Metal–organic framework (MOFs) two‐dimensional (2D) nanosheets have many coordinatively unsaturated metal sites that act as active centres for catalysis. To date, limited numbers of 2D MOFs nanosheets can be obtained through top‐down or bottom‐up synthesis strategies. Herein, we report a 2D oxide sacrifice approach (2dOSA) to facilely synthesize ultrathin MOF‐74 and BTC MOF nanosheets with a flexible combination of metal sites, which cannot be obtained through the delamination of their bulk counterparts (top‐down) or the conventional solvothermal method (bottom‐up). The ultrathin iron–cobalt MOF‐74 nanosheets prepared are only 2.6 nm thick. The sample enriched with surface coordinatively unsaturated metal sites, exhibits a significantly higher oxygen evolution reaction reactivity than bulk FeCo MOF‐74 particles and the state‐of‐the‐art MOF catalyst. It is believed that this 2dOSA could provide a new and simple way to synthesize various ultrathin MOF nanosheets for wide applications.
Metal–organic frameworks (MOFs) have recently
emerged as
promising electrocatalysts because of their atomically dispersed metal
sites and porous structures. The active sites of MOF catalysts largely
exist as coordinatively unsaturated metal sites (CUMSs). In this study,
facile microwave-induced plasma engraving is applied to fine-tune
the CUMSs of cobalt-based MOF (Co-MOF-74) without destroying its phase
integrity by controlling the plasma-engraving species, intensity,
and duration. The electrochemical activity of the engraved MOF is
found to be quantitatively correlated to the coordination geometry
of the metal centers corresponding to CUMSs. Specifically, the hydrogen
plasma-engraved Co-MOF-74 shows an enhanced catalytic activity of
oxygen evolution reaction, which exhibits a low overpotential (337
mV at 15 mA cm–2), high turnover frequency (0.0219
s–1), and large mass activity (54.3 A g–1). The developed CUMS control strategy and the revealed CUMSs activity
correlation can inspire the further microstructure tuning of MOFs
for various applications.
Metal-organic framework (MOFs) two-dimensional (2D) nanosheets have many coordinatively unsaturated metal sites that act as active centres for catalysis.T od ate,l imited numbers of 2D MOFs nanosheets can be obtained through topdown or bottom-up synthesis strategies.Herein, we report a2D oxide sacrifice approach (2dOSA) to facilely synthesizeultrathin MOF-74 and BTC MOF nanosheets with af lexible combination of metal sites,whichc annot be obtained through the delamination of their bulk counterparts (top-down)o rt he conventional solvothermal method (bottom-up). The ultrathin iron-cobalt MOF-74 nanosheets prepared are only 2.6 nm thick. The sample enriched with surface coordinatively unsaturated metal sites,e xhibits as ignificantly higher oxygen evolution reaction reactivity than bulk FeCo MOF-74 particles and the state-of-the-art MOF catalyst. It is believed that this 2dOSA could provideanew and simple way to synthesize various ultrathin MOF nanosheets for wide applications.
Manipulating
the exposed facets of metal–organic frameworks
(MOFs) is of importance toward understanding their facet-dependent
property in a variety of applications. Herein, we apply a novel inorganic
competitive coordination strategy to control the growth orientation
of copper-based MOFs (HKUST-1, MOF-14, and Cu-MOF-74) without sacrificing
the pore accessibility and crystallinity. Through monitoring the reactant
composition, we find that the competitive coordination induced by
the added aluminium nitrate mainly affects the crystal growth stage
rather than the nucleation stage. The kinetic study further reveals
that Al3+ competes with Cu2+ to coordinate with
ligands, restraining the growth rate of certain facets and resulting
in the orientated growth of copper-based MOFs. Compared to the reduced
pore accessibility of HKUST-1 crystals modulated by the organic modulation
method, Al3+-modulated HKUST-1 displays a much larger surface
area (>2200 m2/g) and more accessible Cu active sites.
Hydroxylation of toluene was utilized as a model reaction to investigate
the facet-catalytic activity for as-synthesized HKUST-1. The selectivity
of the preferred product cresol increases with the morphology transformation
of HKUST-1 from octahedron to cube.
Recently, the development of the Industrial Internet of Things (IIoT) has led enterprises to re-examine the research of the equipment-state-prediction models and intelligent manufacturing applications. Take industrial robots as typical example. Under the effect of scale, robot maintenance decision seriously affects the cost of spare parts and labor deployment. In this paper, an evaluation method is proposed to predict the state of robot lubricating oil based on support vector regression (SVR). It would be the proper model to avoid the structural risks and minimize the effect of small sample volume. IIoT technology is used to collect and store the valuable robot running data. The key features of the running state of the robot are extracted, and the machine learning model is applied according to the measured element contents of the lubricating oil. As a result, the cost of spare parts consumption can be saved for more than two million CNY per year.
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