Modulating Hierarchical Micro/Mesoporosity by a Mixed Solvent Approach in Al-MOF: Stabilization of MAPbBr3 Quantum Dots

Various hierarchical micro/mesoporous MOFs based on {[Al(μ-OH)(1,4-NDC)]⋅H₂ O} (MOF1) with tunable porosities (pore volume and surface area) have been synthesized by assembling Al^III and 1,4-NDC (1,4-naphthalenedicarboxylate) under microwave irradiation by varying water/ethanol solvent ratio. Water/ethanol mixture has played a crucial role in the mesopore generation in MOF1M₂₅ , MOF1M₅₀ , and MOF1M₇₅ , which is achieved by in situ formation of water/ethanol clusters. By adjusting the ratio of water/ethanol, the particle size, surface area and micro/mesopore volume fraction of the MOFs are controlled. Furthermore, reaction time plays a critical role in mesopore formation as realized by varying reaction time for the MOF with 50 % ethanol (MOF1M₅₀ ). Additionally, hierarchical MOF (MOF1M₅₀ ) has been used as a template for the stabilization of MAPbBr₃ (MA=methylammonium) perovskite quantum dots (PQDs). MAPbBr₃ PQDs are grown inside MOF1M₅₀ , where mesopores control the size of PQDs which leads to quantum confinement.

Hollow Functional Materials Derived from Metal-Organic Frameworks: Synthetic Strategies, Conversion Mechanisms, and Electrochemical Applications

Hollow materials derived from metal-organic frameworks (MOFs), by virtue of their controllable configuration, composition, porosity, and specific surface area, have shown fascinating physicochemical properties and widespread applications, especially in electrochemical energy storage and conversion. Here, the recent advances in the controllable synthesis are discussed, mainly focusing on the conversion mechanisms from MOFs to hollow-structured materials. The synthetic strategies of MOF-derived hollow-structured materials are broadly sorted into two categories: the controllable synthesis of hollow MOFs and subsequent pyrolysis into functional materials, and the controllable conversion of solid MOFs with predesigned composition and morphology into hollow structures. Based on the formation processes of hollow MOFs and the conversion processes of solid MOFs, the synthetic strategies are further conceptually grouped into six categories: template-mediated assembly, stepped dissolution-regrowth, selective chemical etching, interfacial ion exchange, heterogeneous contraction, and self-catalytic pyrolysis. By analyzing and discussing 14 types of reaction processes in detail, a systematic mechanism of conversion from MOFs to hollow-structured materials is exhibited. Afterward, the applications of these hollow structures as electrode materials for lithium-ion batteries, hybrid supercapacitors, and electrocatalysis are presented. Finally, an outlook on the emergent challenges and future developments in terms of their controllable fabrications and electrochemical applications is further discussed.

Intentional Closing/Opening of "Hole-in-Cube" Fullerene Crystals with Microscopic Recognition Properties

We report production of highly crystalline fullerene C₇₀ cubes possessing an open-hole structure at the center of each of their faces using a solution-based self-assembly strategy. The holes are isolated with a solid core at the interiors of the cubes. The open-hole structure of the cubes can be intentionally closed by introducing additional C₇₀ and reopened by applying electron beam irradiation. The open-hole cubes exhibit preferential recognition of graphitic carbon particles over polymeric resin particles of similar dimensions due to the cubes' sp²-rich carboniferous nature.

Fe2O3/Al2O3microboxes for efficient removal of heavy metal ions

Pictorial representation of removal of mercury ions using Fe₂O₃/Al₂O₃MOFs.

Synthesis of highly monodispersed Ga-soc-MOF hollow cubes, colloidosomes and nanocomposites

Highly monodispersed Ga-soc-MOF hollow cubes, colloidosomes and nanocomposites were synthesized for the first time.

Well-Defined Metal-Organic-Framework Hollow Nanostructures for Catalytic Reactions Involving Gases

The miniaturization of metal-organic-framework (MOF) crystals to the nanoscale brings enhanced or novel properties and fulfils specific application needs. The focus here is on a kind of nanoMOF with special configurations and outstanding properties - the hollow structure. Firstly recent advances on the synthesis of MOF hollow nanostructures are introduced. Then, a novel approach based on a heterometallic system is highlighted, by which the facile synthesis of well-defined hollow MOF structures with high complexity is achieved. Moreover, MOF hollow nanostructures are emphasized as hosts/shell materials to incorporate functional catalysts that show dramatically enhanced performances in gas-involved reactions due to their inherent gas-absorption/storage properties.