In the present work,a Pd/graphene/cordierite(Pd/Gr/Cor)composite was prepared as a monolithic catalyst for low-temperature combustion of toluene.We mainly focused on understanding the role of graphene coating through investigation of catalytic performance and adsorption behavior of the composite.Compared with the traditional Pd/Cor catalyst without graphene coating,Pd/Gr/Cor catalyst delivered much higher activity and stability for toluene catalytic combustion in both dry and moist conditions.Transmission electron microscopy(TEM)and hydrophobic characterizations indicated that graphene coating can considerably improve the dispersity of Pd nanoparticles and enhance the hydrophobicity of the cordierite support.The adsorption behavior of the above two catalysts,including adsorption isothermal,adsorption kinetics,and adsorption thermodynamics were carefully investigated.The simulation results indicated that a large amount of toluene was adsorbed on graphene surface through relatively weak interaction,whereas only a relatively small amount of toluene was adsorbed on Pd surface with strong affinity.The adsorption thermal calculation indicated that the adsorption of toluene on graphene was a process with reduced entropy,indicating highly-ordered assembly of toluene molecular on graphene.It is the significant concentration and affinity gap between graphene and Pd that ensures a simultaneously and rapid transfer of toluene during the reaction process.
Wen LiHongqi YeGonggang LiuHongchao JiYonghua ZhouKai Han
In order to obtain a safe,reliable,long-lived battery system without use of flammable,volatile,and relatively unstable organic liquid-based electrolytes,lithium garnet oxides with formulas Li7-xLa3Zr2-xTaxO12（x=0.2-1）were synthesized by the solid state reaction method.Single cubic phases were observed in the composition x range between 0.2 and 1.The lattice parameters decreased with the addition of Ta due to the smaller ionic radius of Ta^5＋compared with that of Zr^4＋,following the Vegard＇s law.The total conductivity of the x=0.3 composition is 6.03×10^-5 S·cm^-1at room temperature with an activation energy of 0.30 eV.These lithium garnet oxides exhibit lithium ionic transport that is relevant to lithium battery application.
