Design and construction of low-cost electrocatalysts with high catalytic activity and long-term stability is a challenging task in the field of catalysis. Metal-organic frameworks (MOF) are promising candidates as precursor materials in the development of highly efficient electrocatalysts for energy conversion and storage applications. This review starts with a summary of basic concepts and key evaluation parameters involved in the electrochemical water-splitting reaction. Then, different synthesis approaches reported for the cobalt-based Zeolitic imidazolate framework (ZIF-67) and its derivatives are critically reviewed. Additionally, several strategies employed to enhance the electrocatalytic activity and stability of ZIF-67-based electrocatalysts are discussed in detail. The present review provides a succinct insight into the ZIF-67 and its derivatives (oxides, hydroxides, sulfides, selenides, phosphide, nitrides, telluride, heteroatom/metal-doped carbon, noble metal-supported ZIF-67 derivatives) reported for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting applications. Finally, this review concludes with the associated challenges and the perspectives on developing the best economic, durable electrocatalytic materials. 

Critical Review, Recent Updates on Zeolitic Imidazolate Framework‐67 (ZIF‐67) and Its Derivatives for Electrochemical Water Splitting

Achieving energy-efficient hydrogen production via hybrid water electrolysis systems requires not only a well-chosen alternative anodic reaction to replace the sluggish oxygen evolution reaction, but also highly efficient electrocatalysts. Herein, N-doped carbon coated Ni-Mo-N nanowire arrays supported on a nickel foam substrate (NC/Ni-Mo-N/NF) are constructed as a bifunctional electrocatalyst to facilitate electrocatalytic hydrogen production and selectively oxidize glycerol to formate simultaneously. With the desirable structural and compositional advantages of modified surface properties, optimized electronic structure, and Ni/Ni0.2Mo0.8N interfacial synergy effect, the resultant self-supported NC/Ni-Mo-N/NF electrode displays excellent electrocatalytic performance for both the hydrogen evolution reaction and glycerol oxidation reaction in alkaline conditions. Remarkably, the NC/Ni-Mo-N/NF||NC/Ni-Mo-N/NF two-electrode system needs only a cell voltage of 1.38 V at 10 mA cm−2 in 1 M KOH containing 0.1 M glycerol, much lower than that of conventional overall water splitting system (1.57 V at 10 mA cm−2).

Integrating electrocatalytic hydrogen generation with selective oxidation of glycerol to formate over bifunctional nitrogen-doped carbon coated nickel-molybdenum-nitrogen nanowire arrays

Hierarchical design of FeCo-based microchains for enhanced microwave absorption in C band

Engineering the abundant heterointerfaces of integrated bimetallic sulfide-coupled 2D MOF-derived mesoporous CoS2 nanoarray hybrids for electrocatalytic water splitting

Strategies for the enhanced water splitting activity over metal–organic frameworks-based electrocatalysts and photocatalysts

For overall water electrolysis, the hydrogen evolution reaction (HER) is severely limited by the sluggish kinetics of the anodic oxygen evolution reaction (OER). Therefore, replacing the OER with a more favorable anodic oxidation reaction with remarkable kinetics is of paramount significance, especially the one that can produce value-added chemicals. Moreover, time-saving and cost-effective strategies for the fabrication of electrodes are helpful for the wide application of electrolysis. Herein, thermodynamically more favorable iodide electrooxidation over Ni doped Co(OH)2 nanosheet arrays (NSAs) in alkaline solution is presented as the alternative to the OER to boost the HER. And the active species are determined to be the reverse redox of the Co(IV)/Co(III) couple. Remarkably, a negative shift of voltage of 320 mV is observed at a current density of 10 mA cm−2 after using iodide electrolysis to replace ordinary water splitting. The synthetic strategy and iodide oxidation in this work expand the application of Co-based materials in the field of energy-saving hydrogen production.

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Yue Yao

Papers

Strategies for the enhanced water splitting activity over metal–organic frameworks-based electrocatalysts and photocatalysts

Boosting hydrogen generation by anodic oxidation of iodide over Ni–Co(OH)2 nanosheet arrays

Designed construction of hierarchical CoOOH@Co–FeOOH double-shelled arrays as superior water oxidation electrocatalyst

Engineering Different Reaction Centers on Hierarchical Ni/NiFe Layered Double Hydroxide Accelerating Overall Water Splitting

Scalable Synthesis of NiFe-LDH/Ni9S8/NF Nanosheets by Two-Step Corrosion for Efficient Oxygen Electrocatalysis