Metal–Organic-Framework-Derived Atomically Dispersed Mn–N–C Electrocatalysts Boosting Oxygen Reduction Modulated by Anion Exchange of Permanganate

Abstract

Mn–N–C materials have received increasing interest in recent years because of their low Fenton reactivity and ORR activity comparable to those of their Fe–N–C and Co–N–C counterparts. In this contribution, an atomically dispersed Mn–N–C electrocatalyst with a prominent oxygen reduction performance was constructed by employing a cationic Cd-MOF as a precursor that can facilely and accurately introduce MnO4 – anions through anion exchange. The best-performing Mn–N–C catalyst displays a 0.96 V (vs RHE) E onset (onset potential) and a 0.87 V (vs RHE) E 1/2 (half-wave potential) in an alkaline solution, which exceed those of the benchmark Pt/C catalyst. In particular, the maximal power density of the self-made zinc-air battery reaches 200 mW·cm–2, surpassing that of most reported Mn–N–C materials.

Recent Progress and Prospects of Manganese–Nitrogen–Carbon Electrocatalysts for Oxygen Reduction Reaction

“…134,135 Metal organic framework (MOFs) consist of metal atoms linked by covalent bonds, forming an ordered three-dimensional porous structure. 65,136 MOFs containing N and C elements are chemically bonded to metal ions and can undergo conversion into M−N−C active centers in situ. 34,65,103 The hybrid organic/inorganic structure with metal nitrogen coordination effectively hinders the migration of Mn atoms and facilitates their distribution.…”

“…It entails restricting or encapsulating metal atoms within a nanometer or subnanometer space to regulate chemical reactions and prevent their migration to achieve atomic dispersion. ,,, The confined microenvironment inhibits the agglomeration and oxidation issues that may arise active sites, while promoting the transfer of intermediate products, and reactants within the confined space. This leads to enhanced activity anddurability of the catalyst. , Metal organic framework (MOFs) consist of metal atoms linked by covalent bonds, forming an ordered three-dimensional porous structure. , MOFs containing N and C elements are chemically bonded to metal ions and can undergo conversion into M–N–C active centers in situ . ,, The hybrid organic/inorganic structure with metal nitrogen coordination effectively hinders the migration of Mn atoms and facilitates their distribution. ,, This process contributes to the formation of Mn–N–C with catalytic activity, enhancing ORR reactivity. MOFs show significant potential as initial materials or self-sacrificing carriers for carbon networks in synthesizing M–N–C catalysts via pyrolysis .…”

“…65,136 MOFs containing N and C elements are chemically bonded to metal ions and can undergo conversion into M−N−C active centers in situ. 34,65,103 The hybrid organic/inorganic structure with metal nitrogen coordination effectively hinders the migration of Mn atoms and facilitates their distribution. 69,137,138 This process contributes to the formation of Mn−N−C with catalytic activity, enhancing ORR reactivity.…”