空间受限二聚金属中心的选择性C-C偶联
Selective C-C Coupling by Spatially Confined Dimeric Metal Centers
摘要：
将二氧化碳（CO2）直接转化为高能量燃料和高价值化学品是一项迷人的可持续战略。然而，对于目前大多数用于CO2还原的电催化剂，多碳产物被大的过电位和低选择性抑制。对于实际应用，在正确操作C-C耦合过程方面仍然存在很大的知识缺口。在这里，我们利用分散的三维过渡金属二聚体作为空间限制的双反应中心，用于选择性还原CO2为液体燃料。各种氮化多孔碳单层被证明是有前途的模板，以稳定这些金属二聚体，并决定其电子结构，允许精确控制的催化活性和产品的选择性。通过全面的第一性原理计算，我们筛选出合适的过渡金属二聚体，普遍具有较高的活性乙醇（C2 H5 OH）。此外，显着的选择性C2 H5 OH对其他C1和C2的产品被发现锚定在C2 N单分子层的Fe 2二聚体。研究了负载金属二聚体的活性与d带中心的相关性以及金属二聚体与碳底物之间的电子耦合作用。
英文摘要：
Direct conversion of carbon dioxide (CO2) to high-energy fuels and high-value chemicals is a fascinating sustainable strategy. For most of the current electrocatalysts for CO2 reduction, however, multi-carbon products are inhibited by large overpotentials and low selectivity. For practical applications, there remains a big gap of knowledge in proper manipulation of the C-C coupling process. Herein, we exploit dispersed 3d transition metal dimers as spatially confined dual reaction centers for selective reduction of CO2 to liquid fuels. Various nitrogenated holey carbon monolayers are shown to be promising templates to stabilize these metal dimers and dictate their electronic structures, allowing precise control of the catalytic activity and product selectivity. By comprehensive first-principles calculations, we screen the suitable transition metal dimers that universally have high activity for ethanol (C2H5OH). Furthermore, remarkable selectivity for C2H5OH against other C1 and C2 products is found for Fe2 dimer anchored on C2N monolayer. The correlation between the activity and d band center of the supported metal dimer as well as the role of electronic coupling between the metal dimer and the carbon substrates are thoroughly elucidated.
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