The electrochemical CO₂ reduction reaction (CO₂RR) is a promising route for converting CO₂ and excess renewable energy into valuable chemicals and synthetic fuels. Recently, carbon-based solid materials containing dopant-levels of transition metal and nitrogen (M–N–C) have emerged as a cost-effective, energy-efficient catalyst for the direct coreduction of CO₂ and H₂O to CO. Fe–N–C catalysts are particularly interesting as they can reduce CO further to hydrocarbons. Despite these promising reports, the influence of the reaction conditions on the catalytic performance of Fe–N–C catalysts has not been addressed. Here, we study the role of the electrolyte on the CO₂RR selectivity. Unlike hydrogen or methane generation, catalytic CO production is independent of the electrolyte pH on the normal hydrogen electrode potential scale, suggesting a decoupled elementary proton–electron transfer mechanism for CO formation. The similarity between this heterogeneous charge-transfer reaction mechanism and that of molecular metal–nitrogen porphyrin-type macrocyclic complexes strongly suggests that the carbon-embedded FeN_x motifs of the solid-state electrocatalyst act as the primary catalytically active center and illustrates yet another example of unifying concepts between molecular and solid-state catalysis.

中文翻译：

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pH值对嵌入石墨烯的Fe–N–C基序上电催化CO ₂还原选择性的影响：分子均相和固态多相催化之间的桥接概念

电化学的CO ₂还原反应（CO ₂ RR）是将CO ₂和过量的可再生能源转化为有价值的化学品和合成燃料的有前途的途径。最近，含有掺杂剂水平的过渡金属和氮（MC–N）的碳基固体材料已经成为一种经济高效，节能的催化剂，可将CO ₂和H ₂ O直接共轭成CO。 –N–C催化剂特别有趣，因为它们可以将CO进一步还原为碳氢化合物。尽管有这些令人鼓舞的报道，但尚未解决反应条件对Fe–N–C催化剂催化性能的影响。在这里，我们研究了电解质对CO _2的作用RR选择性。与产生氢气或甲烷不同，在正常的氢电极电势规模上，催化性CO的产生与电解质的pH无关，这表明用于CO形成的元素质子-电子传递机理是解耦的。这种异质电荷转移反应机理与分子金属-氮卟啉型大环配合物之间的相似性强烈表明，固态电催化剂的碳嵌入FeN _x基序充当了主要的催化活性中心，并举例说明了另一个例子。分子催化和固态催化的统一概念