The Preparation Of Cu₂O/Ag Nanocomposite And Its Electrochemical Sensing Properties

Electrochemical sensors have the advantages of relatively simple structure,low cost,high sensitivity,and the ability for real-time monitoring.Therefore,they are widely used in health,chemical industry,coal,environmental protection and other fields for the detection of specific liquid,gas and other chemical substances.Silver（Ag）nanomaterials have been widely used in constructing electrochemical sensors because of their excellent electrochemical properties.However,due to the poor dispersion and low stability of standalone Ag nanoparticles,Ag nanocomposites is usually used for applications.Cu₂O is also available on electrochemical sensors because of its low cost,simple preparation,and suitable oxidation-reduction potential.Therefore,this work aimed at the fabrication of Cu₂O/Ag nanocomposites and their electrochemical sensing properties.A facile one-step method to obtain Cu₂O/Ag nanocomposites is developed and the corresponding H₂O₂electrochemcial sensor is fabricated.In addition,we have also discovered a phenomenon in which silver spiral nanoribbons are prepared by reduction of micron-sized Cu₂O particles.The preparation conditions,microstructure and formation mechanism of the spiral silver nanobelts were studied in detail.The main points are as follows:1.The one-step preparation and material characterization of Cu₂O/Ag nanocomposites:A one-step method for preparing and adjusting the particle size of the Cu₂O/Ag composite structure was developed.In detail,the reaction is carried out in an alkaline aqueous solution:Glucose is used as a reducing agent,CTAB is used as a surfactant,Cu（NO₃）₂ and AgNO₃ are used as copper and a silver source,respectively.The composition and morphology of Cu₂O/Ag composite nanostructures can be adjusted by adjusting the reaction temperature and the ratio of AgNO₃ and Cu（NO₃）₂.Therefore,we finally found that the optimum conditions were at a reaction temperature of 50°C and a molar ratio of silver nitrate to copper nitrate of 1:10.The materials obtained were studied by scanning electron microscopy（SEM）,powder X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,transmission electron microscopy（TEM）,high resolution transmission electron microscopy（HRTEM）,energy spectroscopy（EDS）,and electrons characterization by diffraction（ED）.2.The preparation of Cu₂O/Ag nanocomposite modified electrode and it’s sensing performance with H₂O₂:The modified Cu₂O/Ag nanocomposite was used to modify the glassy carbon electrode to prepare the H₂O₂ electrochemical sensor.Electrochemical impedance spectroscopy（EIS）,cyclic voltammetry（CV）,and current-time profiles are used to study the sensing performances and the test conditions are optimized.The results show that the obtained sample has strong catalytic capability for H₂O₂ reduction.The sensor based on the current-time profiles has a linear range of 0.2?4000μM,a sensitivity of 87.0μA mM^-1 cm^-2 and a detection limit of 0.2μM.The sensor has good selectivity for H₂O₂ and the recovery test in milk simulating sample samples shows the sensors has the prospect of being used in real-world environments.3.The formation,structure and characterization of spiral silver nanobelts:A phenomenon in which two-dimensional silver spiral nanobelts were grown by reducing the mixed solution of silver nitrate/boron nitrate with micron-sized Cu₂O particles was found.The effects of Cu₂O particle size and morphology and the ratio of silver nitrate/silver nitrate mixed solution on the preparation of silver spiral nanobelts were studied in detail.The appropriate formation condition for spiral silver nanobelts is determined.The microstructure was characterized by optical microscopy（OM）,SEM,TEM and HRTEM and the formation mechanism of spiral silver nanobelts was proposed preliminarily.