No abstract

Quasi-MOFs'' realize both an open-framework structure and a strong interaction with the guest metal nanoparticles (NPs). Through controlled deligandation of metal-NP/MOF composites, metal-NP/quasi-MOF composites can be fabricated, leading to dramatically enhanced catalytic performance.

Micro-/nanocapsules have received substantial attention due to various potential applications for storage, catalysis, and drug delivery. However, their conventional enclosed non-/polycrystalline walls pose huge obstacles for rapid loading and mass diffusion. Here, we present a new single-crystal capsular-MOF with openings on the wall, which is carefully designed at the molecular level and constructed from a crystal-structure transformation. This rare open-capsule MOF can easily load the largest amounts of sulfur and iodine among known MOFs. In addition, derived from capsular-MOF and melamine through pyrolysis−phosphidation, we fabricated a nitrogen-doped capsular carbon-based framework with iron−nickel phosphide nanoparticles immobilized on capsular carbons interconnected by plentiful carbon nanotubes. Benefiting from synergistic effects between the carbon framework and highly surface-exposed phosphide sites, the material exhibits efficient multifunctional electrocatalysis for oxygen evolution, hydrogen evolution, and oxygen reduction, achieving well-qualified assemblies of an overall water splitting (low potential of 1.59 V at 10 mA•cm −2 ) and a rechargeable Zn−air battery (high peak power density of 250 mW•cm −2 and excellent stability for 500 h), which afford remarkably practical prospects over previously known electrocatalysts.

In this work, a hierarchically porous carbon was prepared from carbonization of a nitrogen-containing metal–organic framework, followed by activation under ultrasonication in aqueous potassium hydroxide (aq KOH). The activated carbon was applied as a support for immobilizing ultrafine palladium (Pd) nanoparticles (1.1 ± 0.2 nm). As a result, the as-prepared Pd nanoparticles on N-doped porous carbon with both micro- and mesoporosity exhibit an excellent activity for the dehydrogenation of formic acid, showing a high turnover frequency (TOF, 14 400 h–1) at 60 °C. This activation approach of carbon opens an avenue for the syntheses of highly active supported ultrafine metal NPs for catalysis.

Oxygen evolution reaction (OER) demands cost‐effective electrocatalysts with high catalytic performance. In this effort, metal–organic framework (MOF)‐derived nanocomposites are presenting promising prospects to achieve this goal. Herein, FeCo bimetallic MOFs with different compositions are prepared through a sodium hydroxide assisted approach. By means of a successive carbonization and phosphating reaction, a series of MOF‐derived multicomponent products are synthesized. The resultant P‐doped products present enhance electrocatalytic performance for OER in alkaline electrolyte in comparison with a commercial RuO2 catalyst, which paves the way for their practical applications for water splitting. The developed method herein also offers an opportunity for the large‐scale preparation of MOF‐derived product toward energy conversion applications.

superstructure with a large radius of curvature, such as spherical organization, is still a challenge. So far, only a few kinds of 1D oxides could be assembled into 3D spherical superstructures. [13][14][15] Low-dimensional carbon nanomaterials have been widely used in energy storage and conversion owing to their distinct electrochemical properties and mechanical and thermal stability. [16][17][18] 3D superstructures constructed from lowdimensional components such as carbon nanorods/wires or graphene nanorribbons can inherit the exceptional properties of their building blocks and acquire certain unconventional advantages. [19,20] However, the self-assemblies of 1D carbon nanomaterials into 3D ordered spherical superstructures are considerably challenging owing to the reduced accessible contact areas between the building blocks and core templates. Although various synthetic approches have been developed for the synthesis of lowdimensional carbon nanostructures with well-defined size and controllable composition, [21][22][23] no techniques have been applied for controlling the assembly of 1D carbon nanomaterials into 3D spherical superstructure with uniform morphology.Metal-organic frameworks (MOF) are a class of porous crystalline materials that are constructed by metal ions/clusters and organic linkers. [24] The use of MOF as a template or precursor to synthesize carbon nanostructure is an efficient approach to produce carbon materials with controlled morphology and Hierarchical superstructures in nano/microsize have attracted great attention owing to their wide potential applications. Herein, a self-templated strategy is presented for the synthesis of a spherical superstructure of carbon nanorods (SS-CNR) in micrometers through the morphology-preserved thermal transformation of a spherical superstructure of metal-organic framework nanorods (SS-MOFNR). The self-ordered SS-MOFNR with a chestnut-shell-like superstructure composed of 1D MOF nanorods on the shell is synthesized by a hydrothermal transformation process from crystalline MOF nanoparticles. After carbonization in argon, the hierarchical SS-MOFNR transforms into SS-CNR, which preserves the original chestnut-shell-like superstructure with 1D porous carbon nanorods on the shell. Taking the advantage of this functional superstructure, SS-CNR immobilized with ultrafine palladium (Pd) nanoparticles (Pd@SS-CNR) exhibits excellent catalytic activity for formic acid dehydrogenation. This synthetic strategy provides a facile method to synthesize uniform spherical superstructures constructed from 1D MOF nanorods or carbon nanorods for applications in catalysis and energy storage. 3D SuperstructuresHierarchical superstructures are ubiquitous in the biological systems (e.g., proteins, lipids, and carbohydrates). From the aspect of synthesis, self-assembly of simple building blocks into 3D, highly ordered superstructure with novel properties has attracted great interest in the fields of optics, catalysis, and energy storage. [1][2][3][4] Highly organized building bloc...

No abstract

Dehydrogenation of formic acid (FA) is a promising alternative to fossil fuels, to provide clean energy for the future energy economy. The synthesis of highly active catalysts for FA dehydrogenation at room temperature has attracted a lot of attention. Herein, for the first time, highly active aurum-palladium nano particles (AuPd NPs) immobilized on nitrogen (N)-doped porous carbon are fabricated through a phosphate-mediation approach. The N-doped carbon anchored with phosphate, which can be removed in alkaline solution during the reduction process of metal ions, shows an enhanced performance of absorbing and dispersion of both Au and Pd ions, which is a key to the synthesis of highly dispersed ultrafine AuPd NPs. The as-prepared catalyst (designated as Au 2 Pd 3 @(P)N-C) exhibits an extraordinarily high turnover frequency of 5400 h −1 and a 100% H 2 selectivity for FA dehydrogenation at 30 °C. This phosphate-mediation approach provides a new way to fabricate highly active metal NPs for catalytic application, pushing heterogeneous catalysts forward for practical usage in energy storage and conversion.