We investigate oxidative methane activation on a wide range of single transition metal atom catalysts embedded on N-doped graphene derivatives using density functional theory calculations. An inverse scaling relationship between *O formation and its hydrogen affinity is observed, consistent with a previous report. However, we find that the latter scaling line can be shifted towards a more reactive region by tuning the coordination number (CN) of the active metal sites. Specifically, we find that lowering the CN plays an important role in increasing the reactivity for methane activation via a radical-like transition state by moving the scaling lines. Thus, in the new design strategy suggested here, different from the conventional efforts focusing mainly on breaking the scaling relations, one maintains the scaling relations but moves them towards more reactive regions by controlling the coordination number of the active sites. With this design principle, we suggest several single atom catalysts with lower C–H activation barriers than some of the most active methane activation catalysts in the literature such as Cu-based zeolites.

中文翻译：

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通过调整配位数来改变单原子催化剂用于甲烷活化的比例关系

我们使用密度泛函理论计算研究了嵌入N掺杂石墨烯衍生物上的各种单一过渡金属原子催化剂上的氧化甲烷活化。观察到* O形成与其氢亲和力之间成反比例关系，与先前的报道一致。但是，我们发现可以通过调整活性金属位点的配位数（CN）来将后一个缩放线移向更具反应性的区域。具体而言，我们发现，降低CN对于增加甲烷活化反应中起重要作用通过通过移动缩放线来实现类似自由基的过渡状态。因此，在这里提出的新设计策略中，与传统的努力主要集中在打破比例关系上不同，它保持比例关系，但是通过控制活性位点的配位数将它们移向反应性更大的区域。以此设计原理为基础，我们建议使用几种具有比文献中最活跃的甲烷活化催化剂（例如铜基沸石）更低的CH活化势的单原子催化剂。