Preparation Of Supported Au,Cu Catalytic Materials By Atmospheric-pressure Cold Plasma And Their Applications

Preparation and application of gold catalytic materials have become a research hotspot since Haruta et al.prepared gold nanoparticles with excellent low-temperature CO oxidation activity in 1987.Additionally,inexpensive nano-copper catalytic materials also exhibit extensive application prospects.Compared with traditional techniques,atmospheric-pressure(AP)cold plasma is an effective method for synthesizing supported metal catalytic materials due to its simpleness,rapidness and green.In this thesis,supported gold catalytic materials were synthesized by a modified impregnation method with the assistance of AP cold plasma.In addition,AP cold plasma was also adopted to synthesize copper catalytic materials.The main research contents were listed as follows:lwt%Au/TiO2 catalytic materials were synthesized by a modified impregnation method with the assistance of AP cold plasma using chloroauric acid as gold precursor.The effect of discharge voltage,discharge time and working gas on the structure and performance of Au/TiO2 catalytic materials were investigated.The activation mechanism of Au/TiO2 catalytic materials prepared by AP cold plasma was also discussed.The results indicated that the best conditions for activating Au/TiO2 catalytic materials were oxygen plasma,discharge voltage 29kV and discharge time lmin.The supported gold species can be reduced to metallic gold,and the active oxygen species on the Au/TiO2 catalytic materials can be decreased simultaneously.The Au/TiO2 catalytic materials prepared by oxygen plasma displayed the highest low-temperature CO oxidation activity since oxygen cold plasma can not only reduce oxidized gold species but also keep more active oxygen species.Cu/Ti02 precursor was synthesized via a simple impregnation method using Cu(NO3)2 and P25 as copper source and support,respectively.Then Cu/TiO2 catalytic materials were synthesized by cold plasma,and cold plasma followed 4 hours calcination at 3000C.The interaction between AP cold plasma and copper catalytic materials was characterized and analyzed by XRD,UV-Vis and XPS.The results showed that part of copper oxide can be reduced into metallic copper by AP cold plasma with or without 4 hours calcination at 300℃.Interestingly,copper hydroxide nitrate was detected in the catalytic material prepared by direct AP cold plasma treatment.Although the copper catalytic materials exhibited poor CO oxidation activity and photocatalytic activity,the copper catalytic material prepared by direct AP cold plasma treatment exhibited high adsorption capacity for methyl orange.Copper hydroxide nitrate nanosheets with the thickness of 100-400nm and the length of 1-6μm were successfully synthesized by AP argon cold plasma using Cu(NO3)2 solution without any other chemical reagents.Interestingly,this can also be achieved by AP air cold plasma although the thickness and the length of the nanosheets were decreased.Copper hydroxide nitrate nanosheets have a saturated adsorption capacity of 428.8 mg MO g-1,which is approximately twice as much as that prepared by the solvothermal method.Combined with OES analysis,the formation of copper hydroxide nitrate was ascribed to the synergetic effect between the strong electric field and the increase in pH in AP cold plasma.