Supramolecular Modulation of Molecular Conformation of Metal Porphyrins toward Remarkably Enhanced Multipurpose Electrocatalysis and Ultrahigh-Performance Zinc-Air Batteries
Supramolecular Modulation of Molecular Conformation of Metal Porphyrins toward Remarkably Enhanced Multipurpose Electrocatalysis and Ultrahigh-Performance Zinc-Air Batteries
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DOI：
10.1002/aenm.202102062
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发表时间：
2021-10-13
影响因子：
27.8
通讯作者：
Xu, Yuxi
中科院分区：
文献类型：
--
作者：
Cui, Kai;Wang, Qingtao;Xu, Yuxi
调节分子催化剂的固有催化活性以改善电催化性能是重要但具有挑战性的。本文报道了一种简单而有效的策略，通过静电和π-π相互作用，将Co（III）meso-四（N-甲基-4-吡啶基）卟啉（Co-TMPyP）与化学转化的石墨烯（CCG）超分子组装，诱导分子扁平化。这种独特的分子构象变化导致了Co-N配位键的缩短和从卟啉大环到金属离子的电子转移的增强，从而优化了Co-TMPyP分子中催化活性中心的电子结构。因此，CCG上的平坦化Co-TMPyP（Co-TMPyP/CCG）对氧还原反应（ORR）、析氢反应（HER）和析氧反应（OER）的高半波电位（0.824V）、低的过电位（320 mV）、低的过电位（379 mV），表明该催化剂具有良好的催化活性在10 mA cm（-2）下，不仅比原始Co-TMPyP好得多，而且在ORR、OER和HER的每个方面都是迄今为止分子催化剂的最佳结果。作为一个实际的演示，Co-TMPyP/CCG催化剂用于组装可充电锌-空气电池，它显示出最高的比容量（793 mAh g（-1））和功率密度（225.4 mW cm（-2））在所有的分子催化剂为基础的锌-空气电池的报道。
Modulating the intrinsic catalytic activity of molecular catalysts to improve electrocatalytic performance is significant but challenging. Herein, a simple yet effective strategy to induce molecular flattening of Co (III) meso-tetra (N-methyl-4-pyridyl) porphyrine (Co-TMPyP) by supramolecular assembly with chemically converted graphene (CCG) via synergistic electrostatic and pi-pi interactions is reported. This unique variation in molecular conformation leads to a shortened Co-N coordination bond and enhanced electron transfer from the porphyrin macrocycle to the metal ion, thereby optimizing the electronic structure of the catalytic active center in Co-TMPyP molecule. Thus, the flattened Co-TMPyP on CCG (Co-TMPyP/CCG) demonstrates remarkable electrocatalytic performance for the oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER) simultaneously as a tri-functional molecular catalyst for the first time with a high half-wave potential of 0.824 V for ORR and a low overpotential for HER (320 mV) and OER (379 mV) at 10 mA cm(-2), respectively, not only much better than the pristine Co-TMPyP but also among the best results of molecular catalysts in each aspect of ORR, OER, and HER achieved thus far. As a practical demonstration, the Co-TMPyP/CCG catalyst is used to assemble a rechargeable Zn-air battery, which shows the highest specific capacity (793 mAh g(-1)) and power density (225.4 mW cm(-2)) among all molecular catalyst-based Zn-air batteries ever reported.