The Electrochemical H₂O₂ Sensors Based On Low Dimensional Carbon/noble Metal Composites

Hydrogen peroxide?H₂O₂?is an important material of industrial process,which has been widely used in many important research fields and industrial production processes,such as biological medicine,textile printing,industry manufacturing and so on.However,the discharging of H₂O₂ solution with high concentration of will seriously damage the environment due to its strong oxidizability.Moreover H₂O₂ is a kind of intermediate product of enzymatic reactions of proteases in human body,and acts as an important role in normal physiological reactions.Therefore,the accurate detection of H₂O₂ concentration is of great significance.Among H₂O₂ detection technologies,the electrochemical method takes the advantages of low detection limit,fast response and low cost,becoming a research hotspot in the field of academic research and industrial process.The sensitive material is the key factor of the sensitivity of electrochemical H₂O₂ sensors.Hence,the development of novel electrode materials is of great requirement to enhance the detection limit,linear range and selectivity of electrochemical H₂O₂ sensor.The rapid development of micro-nano functional materials bringsa opportunity for the development of high-performance electrode material.Among many sensitive materials,noble metals exhibit excellent electrocatalytic activity and electron transport properties for H₂O₂,which is beneficial for the development of high-performance electrochemical H₂O₂ sensor.However,the development of H₂O₂sensors based on noble metals has been limited by the high price and the agglomeration of metal nanoparticles.In recent years,the emerging low-dimensional carbon materials with unique physical and chemical properties attract widely attention of many researchers.Their large specific surface area is beneficial for loading active substances and providing more active sites for electrochemical reactions.Furthermore,the higher electron mobility can accelerate the transfer of charge during electrochemical reactions.Therefore,the composition of low-dimensional carbon and noble metal nanomaterials is an effective method to improve the sensitivity of electrochemical H₂O₂ sensor.This dissertation mainly focuses on following research:?1?A simple and green method for preparation of Au nanoparticles by reduction of HAuCl₄ using carbon nanodots as the reducing agent is reported.The carbon nanodots were prepared by a green method as well,using hydrothermal treatment of grass.It is observed that Au nanoparticles show obvious electrochemical catalytic ability for reduction of hydrogen peroxide,leading to its application of a high-performance non-enzymatic hydrogen peroxide sensor.The hydrogen peroxide sensor based on Au nanoparticles was made,with the detection limit at 23.0?M and linear range between 0.1–160.0 mM.?2?AgreenmethodhasbeendevelopedforpreparationofAg nanoparticles/reduced graphene oxide?AgNPs/rGO?nanocomposites by infrared light irradiation.The characterizations indicate the successful preparation of AgNPs/rGO nanocomposites.Most importantly,AgNPs/rGO nanocomposites exhibit excellent electrocatalytic activity for reduction of H₂O₂,leading to a high-performance non-enzymatic H₂O₂ sensor with linear detection range and detection limit about 0.1 mM to 140.0 mM?r=0.9896?and 3.0?M,respectively.?3?Ag nanocubes-reduced graphene oxide?AgNCs-rGO?nanocomposite was successfully prepared by an in situ synthesis method,in which AgNCs were loaded onto the surface of rGO during the formation of AgNCs in an ethylene glycol solution.Characterization by X-ray diffraction,UV-Vis spectroscopy,and scanning electron microscopy indicated the successful preparation of the AgNCs-rGO nanocomposite.Most importantly,the AgNCs-rGO nanocomposite exhibited excellent electrocatalytic activity for the reduction of H₂O₂,leading to a high-performance non-enzymatic H₂O₂ sensor with a linear detection range and detection limit of approximately 0.1 mM to 70.0 mM?r=0.999?and 0.58?M,respectively.Our present work provides a new and highly efficient method for fabricating high-performance electrochemical sensors.