NH_(3)在TaC(0001)表面吸附和解离的第一性原理研究  

First principle study of adsorption and desorption behaviors of NH_(3) molecule on the TaC(0001)surface

作　　者：李小林[1,2] 袁坤 何嘉乐 刘洪峰 张建波 周阳[1,2] Li Xiao-Lin;Yuan Kun;He Jia-Le;Liu Hong-Feng;Zhang Jian-Bo;Zhou Yang(Faculty of Materials Metallurgy and Chemistry,Jiangxi University of Science and Technology,Ganzhou 341000,China;Engineering Research Institute,Jiangxi University of Science and Technology,Ganzhou 341000,China)

机构地区：[1]江西理工大学,材料冶金化学学部,赣州341000 [2]江西理工大学,工程研究院,赣州341000

出　　处：《物理学报》2022年第1期227-233,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:21865012);江西理工大学清江青年英才支持计划资助。

摘　　要：采用自旋极化密度泛函理论(DFT)并结合周期平板模型的方法,研究了NH_(3)在TaC表面的吸附和分解反应机理.表面能计算结果显示,以Ta为终止的TaC(0001)面为最稳定的表面;NH_(3)分子通过其孤对电子优先吸附在顶位top位,而NH_(2)和H最稳定吸附位置为三重hcp位,NH和N吸附在三重fcc位.过渡态结果表明氮原子的复合反应脱附为整个反应的限速步骤.电子结构计算结果表明,NH_(3)分子及其片段通过其N原子的2pz轨道与底物Ta的5d_(z)2轨道混合吸附于表面.随着脱氢反应的进行,电荷转移现象变得逐渐明显,吸附质和底物之间的电荷转移在加速NH_(3)脱氢催化过程中发挥重要作用.The adsorption and desorption behaviors of ammonia on TaC(0001)surface are studied by employing spin-polarized density function theory calculations.The surface energy calculation results show that the TaC(0001)terminating with Ta is the most stable surface.According to the optimized structural and energetic properties,it is found that NH_(3) prefers to adsorb on the top site,whereas NH_(2),H prefer to adsorb on the triple hcp site and NH,N prefer to stay on the triple fcc site.In addition,three transition states are found for analyzing the mechanism of dehydrogenation of NH_(3),and the N recombination reaction is also considered.The results show that the desorption of nitrogen atoms is the rate-determining step in the overall reaction.Finally,in order to further elucidate the mechanism of NH_(3) adsorption and dissociation on the surface of Ta-TaC,the electronic structure of the most stable adsorption position is analyzed from the perspective of charge density distribution and electron density of states.The results of electronic structure calculation show that NH_(3) molecule is adsorbed on the surface through the mixture of 2pz orbital of N atom and 5d_(z)2 orbital of substrate Ta.With the progress of dehydrogenation,the charge transfer phenomenon becomes more and more serious.The charge transfer between adsorbate and substrate plays an important role in accelerating NH_(3) dehydrogenation catalytic process.

关 键 词：密度泛函理论 NH_(3) TaC 吸附 

分 类 号：TQ116.2[化学工程—无机化工] O643.36[理学—物理化学] O469[理学—化学]