Fe、La掺杂和氧缺陷对CeO_(2)表面吸附As_(2)O_(3)的密度泛函理论研究  

Density functional theory study of adsorption of As_(2)O_(3)on CeO_(2)surface by Fe,La doping and oxygen defects

作　　者：卢鲲鹏 张凯华[1] 张锴[1] LU Kunpeng;ZHANG Kaihua;ZHANG Kai(Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation,North China Electric Power University,Beijing 102206,China)

机构地区：[1]华北电力大学热电生产过程污染物监测与控制北京市重点实验室,北京102206

出　　处：《燃料化学学报（中英文）》2024年第8期1149-1161,共13页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金委与山西煤基低碳联合基金重点项目(U1910215);国家重点研发计划(2020YFB0606201)资助。

摘　　要：采用密度泛函理论研究了As_(2)O_(3)(g)在Fe、La掺杂CeO_(2)(110)表面及氧缺陷LaCeO(110)表面的吸附行为,探索了LaCeO表面砷吸附能力显著高于FeCeO表面的主要原因。结果表明,As_(2)O_(3)(g)的吸附效果与吸附位点数量、吸附能、键长和电荷转移密切相关。纯CeO_(2)表面的吸附主要为化学吸附,吸附能绝对值大于−4.22 eV,电荷转移量为(−0.19)−(−0.31)e,As_(2)O_(3)得到电荷带负电,起表面受主作用,因此吸附量较小。FeCeO(110)表面新增Fe顶位和Bridge-2桥位两个吸附位,其中,Fe顶位为化学吸附,Fe掺杂改变了FeCeO表面电子分布和晶格结构,但并未改变As_(2)O_(3)与FeCeO之间的电荷转移方向,因此,As_(2)O_(3)仍呈负离子形式吸附。LaCeO(110)表面新增了三个吸附位:La顶位、Bridge-3桥位和Hollow-2空位,La掺杂改变了As_(2)O_(3)与LaCeO之间的电荷转移方向,使得As_(2)O_(3)失电子呈正离子吸附,起表面施主作用,因此,吸附能力增强。无O_(2)环境下,单一O缺陷LaCeO(110)表面吸附能力低于完整LaCeO表面;有O_(2)环境下,O缺陷有利于As_(2)O_(3)的吸附。Density functional theory(DFT)was used to study the adsorption behavior of As_(2)O_(3)(g)on iron and lanthanum doped CeO_(2)(110)and oxygen-deficient LaCeO(110)surfaces,and the reasons for the arsenic adsorption capacity of LaCeO surface was significantly higher than that of FeCeO surface was explored.The results show that the adsorption effect of As_(2)O_(3)(g)is closely related to the number of adsorption sites,adsorption energy,bond length and charge transfer amount.Ce and O atoms on the surface of pure CeO_(2)are both active sites,and the adsorption is mainly chemisorption,the absolute adsorption energy is greater than−4.22 eV,and the charge transfer amount is(−0.19)−(−0.31)e.As_(2)O_(3)has a negative charge and acts as a surface accepter,while CeO_(2)loses electrons and has a positive charge on the surface,which acts as a surface donor.The number of free electrons in the CeO_(2)conduction band gradually decreases,the conductivity decreases,and it is difficult to provide more electrons continuously,so the adsorption amount is small.Two adsorption sites are added on the surface of FeCeO(110):Fe top site and Bridge-2 Bridge site,where Fe top site is chemical adsorption and Bridge-2 Bridge site is physical adsorption.The gap doping of Fe changes the electron distribution and lattice structure on the surface of FeCeO,resulting in obvious deformation of the lattice and reducing the difficulty of bonding,thus increasing the configurational adsorption energy of some configurations.However,it does not change the charge transfer direction between As_(2)O_(3)and FeCeO,thus not changing the surface adsorption form of As_(2)O_(3).As_(2)O_(3)is still adsorbed in the form of negative ions,which plays the role of surface acceptor,and the adsorption amount is small.LaCeO(110)has three new adsorption sites:La top site,Bridge-3 Bridge site and Hollow-2 vacancy,among which the La top site and Bridge-3 Bridge site are chemical adsorption.La doping changes the charge transfer direction between As_(2)O_(3)and LaCeO,resulti

关 键 词：密度泛函理论 二氧化铈 Fe、La掺杂 As_(2)O_(3)吸附 O缺陷 

分 类 号：TK22[动力工程及工程热物理—动力机械及工程]