Recent Advances in ZIF‐Derived Atomic Metal–N–C Electrocatalysts for Oxygen Reduction Reaction: Synthetic Strategies, Active Centers, and Stabilities

Abstract

oxidation reaction on the anode, while the oxygen undergoes a reduction reaction on the cathode. However, the sluggish kinetics and instability of oxygen reduction reaction (ORR) electrocatalysts, especially in the practical acidic and oxidation environments, have severely hindered their further developments. Therefore, engineering ORR electrocatalysts with high activity and good stability is desired to promote energy transformation efficiency. By far, the most popular ORR electrocatalysts are the costly platinum group metal (PGM)-derived ones. However, the use of expensive, unsatisfied stability, and scarce PGM materials as ORR electrocatalyst limits the developments of this field. [8][9][10][11][12][13][14][15][16][17][18] To improve catalytic efficiency and cut the high expenditure, various strategies have been studied in recent years. Among them, electrocatalysts based on the metal-N-C (M-N-C) structures have attracted extensive attention in recent years due to their unique electronic structure to bind with the intermediates, abundant substitutional metal elements, maximum atomic utilization efficiency, as well as excellent stability. [19][20][21][22][23][24][25] Besides, compared to ORR electrocatalysts loaded with nanoclusters or nanoparticles, the M-N-C presents unambiguous catalytic sites and facile synthesis, which help the understanding of ORR mechanisms by precise theoretical calculations and in Exploring highly active, stable electrocatalysts with earth-abundant metal centers for the oxygen reduction reaction (ORR) is essential for sustainable energy conversion. Due to the high cost and scarcity of platinum, it is a general trend to develop metal-N-C (M-N-C) electrocatalysts, especially those prepared from the zeolite imidazolate framework (ZIF) to replace/minimize usage of noble metals in ORR electrocatalysis for their amazingly high catalytic efficiency, great stability, and readily-tuned electronic structure. In this review, the most pivotal advances in mechanisms leading to declined catalytic performance, synthetic strategies, and design principles in engineering ZIF-derived M-N-C for efficient ORR catalysis, are presented. Notably, this review focuses on how to improve intrinsic ORR activity, such as M-N x -C y coordination structures, doping metal-free heteroatoms in M-N-C, dual/ multi-metal sites, hydrogen passivation, and edge-hosted M-N x . Meanwhile, how to increase active sites density, including formation of M-N complex, spatial confinement effects, and porous structure design, are discussed. Thereafter, challenges and future perspectives of M-N-C are also proposed. The authors believe this instructive review will provide experimental and theoretical guidance for designing future, highly active ORR electrocatalysts, and facilitate their applications in diverse ORR-related energy technologies.

γ-CD-MOF-derived heterostructures as bifunctional electrocatalysts for rechargeable zinc–air batteries

“…Specifically, cobalt-based N-doped carbon (Co–N–C) has emerged as a promising catalyst for oxygen electrocatalysis, attributed to its appropriate intermediate adsorption–desorption free energy of reaction dynamics. 9 Metal–organic frameworks (MOFs) assembled from metal nodes and organic ligands are good candidates for M–C x formation. 10 Generally, zeolitic imidazolate frameworks (ZIFs), composed of transition metal cations (Zn, Co, Fe, and Ni) and imidazole linkers, are used for M–N–C formation.…”

Heteroatom doped M–N–C single-atom catalysts for high-efficiency oxygen reduction reaction: regulation of coordination configurations

“…Numerous studies have demonstrated that the catalytic activity of transition metal-derived catalysts is mainly attributed to these M-N-C sites. 15,16 At present, it is generally believed that the active conguration of M-N-C SACs is M-N 4 , [17][18][19][20] among which the Fe-N 4 conguration shows superior ORR activity. [21][22][23] Xie et al 24 prepared Fe SACs containing FeN 4 single-atom sites with a half-wave potential (E 1/2 ) of 0.94 V (vs. RHE) in an alkaline electrolyte.…”

Porous Fe−N−C Aerogels Derived from Metal‐Organic Aerogels as Electrocatalysts for the Oxygen Reduction Reaction

“…[9,[11][12][13] As a typical kind of porous materials, metal-organic frameworks (MOFs) represent an excellent precursor for pyrolysis synthesis of 3D porous FeÀ NÀ C catalysts. [14][15][16][17] In the meanwhile, metal-organic aerogels (MOAs) emerged as a novel porous material, which features unique micropores and mesopores resulted from its nano-scale MOF particles and interconnected network structure, respectively. [18][19][20] Owing to its ultra-high porosity and specific surface area, it has been widely used in adsorption, thermal batteries, catalysis, and other fields.…”

“…In this regards, various 3D porous Fe−N−C catalysts have been explored for efficient ORR [9,11–13] . As a typical kind of porous materials, metal‐organic frameworks (MOFs) represent an excellent precursor for pyrolysis synthesis of 3D porous Fe−N−C catalysts [14–17] . In the meanwhile, metal‐organic aerogels (MOAs) emerged as a novel porous material, which features unique micropores and mesopores resulted from its nano‐scale MOF particles and interconnected network structure, respectively [18–20] .…”