Platinum/Silver Nanomaterials Supported On TiO₂/C For Methanol Oxidation And Antibacterial Study

Platinum-based nanomaterials have been widely used because of their good electrocatalytic properties.However,natural platinum resources are very limited.How to further improve the electrocatalytic efficiency of platinum has become an urgent problem to be solved.In addition,platinum nanomaterials also exhibit a certain bactericidal activity,but their bactericidal performance needs to be improved.Silver nanomaterials have been widely used in the field of sterilization.Therefore,it is possible to obtain a bactericidal material with better bactericidal performance through the composite of platinum-silver nanomaterials.Based on the above considerations,in this thesis,two nanocomposites were prepared by loading platinum nanowires and Ag/Pt nanowires on TiO₂/C,and then applied to the electrocatalytic oxidation of methanol under acidic conditions and the sterilization of Gram-negative Escherichia coli.The main content and results are as follows:(1)Using Staphylococcus aureus(SAU)as a biological template,we synthesized TiO₂nanosheet assembed microspheres with the sol-gel method.The microspheres were with good dispersion and uniform size,and the diameter of the microspheres is in the range of600 nm-800 nm.Then the microspheres calcined at high temperature in an argon atmosphere to obtain TiO₂/carbon microspheres(TiO₂/C MS).The crystalline form of the calcined TiO₂ was anatase as measured by XRD.Next,we used chloroplatinic acid as the precursor and formic acid as the reducing agent to grow Pt nanowires(PtNW)on the surface of TiO₂/C MS,which were uniform in size and grown along the(111)crystal plane.Through the electrocatalytic test of methanol oxidation under acidic conditions,we found that the PtNW/TiO₂/C MS composite material with a theoretical Pt loading of 60 wt%has the best electrocatalytic activity.According to ICP-MS,its actual loading of Pt is 27.36wt%.When the modified concentration on the electrode is 4 mg/m L,its mass activity is2.56 times that of the commercial Pt/C catalyst.(2)With silver nitrate as the precursor and ascorbic acid as the reducing agent,silver nanoparticles were loaded on the surface of 60 wt%PtNW/TiO₂/C MS,and Ag-PtNW/TiO₂/C MS composite material was successfully prepared by chemical reduction method,and the actual loading of Ag is measured to be 14.30 wt%.In the TMB oxidation experiment,we found that the composite material has good peroxidase activity under neutral conditions.Then,a preliminary study on its antibacterial effect was carried out based on the plate dilution count bacteria,the results showed that Ag-PtNW/TiO₂/C MS with a concentration of 2?g/m L can kill all bacteria.At the same time,we also explored the effect of H₂O₂ on the reaction system.When 1 mmol/L H₂O₂ is added to the reaction system,the composite material concentration of 0.25?g/m L can kill 91.29%of the bacteria,which is only one-eighth of the original concentration.Then we determined the minimum inhibitory concentration of Ag-PtNW/TiO₂/C MS as 25?g/m L.Finally,we observed the morphology of the bacteria after drug treatment with SEM,and concluded that the bactericidal mechanism may be related to the damage of cell walls.