Integrating covalent organic frameworks (COFs) with other functional materials is a useful route to enhancing their performances and extending their applications. We report herein a simple encapsulation method for incorporating catalytically active Au nanoparticles with different sizes, shapes, and contents in a two-dimensional (2D) COF material constructed by condensing 1,3,5-tris(4-aminophenyl)benzene (TAPB) with 2,5-dimethoxyterephthaldehyde (DMTP). The encapsulation is assisted by the surface functionalization of Au nanoparticles with polyvinylpyrrolidone (PVP) and follows a mechanism based on the adsorption of nanoparticles onto surfaces of the initially formed polymeric precursor of COF. The incorporation of nanoparticles does not alter obviously the crystallinity, thermal stability, and pore structures of the framework matrices. The obtained COF composites with embedded but accessible Au nanoparticles possess large surface areas and highly open mesopores and display recyclable catalytic performance for reduction of 4-nitrophenol, which cannot be catalyzed by the pure COF material, with activities relevant to contents and geometric structures of the incorporated nanoparticles.

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fabricated. Combined with controlled synthesis, MOF materials are endowed with abundant various of structures, morphologies, and properties. [8-11] In addition, the as-prepared MOFs can be artificially modified via postsynthetic approaches utilizing their available pores and active sites of metal clusters or linkers. [12,13] As a result, not only the number of MOFs is further increased but also many interesting properties, such as high specific surface areas, tailorable pore sizes, modifiable structures, and properties are endowed with MOFs, which make them become potential candidates in storage/separation, catalysis, sensing, etc. [14,15] Another important application of MOFs is that they can act as conductive materials for electrocatalysis, sensing, and energy conversion, etc. [16-19] The existence of quantitative amounts of active metal centers, permanent porosity, and structural rigidity can facilitate surface contact and mass transfer as well as increase catalysis stability, making MOFs as ideal electrocatalysts. [20-22] In addition, they possess high specific surface areas, tunable bandgaps, and good charge transport properties, which extend their applications in sensing and energy storage. [23] Besides, the morphologies and characteristics of MOFs can be artificially modified to form 1D, 2D, or 3D structures via liquid phase selfassembly, physical/chemical exfoliation, layer-by-layer assembly, etc., promoting their applications in electrochemical devices and electronics. [24-26] With further structural design through postsynthesized modification, the performances of MOFs can be largely improved, facilitating their applications as conductive materials. [27-29] However, most MOFs are intrinsically electrically insulated, which seriously hinders their electrochemical applications. [29] The connected rigid metal ions and redox-inactive organic ligands increase the energy barrier for electron transfer, making them as electrical insulators. To overcome the drawbacks of MOFs, many feasible strategies have been adopted to promote the electron transfer in the structures of MOFs. [27,30-32] The high electrical conductivity of MOFs can be realized by integrating the conjugated planes or 1D chains in the structures, which relies on particular structural designs. [33-37] The conductivity of the MOFs can also be increased via doping with guest Metal-organic frameworks (MOFs) have aroused worldwide interest over the last two decades due to their various excellent properties, such as porosity, modifiability, stability, etc. Based on these unique features, they have been widely exploited for applications from electrocatalysis to electrochemical devices. However, most MOFs are inherently insulated due to the lack of free charge carriers and low-energy barriers for charge transfer, which largely restricts their further electrochemical applications. By imparting MOFs with electrical conductivity, their electrochemical process and catalysis efficiency can be effectively improved. Similarly, their applications in sensors, secon...

Processing metal-organic frameworks (MOFs) as films with controllable thickness on asubstrate is increasingly crucial for many applications to realizef unction integration and performance optimization. Herein, we report af acile cathodic deposition process that enables the large-area preparation of uniform films of zeolitic imidazolate frameworks (ZIF-8, ZIF-71, and ZIF-67) with highly tunable thickness ranging from approximately 24 nm to hundreds of nanometers. Importantly,t his oxygen-reduction-triggered cathodic deposition does not lead to the plating of reduced metals (Zn and Co). It is also operable cost-effectively in the absence of supporting electrolyte and facilitates the construction of well-defined submicrometer-sized heterogeneous structures within ZIF films.Metal-organic frameworks (MOFs), ac lass of porous crystalline materials with large surface areas,r egular pore sizes,a nd tailorable surface chemistry, [1] have received considerable attention in av ariety of fields. [2][3][4][5][6][7][8] Form any applications,s uch as separations, [3] energy storage [5] and conversion, [6] chemical sensing, [7] and electronics, [8] it is often necessary to process MOF materials as films on as pecific substrate.A mong methods established for preparing MOF films, [9,10] strategies based on electrochemical synthesis are attractive for many advantages including technological flexibility,scalable preparation, and industrial production potential. [11] Nevertheless,t heir potential for preparing MOF films with precisely tunable morphology and thickness has not been fully explored. These variables,h owever,a re critically important for structure integration and performance optimization in (especially device) applications. [8,9] MOFs could be deposited on the electrode surface anodically [12] or cathodically. [13] In cathodic deposition, reduction of some special molecules or ions (e.g.n itrate ions) on electrode surface results in an increase in pH, which promotes the deprotonation of organic ligands and induces the formation of MOFs.Atfirst glance,cathodic deposition appears to be attractive for the direct synthesis of MOFs on conductive substrates.H owever,r eports on the cathodic deposition of MOFs are comparably few.The challenge arises from the more negative reduction potential of nitrate ions relative to those of some important metal ions,f or example, Zn II ,C o II ,a nd Cu II ,w hich constitute the most extensively studied MOFs. [13b,g] As ar esult, cathodic deposition of these MOF materials is commonly accompanied with plating of the corresponding metals, [13a,e] which is in most cases undesirable.Herein, we report the first cathodic deposition of zeolitic imidazolate framework materials (ZIFs), an important subgroup of MOFs that have been extensively studied owing to their outstanding thermal stability and chemical robustness. [14,15] Our strategy is based on an oxygen reduction triggered-electrochemical-chemical-reaction Scheme responsible for the formation of ZIF materials (Scheme 1). Electrochemical oxyge...

As the amount of reactive nitrogen (N) generated and emitted increases the amount of N deposition and its contribution to eutrophication or harmful algal blooms in the coastal zones are becoming issues of environmental concern. To quantify N deposition in coastal seas of China we selected six typical coastal sites from North to South in 2011. Concentrations of NH 3 , HNO 3 , NO 2 , particulate NH 4 + (pNH 4 + ) and pNO 3 − ranged from 1.97-4.88, 0.46 -1.22, 3.03 -7.09, 2.24 -4.90 and 1.13-2.63 μg N m −3 at Dalian (DL), Changdao (CD), Linshandao (LS), Fenghua (FH), Fuzhou (FZ), and Zhanjiang (ZJ) sites, respectively. Volume-weighted NO 3 − -N and NH 4 + -N concentrations in precipitation varied from 0.46 to 1.67 and 0.47 to 1.31 mg N L −1 at the six sites. Dry, wet and total deposition rates of N were 7. 8-23.1, 14.2-25.2 and 22.0 -44.6 kg N ha −1 yr −1 across the six coastal sites. Average N dry deposition accounted for 45.4% of the total deposition and NH 3 and pNH 4 + contributed to 76.6% of the dry deposition. If we extrapolate our total N deposition of 33.9 kg N ha −1 yr −1 to the whole Chinese coastal sea area (0.40 million km 2 ), total N deposition amounts to 1.36 Tg N yr −1 , a large external N input to surrounding marine ecosystems.

Dithiocarbamate (DTC) pesticides are widely used for fruits, vegetables, and mature crops to control fungal diseases. Their residues in food could pose a threat to human health. Therefore, a surface-enhanced Raman scattering-based (SERS-based) sensor is developed to detect DTC pesticides because SERS can provide the characteristic spectrum of pesticides and avoid the use of a molecular recognition probe in the sensor. For the acquisition of high sensitivity, good anti-interference ability, and robustness of the SERS sensor, a silver nanocube-reduced graphene oxide (AgNC-rGO) sponge is devised. In the AgNC-rGO sponge, the rGO sheets form a porous scaffold that physically holds the AgNCs, which create narrow gaps between the neighboring AgNCs, leading to the formation of "hot spots" for SERS-signal amplification. When DTC pesticides coexist with aromatic pesticides in a sample matrix, the AgNC-rGO sponge can selectively detect DTC pesticides because of the preferential adsorption of DTC pesticides on the Ag surface and aromatic pesticides on the rGO surface, which can effectively eliminate the interference of the SERS signals of aromatic pesticides, and facilitate the qualitative and quantitative analysis of DTC pesticides. The AgNC-rGO sponge shows great potential as a SERS substrate for selective detection of DTC pesticides.

Hybrid metal/COF stack multilayers and patterned COF films were fabricated via the flexible combination of solvothermal deposition and compatible film processing techniques.

Producing hydrogen by water electrolysis with solar and wind energy will be one of the main methods of hydrogen production. The inherent intermittency and volatility are, however, the biggest obstacles to the utilization of these low-carbon resources. This limitation leads to an urgent need for fundamental analysis and system integration of renewable energy sources. In this paper, the random fluctuations of wind and solar energy were characterized by the spectral analysis method to explore underlying laws within. The base models of wind power and photoelectric (PV) power were defined to reveal the intermittent characteristics and phase difference. On this basis, we proposed the theoretical foundation of wind–PV complementation. For a case study, an industrial-scale wind–solar to hydrogen system (WPTH) is proposed to provide high-purity hydrogen. We chose the hydrogen production scale of the system to be 3.4 t/h with a fluctuation of hydrogen supply less than 7.5%, according to the reasonable unit capacity configuration. Through life cycle model analysis, the carbon footprint of this process is 1.19 kg CO2/kg H2, far lower than that of coal based hydrogen production. On the other hand, this process is found to have the close cost of 3.59 $/kg H2 to that of coal based processes.