| The present situation of nitrite in water environment is harmful to the environment and human health.It is very important to study the rapid and sensitive detection method of nitrite.This study reduces the cost of electrochemical sensors and makes them convenient for real-time monitoring,so that it has the high sensitivity and low detection limit of existing research,and provides faster and more convenient analysis of nitrite in groundwater.The monitoring methods of this kind will pave the way for further research on electrochemical methods.In this paper,two novel electrochemical sensors based on laser-induced graphene were constructed for the detection of nitrite in water environment.The results are as follows:（1）Based on the Laser micromachining system,laser-induced Graphene（LIG）electrode was prepared,on which glycine-modified carbon nanoparticles（Gly-C）and gold nanoparticles（Au NPs）were modified,and Gly-C/Au NPs/LIG was constructed for the detection of NO2-.Field emission scanning electron microscopy（SEM）and Fourier transform infrared spectroscopy（FT-IR）analysis results show that the successful loading of Au NPs and Gly-C and the successful introduction of-NH2and-COOH.The electrochemical performance of LIG was improved by improving the catalytic performance of the electrode and the adsorption capacity of NO2-.Au NPs had a good catalytic effect on the electrochemical oxidation of NO2-,and Gly-C could adsorb more NO2-on the surface of the electrode.Under optimized experimental conditions,the linear range of the sensor is 7μg/L～700μg/L and 700μg/L～1.05 mg/L,and the detection limit is 0.84μg/L.The sensor has good reproducibility and stability,and can be used in actual detection.（2）Au-Ni-Rh/LIG was prepared by the modification of Au-Ni-Rh tri-metal composite on LIG by a simple and rapid one-step electrodeposition method,which was used for the determination of NO2-.Field emission scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray electron spectroscopy（XPS）and contact Angle（CA）were used to analyze the interface morphology,metal morphology,modified material valence state,hydrophilicity and hydrophobicity of LIG electrode.Electrochemical impedance spectroscopy（EIS）was used to characterize the electron transfer impedance of LIG electrode.The three metals were deposited on the graphene on the surface of LIG at the same time to improve the electrochemical activity of the sensor in terms of catalysis and increasing the electrode surface area,respectively.The linear range of the sensor is 14μg/L～14 mg/L and the detection limit is4.2μg/L under the optimal experimental conditions.The sensor has good anti-interference and repeatability,and can be used for actual water sample detection.In this paper,the electrochemical performance of the sensor was improved from two different perspectives of adsorption and catalysis respectively,providing a new idea for the electrochemical detection of nitrite.The sensor can be used for practical detection and has advantages in field detection due to its low cost and portability. |
