Preparation Of Novel Metal Nanowires/MWNTs/Sponge Electrodes And Their Catalytic Properties For Dielectric Barrier Discharge

In this paper,the catalyst is added in the dielectric barrier plasma discharge(DBD)system to reduce the system energy consumption and improve the treatment efficiency of pollutants.Multi-walled carbon nanotubes(MWNTs)/Sponge electrode was prepared by adsorption.Compared to the hydrophobicity of pure sponge,MWNTs/Sponge electrode has the property of hydrophily.The catalytic activity for phenol degradation was evaluated in the DBD system.The operation experiments with different input voltages and electrode distances were carried out to determine the optimum degradation parameter that input voltage of 30 V and electrode distance of 2 mm.CuO@Cu nanowires and Ag nanowires were prepared by thermostatic hydrothermal method.The CuO@Cu/Ag/MWNTs/Sponge electrode was finally prepared by adsorption of CuO@Cu and Ag nanowires methanol solution in MWNTs/Sponge substance.The surface structure,microscopic morphology and electrochemical properties of the composite electrode were characterized in detail.Compared with pure sponge and MWNTs/Sponge,CuO@Cu/Ag/MWNTs/Sponge electrodes show significant advantages:(1)The introduction of metal nanowires further reduces the electrode resistance;(2)Electrochemical workstation detection shows that the i-t response is enhanced.In the DBD system,the degradation of phenol by pure sponge is 30%for reaction within 60 min.With the introduction of MWNTs to sponge,the degradation rate can increase to 90%.Then,CuO@Cu nanowires,Ag nanowires,or CuO@Cu/Ag mixed nanowires were introduced to prepare different metal nanowires/MWNTs/Sponge electrode,which determined that when CuO@Cu nanowires and Ag nanowires are co-modified,and the ratio is 3:5,the CuO@Cu/Ag//MWNTs/Sponge electrode has the best effect on phenol treatment in DBD system,achieving 100%degradation within 30 min.With the addition different capture agents,it indicated that the main active species for the reaction system was OH.And cyclic experiments show that CuO@Cu/Ag/MWNTs/Sponge electrode has good stability.Further introduction of highly toxic and unbiodegradable 2,4,5-trichlorobiphenyl as a pollutant,the degradation efficiency of contaminants in the DBD system by CuO@Cu/Ag/MWNTs/Sponge electrode can still reach 65%within 60 min,which also shows good plasma catalytic activity of the composite electrode.The ZnCo2O4 nanowires were prepared by template method,and the nanowires and MWNTs were adsorbed together in a pure sponge to prepare ZnCo2O4/MWNTs/Sponge electrodes.The surface structure,microscopic morphology and electrochemical properties of the combined electrode were characterized in detail.The i-t curves of different concentrations of ZnCo2O4/MWNTs/Sponge electrode were tested.The phenol degradation experiment was carried out in DBD system,and the optimum concentration of ZnCo2O4 nanowires contained in ZnCo2O4/MWNTs/Sponge electrode was determined to be 0.6 g/L.The degradation efficiency of phenol can reach 100%in 60 min.Then hydroquinone,nitrobenzene and p-nitrophenol were selected as benzene series pollutants for degradation in ZnCo2O4/MWNTs/Sponge electrode-DBD system.The degradation of single benzene series pollutants or combined with hexavalent chromium were also investigated,and the synergistic effect between benzene series pollutants and hexavalent chromium was determined.The ZnCo2O4/MWNTs/Sponge electrode has good stability by cyclic experiments.The main active component of the reaction system was determined by the addition of different capture agents,and the reaction mechanism was explored.The CoFe2O4 nanowires were prepared by template method,and the nanowires and multi-walled carbon nanotubes were adsorbed together in a pure sponge to prepare CoFe2O4/MWNTs/Sponge electrodes.The surface structure,microscopic morphology and electrochemical properties of the combined electrode were characterized in detail.The i-t curves of different concentrations of CoFe2O4/MWNTs/Sponge electrode were tested,and the phenol degradation experiment was carried out in DBD system.The optimum concentration of CoFe2O4 nanowires contained in CoFe2O4/MWNTs/Sponge electrode was determined to be 0.5 g/L.The degradation efficiency of phenol can reach 100%in 50 min.Then hydroquinone,nitrobenzene and p-nitrophenol were selected as benzene pollutants for degradation in CoFe2O4/MWNTs/Sponge electrode-DBD system.The degradation of single benzene series pollutants and combined with hexavalent chromium were also explored.The synergy between benzene series pollutants and hexavalent chromium was studied.The reaction mechanism was also explored.Finally,cyclic experiments show that CoFe2O4/MWNTs/Sponge electrodes have good stability.