Rational Molecular Design of Electrocatalysts Based on Single-Atom Modified Covalent Organic Frameworks for Efficient Oxygen Reduction Reaction,ACS Applied Energy Materials

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Rational Molecular Design of Electrocatalysts Based on Single-Atom Modified Covalent Organic Frameworks for Efficient Oxygen Reduction Reaction
ACS Applied Energy Materials ( IF 5.4 ) Pub Date : 2020-01-13 00:00:00 , DOI: 10.1021/acsaem.9b02141
Kazuyuki Iwase _{1,

2} , Shuji Nakanishi _{2,

3} , Masaru Miyayama ₁ , Kazuhide Kamiya _{2,

3,

4}

Affiliation

The development of oxygen reduction reaction (ORR) electrocatalysts comprising abundant elements is highly desirable for achieving widespread use of fuel cells. Optimal ORR catalysts should have moderate binding strength (ΔE_ads) with O₂-derived intermediates, where the metal species and its coordination numbers are the essential determining factors for ΔE_ads. However, in conventional non-noble-metal-based ORR catalysts, such as metal–nitrogen-doped carbons, the metal species and its coordination structure cannot freely be chosen. In contrast, covalent organic frameworks (COFs), which are cross-linked microporous polymers, have high design flexibility; as such, they can be purposefully designed by using a wide range of monomers. The present work investigated the adsorption strength of ORR intermediates on single 3d metal atoms (Mn, Fe, Co, Ni, and Cu) doped in COFs with different coordination structures using first-principles calculations toward the development of efficient non-noble-metal ORR catalysts. The adsorption strength of the intermediates was found to monotonically increase as either the number of d-electrons or coordination number of metal centers decreased, and a volcano-type relationship was observed between the adsorption energies of the intermediates and the theoretical ORR activities. Therefore, to develop efficient non-noble-metal-based ORR electrocatalysts, the adsorption strength should be tuned close to the volcano peak by an appropriate choice of metal species and/or coordination number as the control parameters. Considering the high designability of metal species and of its coordination numbers in COFs, COFs are expected to become the next-generation platform of supports of single-atom catalysts using the design direction provided by the present work.

中文翻译：

基于单原子修饰的共价有机骨架有效还原氧的电催化剂的合理分子设计

为了实现燃料电池的广泛使用，迫切需要开发包含丰富元素的氧还原反应（ORR）电催化剂。最佳的ORR催化剂应具有与O ₂衍生的中间体的中等结合强度（ΔE _ads），其中金属种类及其配位数是决定ΔE _ads的关键因素。但是，在常规的非贵金属基ORR催化剂中，例如金属氮掺杂的碳，金属种类及其配位结构不能自由选择。相反，作为交联微孔聚合物的共价有机骨架（COF）具有较高的设计灵活性；因此，可以通过使用多种单体来有目的地设计它们。本工作使用第一性原理计算法研究了ORR中间体对掺杂在具有不同配位结构的COF中的单个3d金属原子（Mn，Fe，Co，Ni和Cu）的吸附强度，以开发有效的非贵金属ORR催化剂。发现中间体的吸附强度随着d电子数量或金属中心配位数量的减少而单调增加，并观察到中间体的吸附能与理论ORR活性之间的火山类型关系。因此，为了开发有效的非贵金属为主ORR电催化剂，吸附强度应该接近火山峰由金属物质和/或配位数作为控制参数的适当选择调谐。考虑到金属物种在COF中的高可设计性及其在COF中的配位数，使用当前工作提供的设计方向，COF有望成为单原子催化剂载体的下一代平台。吸附强度应该由金属物种的适当选择和/或配位数作为控制参数被调谐靠近火山峰。考虑到金属物种在COF中的高可设计性及其在COF中的配位数，使用当前工作提供的设计方向，COF有望成为单原子催化剂载体的下一代平台。吸附强度应该由金属物种的适当选择和/或配位数作为控制参数被调谐靠近火山峰。考虑到金属物种在COF中的高可设计性及其在COF中的配位数，使用当前工作提供的设计方向，COF有望成为单原子催化剂载体的下一代平台。

更新日期：2020-01-13

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