Toward improving CO2 dissociation and conversion to methanol via CO-hydrogenation on Cu(100) surface by introducing embedded Co nanoclusters as promoters: A DFT study
Toward improving CO2 dissociation and conversion to methanol via CO-hydrogenation on Cu(100) surface by introducing embedded Co nanoclusters as promoters: A DFT study
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通过引入嵌入的 Co 纳米团簇作为促进剂，通过 Cu(100) 表面上的 CO 氢化来改善 CO2 解离和转化为甲醇：DFT 研究
DOI：
10.1016/j.apsusc.2017.08.107
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发表时间：
2018
影响因子：
6.7
通讯作者：
Zhang Yongfan
中科院分区：
文献类型：
--
作者：
Qiu Mei;Tao Huilin;Li Yali;Li Yi;Ding Kaining;Huang Xin;Chen Wenkai;Zhang Yongfan
采用密度泛函理论（DFT）方法研究了在Cu（100）表面引入不同尺寸的Co纳米团簇后，CO2在Cu（100）表面上的解离和氢化行为.结果表明，Co原子是CO2在所有表面上的吸附位置，在引入Co掺杂剂的初期，CO2的化学吸附行为对Co原子的量敏感.根据预测的CO2分解为CO的路径，发现随着Co原子在表面的分散，能垒先减小后增大，形成“V”形.在Cu（100）表面上，四个Co原子聚集在一起，即Co 4/Cu（100）表面上，CO2分解的最低能垒被预测。进一步确定了CO在该表面上加氢生成甲醇的最佳反应路径为CO* → HCO* → H2 CO * → H3CO * → H3COH*，反应的限速步骤为H3CO物种的加氢，活化能垒为106.4kJ/mol.值得注意的是，相对于纯Cu（100），由于Co改性表面形成了更强的Co单键O吸附键，因此甲醛中间体的稳定性显着增强。相应地，Co 4团簇的引入有利于提高Cu（100）表面上甲醇合成的产率和选择性。
The dissociation and hydrogenation of CO2on Cu(100) surfaces that are modified by introducing Co nanoclusters with different size into the top layer have been investigated using density functional theory method. Our results show that on all surfaces the Co atoms are the sites for the adsorption of CO2, and in the early stage of introducing Co dopant, the chemisorption behavior of CO2is sensitive to the amount of Co atom. According to the predicted pathways for the dissociation of CO2to CO, it is interesting that the energy barrier decreases first and then increases as more Co atoms are dispersed on the surface, forming a “V” shape. The minimum energy barrier of CO2decomposition is predicted on the Cu(100) surface that contains four Co atoms aggregated together on the top layer, namely Co4/Cu(100) bimetallic surface. The most favorable reaction pathway for the hydrogenation of CO to methanol on such surface is further determined, which follows the sequence of CO* → HCO* → H2CO* → H3CO* → H3COH*, and the rate-limiting step is the hydrogenation of H3CO species with an activation barrier of 106.4 kJ/mol. It is noted that with respect to the pure Cu(100), since more stronger Cosingle bondO adsorption bonds are formed on the Co-modified surface, the stability of formaldehyde intermediate is significantly enhanced. Correspondingly, the introducing of Co4cluster tends to improve the productivity and selectivity towards methanol synthesis on Cu(100) surface.