The activity of a pyromellitimide-bridged polyphthalocyanine Fe(Ⅱ) catalyst for O2 reduction is studied by density functional theory calculations.Three model molecules with different polymerization degrees are designed to investigate O2-reduction electrocatalytic reactivity.The molecular and electronic structures of the models and their O2-complexes are optimized with BP86 functional and SVP basis sets.The central Fe atom in the catalyst binds O2 by a double bond followed by a charge transfer to reduce O2.This study indicates that the catalyst has potential for O2-reduction electrocatalytic activity.The calculated frontier molecular orbitals and stabilities of the O2-complexes demonstrate that catalysts with a higher polymerization degree and stronger electron-withdrawing groups will have higher activities for O2 reduction.O2-reduction activity of the catalyst is achieved via an electrocatalytic cycle.%用密度泛函方法研究了一种均苯四甲酰亚胺桥联的聚酞菁亚铁的氧还原反应.设计了三个模型分子以研究此催化剂在不同聚合度时的氧还原催化反应性能.使用BP86泛函和SVP基组进行构型优化得到模型分子及其氧气复合物的电子和分子结构.此催化剂中心的铁原子和氧气以双键结合并发生电荷转移时,氧气被还原.这证明此催化剂具有良好的催化氧还原能力.通过前沿轨道分析以及模型分子氧气复合物稳定性分析证实,具有较高聚合度和较强吸电子取代基的催化剂具有更好的氧还原活性.催化剂的催化性能通过一个电催化循环来实现.在此循环过程中,氧气结合氢离子被还原为水,因此此催化剂需要在酸性介质中使用.
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