Pyrolysis Of Metal-organic Frameworks Research Articles

Polarization regulation in core-shell HNTs@Metal/C for high-performance of electromagnetic wave absorption

Enhancing polarization loss is an effective method to improve electromagnetic wave absorption (EMA) performance. However, constructing more interfaces and inducing defects is a significant challenge in polarization regulation. This paper reports synthesizing a core-shell structure HNTs@M/C (M=Cu, Co, Zn) by pyrolysis of metal-organic frameworks (MOFs). The enhancement of conduction loss is attributed to the electronic conduction network formed by the carbon layer and the metal particles. Co nanoparticles (NPs) create more interfaces with the carbon layer, significantly boosting polarization performance. Additionally, Zn sublimation induces numerous defects in the carbon layer, leading to cumulative amplification of polarization and stronger dielectric resonances in HNTs@Zn/C. With a thickness of 2.4 mm, the HNTs@Zn/C achieve an effective absorption bandwidth (EAB) of 6.9 GHz, covering the entire Ku-band with a minimum reflection loss of −61 dB. This work provides design strategies for interfacial and point interaction of polarization regulation.

Capillary-driven microchip integrated with nickel phosphide hybrid-modified electrode for the electrochemical detection of glucose

BackgroundTransition metal phosphides with properties similar to platinum metal have received increasing attention for the non-enzymatic detection of glucose. However, the requirement of highly corrosive reagent during sample pretreatment would impose a potential risk to the human body, limiting their practical applications. ResultsIn this study, we report a self-powered microfluidic device for the non-enzymatic detection of glucose using nickel phosphide (Ni2P) hybrid as the catalyst. The Ni2P hybrid is synthesized by pyrolysis of metal-organic framework (MOF)-based precursor and in-situ phosphating process, showing two linear detection ranges (1 μM–1 mM, 1 mM–6 mM) toward glucose with the detection limit of 0.32 μM. The good performance of Ni2P hybrid for glucose is attributed to the synergistic effect of Ni2P active sites and N-doped porous carbon matrix. The microchip is integrated with a NaOH-loaded paper pad and a capillary-based micropump, enabling the automatic NaOH redissolution and delivery of sample solution into the detection chamber. Under the optimized condition, the Ni2P hybrid-based microchip realized the detection of glucose in a user-friendly way. Besides, the feasibility of using this microchip for glucose detection in real serum samples has also been validated. SignificanceThis article presents a facile fabrication method utilizing a MOF template to synthesize a Ni2P hybrid catalyst. By leveraging the synergy between the Ni2P active sites and the N-doped carbon matrix, an exceptional electrochemical detection performance for glucose has been achieved. Additionally, a self-powered chip device has been developed for convenient glucose detection based on the pre-established high pH environment on the chip.

Tune and turn the pyrolysis of metal organic frameworks towards stable supported nickel catalysts for the dry reforming of methane

Dry reforming of methane (DRM) is an inimitable approach for eliminating both greenhouse gases, methane and CO2, while producing synthesis gas which further can be converted to added-value fuels. However, the industrialization of DRM has been limited due to sintering and coking to the catalysts under the harsh reaction conditions. Here, we propose a new methodology for producing tunable supported nickel-based catalysts for DRM using metal organic frameworks (MOFs) as precursors of the catalyst components. In particular, Ni- and La-MOFs were coalesced using sonication and then calcined at different temperatures to produce catalysts with tailored Ni metal size (5–20 nm) and tuned strong metal-support interactions (SMSI). Here, the synthesis of nickel and nickel oxide nanoparticles embedded on lanthanum-based supports by controlled calcination of the MOF structures is demonstrated; the Ni supported catalysts were then used for DRM reaction. Among the developed catalysts, the catalyst produced following calcination at 500 °C (Ni-La-500) has shown stable and high CH4 conversion rates under DRM conditions at 800 °C with negligible carbon formation at elevated gas hourly space velocities. Further, the catalytic performance of Ni-La-500 catalyst (sonicated) was compared to the physically mixed MOFs derived catalyst (Ni-La-500-PM), conventional wetness impregnated catalyst (Ni-La-500 WI), Ni-MOF derived unsupported catalyst (Ni-500), and lower Ni concentration catalyst (sonicated, 10Ni-La-500). The observed CH4 conversion rates at 50,000 mL·gcat–1·h−1 GHSV are 81.8, 67.9, 85.4, 34.7, and 57.9 % for Ni-La-500, Ni-La-500 PM, Ni-La-500 WI, Ni-500, and 10Ni-La-500 catalysts, respectively after 24 h of DRM reaction. With isotopic studies, it was found that the 18O exchange rate was higher in case of Ni-La-500-PM catalyst (8.1 mmol·g−1) as compared to Ni-La-500 catalyst (5.5 mmol·g−1). Prior interaction between MOFs, calcination temperatures, reaction conditions, and the carbon pathways during catalytic activity dictates the conversion rates and selectivity of the products. Overall, with the herein proposed approach of MOF-derived supported catalysts exceptional conversion rates and stability during the DRM reaction with nominal coking and sintering were demonstrated, solving the two major challenges faced by conventional and unsupported catalysts.

Fabrication of carbon-based materials derived from a cobalt-based organic framework for enhancing photocatalytic degradation of dyes.

The pyrolysis of metal-organic frameworks (MOFs) has emerged as a promising route to synthesize carbon/metal oxide-based materials with diverse phase compositions, morphologies, sizes and surface areas. In this paper, 1,3,5-benzoic acid (BTC) and 2,4,6-tri(4-pyridinyl)-1-pyridine (TPP) were used as ligands to prepare a novel cobalt-based MOF (Co-MOF) which was used as a precursor to obtain five carbon-based materials at different temperatures (Co-C200/400/600/800/1000). Furthermore, five dyes were used as degradation targets to investigate the photocatalytic degradation performance of the title materials under UV light irradiation. Co-C1000 exhibited the best photocatalytic degradation performance for methyl orange (MO), and the degradation rate could reach 99.21%. The enhanced photocatalytic activity was attributed to narrower band-gaps and a synergistic effect originating from the well-aligned straddling band structures between Co/CoO/Co3O4 and C, also resulting in a faster interfacial charge transfer during the photocatalytic reaction. This study will aid in the development of photocatalysts generated from carbon-based materials via the pyrolysis transformation of MOFs, therefore greatly enhancing the photocatalytic performance.

Removal of Levofloxacin by Activation of Peroxomonosulfate Using T-POMs@ZIF-67

The pyrolysis of metal-organic frameworks (MOFs) is a popular strategy for the synthesis of nanoporous structures. Polymetallic oxides (POMs) are a class of polyhedral structural compounds with unique physicochemical properties. Little effort has been paid to evaluate MOF-POM hybrid-derived materials for peroxomonosulfate (PMS) activation. In this study, a cobalt-based MOF, ZIF-67, together with three types of POMs (phosphomolybdic acid, silicotungstic acid, and phosphotungstic acid), were used as precursors for the synthesis of PMS activation catalyst via pyrolysis. Three T-POMs@ZIF-67 nanohybrids (T-PMo@ZIF-67, T-SiW@ZIF-67, and T-PW@ZIF-67) were obtained by pyrolyzing the prepared precursors at 500 °C. Furthermore, the prepared T-POMs@ZIF-67 nanomaterials were evaluated for the catalytic activation of PMS in the degradation of levofloxacin (LEV). The results showed that the LEV degradation rate could reach 91.46% within 30 min under the optimized conditions when T-PW@ZIF-67 was used as the PMS activation catalyst. The catalytic efficiency of the catalyst decreased by only 9.63% after five cycles, indicating that the material has good stability. This work demonstrates the great potential of POMs@MOF derivatives for application in the field of wastewater treatment.

Oxidation of tetracycline hydrochloride by peroxomonosulfate and peroxodisulfate on a ZnNi@NC carbonaceous catalyst: Role of non-radical species and mediated or direct electron transfer mechanisms

This study investigated the activation pathways of peroxomonosulfate (PMS) and peroxodisulfate (PDS) on a metal-based carbon catalyst (ZnNi@NC) for the degradation of tetracycline hydrochloride (TC). ZnNi@NC was synthesized via pyrolysis of metal-organic frameworks (MOFs), which yielded Ni species encapsulated in a Ni3ZnC0.7 layer and N,O-doped graphitic carbon nanotubes. The catalytic performance of ZnNi@NC in PMS and PDS activation for TC degradation was found to be excellent. The ZnNi@C/PMS and ZnNi@C/PDS systems successfully degraded 13 mg of TC within 100 min. We complemented these results with quenching experiments and utilized characterization techniques, such as electron paramagnetic resonance (EPR) and Fourier transform infrared spectroscopy (FTIR), to verify the activation of PMS and PDS, leading to the production of singlet oxygen and the formation of a surface-active complex. Additionally, our research demonstrated that ZnNi@NC facilitated electron transfer between surface-active PDS and adsorbed TC, as confirmed through electrochemical analytical characterization. Further insights from scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) revealed that active sites, including graphitic N and pyrrolidinic N species, played a pivotal role in singlet oxygen generation. Specifically, PMS activated through a direct electron transfer pathway, while PDS employed an indirect electron transfer pathway. Furthermore, the study emphasized that the N,O-doped graphitic carbon framework played a key role in the formation of surface-activated PMS/PDS. In conclusion, this work provides novel insights into the distinct functionalities of Ni-based carbon catalysts in persulfate activation.

Real-Time Imaging and Quantitative Evolution for Pyrolysis of Carbon Dots-Encapsulated Metal-Organic Frameworks at the Nanoscale by In Situ Environmental Transmission Electron Microscopy.

The pyrolysis of metal-organic frameworks (MOF) has been widely used approach to generate hierarchical structures with the corresponding metal, metal carbide, or metal oxide nanoparticles embedded in a porous carbon matrix with a high specific surface area for industrial catalysis, energy storage and transfer, etc. MOF-derived heterogeneous catalysts can be constructed by the encapsulation of carbon dots (CDs) with plenty of hydroxyl and amine groups to enhance the performance of the final product. Controlled formation of metallic carbon structures at the nanoscale, especially matter cycling and transformation on the nanoscale interface, is important for the production of industrial catalysts as well as the research of materials science and engineering progress. However, the mass transfer at the nanoscale during the processing of MOF pyrolysis remains less understood due to the lack of direct observation. Herein, by using in situ environmental transmission electron microscopy, real-time imaging and quantitative evolution of porous carbon decorated with metal species by the pyrolysis of CDs-encapsulated zeolitic imidazolate framework-67 are achieved. The migration of Co, the flow of aggregates, and the growth of carbon nanotubes observed in the nanoscale pyrolysis laboratory working at 600 °C with an air atmosphere are present. Experimental studies based on reduction and oxidation reaction models reveal that the synergistic effect between doped graphite nitrogen and confined Co nanoparticles is beneficial for boosting catalytic performance.

Designed formation of lignin-derived hollow particle-based carbon nanofibers for high-performance supercapacitors

This work constructs a 1D hollow particle-based carbon nanofibers (HCNFs) derived from Zn-based metal-organic-frameworks (MOFs) particles embedded in biomass-based electrospinning nanofibers as high-performance supercapacitor (SC) electrodes. Abundant mesopores are introduced by the pyrolysis of MOFs, which generates uniformly distributed electrolyte storage pools for a fast electrolyte ions channel. Owing to its uniquely hierarchical pore structure, the derived HCNFs exhibit much enhanced supercapacitive performance. The prepared HCNF-1000 electrode has not only a high specific capacitance (229.6 F g−1 at a current density of 2 A g−1) but also good rate performance (176.8 F g−1 at 10 A g−1, 99.1 F g−1 at 30 A g−1). The two-electrode symmetrical system HCNF-SC has an energy density of 5.1 Wh kg−1 when the power density is 0.5 kW kg−1. HCNF-1000-based solid-state supercapacitor HCNF-FSC shows good electrochemical performance even in different folded states, displaying the potential application value for the development of portable wearable devices.

Ultra-fine Co nanoparticles in-situ anchored on porous conductive nanosheets as efficient electrocatalysts for promoting sulfur redox reaction kinetics

Lithium-sulfur (Li-S) batteries are considered as one of the most promising energy storage devices due to their high theoretical energy density. However, the sluggish conversion kinetics and the polysulfides shuttling cause terrible capacity attenuation, impeding the practical developments. Herein, the Co/N co-doped mesoporous carbon nanosheet is developed after the pyrolysis of metal organic framework on graphene oxide layer, which is further explored as kinetics promotor towards advanced Li-S batteries. In this structure, the mesoporous carbon nanosheets with large specific surface area serve as the polysulfide trappers by physical constraint and the ultra-fine Co nanoparticles provide chemical adsorption and electrocatalytic capability for polysulfides, thus effectively suppressing the shuttle effect and accelerating the reaction kinetics. As a result, the Li-S batteries with modified kinetic modulation separators exhibit a high capacity of 585.3 mAh g−1 after 500 cycles at 1.0 C and excellent rate capability (511.2 mAh g−1 at 3 C).

Research progress on degradation of organic pollutants based on metal–organic frameworks materials

As an advanced oxidation process, Fenton oxidation has attracted much attention because its reactants and products are green and pollution - free. The traditional Fenton oxidation method has some problems, such as high PH requirement and low utilization rate of hydrogen peroxide. Over the past few years, the advancements in application research of Metal-Organic Frameworks (MOFs) have presented innovative and effective ideas for addressing the aforementioned issues. This paper presents the recent advancements in Fenton oxidation technique utilizing Fenton-based materials. Based on literature analysis, it can be seen that Fe-based MOFs were initially used for catalytic reaction and the research shows that the catalytic activity of Fe-based MOFs can be increased by increasing the number of unsaturated Fe metal sites. And the doping of other metals into Fe-based MOF or dual ligand Fe-based MOFs can play a role in changing the structure and increasing the unsaturated metal sites which can further expand the direct application of MOFs in the Fenton oxidation method. However, due to the limited types of iron-based MOFs, non-iron-based MOFs materials and indirect use of MOFs have been reported in the indirect use of MOFs, catalytic active substances can be compounded into MOFs materials through in-situ growth, forming a synergistic effect to improve the efficiency of degradation by means of carbonization or pyrolysis of MOFs, MOFs derived materials can be obtained.

Co-MOF-74 Derived Porous Carbon as a Highly Active and Durable Electrocatalyst for Oxygen Reduction Reaction in Alkaline Media

Pyrolysis of metal-organic framework (MOF) to generate nanostructured carbon-based materials is a potential approach for creating carbon-based materials. The development of a cobalt-based MOF (Co-MOF-74) and its application to oxygen electrocatalysis are described in this study. In alkaline media, the as-obtained Co-PC-400 catalyst displayed superior catalytic performance with the onset potential (Eo = 0.90 V vs. RHE) and more outstanding durability than a Pt/C (20 wt%). Results show that the catalyst has a lot of promise in fuel cells. The Co-MOF successfully catalyzes due to its more significant onset potential, higher current density, and extended durability.

Carboxylate-assisted ZIF-derived Co nanoclusters anchoring hierarchically porous carbon as high-efficient zinc-air batteries cathode catalysts

Metal and nitrogen-doped carbon (M-N-C) catalysts are generally considered to be ideal substitutes for platinum-based noble metal oxygen reduction catalysts. Owing to the significant Fenton effect of the Fe element and the subsequent instability, the Fenton-free Co-based N–C catalyst should perform better in ORR. Pyrolysis of metal-organic frameworks (MOFs) is commonly used to make Co-based N–C catalysts. Still, most of the MOF-derived catalysts reported so far have a microporous structure, which results in hindered mass transfer and partial Co-Nx active sites that cannot function as catalysis. Herein, Co nanoclusters (NCs) with high loading (7.96 wt%) were prepared on hierarchically porous carbon substrates via a carboxylate-assisted strategy. The mesoporous structure of Co nanoclusters/nitrogen-doped hierarchically porous carbon (Co NCs/HPNC) can facilitate mass transport. The smaller size Co nanoclusters can increase the contact area between the carbon matrix and Co-Nx active sites to effectively expose more active centers and increase the density of Co-Nx active sites. A synergistic effect of the two can greatly improve ORR results. Surprisingly, the Co NCs/HPNC catalyst shows excellent ORR activity under alkaline conditions, and Co NCs/HPNC has a better half-wave potential (0.88 V vs. 0.84 V) compared with 20 wt% Pt/C. And it only loses 5% of its current density after 36,000 s of operation, which is significantly less than Pt/C (20%). Furthermore, Co NCs/HPNC battery have a greater open-circuit potential, power density, and specific capacity than Pt/C-based zinc-air batteries (1.51 V, 109.6 mW cm−2, 818.1 mAh gZn−1 vs. 1.46 V, 92.4 mW cm−2, 716.8 mAh gZn−1). This discovery paves the way for high-efficiency electrocatalysts with hierarchically porous architectures and a large number of metal loads to be developed.

Fe3C encapsulated in N-doped carbon as potassium ion battery anode with high capacity and long-term cycling performance

Transition metal carbide is being used as an emerging high-capacity anode material for the next-generation potassium ion batteries (PIBs). Herein, a general method was introduced for the preparation of nanocomposites from metal–organic frameworks (MOFs) coated with ammonium ferric citrate. A novel composite material of Fe 3 C nanoparticles was designed and prepared by pyrolysis of MOF, and embedded in graphitic carbon as a PIB anode (Fe 3 C@MOF–C/N). The Fe 3 C particles were encapsulated in an N-doped carbon shell with a hierarchical porous carbon network. N-doped porous carbon exhibited a large specific surface area and abundant carbon edge defects, which led to the increase in the number of exposed active sites, facilitating the adsorption of potassium ions. As a result, the prepared carbon material shows high structural stability, electrical conductivity, and proton conductivity. As a PIB anode, Fe 3 C@MOF–C/N-1 shows a high capacity of 294 mAh g −1 over 1000 cycles at 200 mA g −1 , revealing its potential application as carbon material in PIB anodes. Fe 3 C in the formation of nanocrystallization is encapsulated in the separate N-doping carbon, and shows remarkably enhanced electrochemical potassium ion storage performance. • ZIF-8 derived porous carbon core provide space for s physical adsorption of the PIBs. • Capacity of 294 mAh g −1 is remained for Fe 3 C@MOF–C/N-1 at 200 mA g −1 after 1000 cycles. • Fe 3 C in the formation of nanocrystallization is encapsulated in the separate N-doping carbon. • The Fe 3 C@MOF–C/N-1 anodes exhibit enhanced cyclic stability and rate performance.

Co3O4/LaCoO3 nanocomposites derived from MOFs as anodes for high-performance lithium-ion batteries

• The lanthanide perovskite LaCoO 3 is synthesized from pyrolysis of MOF. • The introduction of LaCoO 3 improves the lithium storage performance and structural stability of Co 3 O 4 . • The capacitance contribution rate of the composite material reached an incredible 94.7% at 1.0 mV/s. Co 3 O 4 has been extensively studied due to its high theoretical capacity in lithium ion batteries (LIBs) anode materials. Unfortunately, the large volume change of Co 3 O 4 during charging and discharging causes severe capacity degradation, which limits its practical application. In this paper, the metal organic framework (MOF) synthesized by the microwave method was used as the precursor, and the Co 3 O 4 /LaCoO 3 nanocomposite with unique heterostructure was synthesized by calcination. The introduction of LaCoO 3 improves the lithium storage performance and structural stability of Co 3 O 4 . Under the best doping ratio, the reversible charging capacity of Co 3 O 4 /LaCoO 3 reaches 1024 mAh/g (after 100 cycles), breaking the theoretical capacity limit of Co 3 O 4 . Impressively, even at a high current density of 1 A/g, the composite electrode still exhibits an ultra-high reversible capacity of 799 mAh/g. The excellent electrochemical performance of Co 3 O 4 /LaCoO 3 is attributed to the introduction of LaCoO 3 which provides a buffer space for electrode volume changes and shortens the diffusion path of Li + . Finally, kinetic analysis shows that the capacity and stability enhancement mechanism is related to the ultra-high capacitance ratio of the composite material (94.7% at 1 mV/s). This study demonstrates a MOF in-situ synthesis project: a way to overcome the capacity and cycle limitations of Co 3 O 4 in LIBs anodes by compounding lanthanide perovskites.

Highly efficient removal of tetracycline hydrochloride by CuNi-C MOF: Activation of oxygen via radical and non-radical pathways

This work successfully synthesized an outstanding catalyst with high surface area and Cu(0) particles encapsulated in the hierarchically mesoporous structure (CuNi-C), via the pyrolysis of metal organic frameworks (MOFs). CuNi-C exhibited high efficiency for adsorption and great catalytic performance for the oxidative degradation of tetracycline hydrochloride (TC) by activating the dissolved oxygen (DO) with wide pH adaptation (3–10), as well as great recycled performance. It was confirmed by the effect of inorganic anions, quenching experiments, electron paramagnetic resonance (EPR) technology, and electrochemical tests (CV, LSV and OCP) that the outstanding oxidative effectiveness of the CuNi-C/Air system was the credit of the radical (·O2–) and non-radical pathways (mediated electron transfer). Characterizations including HRTEM, HAADF-STEM, XPS and FTIR indicated that the Cu(0) particles encapsulated in the outer graphitic carbon, could transform DO to ·O2– and H2O2. It was also proposed that the N, O-doped graphitic carbon framework provided the main active sites (–OH group, graphitic N and pyridinic N) as the powerful platform for stabilizing oxygen and TC on the CuNi-C surface, which was a key step for non-radical process to initiate the electron transfer. Overall, this work provides a facile and efficient method for organic pollutants decomposition.

Mechanochemical Synthesis of Fluorine-Containing Co-Doped Zeolitic Imidazolate Frameworks for Producing Electrocatalysts.

Catalysts derived from pyrolysis of metal organic frameworks (MOFs) are promising candidates to replace expensive and scarce platinum-based electrocatalysts commonly used in polymer electrolyte membrane fuel cells. MOFs contain ordered connections between metal centers and organic ligands. They can be pyrolyzed into metal- and nitrogen-doped carbons, which show electrocatalytic activity toward the oxygen reduction reaction (ORR). Furthermore, metal-free heteroatom-doped carbons, such as N-F-Cs, are known for being active as well. Thus, a carbon material with Co-N-F doping could possibly be even more promising as ORR electrocatalyst. Herein, we report the mechanochemical synthesis of two polymorphs of a zeolitic imidazole framework, Co-doped zinc 2-trifluoromethyl-1H-imidazolate (Zn0.9Co0.1(CF3-Im)2). Time-resolved in situ X-ray diffraction studies of the mechanochemical formation revealed a direct conversion of starting materials to the products. Both polymorphs of Zn0.9Co0.1(CF3-Im)2 were pyrolyzed, yielding Co-N-F containing carbons, which are active toward electrochemical ORR.

Effect of calcination temperature on the structure and performance of rod-like MnCeOx derived from MOFs catalysts

In our work, metal organic framework (MOFs)-derived MnCeOx catalysts were synthesized by different calcination temperatures. Effect of calcination temperature was characterized by thermogravimetric (TG), X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), N2 adsorption-desorption (BET), X-ray photoelectron spectroscopy (XPS) and temperature programmed H2 reduction (H2-TPR). Performance testing of toluene found that 1Mn1Ce-300 showed the best performance (T90 = 244 °C), good durability and reliable water resistance in catalyzing toluene. The better catalytic performance of 1Mn1Ce-300 was attributed to the higher molar ratios of Ce3+/Ce4+, Mn3+/Mn4+ and Oads/Olatt, more adsorbed oxygen, surface oxygen vacancy and better low-temperature reduction. In situ diffuse reflectance, infrared Fourier transform spectroscopy (in-situ DRIFTS) and thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) proved that benzoic acid and benzene were the main intermediates. This work was instructive for the preparation of metal oxide catalysts by pyrolysis of MOFs.

Defect modulation of MOF-derived ZnFe2O4/CNTs microcages for persulfate activation: Enhanced nonradical catalytic oxidation

• ZnFe 2 O 4 /CNTs-Ar catalysts can efficiently activate PS to degrade BPA in a wide pH range. • Defective and porous microcages exhibit 17.5 times higher activity than blank ZnFe 2 O 4 . • Defect modulation of CNTs facilitated the electron transfer for nonradical degradation. • Magnetic property ensured the convenient collection of catalysts by magnets. • We offer a new strategy to enhance nonradical oxidation through defect modulation. There has been growing interest in the combination of porous metal organic frameworks (MOFs)-derived architectures with conductive carbonaceous materials for the synergistically enhanced catalytic activity. Herein, we described a facile strategy to synthesize a highly efficient and recyclable heterogeneous catalyst through pyrolysis of MOFs as sacrificial templates. We found that creating defective sites in CNTs precursors exhibited significant impact on the charge transfer capability of composite microcages and the coordination environment of Fe centers. With the assistant of persulfate oxidants, ZnFe 2 O 4 /CNTs-Ar with modulated defects exhibited 17.5-fold higher kinetic reaction rate (0.35 min −1 ) than blank ZnFe 2 O 4 microcages for Bisphenol A degradation. Experimental characterizations suggested that defective CNTs played a vital role in shuttling electron from BPA molecules to persulfate, triggered the direct decomposition of pollutants via a non-radical oxidation pathway. Our research provides a new strategy to develop high-performance MOFs-derived catalysts through defect modulation for wastewater treatment.

Metal organic framework assisted Co-Ce mixed oxide catalyst for carbon monoxide and ethylene oxidation

A series of CeO2/Co3O4 mixed nanocomposites with various Ce loading were fabricated by the pyrolysis of MOFs (metal organic frameworks), and their catalytic performance were evaluated by CO and C2H4 oxidation reaction. The prepared catalysts inherited polyhedral morphology of ZIF-67 (Zeolitic Imidazolate Framework-67) nanoparticles. By means of the synergistic effect of two different transition metal oxides, the catalysts exhibited superior performance for CO and C2H4 oxidation. The results show that for 2% - 8% doping ratio of CeO2, the T50 (50% conversion temperature) of CO and C2H4 decreased by 32 and 33 °C, respectively, as compared with the MOF-assisted pure Co3O4 catalyst. Stability of the catalyst was greatly enhanced with optimal Ce doping to Co3O4. A number of characterization techniques were used to study the morphology and physicochemical properties of the prepared catalysts. With the incorporation of Ce, polyhedral Co-Ce catalysts promoted specific surface area and lower reduction temperature. Likewise, Co3+/Co2+ and Oads/Olatt improved with the addition of Ce, which played a significant role in CO and C2H4 oxidation at low temperatures.

N-doped carbon material encapsulated cobalt nanoparticles for bifunctional electrocatalysts derived from a porous Co(II)-based metal-organic frameworks (MOFs)

In this report, a bifunctional electrocatalyst: Co nanoparticles attached on N-doped graphitized carbon material (Co@NC) was obtained by utilizing the porous Co(II)-based metal-organic frameworks (MOFs) as precursors under the one-step thermal treatment. The composites were fully analyzed by XRD, XPS, SEM, TEM, and BET and so on. The electrochemical explorations (OER and HER) show that the overpotential of Co@NC-6h-3 ​at the current density 10 ​mA ​cm−2 is the lower the commercial RuO2 catalyst (350 ​mA for 3; 380 ​mA for RuO2). The Tafel slopes of the composite material are 63 ​mV dec−1, which is comparable to the RuO2 (58 ​mV dec−1). The HER exploration show that the overpotential are 220 mv for 3, and the Tafel slopes of 3 is 119 ​mV dec−1 for 3. The explorations reveals that the composites Co@NC-6h-3 reveals good and stable catalytic performances for HER and OER, providing us with an efficient method to obtain the electrocatalysts via the pyrolysis of MOFs.