铱单原子和纳米粒子在N_(2)O分解反应中的协同催化  

Synergistic Catalysis Between Ir Single Atoms and Nanoparticles for N_(2)O Decomposition

作　　者：杨静怡 李庆贺 乔波涛[1] YANG Jingyi;LI Qinghe;QIAO Botao(Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian 116023,China)

机构地区：[1]中国科学院大连化学物理研究所,大连116023

出　　处：《高等学校化学学报》2022年第9期166-172,共7页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:21961142006,21972135)资助。

摘　　要：原子捕获法是在高温条件下制备高热稳定单原子催化剂的有效方法之一.但该方法制备的单原子催化剂通常面临着催化活性低、反应适用范围窄的问题.因此,拓展这类单原子催化剂的应用是亟待解决的难点.本文采用高温捕获法制备的铱(Ir)单原子催化剂在氮氧化物分解反应中的催化活性较低,但是在继续负载纳米粒子后,单原子与纳米粒子之间表现出显著的协同催化作用.X射线光电子能谱(XPS)和CO吸附的原位漫反射红外光谱(CO-DRIFTs)表征结合反应动力学分析揭示了反应的活性中心是金属态的Ir纳米粒子.虽然氧化态的Ir单原子不能直接活化N_(2)O分子,但是可以改变Ir纳米粒子的电子结构和吸附性能.氧气程序升温脱附(O_(2)-TPD)实验证实,单原子的存在可以促进O_(2)从Ir纳米粒子上脱附,从而提高催化剂的反应活性.“Atom trapping”is one of the effective methods to prepare thermally stable single-atom catalysts(SACs)at high temperature.However,the SACs derived from such methods often suffer from poor activity,which inhibits their application.Therefore,developing the application of these SACs is highly desired.In this work,we found that the Ir SACs prepared via atom trapping are inactive towards N_(2)O decomposition,but exhibit a synergistic effect with Ir nanoparticles(NPs)after loading the nanoparticle counterparts.X-ray photoelectron spectroscopy(XPS)and in situ diffuse reflectance infrared spectroscopy of CO adsorption(CO-DRIFTs)characterization combined with kinetic analysis revealed that the metallic Ir NPs are the real active sites in this reaction.Although Ir single atoms(SAs)with high valance state cannot directly activate the N_(2)O,they change the electronic state and adsorption ability of Ir NPs.O_(2) temperature programmed desorption(O_(2)-TPD)verified that the presence of SAs stimulate the desorption of O_(2) from Ir NPs thus enhance activity.This work provides new insights into the catalytic role of SAs.

关 键 词：单原子催化剂 纳米催化剂 协同催化 原子捕获法 

分 类 号：O643[理学—物理化学]