MOF derived Mesoporous Nitrogen doped Carbons with high Activity towards Oxygen Reduction

Sulfonated Poly Ether Sulfone Membrane Reinforced with Bismuth-Based Organic and Inorganic Additives for Fuel Cells

This research work focuses on developing a robust polymer electrolyte membrane (PEM) with high proton efficiency toward proton exchange membrane fuel cells (PEMFCs). In this study, poly ether sulfone (PES) was sulfonated by chlorosulfonic acid to yield sulfonated poly ether sulfone (SPES) followed by incorporation with bismuth-based additives such as bismuth trimesic acid (BiTMA) and bismuth molybdenum oxide (Bi2MoO6). The composite membrane was thoroughly investigated for its structural and physicochemical properties such as FT-IR, SEM, TGA, contact angle, water uptake, oxidative stability, ion-exchange capacity, and swelling ratio. Incorporation of additives into the polymer was confirmed by XPS and XRD analysis. The proton conductance of the pristine SPES is 4.19 × 10-3 S cm-1, whereas that of the composite membrane SPES/BiTMA-10 is 10 × 10-3 S cm-1 and that of SPES/Bi2MoO6-15 is 7.314 × 10-3 S cm-1; both the composite membranes exhibit higher proton conductivity than the pristine SPES membrane. The physicochemical characteristics and impedance measurements of the electrolyte reported can be viable to the PEM membrane.

High-performance electrocatalyst based on polyazine derived mesoporous nitrogen-doped carbon for oxygen reduction reaction

Nitrogen-doped porous carbon materials have high potential in metal-free electrocatalysts, which is essential for several renewable energy conversion systems. Herein, we report a convenient and environment-friendly method to fabricate a nitrogen doped mesoporous carbon (NMC) using a nonionic surfactant of Pluronic F127 micelles as the template and a Schiff-base polymer (polyazine) as the precursor. The synthesized NMCs were of spheric morphology and mesoporous structures with surface area up to 1174 m² g⁻¹ and high level of nitrogen (2.9–19 at%) and oxygen (4.9–7.4 at%) simultaneously doped. The electrochemical data of NMCs were analyzed in the context of the BET and XPS information. A correlation between ORR activity and the pyridinic-N was found. The NMC-700 demonstrate the highest electrocatalytic activity for ORR among the studied materials, which can be ascribed to the reasonable surface area and mesoporous structure, as well as the most abundant touchable pyridinic-N, thus providing more effective active sites for the oxygen reduction. In comparsion to the control sample, the NMC-700 provides the ORR electrocatalytic activity approximate to that of commercial Pt/C catalyst with a highly long-term stability.

Nitrogen-doped porous carbon materials have high potential in metal-free electrocatalysts, which is essential for several renewable energy conversion systems.

A Gadolinium Metal-Organic Framework Film as a Converter Layer for Neutron Detection

Metal-organic frameworks (MOFs) are known for their versatility in terms of their crystalline structure, porosity, resistance to temperature, radiation damage, and luminescence among others. Gadolinium (Gd) is one of the elements with the highest reported cross-section for low energy neutron capture, producing internal conversion electrons and γ rays as a result of the neutron absorption. The development of Gd-BTC films (BTC=1,3,5-benzenetricarboxylate) is shown that were deposited on Si and Al substrates by airbrushing, and characterized by profilometry, Raman, EDX and X-ray diffraction. Radiation damage, thermal decomposition and neutron absorption of these films were studied as well. Gd-BTC films were attached to CMOS devices (Complementary Metal-Oxide-Semiconductor), which are sensible to the internal conversion electrons, in order to build a neutron detector. The devices Gd-BTC/CMOS could selectively detect neutrons in the presence of γ rays with a thermal neutron detection efficiency of 3.3±0.1 %, a signal to noise ratio of 6 : 1, and were suitable to obtain images.

Rational Design of Hierarchical Structural CoSe@NPC/CoSe@CNT Nanocomposites Derived from Metal-Organic Frameworks as a Robust Pt-free Electrocatalyst for Dye-Sensitized Solar Cells

Transition-metal compounds/carbon hybrids with high electrocatalytic capability possess attractive potential as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). However, the simple structure and agglomeration always result in poor performance. Herein, cobalt selenides confined in hollow N-doped porous carbon interconnected by carbon nanotubes (CNTs) with cobalt selenides encapsulated inside (denoted as CoSe@NPC/CoSe@CNTs) are formed through in situ pyrolysis and selenization process. In this strategy, ZIF-67 is used as the precursor, structure inducer, and carbon source for the orientated growth of CNTs. Such a rational architecture provides a stable interconnected conductive network and a hierarchically porous structure, with more available active sites and a shortened pathway for charge transport, synergistically enhancing the electrocatalytic activity. Specifically, the DSSCs based on CoSe@NPC/CoSe@CNTs demonstrate a high efficiency of 7.36%, even superior to that of Pt (7.16%). Furthermore, the CoSe@NPC/CoSe@CNT CE also demonstrates a good long-term stability in the iodine-based electrolyte.

Synthesis and Performance of MOF-Based Non-Noble Metal Catalysts for the Oxygen Reduction Reaction in Proton-Exchange Membrane Fuel Cells: A Review

Hydrogen is widely regarded as a prime energy carrier for bridging the gap between renewable energy supply and demand. As the energy-generating component of the hydrogen cycle, affordable and reliable fuel cells are of key importance to the growth of the hydrogen economy. However, the use of scarce and costly Pt as an electrocatalyst for the oxygen reduction reaction (ORR) remains an issue to be addressed, and in this regard, metal-organic frameworks (MOFs) are viewed as promising non-noble alternatives because of their self-assembly capability and tunable properties. Herein, recent (2018-2020) works on MOF-based electrocatalysts containing N-doped C, Mn, Fe, Co, multiple metals, and multiple sites are reviewed and summarized with a focus on ORR activity, and the principal physicochemical properties and electrochemical performance of these catalysts realized using rotating electrodes are compared.

Metal Organic Frameworks Modified Proton Exchange Membranes for Fuel Cells

Proton exchange membrane fuel cells (PEMFCs) have received considerable interest due to their low operating temperature and high energy conversion rate. However, their practical implement suffers from significant performance challenge. In particular, proton exchange membrane (PEM) as the core component of PEMFCs, have shown a strong correlation between its properties (e.g., proton conductivity, dimensional stability) and the performance of fuel cells. Metal-organic frameworks (MOFs) as porous inorganic-organic hybrid materials have attracted extensive attention in gas storage, gas separation and reaction catalysis. Recently, the MOFs-modified PEMs have shown outstanding performance, which have great merit in commercial application. This manuscript presents an overview of the recent progress in the modification of PEMs with MOFs, with a special focus on the modification mechanism of MOFs on the properties of composite membranes. The characteristics of different types of MOFs in modified application were summarized.

Biomass Juncus Derived Nitrogen-Doped Porous Carbon Materials for Supercapacitor and Oxygen Reduction Reaction

Juncus is a perennial herb aquatic plant found worldwide, with high reproductive ability in warm regions. It has three-dimensional hierarchical porous triangular networks structures composited of tubular fibers. Here, juncus derived nitrogen-doped porous carbon (NDPC) was prepared by mixing juncus and ZnCl₂ through one-step pyrolysis and activation which is a low-cost, simple, and environmentally friendly method. The NDPC had hierarchical porous structures and a high specific surface area and was applied for supercapacitor and oxygen reduction reaction (ORR). The resulted NDPC-3-800 was prepared by mixing juncus with ZnCl₂ at a mass ratio of 1:3 and then carbonized at 800°C, it was used as electrode material of a supercapacitor. The supercapacitor exhibited excellent specific capacitance of 290.5 F g⁻¹ and 175.0 F g⁻¹ in alkaline electrolyte at the current densities of 0.5 A g⁻¹ and 50 A g⁻¹, respectively. The supercapacitor showed good cycle stability, and the capacitance was maintained at 94.5% after 10,000 cycles. The NDPC-5-800 was prepared by mixing juncus with ZnCl₂ at a mass ratio of 1:5 and then carbonized at 800°C. It exhibited outstanding ORR catalytic activity and stability attributing to their high specific surface area and abundant actives sites. The juncus can derive various materials for application in different fields.

Rational Design of Hierarchical, Porous, Co-Supported, N-Doped Carbon Architectures as Electrocatalyst for Oxygen Reduction

Developing highly active nonprecious-metal catalysts for the oxygen reduction reaction (ORR) is of great significance for reducing the cost of fuel cells. 3D-ordered porous structures could substantially improve the performance of the catalysts because of their excellent mass-diffusion properties and high specific surface areas. Herein, ordered porous ZIF-67 was prepared by forced molding of a polystyrene template, and Co-supported, N-doped, 3D-ordered porous carbon (Co-NOPC) was obtained after further carbonization. Co-NOPC exhibited excellent performance for the ORR in an alkaline medium with a half-wave potential of 0.86 V vs. reversible hydrogen electrode (RHE), which is higher than that of the state-of-the-art Pt/C (0.85 V vs. RHE). Moreover, the substantially improved catalytic performance of Co-NOPC compared with Co-supported, N-doped carbon revealed the key role of its hierarchical porosity in boosting the ORR. Co-NOPC also exhibited a close-to-ideal four-electron transfer path, long-term durability, and resistance to methanol penetration, which make it promising for large-scale application.

Electro- and photoelectro-catalysts derived from bimetallic amorphous metal–organic frameworks

It is developed a synthesis method for the design of new bimetallic amorphous MOFs. Such frameworks serve as precursors to prepare high-performance electro- and photoelectro-catalysts for ORR, OER and HER in both acidic and alkaline media.

Iron-/Nitrogen-Doped Electrocatalytically Active Carbons for the Oxygen Reduction Reaction with Low Amounts of Cobalt

Transition-metal-doped carbon catalysts are promising Pt-free alternatives for low-temperature fuel cells. They are frequently obtained from sacrificial N-rich zeolitic imidazolate frameworks (ZIFs) doped with Co and Fe. The optimal low loading of metals has to be achieved to guarantee the competitive efficiency and facilitate an inquiry into the mechanism of their catalytic activity. We report on microwave-assisted solvothermal synthesis of Zn,Co-ZIFs with a relatively low (1-15 mol %) Co loading, which were further enriched with Fe(II). Materials were pyrolyzed at 700 °C to form catalytically active carbons bearing metal nanoparticles confined in structured carbon. The electrochemistry test of carbons for the oxygen reduction reaction (ORR) in perchloric acid demonstrated their high efficiency even at low cobalt contents. The initial loading of 10 mol % was found efficient, leading to the production of catalytically active carbons allowing for four-electron path of ORR.

Applications of Metal-Organic-Framework-Derived Carbon Materials

Carbon materials derived from metal-organic frameworks (MOFs) have attracted much attention in the field of scientific research in recent years because of their advantages of excellent electron conductivity, high porosity, and diverse applications. Tremendous efforts are devoted to improving their chemical and physical properties, including optimizing the morphology and structure of the carbon materials, compositing them with other materials, and so on. Here, many kinds of carbon materials derived from metal-organic frameworks are introduced with a particular focus on their promising applications in batteries (lithium-ion batteries, lithium-sulfur batteries, and sodium-ion batteries), supercapacitors (metal oxide/carbon and metal sulfide/carbon), electrocatalytic reactions (oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction), water treatment (MOF-derived carbon and other techniques), and other possible fields. To close, some existing problem and corresponding possible solutions are proposed based on academic knowledge from the reported literature, along with a great deal of experimental experience.

Experimental and computational studies on copper–cerium catalysts supported on nitrogen-doped porous carbon for preferential oxidation of CO

Geometric characteristics improve the synergy between Cu2⁺/Cu⁺ and Ce4⁺/Ce3⁺ couples.

Fine Co nanoparticles encapsulated in N-doped porous carbon for efficient oxygen reduction

Through the acid pickling of Co@NPC, which was obtained by one-step calcination of ZIF-67 in N₂ and condition optimization of Co nanoparticle sizes, a catalyst of fine Co nanoparticles encapsulated in N-doped porous carbon with excellent ORR performance was prepared.

Highly active copper catalyst obtained through rapid MOF decomposition

A decomposed copper based metal–organic framework containing amorphous Cu species was found to be a highly reactive carbon supported catalyst (a-Cu@C).

Comparison of new metal organic framework-based catalysts for oxygen reduction reaction

In this article, we collected the most significant and recent data in brief in the field of metal organic frameworks oxygen reduction reaction catalysts, obtained from some of the most recent research papers in the field. We present lists of materials and their key parameters that are relevant to the cathode catalysts in polymer electrolyte membrane fuel cells. All the materials listed in this paper are composed of metal organic frameworks, zeolitic imidazolate frameworks, or their derivatives. These are divided into two main groups: pristine MOFs and MOF-derived materials. The data in this article is a summary of more extensive review (Gonen and Elbaz, 2018) [1].

The development of MOFs-based nanomaterials in heterogeneous organocatalysis

Metal-organic framework (MOF) is a class of inorganic-organic hybrid material assembled periodically with metal ions and organic ligands. MOFs have always been the focuses in a variety of frontier fields owing to the advantageous properties, such as large BET surface areas, tunable porosity and easy-functionalized surface structure. Among the various application areas, catalysis is one of the earliest application fields of MOFs-based materials and is one of the fastest-growing topics. In this review, the main roles of MOFs in heterogeneous organocatalysis have been systematically summarized, including used as support materials (or hosts), independent catalysts, and sacrificial templates. Moreover, the application prospects of MOFs in photocatalysis and electrocatalysis frontiers were also mentioned. Finally, the key issues that should be conquered in future were briefly sketched in the final parts of each item. We hope our perspectives could be beneficial for the readers to better understand these topics and issues, and could also provide a direction for the future exploration of some novel types of MOFs-based nanocatalysts with stable structures and functions for heterogeneous catalysis.