Research On Multi-substrate Hydrogen Sulfide Electrochemical Sensor Based On Screen Printing Technology

Screen printing electrode can be widely used mainly thanks to times development and the progress of science and technology,scientific research personnel through the design of different shape of electrode,improvement of printing operations process,using chemical methods to modified electrode modification,makes the screen printing electrode detection range,sensitivity and speed to a new level.Hydrogen sulfide(H₂S),as a common toxic pollutant in life and industry,poses a potential threat to human body and the environment due to its corrosive,toxic and reductive properties.However,it is difficult to realize the sensitive,rapid and convenient continuous monitoring of H₂S in liquid and gas with the existing detection techniques.Therefore,it is of great significance to develop a screen printed electrochemical sensor which can be used normally in different environments.Carbon nanotube(CNT)is a kind of material with good physical and chemical properties,and it is also an excellent candidate material for doping and post-growth treatment.Among them,the diameter of multi-walled carbon nanotubes was usually less than 100 nm,the carrying rate was up to 10⁹A·cm^-2,and the bending strength was 14.2±8.0 GPa.Macroscopically,multi-walled carbon nanotubes have excellent electrical properties,such as high electron mobility,conductivity and field-effect mobility.If used together with other materials can significantly improve the physical and chemical properties of the material,so it is widely used in various research fields.This article first to make a study of screen printing technology developed can be applied to a variety of printing process of different support materials,by the PET material as the electrode base,the use of multi-walled carbon nanotubes by modifying work electrode surface modification,the p H and the detection of potential conditions under the condition of optimized,in liquid phase and gas phase composition of H₂S in the actual detection.The main research work is as follows:(1)Design a universal electrode pattern and printing template.For materials with different mechanical strength,machine printing and manual printing are used respectively to develop a flexible screen printing electrode(SPE).The SPE surface electrode morphology was characterized by SEM,XRD,cyclic voltammetry(CV),electrochemical impedance(EIS)and a series of characterization methods.The results show that the printing ink is uniformly dispersed on the surface of the electrode substrate material and the crystal shape is good.The sensor has good electrical conductivity and can be used in the actual electrochemical detection.(2)A modified electrode(MWCNT-SPE)was obtained by modifying the surface of the SPE working electrode with MW-CNT nafion and water solution as modificator using PET material as the substrate.The surface morphology of the modified working electrode was characterized by SEM technique.Under the premise of optimizing the p H and detection potential of the electrolyte solution,the response performance of SPE and MWCNT-SPE to hydrogen sulfide in the solution was detected by using the chronoamperometry method(i-t).The results show that the MWCNT-SPE electrode has a wide linear range(0.5?mol/L-7.24mmol/L)for hydrogen sulfide in liquid and a response to as low as 0.5?mol/L for sodium sulfide in liquid after modification of 3?L(3 wt%)carbon nanotube solution in p H 0.9 PBS solution with a detection potential of 0.1V.In addition,the sensor has good anti-interference and selectivity to common interfering substances in sewage.The prepared glove substrate screen printing sensor can be used for real-time monitoring of hydrogen sulfide in liquid.3)Following the screen printing process in the previous chapter,the electrode pattern was manually printed on the flexible PET hydrophobic tape,and multi-walled carbon nanotubes were used as decorations to construct the tape electrode that could be attached to a variety of test materials.A continuous test method is designed which can simply connect the electrochemical test terminal and gas environment.According to the modification methods and test conditions in the previous chapter,the response performance of C-TAPE and MWCNT-TAPE to H₂S was tested respectively.Under the optimized conditions of electrode electrolyte,gas injection mode,electrode adhesion material and electrode folding times,the hydrogen sulfide gas response of the two electrodes was detected by chronoamperometry method(i-t).The results showed that when hydrogen sulfide gas was injected in the direction opposite the electrode and the electrode adhered to the surface of the PET plate,the actual detection limit of MWCNT-TAPE electrode for hydrogen sulfide gas was as low as 5 ppm,and it had a good linear response in the range of 5-130 ppm.The electrodes can be used for up to 30 days in sealed storage.In addition,the electrode has good flexibility and anti-interference,which has a certain value in the field of gas detection.