Dipole-Field Interactions Determine the CO2 Reduction Activity of 2D Fe–N–C Single-Atom Catalysts,ACS Catalysis

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Dipole-Field Interactions Determine the CO2 Reduction Activity of 2D Fe–N–C Single-Atom Catalysts
ACS Catalysis ( IF 11.3 ) Pub Date : 2020-06-05 , DOI: 10.1021/acscatal.0c01375
Sudarshan Vijay ₁ , Joseph A. Gauthier ₂ , Hendrik H. Heenen ₁ , Vanessa J. Bukas ₁ , Henrik H. Kristoffersen ₁ , Karen Chan ₁

Affiliation

Iron–nitrogen-doped graphene (FeNC) has emerged as an exciting earth-abundant catalyst for electrochemical CO₂ reduction (CO₂R). However, standard theoretical approaches based on density functional theory (DFT) suggest complete poisoning of the active sites and are unable to rationalize the experimentally observed dramatic pH dependence and Tafel slopes, which have a critical impact on the electrocatalytic activity. In this work, we overcome these challenges through a rigorous theoretical investigation of FeNC single-atom catalysts using a combination of several state-of-the-art methods: hybrid functionals, continuum solvation, and potential-dependent electrochemical reaction energetics. Our model shows dipole-field interactions in CO₂ adsorption to determine the overall activity, which resolves the contentious origin of experimentally observed pH dependence and rationalizes differences in activity and Tafel slopes among different samples in experimental work. A critical conclusion of our study is that single-atom catalysts can be tuned for electrocatalytic activity not only through the traditionally considered binding energies but also through the corresponding surface dipole moment of rate-determining surface intermediates. Our presented methodology paves the way for accurate mechanistic studies as well as the computational catalyst design of general single-atom catalysts.

中文翻译：

偶极场相互作用决定了二维Fe–N–C单原子催化剂的CO ₂还原活性

铁-氮掺杂的石墨烯（FENC）已经成为用于电化学CO一个激动人心的地球上资源丰富催化剂₂还原（CO ₂ R）。但是，基于密度泛函理论（DFT）的标准理论方法表明活性位点完全中毒，无法合理化实验观察到的剧烈pH依赖性和Tafel斜率，这对电催化活性具有关键影响。在这项工作中，我们通过对FeNC单原子催化剂进行严格的理论研究，克服了这些挑战，这些催化剂结合了几种最先进的方法：杂化功能，连续溶剂化和电势依赖性电化学反应能量学。我们的模型显示了CO _2中的偶极场相互作用通过吸附确定整体活性，从而解决了实验观察到的pH依赖性的争议根源，并使实验工作中不同样品之间的活性差异和Tafel斜率合理化。我们研究的关键结论是，不仅可以通过传统上认为的结合能，而且可以通过相应的决定速率的表面中间体的表面偶极矩，对单原子催化剂的电催化活性进行调节。我们提出的方法学为精确的机理研究以及一般的单原子催化剂的计算催化剂设计铺平了道路。

更新日期：2020-07-17

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