Electrochemical Investigation Of Metal Porphyrin Catalysis Oxygen Reduction Reactions

Liquid/liquid interfaces have been considered as the simple model of biological membranes.It is widely used in heterogeneous catalysis,biological fuel cell,model biomembrane.Among the model of biological membrane oxygen reduction reaction,catalysts which are cheap,efficient and good biological compatibility is currently one of the highlights in agro-scientific research in the liquid/liquid interface.The oxygen reduction reaction（ORR）is a key step of the respiratory chain of aerobic organisms.In nature,ORR occurs at soft interfaces,namely biomembranes that provide both a physical separation of the reactants and products and an electrochemical driving force resulting from the membrane electrical potential difference.Porphyrins and their metal chelates are key ingredients in organism.Recently,they have been widely applied in catalysis,molecular recognition,photo-electron conversions,memorial material and medicinal fields.Porphyrins were studied in the field of self-assembly for their special properties.These researches showed better results than others SAMs constructed by other assembly molecules.Based on this,this thesis takes metalloporphyrin as the research object,a class of biomolecules that is playing an important role in the biological processes,and then systematically investigates metal porphyrin molecular catalysis oxygen reduction reaction.We prepared the three-dimensional（3D）architectures modified electrode and detect the dioxygen reduction in neutral aqueous media.There are four parts in this paper,main contents are as follows:Chapter 1 briefly summarized the development of electrochemistry at the L/L interfaces.The basic theory of electrochemistry at L/L interfaces and its application in electrocatalysis was also introduced.Finally,a prospect to application of electrochemistry at L/L interfaces was given.In addition,the principles of electrocatalytic ORR at L/L interfaces and the experimental methods of four-electrode experiment were also described.In Chapter 2,four-electrode system was used to study the catalysis of metal porphyrin,CoTPP,to ORR by TTF at the water/DCE interfaces.Experiments which were conducted by electrochemical cyclic voltammetric and UV-visible spectroscopy,proved the CoTPP could catalyze ORR by TTF to generate H₂O₂ mainly via two-electron reduction mechanism.In Chapter 3,Gold nanoparticles were immobilized to the gold bulk electrode by self-assembledtechnology,andthethiol-derivatizedcobaltporphyrin（5-[p-（12-mercapto-dodecaoxy）-phenyl]-10,15,20-triphenylporphyrincobalt（II）porphyrin,TDPPCo（II））monolayer was modified on the nanostructure surface using layer-by-layer（LBL）technique.The three-dimensional（3D）architectures modified electrode was fabricated using for electrochemistry detection and electrocatalysis of dioxygen reduction in neutral aqueous media.Results showed that the nano-based electrode exhibited excellent catalytic activity and high stability to dioxygen,a broad cyclic voltammogram reduction peak of dioxygen appears at around-173mV,which is160 m V more negative than that at the bare polycrystalline Au electrode.The dioxygen was mainly reduced through four-electron process to H₂O on the nano-based electrode.In Chapter 4,novel sensitive electrochemical Cu（Ⅱ）ion sensor were made by electrochemicalcoatingfunctionalizedcalix[4]areneswithbenzoyloxyor nitrophenylazo groups on Au electrode on quartz crystal substrate using cyclic voltammetry（CV）.The Cu（Ⅱ）ion-sensing film thus prepared was characterized by scanning electron microscopy（SEM）and electrochemical impedance spectroscopy（EIS）.The response current of the prepared electrochemical Cu（Ⅱ）ion sensors was measured by differential pulse voltammetry（DPV）.The effects of the substituent on calix[4]arene,sweep cycles and pH of buffer solution on the Cu（Ⅱ）ion-sensing properties（response）of the sensors were investigated to reveal the optimal conditions in the decetional of Cu（Ⅱ）ion in water.The electrochemical Cu（Ⅱ）ion sensor that was made of the calix[4]arene functionalized with nitrophenylazo groups exhibited a excellent response,good selectivity,acceptable linearity,a low decetion limit and favorable long-term stability.