MOF Template‐Directed Fabrication of Hierarchically Structured Electrocatalysts for Efficient Oxygen Evolution Reaction

Abstract

transfer and sluggish kinetics process. [4][5][6] Although precious metals, such as Ir and Ru, as well as their oxides have been approved as efficient electrocatalysts for the OER, their high cost and scarcity undoubtedly prohibit the large-scale application in practice, to some extent. [5,6,7,8a] As a result, a great amount of efforts have been devoted to exploit earth-abundant metalsbased electrocatalysts, such as metal phosphates, oxides, hydroxides, chalcogenides, and nitrides for promoting the OER. However, the performance of explored catalysts is still discounted by their low conductivity and inadequate active surface area, resulting in high overpotential and limited kinetics in the OER. [9a,10b] Thus, to satisfy the requirement of efficient water splitting, the development of new materials and/or methodologies to exploit novel electrocatalysts with advantages of fast reaction rate, minimum overpotential, and long-term stability is one of current research hot topics in several research fields.Among resource-rich transition metalbased electrocatalysts, Co-based materials (e.g., Co, Co 3 O 4 , Co 8 S 9 , CoP, and CoN 4 ) have emerged as important candidates for the water splitting due to their low cost-efficiency, environmental benignity, and theoretically high catalytic activity. [11][12][13][14][15] Despite a great deal of efforts, the low intrinsic conductivity and easy self-agglomeration of these catalysts usually lead to a high overpotential and decreased reaction rate. Alternatively, the integration of Co-based materials and other electrocatalysts has been demonstrated to be able to enhance OER activity, however the poor compatibility between them in some composites is an obstacle to further optimize their efficiency. [16][17][18][19] Moreover, in some cases the active components are still not stable enough when being subjected to long time operation or accelerated degradation measurements under strong alkaline electrolytes, which also limits their application.Recently, it was demonstrated that deliberately designing well-defined 3D structures directly grown on the current collectors can endow electrocatalysts with superior water splitting performance, owing to the advantages of their fast electrolyte penetration, great electrical conductivity, and more exposed active sites. [20][21][22][23] It was noticed that Co-based metal-organic frameworks (MOFs) (as the template) derived materials with The ever-increasing demand for clean and renewable power sources has sparked intensive research on water splitting to produce hydrogen, in which the exploration of electrocatalysts is the central issue. Herein, a new strategy, metal-organic framework template-directed fabrication of hierarchically structured Co 3 O 4 @X (X = Co 3 O 4 , CoS, C, and CoP) electrocatalysts for efficient oxygen evolution reaction (OER) is developed, where Co 3 O 4 @X are derived from cobalt carbonatehydroxide@zeolitic-imidazolate-framework-67 (CCH@ZIF-67). Unique hierarchical structure and synergistic effect of resulting catalysts endo...

Metal–Organic Framework Based Catalysts for Hydrogen Evolution

“…[38] Thanks to the unique characteristics of MOFs, they have attracted great attention in a wide range of applications in energy conversion, including oxygen reduction reactions (ORR), [39][40][41] oxygen evolution reactions (OER), [42][43][44] metal-air/O 2 batteries, [45][46][47] CO 2 reductions, [48] as well as catalytic HER. [38] Thanks to the unique characteristics of MOFs, they have attracted great attention in a wide range of applications in energy conversion, including oxygen reduction reactions (ORR), [39][40][41] oxygen evolution reactions (OER), [42][43][44] metal-air/O 2 batteries, [45][46][47] CO 2 reductions, [48] as well as catalytic HER.…”

Phosphorus Incorporation into Co9S8 Nanocages for Highly Efficient Oxygen Evolution Catalysis

“…Transition‐metal‐based nanomaterials have been extensively investigated as an electrocatalyst for OER . However, their OER performances lag behind those of Ru‐/Ir‐based catalysts due to the less catalytic active sites .…”

A Core‐Shell Assembly of Hierarchical Porous Ni@C Nanospheres Synthesized from Metal‐Organic Framework for Electrochemical Energy Application

“…Hierarchical materials based on metal‐organic frameworks (MOFs) show innovative properties with potential energy‐related application . Moreover, the larger mesoporosity of the materials facilitates molecular arrangements, while smaller micro‐pores offer high surface area .…”