The encapsulation of noble-metal nanoparticles (NPs) in metal-organic frameworks (MOFs) with carboxylic acid ligands, the most extensive branch of the MOF family, gives NP/MOF composites that exhibit excellent shape-selective catalytic performance in olefin hydrogenation, aqueous reaction in the reduction of 4-nitrophenol, and faster molecular diffusion in CO oxidation. The strategy of using functionalized cavities of MOFs as hosts for different metal NPs looks promising for the development of high-performance heterogeneous catalysts.

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.

The sluggish ion diffusion and electrolyte freezing with volumetric changes limit the low-T performance of rechargeable batteries. Herein, we report a high-rate aqueous proton battery (APB) operated at and below -78 o C via a 62 wt% (9.5 m) H 3 PO 4 electrolyte. The APB is a rocking-chair battery that operates with protons commuting between a Prussian blue cathode and a MoO 3 anode. At -78 o C, the APB full cells exhibit stable cycle life for 450 cycles, high round-trip efficiency of 85%, and appreciable power performance. The APB delivers 30% of its room-temperature capacity even at -88 o C. The proton storage mechanism is investigated by ex situ synchrotron XRD, XAS, and XPS. The APB pouch cells demonstrate nil capacity fading at -78 o C, which offers a safe and reliable candidate for high-latitude applications.

limits the diffusion of chemical species and their interactions with active sites in MOFs. [ 10 ] One of successful strategy from zeolites, silica, and carbon is the fabrication of mesopore structure which has expanded a large variety of potential and existing commercial applications. [1][2][3] Hence, it is worthwhile to develop methods to fabricate MOFs with mesopores so as to enhance the molecular diffusion while preserving their molecular sieve properties.To date, two major synthetic strategies have been explored to synthesize mesoporous-MOFs (meso-MOFs). [ 11 ] One is through ligand extension, either to increase the length of organic ligands [ 12 ] or to use bulky organic scaffolds [ 13 ] to form mesopores inside MOFs. In this case, the largest pore size reported is 9.8 nm in MOF-74 by increasing the length of organic linker to 5 nm. [ 14 ] Besides the diffi culties in complex ligands synthesis, interpenetration, disintegration, and instability of frameworks almost inevitably occur in MOFs with extended organic linkers, which prevent this functionalization method from being generally adopted in the formation of meso-MOFs. Another approach, the surfactanttemplate method, [ 4d , 15 ] has been introduced to increase the pore size in MOFs. For example, the Zhou group has successfully used cetyltrimethylammonium bromide (CTAB) as soft template to build meso-MOFs. [ 16 ] In this system, surfactant mole cules fi rst self-assembled into micelles serving as a soft template for MOFs growth and were subsequently removed to generate mesopores. The pore diameter of the resulting MOFs could be tuned from 3.8 to 31.0 nm. Nevertheless, as is well known, small molecular micelles are usually unstable under the synthesis conditions of most MOFs, so that only a few series of MOFs (such as carboxylic acid ligands) can be obtained by the surfactant-template method. Recently, some new methods have been successively developed to prepare the meso-MOFs, such as the gelation process, [ 17 ] and switchable solvent. [ 18 ] Moreover, the above methods are suitable for preparation of intrinsic meso-MOFs, but lack of control over the shape, position, and space distribution of mesopores in MOFs makes it hard to meet the demand for the growing applications of MOFs. It is well known that the potential applications of MOFs can be further developed and extended by encapsulating various nanoparticles (NPs) within the frameworks matrix so that the functionalized MOFs can exhibit the novel chemical and physical properties endowed by NPs. [ 7b , 19 ] Thus, to the best of our knowledge, general and versatile strategies of synthesizing functionalized MOFs with size-, shape-, and space-distribution-controlled mesopores have been rarely reported, in spite of the need and the signifi cance in application of functionalized meso-MOFs.Herein, we report a facile strategy of crafting mesopores inside MOFs through encapsulation of NPs followed by etching. Especially, the mesopore morphology, hierarchical structure, and space Porous materials, such as sili...