Preparation Of Porous Silicon Electrode And Electrochemical Detection Of Bisphenol A

Bisphenol A which is widely presented in the food packaging materials, has been potentially dangerous.It has been the key factor in food safety. The paper develops a method of detecting Bisphenol A in food packaging materials through the study of electric catalysis of Bisphenol A on the porous silicon electrode.Monocrystalline silicon wafer which has a large specific area, prepares a porous silicon electrochemical sensor through electrochemical etching. So it accommodates biological molecules well, which can improve the detection sensitivity. Silicon-based material has good biocompatibility and electronic devices compatibility, However, the porous silicon is less stable in the air.To improve the stability of the porous silicon,we cover a layer of carbon on the top of the porous silicon, then modify gold nanoparticles on porous silicon electrode. At last, a specific electrochemical signal comes out. We are able to detect BPA in food packaging materials through this signal.Pulsed Electrochemical etching method has been used in this experiment. The material is a singlesided polished p-type single-crystal silicon chip which is placed in the acetone solution and subjected to ultrasonic treatment, at the same time, we rinse it with purified water. We use hydrofluoric acid (48%), ethanol (98%) whose volume ratio is 3:1 as electrolyte and Pulsed Electrochemical Corrosion System controlled by computer to produce the porous silicon sample.Electrochemical corrosion goes on under constant current state of 30mA in 450 seconds, and in the mixed electrolyte solution constituted by the HF acid and ethanol. NJ-320 constant locator has been used as power to control electrochemical corrosion current. After electrochemical corrosion,the porous silicon is rinsed in ethanol solution, and then dried by passing a stream of nitrogen. Place the above new etching porous silicon in the ozone oxidation for 20 minutes, through the oxidation treatment, we can obtain high purity silicon oxide layer. Fill the porous silicon pores with furfuryl alcohol acetate, then put the sample into a tube furnace, and the temperature maintains at 70℃.After 16 hours, furfuryl alcohol starts process of thermal polymerization under acid-catalyzed.The sample has been carbonized under the nitrogen protected for 5 hours under the temperature of 700℃ C, and ultimately carbon C/PSI diaphragm emerges. The gold thin layer deposits on porous silicon wafer modified carbon by electrochemical deposition. The porous silicon, and a platinum counter electrode respectively represent the anode and cathode. Pour gold chloride acid solution whose concentration is 0.001% to the etching trough. Electrodeposition goes on for 10 minutes under 5mA constant current, then rinse the Au-C/Psi generated after electrochemical deposition with distilled water and ethanol, finally we get Au/C/Si electrode.Characterize the electrochemical properties of BPA on porous silicon electrodes through cyclic voltammetry. Investigate the choice of buffer solution, the pH of buffer solution, adsorption time, scan rate on the electrochemical response of BPA on the electrode. Under optimized conditions, concentration of BPA detecting linear relationship ranges from 5.0 ×10-8mol/Lto 1.0 ×10-5mol/L, the detection limitation is 3.459 ×10-8 mol/L.Recovery results in the range of 82.3%-104.1%, indicating that the method used to detect BPA in food packaging materials is feasible.