Multi‐shelled Hollow Metal–Organic Frameworks

Abstract

Hollow metal–organic frameworks (MOFs) are promising materials with sophisticated structures, such as multiple shells, that cannot only enhance the properties of MOFs but also endow them with new functions. Herein, we show a rational strategy to fabricate multi‐shelled hollow chromium (III) terephthalate MOFs (MIL‐101) with single‐crystalline shells through step‐by‐step crystal growth and subsequent etching processes. This strategy relies on the creation of inhomogeneous MOF crystals in which the outer layer is chemically more robust than the inner layer and can be selectively etched by acetic acid. The regulation of MOF nucleation and crystallization allows the tailoring of the cavity size and shell thickness of each layer. The resultant multi‐shelled hollow MIL‐101 crystals show significantly enhanced catalytic activity during styrene oxidation. The insight gained from this systematic study will aid in the rational design and synthesis of other multi‐shelled hollow structures and the further expansion of their applications.

High Performance Electrocatalyst Based on MIL‐101(Cr)/Reduced Graphene Oxide Composite: Facile Synthesis and Electrochemical Detections

“…Figure 2a and d depict the morphology of MIL-101(Cr), which is truncated octahedral shape and average size is about 200 nm. [29] The SEM and TEM of rGO are showed in Figure 2b and e, respectively. It is clearly that rGO has corrugations [30] because of the aggregation of the graphene sheets.…”

“…[29] To be specific, 0.40 g (1.0 mmol) of chromium (III) nitrate nonahydrate (Cr(NO 3 ) 3 ·9H 2 O) and 0.11 g (0.66 mmol) of 1,4benzene dicarboxylic acid (H 2 BDC) were dissolved in 10 ml of deionized water and then briefly stirred for ten minutes, obtaining a dark blue suspension. [29] To be specific, 0.40 g (1.0 mmol) of chromium (III) nitrate nonahydrate (Cr(NO 3 ) 3 ·9H 2 O) and 0.11 g (0.66 mmol) of 1,4benzene dicarboxylic acid (H 2 BDC) were dissolved in 10 ml of deionized water and then briefly stirred for ten minutes, obtaining a dark blue suspension.…”

Sequential Deconstruction–Reconstruction of Metal–Organic Frameworks: An Alternative Strategy for Synthesizing (Multi)-Layered ZIF Composites

“…[23][24][25][26] Also, ZIF-8/ZIF-67 particles can be etched (top-down) into novel shapes 27,28 or synthesized as hollow or yolk-shelled particles. [29][30][31][32][33][34] Furthermore, both of these ZIFs can grow on the surface of INPs and biosystems, meaning that a rich variety of core-shell [35][36][37][38][39][40][41][42][43][44] and layered composites 17,23,45 could be designed.…”

“…31 And very recently, Liu, Huo et al have applied regrowth processes followed by etching to build multi-shelled hollow particles of the well-known MIL-101. 29 Herein, we report a novel strategy to construct ZIF-on-ZIF and (multi)-layered ZIF-on-INP-on-ZIF particles. Unlike the aforementioned combination (bottom-up/top-down) methods, our method begins with controlled etching followed by MOF-on-MOF growth.…”

A solvent-assisted ligand exchange approach enables metal-organic frameworks with diverse and complex architectures

“…By contrast, only a small number of attempts have been devoted to tailoring MOF architectures on the micro-/nano-scale, even if architectural design is known to have a vital effect on performance [9][10][11] . Some latest significant progresses actually benefit from very common architectures such as MOF@MOF core-shell structures and MOF hollow structures [9][10][11][12][13][14][15][16][17][18] . Nevertheless, unlike inorganic crystals which have abundant nanostructure libraries and well-developed preparation approaches 19,20 , MOFs commonly lack nano-morphological diversity and nanostructural complexity, a large proportion of MOFs are solid particle shapes, which extremely limits the application of MOF materials.…”