Metal–nitrogen–carbon (M–N–C) catalysts are a class of emerging materials for oxygen electrocatalysis. However, a precise understanding of the predominant factors that affect their electrocatalytic activities is still preliminary, significantly hampering the rational design of high-performance M–N–C electrocatalysts. Accurate structure–activity relationship modeling necessitates considering the potential of zero charge (PZC) and solvation effects, pivotal for pH-dependent activities on a reversible hydrogen electrode scale through direct impact on reaction energetics. These factors, however, have been largely omitted in theoretical and microkinetic models due to the computational intensity of explicit solvation models. Herein, we fill in this significant knowledge gap by employing large-scale sampling via ab initio molecular dynamics and structural relaxations based on density functional theory with van der Waals corrections, on twelve distinct M–N–C configurations (M₁-pyridine-N₄ and M₁-pyrrole-N₄; M = Cr, Mn, Fe, Co, Ni, and Cu) with explicit solvation models. Interestingly, our analysis reveals that the PZCs and solvation effects, particularly hydrogen bonding adjustments to crucial reaction intermediates (HO*, O*, and HOO*), vary substantially based on the M–N–C catalysts' structures, notably the metal type and nitrogen configuration (pyridine- or pyrrole-N). Besides, both the PZCs and solvation effects of M–N–C catalysts are found to be a function of HO* binding energy; however, the PZCs follow two distinct trends on the pyridine- and pyrrole-N structures, respectively. This study shows the intricate relationship between PZC/solvation effects and M–N–Cs, and emphasizes that these effects should be considered to further improve the accuracy of microkinetic modeling.

中文翻译：

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单原子 M-N-C 氧电催化催化剂的零电荷潜力和溶剂化效应

金属-氮-碳（M-N-C）催化剂是一类用于氧电催化的新兴材料。然而，对影响其电催化活性的主要因素的准确理解仍处于初步阶段，这极大地阻碍了高性能M-N-C电催化剂的合理设计。准确的构效关系建模需要考虑零电荷电势 (PZC) 和溶剂化效应，这对于可逆氢电极尺度上的 pH 依赖性活性至关重要，因为它直接影响反应能量。然而，由于显式溶剂化模型的计算强度，这些因素在理论和微动力学模型中已被很大程度上忽略。在此，我们通过从头算分子动力学和基于密度泛函理论和范德华校正的结构弛豫，对十二种不同的 M-N-C 构型（M ₁ -吡啶-N）进行大规模采样，填补了这一重大知识空白。₄和 M ₁ -吡咯-N ₄；M = Cr、Mn、Fe、Co、Ni 和 Cu），具有明确的溶剂化模型。有趣的是，我们的分析表明，PZC 和溶剂化效应，特别是对关键反应中间体（HO*、O* 和 HOO*）的氢键调整，根据 M-N-C 催化剂的结构（尤其是金属类型）而有很大差异和氮构型（吡啶-或吡咯-N）。此外，M-N-C 催化剂的 PZC 和溶剂化效应均是 HO* 结合能的函数。然而，PZC 分别遵循吡啶-和吡咯-N 结构的两种不同趋势。这项研究显示了 PZC/溶剂化效应与 M-N-Cs 之间的复杂关系，并强调应考虑这些效应以进一步提高微动力学模型的准确性。