Single/dual-atom and cluster metal catalysts have emerged as a new frontier in catalysis. This review highlights recent advances and provides a state-of-the-art understanding of MOF-based synthesis strategies and their prospective applications.
Nanotubes have attracted great attention. Here, we report the fabrication of the first single-crystal metal−organic framework (MOF) nanotubes. Superlong single-crystal cobalt−organic framework (Co-MOF) nanotubes, which have a diameter of ∼70 nm and length of 20−35 μm with parallel multichannels (window size: 1.1 nm), have been successfully synthesized via an amorphous MOF-mediated recrystallization approach. The synthesized MOF nanotubes can be used as a nanocolumn for separation of large molecules. Carbonization of the Co-MOF nanotubes in an argon atmosphere preserves the 1D morphology, affording long carbon nanofibers. A hierarchical architecture composed of carbon nanofibers wrapped by carbon nanotubes (20−30 nm in diameter and 200−300 nm in length) with cobalt nanoparticles on the top is formed by the carbonization of the Co-MOF nanotubes along with dicyandiamide as a nitrogen and a secondary carbon source. The resulting hierarchical dendrites with carbon nanofiber trunks and carbon nanotube branches exhibit excellent electrocatalytic activity for oxygen reduction reaction and exceptional applications in rechargeable Zn−air batteries. This work demonstrates a new strategy to fabricate MOF nanotubes and relative 1D nanostructures.
■ EXPERIMENTAL SECTIONSynthesis of Co-MOF-74-NP and Co-MOF-74-NT. In a typical process, cobalt(II) acetate tetrahydrate (4.0 mmol) was first dissolved in methanol solution (100 mL) under vigorous stirring. With continued stirring, 50 mL of methanol solution containing 1.5 mmol of 2,
Ternary Ni–Co–P nanoparticles with optimized electronic structures strongly interact with ammonia-borane, resulting in the marked improvement of catalytic activity.
There has been strong and growing interest in the development of cost-effective and highly active oxygen evolution reaction (OER) electrocatalysts for alternative fuels utilization and conversion devices. We report herein that semimetallic Cu3P nanoarrays directly grown on 3D copper foam (CF) substrate can function as effective electrocatalysts for water oxidation. Specifically, the surface oxidation-activated Cu3P only required a relatively low overpotential of 412 mV to achieve a current density of 50 mA cm(-2) and displayed a small Tafel slope of 63 mV dec(-1) in 0.1 M KOH solution, on account of the collaborative effect of large roughness factor (RF) and semimetallic character. Following that, investigations into the mechanism revealed the formation of a unique active phase during the water oxidation process in which conductive Cu3P was the core covered with a thin copper oxide/hydroxide layer. Moreover, this Cu3P 3D electrode was also applied to the hydrogen evolution reaction (HER) and showed good catalytic performance and stability under the same basic conditions.
The development of low-cost and highly active electrocatalysts for two half reactions: H2 and O2 evolution reactions (HER and OER), is still a huge challenge to realize water splitting. Herein, we report that CoP nanoparticles (NPs) can act as a bifunctional catalyst for both HER and OER. Particularly, ultrafine CoP NPs decorated on N-doped multiwalled carbon nanotube (MWCNT) exhibit remarkable catalytic performance for OER in 0.1 M NaOH aqueous solution, with a low onset overpotential of 290 mV, a Tafel slope of 50 mV dec(-1), an overpotential (η) of 330 mV at 10 mA cm(-2), and approximately 100% Faradaic efficiency, paralleling the performance of state-of-the-art Co-based OER catalysts including Co3O4, CoSe2, and Co-Pi. The hybrid catalyst is capable of maintaining a high catalytic current density for at least 10 h without any loss of catalytic activity. Meanwhile, the noble-metal-free catalyst also shows good activity and duarability for HER under the same basic condition.
UIO-67 MOFs functionalized with a [Ru(dcbpy)(bpy)2]2+ photosensitizer and a Pt(dcbpy)Cl2 catalyst display enhanced photocatalytic activity, due to the facile electron transfer from the Ru- to Pt-centers in the MOFs.
Co2P nanoparticles were applied to photocatalytic hydrogen evolution in aqueous acidic media, and simultaneously, dl-mandelic acid was transformed into benzoylformic acid.
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