmission electron microscopy were used to characterize the prepared black phosphorus nanoscale.A mathematical model for preparation of black phosphorus nanosheets based on soya-bean milk machine is calculated and discussed.Based on p-type semiconductor properties of black phosphorus,metal ion sensor was fabricated using black phosphorus nanosheets as substrate materials and MEMS processing technology.The concentration of metal ions and ions is detected in the water by detecting changes in the resistance of the sensor.The detection concentration of the sensor ranges from 10-~6 mol/L to 10-~2 mol/L,and it has a good detection effect for different metal ions.In order to eliminate the interference of water on the sensor,we did the humidity comparison experiment.The experimental results show that the resistance of the sensor decreases with the increase of humidity,which is the opposite of the positive correlation between the metal ion concentration and the sensor resistance.Finally,we,for the first time,the black phosphorus nanosheets as modified material of electrode to detect metal ions.According to the different combination of the black phosphorus nanoscale and nafion,two different modified electrodes were constructed as sandwich modified electrodes and plum pudding cake modified electrode,respectively.The modified electrode was studied under different parameters.Under the appropriate parameters,the single metal ion solution and the mixed metal ion solution were tested,all have high sensitivity and linearity,and the detection range is wide,the detection limit can reach10-~8 mol/L.The actual sample collected was tested to verify the actual application effect.