Cold Plasma Assisted Preparation Of Transitional Metal Oxides And Nitrogen Doped Carbon Materials And Their Applications

Cold plasma is one of the high– and green– technologies in recent times.For the preparation of supported metal and metal oxide nanoparticles,using cold plasma,oxide precursors can be effectively decomposed at low temperature,and eventually convert into composite materials with high dispersed metal or metal oxide nano particles and unique properties;for the preparation of polymer materials,under the action of cold plasma,monomer polymerization can be initiated without additional chemical reagents.Combining the cold plasma technology with the preparation of environmental protection and new energy materials to achieve green preparations and green applications of such materials is our team's research dirtction.Sulfur–containing compounds in vehicle exhaust cause serious damage to the environment and human health.The deep desulfurization of fuel oil is an effective means to reduce the emission of sulfur–containing compounds from automobile engine.Adsorption desulfurization as a kind of deep desulfurization method has been widely concerned due to its mild adsorption conditions,low costs,zero consumption of hydrogen as well as low octane value loss.In this paper,novel adsorption desulfurization materials,MOF@active carboncore–shell magnetic spheres,were successfully fabricated with the assistance of the dielectric barrier discharge(DBD)plasma technology.The morphologization of metal–organic frameworks(MOFs)was achieved by with the fabrication of the core–shell architecture.Compared with the magnetic active carbon sphere,the adsorption capacity of the obtained material for thiophene in the model oil with an initial sulfur concentration of 500 mg S·L–1 increased almost three times,reached up to 12.0 mg S·g–1.Transmission electron microscopy showed that the average particle size of Fe3O4 particles obtained by DBD plasma decomposition was only 2.7 nm,the magnetic test showed that the Fe3O4 nano particles had superparamagnetism,and the saturation magnetization intensity of MOF@active carboncore–shell magnetic spheres was 3.88 emu·g–1.The core–shell sphere with the particle diameter of ~500 micron and 3.88 emu·g–1 saturation magnetization made the used composite material easy to be separated and recycled.Along with the decline of the world's oil reserves and the increasingly serious air pollution,the development of clean energy vehicles has become an inevitable trend.Compressed natural gas(CNG)is now recognized as the ideal alternative automobile energy sources,because of its low pollution,safety,and economy.However,compared with traditional fuel automobiles,CNG vehicles exhaust larger amount of greenhouse gas –methane,which greatly offsets their advantages in other ways.Therefore,removal of the lean methane in CNG automobile exhaust has important scientific significance and social value.In this paper,efficient Co3O4/HZSM–5 catalysts for methane catalytic combustion were prepared using DBD plasma technology.Compared with traditional calcination method,the Co3O4/HZSM–5 catalysts prepared by DBD plasma decomposition possess many advantages.Such as smaller Co3O4 particle size,better reducibility of Co3+,higher Co3+ content,higher surface concentration of Co3O4 lattice oxygen and adsorbed oxygen species,and not easy formation of Co–formate which made DBD decomposed catalysts have excellent catalytic activity.Nitrogen doped nanostructured carbon materials show excellent performance in the field of fuel cell,super capacitor,chemical sensors and catalysis,etc.,due to their unique physical and chemical properties.Thus,they have become one of research hotspots in the field of carbon materials.In this paper,using the glow discharge plasma polymerization technologywith ionic liquids as sources of carbon and nitrogen,water as solvent and initiator,~20–nanometer–thick ionic liquid film was prepared.Thereafter,free–standing nitrogen doped ultrathin carbon film with the average thickness of only 4.6 nm was obtained by the high temperature carbonization of the ionic liquid film.Oxygen reduction reaction catalytic activity of the as prepared carbon film was preliminarily tested.Results indicated that although the initial potential of the carbon film was a bit more negative than commercial Pt/C catalyst,it had a larger limit current density,therefore,showed potential application value as a fuel cell cathode material.