Preparation Of Noble Metal-based Nanomaterials And Their Applications In The Field Of Electroanalysis

With the sustainable development of the world's analytical technology,electrochemical analysis has emerged and gradually attracted worldwide attention.In the field of electroanalysis,due to their high thermodynamic and chemical stability,reversible redox,controllable size as well as their precise structure,noble metal-based nanomaterials have been extensively studied and used in the fields of photocatalysis,electrochemistry and optoelectronics.The superiority in other fields has become one of the current hot research directions in the materials science.In the field of electrochemistry,noble metal-based nanomaterials have received more and more research attention due to their excellent catalytic activity and good cycle stability.And in the field of analysis and testing,due to their excellent oxidase and/or peroxidase activities as well as their good affinity with reaction substrates,noble metal-based nanomaterials have attracted more and more attention.Therefore,in this thesis,taking the precious metals Pd and Ru as sample,we have obtained the Ru nanoclusters which are directly grown on the surface of carbon nanotubes without surfactant.Subsequently,the Ru NCs/CNTs were treated with H₂O₂ to obtain the catalyst O-Ru NCs/CNTs.In addition,a Pd cube@CeO₂ core-shell nanostructure composite material was prepared by a two-step method.And then we studied the application of these noble metal-based nanomaterials in electrochemical hydrogen evolution and colorimetric detection.The specific work are as follows:1.We prepared Ru NCs/CNTs nanocatalysts without adding any surfactants,and then used the H₂O₂ to oxidize the as-prepared catalysts.Some of the oxygen-containing functional groups especially the acidic C=O groups are generated on the surface of carbon nanotubes.Due to the coupling effect of surfactant-free Ru nanoclusters and acidic oxygen-containing functional groups on the surface carbon of carbon nanotubes,the charge transfer efficiency and catalytic reaction performance are greatly improved.At the same time,it shows excellent cycle stability,which is comparable to commercial Pt/C.2.We first prepared Pd nanocubes,and then encapsulated with a layer of CeO₂ on the surface of the Pd nanocubes to prepare a Pd cube@CeO₂ nano-core-shell structure catalyst.The catalyst has strong oxidase activity which can oxidize colorless 3,3',5,5'-tetramethylbenzidine(TMB)to blue ox TMB(oxidation state TMB)without adding H₂O₂.On the other hand,ALP can hydrolyze AAP to produce AA And AA has reductive properties,which can reduce the blue ox TMB to colorless TMB and thus inhibit the oxidase activity of the Pd cube@CeO₂.Based on this principle,the detection of ALP has been fabricated.We optimized the reaction conditions of the detection system,and determined the linear range of the detection system for AA and ALP detection,and then analyzed the ALP in the actual sample and the anti-interference ability of the detection system.The results obtained are satisfactory.3.We loaded Ru nanoclusters on the surface of carbon nanotubes to prepare the Ru NCs/CNTs catalysts and used for cholesterol detection.Cholesterol can be hydrolyzed to produce H₂O₂ in the presence of cholesterol enzymes.The catalyst can catalyze the oxidation of TMB by H₂O₂,turning colorless TMB into blue ox TMB.Based on this principle,the detection of cholesterol is completed.After that,we use different free radical scavengers to remove free radicals from the detection system.The final experimental results show that a small amount of hydroxyl radicals(·OH)are produced during the catalysis process,almost no singlet oxygen is produced,and superoxide radicals(·O₂^-)play the main catalytic role.Subsequently,the conditions of the detection system were optimized,the linear analysis of cholesterol concentration,and the analysis of actual samples were also carried out.It provides a new idea and method for the detection of cholesterol.