物理化学学报2020，Vol.36Issue(8)：63-71,9.DOI:10.3866/PKU.WHXB201907057
Pt@Au/Al2O3核壳纳米粒子的制备和表征及其在催化氧化甲苯中的应用
Preparation and Characterization of Pt@Au/Al2O3 Core-Shell Nanoparticles for Toluene Oxidation Reaction
摘要
Abstract
Customizing core-shell nanostructures is considered to be an efficient approach to improve the catalytic activity of metal nanoparticles.Various physiochemical and green methods have been developed for the synthesis of core-shell structures.In this study,a novel liquid-phase hydrogen reduction method was employed to form core-shell Pt@Au nanoparticles with intimate contact between the Pt and Au particles,without the use of any protective or structure-directing agents.The Pt@Au core-shell nanoparticles were prepared by depositing Au metal onto the Pt core;AuCl4-was reduced to Au(0) by H2 in the presence of Pt nanoparticles.The obtained Pt@Au core-shell structured nanoparticles were characterized by transmission electron microscopy (TEM),energy-dispersive X-ray spectroscopy (EDX),high-resolution TEM,fast Fourier transform,powder X-ray diffraction (PXRD),X-ray photoelectron spectroscopy (XPS),Fourier transform infrared spectroscopy (FTIR),and H2-temperature programmed reduction (H2-TPR) analyses.The EDX mapping results for the nanoparticles,as obtained from their scanning transmission electron microscopy images in the high-angle annular dark-field mode,revealed a Pt core with Au particles grown on its surface.Fourier transform measurements were carried out on the high-resolution structure to characterize the Pt@Au nanoparticles.The lattice plane at the center of the nanoparticles corresponded to Pt,while the edge of the particles corresponded to Au.With an increase in the Au content,the intensity of the peak corresponding to Pt in the FTIR spectrum decreased slowly,indicating that the Pt nanoparticles were surrounded by Au nanoparticles,and thus confirming the core-shell structure of the nanoparticles.The XRD results showed that the peak corresponding to Pt shifted gradually toward the Au peak with an increase in the Au content,indicating that the Au particles grew on the Pt seeds;this trend was consistent with the FTIR results.Hence,it can be stated that the Pt@Au core-shell structure was successfully prepared using the liquid-phase hydrogen reduction method.The catalytic activity of the nanoparticles for the oxidation of toluene was evaluated using a fixed-bed reactor under atmospheric pressure.The XPS and H2-TPR results showed that the Pt1@Au1/Al2O3 catalyst had the best toluene oxidation activity owing to its lowest reduction temperature,lowest Au 4d & 4fand Pt 4d & 4f binding energies,and highest Au0/Auδ+ and Pt0/Pt2+ proportions.The Pt1@Au2Al2O3 catalyst showed high stability under dry and humid conditions.The good catalytic performance and high selectivity of Pt@Au/Al2O3 for toluene oxidation could be attributed to the high concentration of adsorbed oxygen species,good low-temperature reducibility,and strong interaction.关键词
催化剂/协同作用/纳米材料/核壳结构/VOCsKey words
Catalyst/Synergy/Nanomaterials/Core-shell structure/VOCs分类
化学化工引用本文复制引用
张超,李思汉,吴辰亮,李小青,严新焕..Pt@Au/Al2O3核壳纳米粒子的制备和表征及其在催化氧化甲苯中的应用[J].物理化学学报,2020,36(8):63-71,9.基金项目
The project was supported by the National Key R&D Program (2017YFC0210900) and Zhejiang Science and Technology Plan Project,China (2016C31104).国家重点研发计划(2017YFC0210900)与浙江省科技计划项目(2016C31104)资助 （2017YFC0210900）
