Molecular Cleavage of Metal‐Organic Frameworks and Application to Energy Storage and Conversion

Abstract

topology, and pore structure. This has led to research via various chemical approaches to control precisely chemical moieties within the structure of MOFs. [3] However, the direct (bottom-up) synthesis of MOFs from metal ions and ligands is not always feasible due to factors, including limited reactant concentration, lack of solvent, improper reaction temperature, and undesired side reactions. [4] Therefore, postsynthesis (top-down) methods are receiving increased research attention. This approach is seen as being flexible to modulate the structure of assynthesized MOFs. [5] For example, the synthesis of defects via missing clusters can regulate the pore volume of derived MOFs to boost CO 2 capture from flue gas. [6] Additionally, missing linkers not only create vacancy sites in MOF-808 (Zr 6 O 5 (OH) 3 (BTC) 2 (HCOO) 5 (H 2 O) 2 , BTC = 1,3,5-benzenetricarboxylate) and UiO-66 (University in Oslo, Zr 6 O 4 (OH) 4 (BDC) 6 , BDC = terephthalic acid) but introduce OH groups, which work as Brønsted bases to facilitate tertbutyl alcohol catalytic dehydration. [7] Weakening of the energy of metal-linker coordination bonds provides an opportunity to achieve postsynthesis of MOFs. [8] Using simple thermal pyrolysis, derivatives such as transitionmetal-based materials, single-atom catalysts, and carbon materials have been prepared for catalysis and energy-related applications. [9] However, the structure of MOFs is destroyed during many of these treatments. As a result, MOFs serve only as precursors for the derivatives rather than the direct active materials in catalytic application. [] Here, we focus on postsynthesis methods involving selective chemical bond cleavage to tailor composites and create new MOF structures. This method is advantageous because the reticular chemistry structure of the parent is not destroyed.Posttreatment of MOFs can be conveniently categorized as one of each of three distinct methods: 1) introduction of foreign metal ions or ligands into a pristine structure via exchange reactions; [4] 2) solvent-assisted incorporation of linkers on vacant/labile sites into the structure; [11] and 3) partial destruction to a new structure. [12] Generally, for the first two, the insertion of linkers with desired functional groups is not always trivial because these groups coordinate to metal sites during synthesis, losing functionalities. [13] The destruction of MOFs by cleavage of coordination bonds between metal and solvent molecules/linkers to precisely tune structures generates opening of metal sites, defects, hierarchical pores, orThe physicochemical properties of metal-organic frameworks (MOFs) significantly depend on composition, topology, and porosity, which can be tuned via synthesis. In addition to a classic direct synthesis, postsynthesis modulations of MOFs, including ion exchange, installation, and destruction, can significantly expand the application. Because of a limitation of the qualitative hard and soft acids and bases (HSAB) theory, posttreatment permits regulation of MOF structure by cleavi...

Customizing the microenvironment of CO2 electrocatalysis via three‐phase interface engineering

“…35 For example, electrolyte cations affect the double electrical layer, thus enabling the possibility to regulate the reaction rates and selectivity of the CRR. 37 To date, excellent reviews on the design of electrocatalysts and reaction cells for CRR have been published [38][39][40][41][42][43] ; a comprehensive review focusing on tuning the catalyst microenvironment to promote the CRR is therefore timely.…”

2D π‐conjugated metal–organic frameworks for CO2 electroreduction

“…With the recent advance in 2D MOFs, much effort has been devoted to exploring their potential for practical CO 2 RR applications. And a series of atomic‐level engineering strategies have been proposed to optimize their structural and catalytic properties, such as active‐site engineering, thickness control, structure reconstructing, heterostructure construction, and molecular cleavage 59–62 . For instance, the density of active sites will increase with thickness down to 1 nm, which strongly promotes the intrinsic activity of 2D MOF 56 .…”

“…And a series of atomic-level engineering strategies have been proposed to optimize their structural and catalytic properties, such as activesite engineering, thickness control, structure reconstructing, heterostructure construction, and molecular cleavage. [59][60][61][62] For instance, the density of active sites will increase with thickness down to 1 nm, which strongly promotes the intrinsic activity of 2D MOF. 56 Thus, the precise control of layer number becomes an effective approach to optimize their catalytic activities.…”

Toward High‐Performance CO2‐to‐C2 Electroreduction via Linker Tuning on MOF‐Derived Catalysts

“…Electrochemical reduction of CO 2 (eCO 2 RR) to achieve valueadded chemicals, especially C 2 products ethylene (C 2 H 4 ) [1,2] and ethanol (C 2 H 5 OH) [3] has been identified as the most potential solution to mitigate the greenhouse effect and the energy crisis. [4] As a kind of porous material, metal-organic frameworks (MOFs) have been extensively explored in eCO 2 RR due to their ordered structure, [5,6] high porosity, [7,8] adjustable chemical functionality, [9][10][11] and flexibility in the structure design. [10,12] Additionally, the structures of MOF catalysts are easy to be in situ reconstructed under electrochemical conditions to be derive to new structures, [2,13] which are commonly referred to as MOF-derived catalyst.…”

“…[4] As a kind of porous material, metal-organic frameworks (MOFs) have been extensively explored in eCO 2 RR due to their ordered structure, [5,6] high porosity, [7,8] adjustable chemical functionality, [9][10][11] and flexibility in the structure design. [10,12] Additionally, the structures of MOF catalysts are easy to be in situ reconstructed under electrochemical conditions to be derive to new structures, [2,13] which are commonly referred to as MOF-derived catalyst. Due to the diverse structural regulation released Cu + ions slowly, and the Cu + ions were further oxidized by O 2 in the solution to form a 2D framework.…”