Preparation And Propoties Of Sensitive Materials Based On Three-dimensional Frame Nickel Foam

Chemical sensors have been widely used in environmental protection,medical diagnosis,industrial production,food safety,etc.The key to the research of highperformance sensors is to prepare sensitive materials with excellent performance.The preparation of the sensitive material withhigh sensitivity,low limit,fast response,high selectivity has always been an important topic in the field of materials research.Nano-materials have the surface effect,small size effect,quantum tunneling effect,quantum size effect and so on,so that nanomaterial as a kind of sensitive material has a unique advantage.Porous foam metal material is a kind of functional material with three-dimensional porous network structure.Compared with dense metal materials,porous metal has many excellent characteristics,such as small density,large specific surface area.In the sensor test,we directly grow a variety of sensitive nanomaterial on the three-dimensional porous network structure,make the best of pore structure and nanomaterial characteristics.The sensitive materials haveeffectively played material morphology and structure advantages.The sensitivity of the sensor can be further improved,and the low concentration detection can be achieved.In this paper,We combined sensitive materials and nickel foam with a variety of methods to control the reaction conditions,grown the sensitive material directly on the foam nickel substrate,developed with some electrochemical sensors and semiconductor gas sensors withhigh selectivity,high sensitivity,The main contents are as follows:Firstly,we study the electrochemical sensitive property of indium oxide/nickel oxide towards glucose.The co-growth and deposition of this two materials on nickel foam were realized by one-step oxidation process.Through SEM and XPS analysis,we prove the regulating effect of indium during the growth of nickel oxide material.After optimizing the growth technics,this material exhibits improved glucose sensitive property.The maximum sensitivity reaches 58170 mA mM^-1 cm^-2 and the limit of detection is 0.01mmol/L.Considering the tin oxide material also have the catalytic ability towards glucose,we endeavor to introduce tin oxide material into the indium oxide/nickel oxide composite in order to further enhance the sensitive property.The electrochemical measurements show that this material gains a remarkable sensitivity of 107970 mA mM^-1 cm^-2 with a limit of detection of 0.01 mmol/L.In the study of gas sensor,we designed a testing system to test the gas sensitivity of three-dimensional network structure sensitive materials or general sheet/film sensitive materials,the resistance measurement range is 1-200 Mega Ohm.The system provided a test condition for the development of new gas sensitive materials.Then,we used the foam nickel as the substrate to grow p-type nickel oxide by high temperature sintering.SEM and XRD were used to analyze and characterize the morphology and structure of nickel foam/nickel oxide.We tested the gas sensitive properties of the products by using the gas sensitive material testing system,explored the optimal growth conditions,and laid the foundation for the preparation of gas sensitive materials with p-n structure.We used hydrothermal method to grow a layer of indium oxide nanoparticles on the surface of nickel foam/nickel oxide,the products were characterized by SEM and XRD,the effects of reaction conditions on the morphology and gas sensitive properties of nickel foam/nickel oxide/indium oxide were investigated.Further,we used glucose as a template to grow indium oxide on nickel foam/nickel oxide substrate,after the optimization of the preparation conditions,the sensitivity of indium oxide material grown on nickel foam/nickel oxide substrate to 100 ppm ethanol could be 8.The modification of the electrode may improve its performance,after the successful preparation of the MoO₃ modified In₂O₃,we use it as the electrode material in the plane NO₂ sensor,so that the performance of the sensor is improved obviously.In addition to indium oxide,we also tried to grow tin oxide nanoparticles on the surface of nickel foam /nickel oxide,and studied its gas sensitive properties.We used sol-gel method and hydrothermal method to prepare nickel foam/nickel oxide/tin oxide nanomaterial,used XRD and SEM to characterize the product,optimized the reaction conditions,studied the effects of preparation conditions on the gas sensing properties.The sensitivity of the product was greatly improved by doping lanthanum,and the sensitivity to 100 ppm ethanol was increased to 14,compared with the undopedproduct,the sensitivity increased by more than two times.Finally,we established the equivalent circuit of the gas sensitive test of foam nickel based p-n structure by taking the nickel foam/nickel oxide/tin oxide as an example.We analyzed the factors that affect the sensitivity of the structure,and laid the foundation for further improving the sensitivity of the p-n structure.To sum up,we have tried to develop the quality of sensitive through enlarge the a ctive lattice oxygen defects and multi-composition.We creatively make use of the 3D nickel foam in the gas sensor field.Through the large surface area and the p-n structur e,we promote the gas sensing property and provide a new way to acquire new type se nsor.