Symmetric Electronic Structures of Active Sites to Boost Bifunctional Oxygen Electrocatalysis by MN4+4 Sites Directly from Initial Covalent Organic Polymers,Advanced Functional Materials

当前位置： X-MOL 学术 › Adv. Funct. Mater. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Symmetric Electronic Structures of Active Sites to Boost Bifunctional Oxygen Electrocatalysis by MN4+4 Sites Directly from Initial Covalent Organic Polymers
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2023-05-25 , DOI: 10.1002/adfm.202303235
Chunxia Mi ₁ , Haifeng Yu ₁ , Linkai Han ₁ , Lirong Zhang ₁ , Lingling Zhai ₁ , Xueli Li ₁ , Yujia Liu ₂ , Zhonghua Xiang ₁

Affiliation

Transition metal-nitrogen-carbon (M-N-C) catalysts with CoN₄ centers have attracted great attention as a potential alternative to precious metal catalysts for bifunctional oxygen electrocatalysis. However, the asymmetric charge environment of the active site of MN₄ obtained by conventional pyrolysis strategy makes the unbalanced adsorption of oxygen molecules, which restricts the activities of both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Herein, a series of well-defined quasi-phthalocyanine conjugated 2D covalent organic polymer (COP_BTC-M) is developed with MN₄₊₄ active sites through a pyrolysis-free strategy. Compared to CoN₄ site, the additional subcentral N₄ atoms in MN₄₊₄ site in COP_BTC-Co catalyst balance the charge environment and form a symmetric charge distribution, which changes the antibonding orbital of the active metal and regulate the oxygen species adsorption, thus improving the activity of the bifunctional oxygen electrocatalysis. In Silico screening demonstrates that cobalt has the best ORR and OER activity for COP_BTC-M with MN₄₊₄ sites, which can be attributed to the fewer anti-bonding orbital below the Fermi level, which weakens the oxygen species adsorption. Both theoretical and experimental results verify that the COP_BTC-Co possesses unique CoN₄₊₄ active sites and the harmonious coordinating environment can lead to superior bifunctional oxygen catalytic activity with a high bifunctional oxygen catalytic activity (ΔE [Ej₁₀ – E_1/2] = 0.76 V), which is comparable with the benchmark Pt/C-IrO₂ pairs. Accordingly, the as-assembled Zn–air battery exhibits a maximum power density of 157.7 mW cm ⁻² with stable operation for >100 cycles under an electric density of 10 mA cm ⁻². This study provides a characteristic understanding of the intrinsic active species toward MN_x centers and could inspire new avenues for designation of advanced bifunctional electrocatalysts that catalyze ORR and OER processes simultaneously.

中文翻译：

活性位点的对称电子结构可直接来自初始共价有机聚合物的 MN4+4 位点促进双功能氧电催化

_{具有CoN 4}中心的过渡金属-氮-碳（MNC）催化剂作为双功能氧电催化贵金属催化剂的潜在替代品引起了极大的关注。然而，传统热解策略获得的MN 4_活性位点的不对称电荷环境使得氧分子的吸附不平衡，从而限制了析氧反应（OER）和氧还原反应（ORR）的活性。在此，通过无热解策略开发了一系列具有MN ₄₊₄活性位点的明确的准酞菁共轭2D共价有机聚合物（COP _{BTC -M）。}与 CoN ₄位点相比，额外的次中心 N ₄COP _BTC -Co催化剂中MN ₄₊₄位点的原子平衡了电荷环境，形成对称的电荷分布，改变了活性金属的反键轨道，调节了氧物种的吸附，从而提高了双功能氧电催化的活性。In Silico筛选表明，钴对具有MN _{4+4位点的COP}_BTC -M具有最佳的ORR和OER活性，这可归因于费米能级以下的反键轨道较少，从而削弱了氧物质的吸附。理论和实验结果均验证了COP _BTC -Co具有独特的CoN ₄₊₄活性位点和和谐的配位环境可以带来优异的双功能氧催化活性，具有高双功能氧催化活性（Δ E [ E j ₁₀ – E _1/2 ] = 0.76 V），可与基准 Pt/C- 相媲美。氧化铁₂对。因此，组装后的锌空气电池表现出157.7 mW cm ^{-2的最大功率密度，在10 mA cm}^-2的电密度下稳定运行>100次循环。_{这项研究提供了对 MN x}内在活性物质的特征性理解中心，并可以激发指定同时催化 ORR 和 OER 过程的先进双功能电催化剂的新途径。

更新日期：2023-05-25

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南