氧吸附诱导ε-Fe2C表面重构的理论研究
Theoretical study of ε-Fe2C surface reconstruction induced by oxygen adsorption
阮志慧 1张煜华 1李哲 1李金林1
作者信息
- 1. 中南民族大学催化转化与能源材料化学教育部重点实验室,催化与材料科学湖北省重点实验室,湖北武汉 430074
- 折叠
摘要
基于第一性原理的密度泛函理论(DFT)计算,研究ε-Fe2C表面氧吸附结构,考查不同氧覆盖度(θo)和氧势(μo)条件下的Wulff结构演变,以及氧消除反应机理.结果发现在低氧覆盖度(θo=0.25)和较低氧势(μo＜-7.1 eV)条件下,高活性(1(2)1)表面保持优势占比(55％～90％),惰性(101)表面占比小于25％.升高氧势和氧覆盖度,ε-Fe2C暴露表面以(2(2)1)和(100)为主.在实际反应条件(300 ℃,1 000 kPa,V(CO)/V(H2)=1)下,其μo约为-7.5 eV,ε-Fe2C表面以(1(2)1)为主,表明其具有抗氧化性能.氧消除反应计算结果显示,(1(2)1)表面易于发生氧消除,能垒为1.33 eV,与Wulff形貌模拟结果一致.
Abstract
In this study we performed density functional theory calculations of the adsorption of oxygen on the ε-Fe2C surfaces to investigate the Wulff construction evolution at different oxygen coverage(θo)and potential(μo)as well as the mechanism of oxygen removal.At low oxygen coverage(θo=0.25)and po-tential(μo＜-7.1 eV),the(1(2)1)facets with high activity remain the high exposure(55％to 90％)while the inert(101)facets contribute less than 25％.With increasing the μo and θo,the(2(2)1)and(100)be-come the main exposing facets.Considering the reaction condition(300 ℃,1 000 kPa,V(CO)/V(H2)=1),the po is determined as-7.5 eV.Thus,the ε-Fe2C exposes mainly the(1(2)1)surfaces indicating its antioxidation ability.Oxygen removal mechanisms indicate that the adsorbed oxygen is easily removed on(1(2)1)surface with a barrier of 1.33 eV in good agreement with the simulated Wulff constructions.
关键词
ε-Fe2C/表面重构/吸附氧消除反应/Wulff结构Key words
iron carbide/surface reconstruction/Fischer-T ropsch synthesis/Wulff construction引用本文复制引用
基金项目
National Natural Science Foundation of China(21972170)
National Natural Science Foundation of China(22072184)
Fundamental Research Funds for the Central Universities()
South-Central Minzu University(CZY13005)
South-Central Minzu University(CZT20010)
出版年
2024
NETL
NSTL
万方数据