Synthesis of Heterostructure Materials Using Coordination Polymers and Metal-Organic

This coordination polymer is a convenient precursor for synthesizing the complex functional material, (Ni,Co)9S8/(Ni,Co)0@NSC (NSC is N,S-doped carbon) through thermal conversion of the coordination polymer into rigid. Two types of products from the conversion of nickel-cobalt coordination polymer and nickel-copper coordination polymer were evaluated as electrocatalysts for the hydrogen evolution reaction. This temperature range above liquid nitrogen is meaningful as a case that overcomes the cryogenic temperature limitation for hydrogen isotope fission.

Therefore, one of the solutions for low uptake of isotope could be core-shell type heterostructure. Although not homogeneous reaction with unreacted core MOF crystal, this result suggests a possibility to synthesize core–shell material for hydrogen isotope separation. -based macrocyclic complex, NiL4py. a) one-dimensional coordination chain of the coordination polymer (b) ab-plane (left) and ac-plane view of the coordination polymer.

XRPD pattern of copper-containing coordination polymer compared to simulated pattern from {[NiL4pyCo(SO4)2·4H2O]·2H2O}. LSV curves of hydrogen evolution reaction (a, c) are LSV curves in acidic condition (0.5 M H2SO4) and (b, d) are LSV curves in basic condition (1 M KOH).

General Introduction

The first is the introduction of heterostructural material of the type which was synthesized by the thermal conversion of bimetallic coordination polymers. The core material has larger pores than the shell materials to serve as storage for gas molecules. On the other hand, the shell material has smaller pore opening size, which can provide selectivity to the gas molecule by the molecular sieve effect than the pore opening size of the core material.

Figure 1.1. Illustration for different types of heterogeneous materials

Heterostructure synthesized by conversion of coordination polymers

Experimental section

All chemicals and solvents used in the synthesis were of reagent grade and were used without further purification. Elemental analysis was carried out by the UNIST Central Research Facilities Center (UCRF) at the Ulsan National Institute of Science and Technology (UNIST). After reflux, the solution was filtered hot and the filtrate was concentrated to approximately half the original volume using a rotary evaporator.

Deprotonated form of macrocycle was prepared by adding an excess amount of triethylamine (1.9 mL), which was dried over molecular sieves, to acetonitrile solution (40 mL), which NiL4py+2H(ClO4)4·2H2O (2, 5 g) was dispersed. Synthesis was carried out using the same procedure with {[NiL4pyCo(SO4)2·4H2O]·2H2O} except metal precursor CuSO4·5H2O instead of CoSO4·7H2O.

Figure 2.6. Nickel-based macrocyclic complex, NiL 4py

Results and discussion

The composition of this coordination polymer has two metal ions, nickel and cobalt, nitrogen atoms in macrocycle and sulfur atoms in sulfate anion. After thermal treatment, conversion of these coordination polymer crystals was continued to yield metal sulfide/metal heterodoped carbon composite. Furthermore, HR-TEM EDS analysis and XPS analysis were continued to characterize the elemental information of carbon matrix and the nanoparticles expected to have heteroatoms in carbon matrix such as nitrogen or sulfur to have bimetallic composition in nanoparticles.

XPS data confirm that the carbon matrix is doped with sulfur and nitrogen, and that the metal phase and the metal sulfide phase contain a total of nickel and cobalt in each phase. A lower value of this ratio means that the state of the carbon matrix is more graphitic, similar to graphene. The ID/IG ratio is comparable to the ID/IG ratio of graphene oxide and reduced graphene oxide (ID/IG ratio. Therefore, this product has a similar ID/IG ratio, and the reason why the ratio is close to graphene oxide is the doping with heteroatoms, nitrogen and sulfur .

The white part of the eyeball consisting of bimetallic sulfides and the black part of the eyeball consisting of metallic phases with both metal species. A possibility for metal nanoparticles to aggregate may lead to increased peak intensity from the metal phase. The reason why the maximum intensity of metallic phase growth at 1000 oC may be the large particle created by the aggregation of nanoparticles.

Moreover, after the etching process in nitric acid with sonication and heating, some nanoparticles in the carbon matrix and aggregated particles were removed and the pores emerged from the remaining carbon matrix after the nanoparticles left. The etching was performed as hard as possible, but the whole particles in the carbon matrix were not removed. The reason why some particles remained could be that the carbon shells cover the nanoparticles well.

TEM images showing different degrees of etching (a) fully etched carbon matrix (b, c) partially etched carbon matrix. Unfortunately, the single crystal of copper-containing coordination polymer was not obtained although XRPD pattern showed crystallinity. After thermal conversion, metal-nickel-copper alloy nanoparticles were found in carbon matrix without sulfidation.

Table 1. X-ray crystallographic data of {[NiL 4py Co(SO 4 ) 2 ·4H 2 O]·2H 2 O}

Conclusion

Recycling of nonporous coordination polymers: Controllable conversion to porous N-doped carbons and their electrocatalytic activity in seawater battery. Nanoporous metal oxides with tunable and nanocrystalline frameworks through the conversion of metal-organic frameworks Nanoporous metal oxides with tunable and nanocrystalline frameworks through the conversion of metal-organic frameworks. Post-synthetic modifications of framework metal ions in isostructural metal-organic frameworks: core-shell heterostructures via selective transmetalations.

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Heterostructure synthesized by self-assembly of two metal-organic frameworks

Experimental section

Results and discussion

NicyclamBPDC, NiLethylBPDC, and NiLpropylBPDC were synthesized by the self-assembly of nickel-based macrocyclic compounds and sodium biphenyldicarboxylate (Na2BPDC) in MeCN/H2O mixture solvent system. Single-crystal X-ray diffraction analysis revealed that three products have isorecticular structure with the same space group R-3 and almost the same lattice parameters. The size of the pore opening can be controlled by the length of the functional group of the macrocyclic compounds.

NiLpropylBPDC has a diameter of the pore opening size of 0.32 Å crystallographically (van der waals radii were taken into account). This pore opening size is expected to occur kinetic quantum sieve effect, which is useful for separating hydrogen isotopes. Three metal-organic frameworks, NicyclamBPDC, NiLethylBPDC and NiLpropylBPDC were measured by XRPD, and each pattern of products has well-matched results compared to simulated patterns from single crystal X-ray diffraction analysis.G.

XRPD patterns of NiLpropylBPDC (simulated model, red; synthesized compound, black) measured N2 isotherms for each metal–organic framework. As expected from the pore opening sizes based on the single crystal X-ray analysis results, the N2 isotherm result of NicyclamBPDC showed typical type I sorption behavior with the largest pore volume, 0.3830 cm3/g , compared to two other products. There is a diffusion barrier from the small pore opening size from the propyl groups indicating isotope fractionation desorption at high temperature, 110 K.

TDS spectra of NiLpropylBPDC exposed to a gas mixture of H2/D2 at 10 mbar, with a ratio of 1:1, for 10 minutes. To overcome the limitation of performance in hydrogen isotope separation, core-shell material synthesis was attempted. NicyclamBPDC was chosen as a core material candidate that can store sieved deuterium because it has the largest pore opening size and volume among three of the isorecticular metal-organic frameworks.

The smaller pore opening size which prevents more effective quantum sieve effect than NicyclamBPDC is the main reason to choose NiLethylBPDC or NiLpropylBPDC as shell material to separate hydrogen isotopes. Accordingly, NicyclamBPDC was put into shell-MOF solution as diluted since homogeneous nucleation did not occur. However, some acicular core crystal that did not react with shell MOF was easily found in fig .3.16.

Table 2. X-ray crystallographic data of NicyclamBPDC.

Conclusion

Synthetic products are generally nanoporous and/or nanocrystalline due to the sacrificial template effect of the original MOF network; these are the essential characteristics of excellent sorbents or catalysts.10 Therefore, the conversion reaction of MOFs is a synthetic method that provides inorganic materials with new properties. All Li + ions have distorted tetrahedral geometries ( Fig. 2a and Table S2† ): Li3 and Li4 are bound to the carboxylate oxygen atoms attached to four different TCS4 moieties. Due to the pore blocking of two coordinating DEF molecules, this 3D MOF possesses 1D channels (Fig. 2c and d).

The morphology of the prepared Li4SiO4 was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We have previously suggested that organics generated during the thermal decomposition of the MOF are limited to act as templates; 8 afterwards they are converted into nanopores. To verify the advantages of the special morphology of Li4SiO4 with respect to CO2 capture, CO2 absorption experiments were performed using a TGA apparatus.

3 XRPD patterns of the synthesized Li4SiO4(a) before and (b) after thermolysis under air at 650 °C. 4 (a) SEM and (b) TEM images of the as-synthesized Li4SiO4, showing its coral-like morphology. b) Changes in the mass uptake of Li4SiO4. The Li4SiO4 reported herein exhibits a CO2 sorption behavior superior to that of the Li4SiO4-based absorbents previously prepared by conventional solid-state synthesis (maximum uptake at 550 °C of 7.8 wt%; 3.3 wt% uptake at 550 °C thereafter). 5 min) (dashed line in Figure 5b).

The stability of the coral-like Li4SiO4 was also tested by cyclic absorption/desorption experiments. The test results indicate a severe decrease in the absorption amounts during the first four cycles, dropping from 22.4 wt% to 11.4 wt%. SEM images of the solid at the end of the experiment show that the porous coral-like morphology was mostly collapsed (Fig. S7†).

This result indicates that the deterioration of CO2 capture capacity is directly related to the destruction of material morphology. Meanwhile, the same cyclic test for the morphologically featureless rocky Li4SiO4 showed a gradual decrease in absorbency from 6.5 wt% to 2.2 wt% over the 25 cycles (red dashed line in Fig. 5c). The result implies that in addition to the morphological change, there may be other factors that have a bad influence on the reversibility of the CO2 absorption processes.