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![a) Schematic illustration of Mo‐Co(OH)2 HNTs organized by cross‐linked porous NSs formation process. b) TEM and c) HRTEM image of Mo‐Co(OH)2. d) LSV curves of the Mo‐Co(OH)2 HNTs, Co(OH)2, MoO3 for OER. e) The chronoamperometry curve for OER. f) LSV curves of the Mo‐Co(OH)2 HNTs, Co(OH)2, MoO3 for HER. g) The chronoamperometry curve for HER. Reproduced with permission.[¹⁶⁹] Copyright 2020, Elsevier. h) Schematic illustration for the formation of Rh‐doped CoFe‐ZLDH@NF using EDSE strategy. i,j) SEM and TEM images of Rh‐doped CoFe‐ZLDH. k) The calculation model of CoFe‐LDH and Rh‐doped CoFe‐LDH. l) The free energy barrier on (010) slab and m) (100) slab. n) LSV curves of Rh‐doped CoFe‐ZLDH@NF and Pt/C ‖RuO2 for overall water splitting (inset: the picture of electrolyzer driven by a single‐cell AAA battery). Reproduced with permission.[²³⁵] Copyright 2020, John Wiley and Sons.](publication/356657988/figure/fig9/AS:11431281173306809@1688829652330/a-Schematic-illustration-of-Mo-CoOH2-HNTs-organized-by-cross-linked-porous-NSs.png)
a) Schematic illustration of Mo‐Co(OH)2 HNTs organized by cross‐linked porous NSs formation process. b) TEM and c) HRTEM image of Mo‐Co(OH)2. d) LSV curves of the Mo‐Co(OH)2 HNTs, Co(OH)2, MoO3 for OER. e) The chronoamperometry curve for OER. f) LSV curves of the Mo‐Co(OH)2 HNTs, Co(OH)2, MoO3 for HER. g) The chronoamperometry curve for HER. Reproduced with permission.[¹⁶⁹] Copyright 2020, Elsevier. h) Schematic illustration for the formation of Rh‐doped CoFe‐ZLDH@NF using EDSE strategy. i,j) SEM and TEM images of Rh‐doped CoFe‐ZLDH. k) The calculation model of CoFe‐LDH and Rh‐doped CoFe‐LDH. l) The free energy barrier on (010) slab and m) (100) slab. n) LSV curves of Rh‐doped CoFe‐ZLDH@NF and Pt/C ‖RuO2 for overall water splitting (inset: the picture of electrolyzer driven by a single‐cell AAA battery). Reproduced with permission.[²³⁵] Copyright 2020, John Wiley and Sons.
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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...
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Metal–nitrogen–carbon (M–N–C) materials have attracted much interest in bifunctional oxygen‐involving electrocatalysis for rechargeable Zn–air batteries. Such M–N–C electrocatalysts with M–Nx sites show good activity for the oxygen reduction reaction (ORR) but moderate activity for the oxygen evolution reaction (OER). Herein, an oxygen‐rich M–N–C m...
In the present work, a facile synthesis of beta-cobalt hydroxide (ß-CoOH) nanosheets from ZIF-67 structure using thermolysis method has been described. The cobalt hydroxide nanosheets grown on carbon cloth would be highly benificial for wide-ranging applications including catalysis and batteries. The XRD studies show that the crystallite sizes are...
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... [1] Among the different techniques for producing hydrogen, electrolysis of water has the advantage of producing hydrogen with high purity and renewable water as the reactant over the traditional fossil energy production of hydrogen with large amounts of carbon dioxide, which is required to achieve the goal of a carbon-neutral society. [2][3][4] In contrast to the cathodic Hydrogen evolution reaction (HER) where double electron transfer occurs, anodic Oxygen evolution reaction (OER) is a four-electron transfer process that requires suitable electrocatalysts to accelerate the reaction rate. [5] Precious metals such Ru and Ir frequently serve as important electrocatalysts for OER, however their high cost and scarcity significantly limit their large-scale utilization. ...
To address the substantial energy needs of the quickly evolving modern civilization, efforts are still needed to provide sustainable renewable energy sources. The electrocatalytic Oxygen evolution reaction (OER) is one of the essential technologies used in the various hydrogen production techniques. ZIF‐67 nanocubes (ZIF‐67 NCs) were synthesized in an aqueous solution and used as sacrificial templates. Cobalt nitrate hexahydrate was added under water bath conditions, resulting in the evolution of numerous small layered layers of cobalt hydroxide. This ultimately led to the formation of multilayered, three‐dimensionally crosslinked Co‐LDH with a porous networked cubic morphology. Hydrolysis of Co²⁺ at different concentrations produces different degrees of weak acidic environments, and the loose LDH on the cubic structure of the best catalyst, Co‐LDH‐1, exposes more active cobalt sites for the OER, which results in a high electrochemically active surface area, with an overpotential of 354 mV and a Tafel slope of 79.06 mV dec⁻¹ at a current density of 10 mA cm⁻², and good stability and low activation under alkaline condition also has good stability and low activation energy. It provides us an easy and practical plan for logically creating ZIF‐derived hydroxide materials, leading to the development of affordable and effective electrocatalysts.
... It powers factories and machinery, enabling the production of goods and services on a large scale. Energy is the foundation of modern society, influencing economic prosperity, technological advancement, environmental sustainability, and overall quality of life (1). As global energy demands grow, finding sustainable and efficient ways to produce, distribute, and use energy becomes increasingly crucial. ...
Energy conversion and storage devices (ECSDs) made from clean, green and eco-friendly agricultural/bio waste is achieving more attention of researchers/scientists due to its recyclability, low cost, sustainability, and excellent supercapacitance performance. The role of green electrolytes (GEs) (such as, quasi/novel solid), separators, current collectors, and electrode materials (for instance, biomass waste-derived from activated carbon (AC), reduced graphene-oxide (rGO), metal-oxides (MOs), metal-organic frameworks (MOFs), and conducting polymers (CPs)) for ECSDs is highlighted in this chapter. The depletion of energy supplies and trashing of agricultural waste has become a worldwide concern, throbbing the world’s economy and ecosystem via the fuel crisis and pollution and hence the idea of Green/Eco-Friendly Supercapacitors (GSs) is pointed out in this chapter. In the last section, the future research prospects and challenges of green electrode-electrolyte based ECSDs at industrial scale for energy sector are also projected, keeping in view their health related concerns and disposal.
... Layered double hydroxide (LDH), comprising 2D ultrathin nanosheets, is a reliable option for this objective. It has an ultrahigh surface area and facile synthesis methods, making it a viable option for imparting the electrocatalyst with the benefits of extensive surface areas and making it cost effective for enhancing its catalytic capabilities [13]. Recently, various LDH nanomaterials derived from ZIF-67, which was used as self-sacrificial template, have been widely studied. ...
The electrochemical splitting of seawater is promising but also challenging for sustainable hydrogen gas production. Herein, ZIF-67 nanosheets are grown on nickel foam and then etched by Ni2+ in situ to obtain a hierarchical hollow nanosheets structure, which demonstrates outstanding OER performance in alkaline seawater (355 mV at 100 mA cm−2). Diven by a silicon solar panel, an overall electrolysis energy efficiency of 62% is achieved at a high current of 100 mA cm−2 in seawater electrolytes. This work provides a new design route for improving the catalytic activity of metal organic framework materials.
... [24][25][26][27] Cobalt-based ZIFs exhibit good stability in highconcentration alkaline environments owing to their excellent binary reversible redox pairs. [28][29][30][31][32] In contrast, increasing the strength of the metal-ligand coordination bonds can effectively enhance the thermal stability of nano MOFs. [33] In our previous work, we confirmed that Ni 2+ has a stronger coordination ability with N than that with Co 2+ . ...
... [23,36,37] In particular, Ni-, Co-, and Fe-based phosphides exhibit high electron densities and excellent conductivities near the Fermi level. [31,32] Nano-MOF/polymetallic phosphide composites can effectively address the poor conductivity of MOF composite materials. [38] The use of Co-and Ni-based MOFs as sacrificial templates to directly calcine and oxidize nano MOF and transition-metal phosphides is a feasible strategy. ...
Polymetallic phosphides exhibit favorable conductivities. A reasonable design of nano‐Metal‐organic frame (MOF) composite morphologies and in‐situ introduction of polymetallic phosphides into the framework can effectively improve electrolyte penetration and rapid electron transfer. To address existing challenges, Ni, with a strong coordination ability with N, is introduced to partially replace Co in the nano‐Co‐MOF composite. The hollow nanostructure is stabilized through CoNi bimetallic coordination and a low‐temperature controllable polymetallic phosphide generation rate. The Ni, Co, and P atoms, generated during reduction, effectively enhance the electron transfer rate within the framework. X‐ray absorption fine structure (XAFS) characterization results further confirmed the existence of Ni‐N, Ni‐Ni, and Co‐Co structures in the nanocomposite. The changes in each component during the charge‐discharge process of the electrochemical reactions were investigated using in situ X‐ray diffraction (XRD). Theoretical calculations further confirmed that P can effectively improve conductivity. VZNPGC//MXene MSCs, constructed with active materials derived from the hollow nano MOF composites synthesized through the Ni ²⁺ stabilization strategy, demonstrate a specific capacitance of 1184 mF cm ⁻² , along with an energy density of 236.75 μWh cm ⁻² (power density of 0.14 mW cm ⁻² ). This approach introduces a new direction for the synthesis of highly conductive nano‐MOF composites.
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... ZIFs have been widely investigated for the synthesis of nanocomposites that exhibit promising catalytic properties [40][41][42][43][44][45][46]. The active sites they demonstrate possess a high level of activity, resulting in superior catalytic performance across several reactions [47]. ...
... Rights reserved. J Mater Sci between metal ions and organic ligands [13][14][15][16]. In recent years, MOF-based materials are increasingly favored for electrocatalytic OER applications due to their porous characteristics and structural diversity [15,17]. ...
... In recent years, MOF-based materials are increasingly favored for electrocatalytic OER applications due to their porous characteristics and structural diversity [15,17]. In particular, the MOFs containing the firstrow transition metals (such as Fe, Co, Ni, Mn, etc.) exhibit impressive performance in electrocatalytic water splitting [13,18]. Yet, the unsatisfactory electrical conductivity and insufficient active sites limit their intrinsic activity [15,19]. ...
... Metal organic frameworks (MOFs) feature highly ordered porous network structure, which is obtained by forming multifunctional coordination bonds J Mater Sci to the sufficient exposure of catalytic active sites and boosting efficient electron transfer [13,21]. However, pure ZIF-67 shows less satisfactory OER catalytic activity and massive studies have been devoted to further optimize and modify the ZIF-67 [13,21,26]. ...
Cobalt-based transition metal phosphides (TMPs) exhibit huge potential as efficient OER electrocatalysts for commercial applications. Zeolitic imidazolate framework-67 (ZIF-67) has been served as an appealing precursor for the synthesis of cobalt-based TMPs owing to its distinctive structural advantages. However, the poor conductivity and structural variability of ZIF-67 affect the materials’ OER electrocatalytic performance. To enhance the structural stability and OER performance of ZIF-67 derived TMPs, in this work, a polyhedral TMP nanocomposite with porous hollow structure, featuring Fe-CoP on the outer shell and CoP nanoparticles within the cavity, was synthesized using ZIF-67 as template. The ZIF-67 served as both Co precursor and structure template, and the [Fe(CN)6]³⁻ served as precursor of Fe dopant and structure stabilizer. The resulting TMP composite electrode (Fe-CoP) effectively retains the framework of ZIF-67, exhibiting prominently improved OER activity (η10 = 297 mV) and exceptional stability (over 260 h). The Fe–C≡N–Co bonds positively influence the preservation of the sample’s morphology after phosphorization. Additionally, a ligand-substitution strategy is proposed for the formation of the designed structure. This strategy, regulating the morphology of 3D structured MOFs, offers a new understanding on stabilizing the geometric structure of MOFs and their derivatives as structure templates.
Graphical abstract
... On this basis, pristine MOFs have been used as functional materials for several applications, including energy storage and conversion (supercapacitors, batteries, electrocatalysis, etc.) [19]. Among existing MOFs, ZIF-67, which belongs to the ZIF subclass, exhibits good thermal stability, high surface area, very good compositional control and extraordinary flexibility in morphological/structural engineering, and has, therefore, attracted more attention in electrocatalysis applications [20]. The imidazole organic linker in ZIF-67 is a source of nitrogen that plays a positive role in enhancing the conductive matrix. ...
Efficient electrocatalysts for the hydrogen evolution reaction (HER) in alkaline electrolytes can ensure both durability and safety in electrolysis devices. The synergistic integration of metal-organic frameworks and two-dimensional materials holds promise for advancing electrocatalytic performance. Herein, we hybridized V2C MXene and the cobalt-based imidazolate zeolitic framework (ZIF-67) by an in-situ precipitation method and investigated its electrocatalytic properties for HER in 1 M KOH solution. Characterization unveiled the successful intercalation of ZIF-67 within the layers of V2C MXene nanosheets. The resulting V2C/ZIF-67 hybrid achieves a good current density of 10 mAcm−2 at a modest overpotential of 197 mV vs RHE and a Tafel slope of 76 mVdec−1. Significantly, the hybrid material shows excellent stability with a minor overpotential loss of 5.5 mV, whereas the Pt/C-20% exhibits a more pronounced loss of 15.3 mV after 12 h of chronopotentiometry. Capitalizing on ZIF-67's substantial active surface and exceptional electrical conductivity of V2C MXene, hybrid material enables the fast transfer of charges and ions across the interface, culminating in its superior electrocatalytic prowess.
... ZIF-67 stands out as a ZIF variant with high metal content and a well-organized carbon framework [10]. It has found widespread use in various electrochemical applications, as documented in several reviews [11,12]. ...
... [1][2][3] Notably, MOFs are often employed in catalysis as they offer considerable surface areas and have highly tuneable porosity owing to the choice of the metal ion and length of the organic linker. However, MOFs are typically poor conductors (less than 10 −8 S m −1 ), [2,4] and unstable in harsh reaction conditions (e.g., low pH), [5] making them unfavourable electrocatalysts. Consequently, recent work has focused on improving their conductivity, generating a series of 2D MOFs with conductivity values above 40 S m −1 . ...
... [15,16] In this study, we specifically focus on zeolitic imidazolate frameworks (ZIFs), a well-studied subset of MOFs that can be readily tailored for electrocatalysis. [4,17] The fabrication only involves a one-step impregnation of VG into a ZIF precursor, which successfully assembles a series of ZIFs, including ZIF-7, ZIF-8, and ZIF-67. These ZIFs are uniformly dispersed on the VG surface with adjustable sizes and shapes. ...
The integration of graphene and metal–organic frameworks (MOFs) has numerous implications across various domains, but fabricating such assemblies is often complicated and time‐consuming. Herein, a one‐step preparation of graphene‐MOF assembly is presented by directly impregnating vertical graphene (VG) arrays into the zeolitic imidazolate framework (ZIF) precursors under ambient conditions. This approach can effectively assemble multiple ZIFs, including ZIF‐7, ZIF‐8, and ZIF‐67, resulting in their uniform dispersion on the VG with adjustable sizes and shapes. Hydrogen defects on the VG surface are critical in inducing such high‐efficiency ZIF assembly, acting as the reactive sites to interact with the ZIF precursors and facilitate their crystallisation. The versatility of VG‐ZIF‐67 assembly is further demonstrated by exploring the process of MOF amorphization. Surprisingly, this process leads to an amorphous thin‐film coating formed on VG (named VG‐IL‐amZIF‐67), which preserves the short‐range molecular bonds of crystalline ZIF‐67 while sacrificing the long‐range order. Such a unique film‐on‐graphene architecture maintains the essential characteristics and functionalities of ZIF‐67 within a disordered arrangement, making it well‐suited for electrocatalysis. In electrochemical oxygen reduction, VG‐IL‐amZIF‐67 exhibits exceptional activity, selectivity, and stability to produce H2O2 in acid media.
... ZIF-67 stands out as a ZIF variant with high metal content and a well-organized carbon framework [10]. It has found widespread use in various electrochemical applications, as documented in several reviews [11,12]. ...
Efforts to enhance the electrochemical properties of materials have become the focus of numerous studies because these properties are essential in various fields of application. Zeolitic imidazole framework-67 (ZIF-67) is a type of metal-organic framework (MOFs) expected to demonstrate excellent performance in electrochemical applications due to its numerous distinct properties. Consequently, various strategies and techniques have been developed to improve the electrochemical performance of ZIF-67. In this study, we employed bimetallic ZIF-67 constructed with cobalt (Co) and copper (Cu) metal ions within the imidazole frameworks. The use of bimetal is expected to increase conductivity and fine-tune the physicochemical properties of ZIF-67. Using coprecipitation methods, we synthesized both single-metal and bimetallic ZIF-67 and compared their characterizations. The addition of Cu metal ions does not alter the materials phase, ensuring compatibility with the single-metal ZIF-67 structure. However, the rhombic dodecahedron morphology of ZIF-67 shifts from a smooth to a concave and rough surface in Co/Cu ZIF-67. Furthermore, Co/Cu ZIF-67 exhibits higher peak current on their cyclic voltammetry (CV) curve by 46.15 µA. The results effectively illustrate the advantages of bimetal on ZIF-67 properties and performance. Finally, this study succesfully briefly demonstrate the potential development of Co/Cu-based ZIF-67 for various electrochemical applications.
