DFT-D3 study of H2 and N2 chemisorption over cobalt promoted Ta3N5-(100), (010) and (001) surfaces.
DFT-D3 study of H2 and N2 chemisorption over cobalt promoted Ta3N5-(100), (010) and (001) surfaces.
复制标题
钴促进 Ta3N5-(100)、(010) 和 (001) 表面上 H2 和 N2 化学吸附的 DFT-D3 研究。
DOI：
10.1039/c7cp00806f
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
C. Catlow
中科院分区：
文献类型：
--
作者：
C. Zeinalipour;J. Hargreaves;S. Laassiri;C. Catlow
采用密度泛函理论（DFT）研究了氨合成反应物在氮化钽表面上的吸附情况。发现氮的吸附主要是分子吸附和非活化吸附，具有侧向、端向和倾斜结构。在桥接氮位点 (Ta-N-Ta) 处，形成叠氮化物官能团，形成能为 205 kJ mol-1。还发现 H2 也可以分子化学吸附，吸附能在 -81 至 -91 kJ mol-1 范围内。在桥氮位点，它吸附解离形成 >NH 基团，放热形成能为 -175 kJ mol-1/H2。与其他金属氮化物相比，普通、表面共吸附钴和亚表面共吸附钴Ta3N5-(010)的氮空位形成能相对较高，分别为2.89 eV、2.32 eV和1.95 eV。研究发现钴的共吸附主要发生在表面富氮位点，吸附能范围在 -200 至 -400 kJ mol-1 之间。研究发现钴的共吸附增强了 Ta3N5 表面氢分子的解离。这些研究为在钴促进剂存在下氮气和氢气与氮化钽表面的化学反应提供了重要的新见解。
The reactants for ammonia synthesis have been studied, employing density functional theory (DFT), with respect to their adsorption on tantalum nitride surfaces. The adsorption of nitrogen was found to be mostly molecular and non-activated with side-on, end-on and tilt configurations. At bridging nitrogen sites (Ta-N-Ta) it results in an azide functional group formation with a formation energy of 205 kJ mol-1. H2 was found also to chemisorb molecularly with an adsorption energy in the range -81 to -91 kJ mol-1. At bridging nitrogen sites it adsorbs dissociatively forming >NH groups with an exothermic formation energy of -175 kJ mol-1 per H2. The nitrogen vacancy formation energies were relatively high compared to other metal nitrides found to be 2.89 eV, 2.32 eV and 1.95 eV for plain, surface co-adsorbed cobalt and sub-surface co-adsorbed cobalt Ta3N5-(010). Co-adsorption of cobalt was found to occur mostly at nitrogen rich sites of the surface with an adsorption energy that ranged between -200 to -400 kJ mol-1. The co-adsorption of cobalt was found to enhance the dissociation of molecular hydrogen on the surface of Ta3N5. The studies offer significant new insight with respect to the chemistry of N2 and H2 with tantalum nitride surfaces in the presence of cobalt promoters.