Xue Qian, Qi Xueqiang, Yang Tingting, Jiang Jinxia, Zhou Qi, Fu Chuang, Yang Na
School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China.
Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization, School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China.
Nanomaterials (Basel). 2022 Jun 29;12(13):2239. doi: 10.3390/nano12132239.
The catalytic conversion of CO to C products through the CO reduction reaction (CORR) offers the possibility of preparing carbon-based fuels and valuable chemicals in a sustainable way. Herein, various Fe and Co clusters are designed to screen out the good catalysts with reasonable stability, as well as high activity and selectivity for either CH or CHCHOH generation through density functional theory (DFT) calculations. The binding energy and cohesive energy calculations show that both Fe and Co clusters can adsorb stably on the N-doped carbon (NC) with one metal atom anchored at the center of the defected hole via a classical MN structure. The proposed reaction pathway demonstrates that the Fe-NC cluster has better activity than Co-NC, since the carbon-carbon coupling reaction is the potential determining step (PDS), and the free energy change is 0.22 eV lower in the Fe-NC cluster than that in Co-NC. However, Co-NC shows a better selectivity towards CH since the hydrogenation of CHCHO to CHCHO becomes the PDS, and the free energy change is 1.08 eV, which is 0.07 eV higher than that in the C-C coupling step. The larger discrepancy of d band center and density of states (DOS) between the topmost Fe and sub-layer Fe may account for the lower free energy change in the C-C coupling reaction. Our theoretical insights propose an explicit indication for designing new catalysts based on the transition metal (TM) clusters supported on N-doped carbon for multi-hydrocarbon synthesis through systematically analyzing the stability of the metal clusters, the electronic structure of the critical intermediates and the energy profiles during the CORR.
通过一氧化碳还原反应（CORR）将CO催化转化为C产物，为以可持续方式制备碳基燃料和有价值的化学品提供了可能性。在此，通过密度泛函理论（DFT）计算设计了各种Fe和Co团簇，以筛选出具有合理稳定性、对生成CH或CHCHOH具有高活性和选择性的优良催化剂。结合能和内聚能计算表明，Fe和Co团簇都可以稳定地吸附在N掺杂碳（NC）上，一个金属原子通过经典的MN结构锚定在缺陷孔的中心。所提出的反应途径表明，Fe-NC团簇比Co-NC具有更好的活性，因为碳-碳偶联反应是潜在的决速步骤（PDS），并且Fe-NC团簇中的自由能变化比Co-NC中的低0.22 eV。然而，Co-NC对CH表现出更好的选择性，因为CHCHO加氢生成CHCHO成为PDS，自由能变化为1.08 eV，比C-C偶联步骤中的高0.07 eV。最顶层Fe和次层Fe之间d带中心和态密度（DOS）的较大差异可能是C-C偶联反应中自由能变化较低的原因。我们的理论见解通过系统分析金属团簇的稳定性、关键中间体的电子结构以及CORR过程中的能量分布，为设计基于N掺杂碳负载的过渡金属（TM）团簇用于多碳氢化合物合成的新型催化剂提供了明确的指示。
