Showing papers on "Mesoporous material published in 2013"
TL;DR: In this article, a route for the controlled synthesis of mesoporous polymer nanospheres, which can be further converted into carbon nanosphere through carbonization, is presented.
Abstract: The controlled synthesis of monodisperse nanospheres faces a number of difficulties, such as extensive crosslinking during hydrothermal processes. Here, the authors show a route for the controlled synthesis of mesoporous polymer nanospheres, which can be further converted into carbon nanospheres through carbonization.
1,542 citations
TL;DR: The unprecedented performance of these NPM catalysts in ORR was attributed to their well-defined porous structures with a narrow mesopore size distribution, high Brunauer-Emmett-Teller surface area, and homogeneous distribution of abundant metal-Nx active sites.
Abstract: A family of mesoporous nonprecious metal (NPM) catalysts for oxygen reduction reaction (ORR) in acidic media, including cobalt–nitrogen-doped carbon (C–N–Co) and iron–nitrogen-doped carbon (C–N–Fe), was prepared from vitamin B12 (VB12) and the polyaniline-Fe (PANI-Fe) complex, respectively. Silica nanoparticles, ordered mesoporous silica SBA-15, and montmorillonite were used as templates for achieving mesoporous structures. The most active mesoporous catalyst was fabricated from VB12 and silica nanoparticles and exhibited a remarkable ORR activity in acidic medium (half-wave potential of 0.79 V, only ∼58 mV deviation from Pt/C), high selectivity (electron-transfer number >3.95), and excellent electrochemical stability (only 9 mV negative shift of half-wave potential after 10 000 potential cycles). The unprecedented performance of these NPM catalysts in ORR was attributed to their well-defined porous structures with a narrow mesopore size distribution, high Brunauer–Emmett–Teller surface area (up to 572 m2...
1,076 citations
TL;DR: In this paper, a functionalized three-dimensional hierarchical porous carbon (THPC) is prepared via a facile modified chemical activation route with polypyrrole microsheets as precursor and KOH as activating agent.
Abstract: Functionalized three-dimensional hierarchical porous carbon (THPC) is prepared via a facile modified chemical activation route with polypyrrole microsheets as precursor and KOH as activating agent. The as-obtained THPC presents a large specific surface area (2870 m2 g−1), high-level heteroatom doping (N: 7.7 wt%, O: 12.4 wt%), excellent electrical conductivity (5.6 S cm−1), and hierarchical porous nano-architecture containing macroporous frameworks, mesoporous walls and microporous textures. Such unique features make the THPC an ideal electrode material for electrochemical energy storage. As the electrode material for a supercapacitor, the THPC exhibits a high capacitance, excellent rate performance and long-term stability in both aqueous and organic electrolytes.
1,029 citations
TL;DR: As a highly integrated binder- and conductive-agent-free electrode for supercapacitors, the mesoporous NiCo(2) O(4) nanosheets supported on Ni foam deliver ultrahigh capacitance and excellent high-rate cycling stability.
Abstract: Mesoporous NiCo(2) O(4) nanosheets can be directly grown on various conductive substrates, such as Ni foam, Ti foil, stainless-steel foil and flexible graphite paper, through a general template-free solution method combined with a simple post annealing treatment. As a highly integrated binder- and conductive-agent-free electrode for supercapacitors, the mesoporous NiCo(2) O(4) nanosheets supported on Ni foam deliver ultrahigh capacitance and excellent high-rate cycling stability.
943 citations
TL;DR: In this article, the structure of mesoporous cellular foam with egg white-derived proteins was used to obtain hierarchically mesophorous (pores centered at ∼4 nm and at 20-30 nm) partially graphitized carbons with a surface area of 805.7 m2 g−1 and a bulk N content of 10.1 wt%.
Abstract: In this work we demonstrate that biomass-derived proteins serve as an ideal precursor for synthesizing carbon materials for energy applications. The unique composition and structure of the carbons resulted in very promising electrochemical energy storage performance. We obtained a reversible lithium storage capacity of 1780 mA h g−1, which is among the highest ever reported for any carbon-based electrode. Tested as a supercapacitor, the carbons exhibited a capacitance of 390 F g−1, with an excellent cycle life (7% loss after 10 000 cycles). Such exquisite properties may be attributed to a unique combination of a high specific surface area, partial graphitization and very high bulk nitrogen content. It is a major challenge to derive carbons possessing all three attributes. By templating the structure of mesoporous cellular foam with egg white-derived proteins, we were able to obtain hierarchically mesoporous (pores centered at ∼4 nm and at 20–30 nm) partially graphitized carbons with a surface area of 805.7 m2 g−1 and a bulk N-content of 10.1 wt%. When the best performing sample was heated in Ar to eliminate most of the nitrogen, the Li storage capacity and the specific capacitance dropped to 716 mA h g−1 and 80 F g−1, respectively.
906 citations
TL;DR: In this paper, the authors present the state-of-the-art of adsorption characterization of mesoporous and microporous materials by using the density functional theory (DFT) methods.
903 citations
TL;DR: A controllable one-pot method to synthesize ordered mesoporous carbons (NMC) with a high N content by using dicyandiamide as a nitrogen source via an evaporation-induced self-assembly process is reported in this article.
Abstract: A controllable one-pot method to synthesize N-doped ordered mesoporous carbons (NMC) with a high N content by using dicyandiamide as a nitrogen source via an evaporation-induced self-assembly process is reported. In this synthesis, resol molecules can bridge the Pluronic F127 template and dicyandiamide via hydrogen bonding and electrostatic interactions. During thermosetting at 100 °C for formation of rigid phenolic resin and subsequent pyrolysis at 600 °C for carbonization, dicyandiamide provides closed N species while resol can form a stable framework, thus ensuring the successful synthesis of ordered N-doped mesoporous carbon. The obtained N-doped ordered mesoporous carbons possess tunable mesostructures (p6m and Imm symmetry) and pore size (3.1–17.6 nm), high surface area (494–586 m2 g−1), and high N content (up to 13.1 wt%). Ascribed to the unique feature of large surface area and high N contents, NMC materials show high CO2 capture of 2.8–3.2 mmol g−1 at 298 K and 1.0 bar, and exhibit good performance as the supercapacitor electrode with specific capacitances of 262 F g−1 (in 1 M H2SO4) and 227 F g−1 (in 6 M KOH) at a current density of 0.2 A g−1.
845 citations
TL;DR: In this review, the phenomenon of complementary macropore incorporation into mesoporous and/or microporous solids in order to enhance their catalytic performance in fuels and chemicals synthesis is discussed.
Abstract: In this review, we discuss the phenomenon of complementary macropore incorporation into mesoporous and/or microporous solids in order to enhance their catalytic performance in fuels and chemicals synthesis.
833 citations
TL;DR: In this article, the electrochemical performance of mesoporous carbon (C)/tin (Sn) anodes in Na-ion and Li-ion batteries is systematically investigated, showing that the desodiation potential of Sn anodes is approximately 021 V lower than delithiation potential, due to the large Na ion size and large volume change of porous C/Sn composite anode during alloy/dealloy reactions.
Abstract: The electrochemical performance of mesoporous carbon (C)/tin (Sn) anodes in Na-ion and Li-ion batteries is systematically investigated The mesoporous C/Sn anodes in a Na-ion battery shows similar cycling stability but lower capacity and poorer rate capability than that in a Li-ion battery The desodiation potentials of Sn anodes are approximately 021 V lower than delithiation potentials The low capacity and poor rate capability of C/Sn anode in Na-ion batteries is mainly due to the large Na-ion size, resulting in slow Na-ion diffusion and large volume change of porous C/Sn composite anode during alloy/dealloy reactions Understanding of the reaction mechanism between Sn and Na ions will provide insight towards exploring and designing new alloy-based anode materials for Na-ion batteries
775 citations
TL;DR: In this article, general principles and recent developments in the synthesis of gold nanoparticles (AuNPs) are reviewed and a review of seed-growth methods have allowed a precise control of AuNP sizes in a broad range and multiple shapes.
758 citations
TL;DR: This paper shows that both isolated MSCs and ensembles incorporated into films have substantially higher conductivities and electron mobilities than does nanocrystalline TiO2, and fabricated all-solid-state, low-temperature sensitized solar cells that have 7.3 per cent efficiency, the highest efficiency yet reported.
Abstract: A new low-temperature synthetic method of growing semiconductor mesoporous single crystals of titanium dioxide is described; the resulting films have much higher conductivities and electron mobilities than nanocrystalline titanium dioxide. Mesoporous semiconductors and ceramics have large surface areas that can be exploited in high-performance solar cells, as photocatalysts and in batteries. This paper describes a low-temperature (below 150 °C) general synthetic method of growing micrometre-sized semiconductor mesoporous single crystals of a form of titanium dioxide (TiO2) known as anatase, based on seeded nucleation and growth inside a mesoporous template immersed in a dilute reaction solution. The authors demonstrate that both isolated crystals and ensembles incorporated into films exhibit dramatically higher conductivities and electron mobilities than nanocrystalline TiO2. Dye-sensitized solar cells made from these materials demonstrate 7.3% efficiency, the highest value so far reported using low-temperature processing. The synthesis method should be generally applicable to other functional ceramics and semiconductors. Mesoporous ceramics and semiconductors enable low-cost solar power, solar fuel, (photo)catalyst and electrical energy storage technologies1. State-of-the-art, printable high-surface-area electrodes are fabricated from thermally sintered pre-formed nanocrystals2,3,4,5. Mesoporosity provides the desired highly accessible surfaces but many applications also demand long-range electronic connectivity and structural coherence6. A mesoporous single-crystal (MSC) semiconductor can meet both criteria. Here we demonstrate a general synthetic method of growing semiconductor MSCs of anatase TiO2 based on seeded nucleation and growth inside a mesoporous template immersed in a dilute reaction solution. We show that both isolated MSCs and ensembles incorporated into films have substantially higher conductivities and electron mobilities than does nanocrystalline TiO2. Conventional nanocrystals, unlike MSCs, require in-film thermal sintering to reinforce electronic contact between particles, thus increasing fabrication cost, limiting the use of flexible substrates and precluding, for instance, multijunction solar cell processing. Using MSC films processed entirely below 150 °C, we have fabricated all-solid-state, low-temperature sensitized solar cells that have 7.3 per cent efficiency, the highest efficiency yet reported. These high-surface-area anatase single crystals will find application in many different technologies, and this generic synthetic strategy extends the possibility of mesoporous single-crystal growth to a range of functional ceramics and semiconductors.
TL;DR: In this paper, a facile synthesis of mesoporous g-CN using molecular cooperative assembly between triazine molecules is reported, which is a promising heterogeneous metal-free catalyst for organic photosynthesis, solar energy conversion, and photodegradation of pollutants.
Abstract: Graphitic carbon nitride (g-CN) is a promising heterogeneous metal-free catalyst for organic photosynthesis, solar energy conversion, and photodegradation of pollutants. Its catalytic performance is easily adjustable by modifying texture, optical, and electronic properties via nanocasting, doping, and copolymerization. However, simultaneous optimization has yet to be achieved. Here, a facile synthesis of mesoporous g-CN using molecular cooperative assembly between triazine molecules is reported. Flower-like, layered spherical aggregates of melamine cyanuric acid complex (MCA) are formed by precipitation from equimolecular mixtures in dimethyl sulfoxide (DMSO). Thermal polycondensation of MCA under nitrogen at 550 °C produces mesoporous hollow spheres comprised of tri-s-triazine based g-CN nanosheets (MCA-CN) with the composition of C3N4.14H1.98. The layered structure succeeded from MCA induces stronger optical absorption, widens the bandgap by 0.16 eV, and increases the lifetime of photoexcited charge carriers by twice compared to that of the bulk g-CN, while the chemical structure remains similar to that of the bulk g-CN. As a result of these simultaneous modifications, the photodegradation kinetics of rhodamine B on the catalyst surface can be improved by 10 times.
TL;DR: It is demonstrated that the special structural features of the NiCo(2)O(4) microspheres including uniformity of the surface texture, the integrity and porosity exert significant effect on the electrochemical performances.
Abstract: Binary metal oxides have been regarded as ideal and potential anode materials, which can ameliorate and offset the electrochemical performance of the single metal oxides, such as reversible capacity, structural stability and electronic conductivity. In this work, monodisperse NiCo2O4 mesoporous microspheres are fabricated by a facile solvothermal method followed by pyrolysis of the Ni0.33Co0.67CO3 precursor. The Brunauer–Emmett–Teller (BET) surface area of NiCo2O4 mesoporous microspheres is determined to be about 40.58 m2 g–1 with dominant pore diameter of 14.5 nm and narrow size distribution of 10–20 nm. Our as-prepared NiCo2O4 products were evaluated as the anode material for the lithium-ion-battery (LIB) application. It is demonstrated that the special structural features of the NiCo2O4 microspheres including uniformity of the surface texture, the integrity and porosity exert significant effect on the electrochemical performances. The discharge capacity of NiCo2O4 microspheres could reach 1198 mA h g–1...
TL;DR: This tutorial review highlights the latest development in the synthesis and applications of mesoporous N-doped carbon and carbon nitride supportedMetal nanoparticles, and concentrates on the catalytic effect of the charge transfer between the metal nanoparticles and semiconductive components.
Abstract: Porous carbons and porous carbon nitrides are well known support materials. Some of these materials are, however, not only a geometric construct for immobilization, enabling mass transport at the same time, but contribute due to their extended electronic structure to a potential catalytic event as such. When appropriate band schemes and electron reactivity are chosen, immobilized metal nanoparticles can exhibit a highly enhanced chemical reactivity. This is due to electronic interaction and electron transfer between the metal and semiconductor, as introduced by Mott and Schottky for planar metal–semiconductor interfaces. A rational choice of mesoporous semiconductor and metal particle allows to create a new generation of catalysts and catalytic schemes with unparalleled performances. This tutorial review highlights the latest development in the synthesis and applications of mesoporous N-doped carbon and carbon nitride supported metal nanoparticles, and concentrates on the catalytic effect of the charge transfer between the metal nanoparticles and semiconductive components.
TL;DR: In this article, a highly active and stable electrocatalyst for hydrogen evolution is developed based on the in situ formation of MoS2 nanoparticles on mesoporous graphene foams (MoS2/MGF).
Abstract: A highly active and stable electrocatalyst for hydrogen evolution is developed based on the in situ formation of MoS2 nanoparticles on mesoporous graphene foams (MoS2/MGF). Taking advantage of its high specific surface area and its interconnected conductive graphene skeleton, MGF provides a favorable microenvironment for the growth of highly dispersed MoS2 nanoparticles while allowing rapid charge transfer kinetics. The MoS2/MGF nanocomposites exhibit an excellent electrocatalytic activity for the hydrogen evolution reaction with a low overpotential and substantial apparent current densities. Such enhanced catalytic activity stems from the abundance of catalytic edge sites, the increase of electrochemically accessible surface area and the unique synergic effects between the MGF support and active catalyst. The electrode reactions are characterized by electrochemical impedance spectroscopy. A Tafel slope of ≈42 mV per decade is measured for a MoS2/MGF modified electrode, suggesting the Volmer-Heyrovsky mechanism of hydrogen evolution.
TL;DR: The synthesis of novel carbon-based materials that can contribute to solving the challenges associated with ORR are reported, with metal-free, PANI-derived mesoporous carbon (dubbed PDMC), in particular, exhibited the highest activity, challenging conventional paradigms.
Abstract: The oxygen reduction reaction (ORR)—one of the two half-reactions in fuel cells—is one of the bottlenecks that has prevented fuel cells from finding a wide range of applications today. This is because ORR is inherently a sluggish reaction; it is also because inexpensive and sustainable ORR electrocatalysts that are not only efficient but also are based on earth-abundant elements are hard to come by. Herein we report the synthesis of novel carbon-based materials that can contribute to solving these challenges associated with ORR. Mesoporous oxygen- and nitrogen-doped carbons were synthesized from in situ polymerized mesoporous silica-supported polyaniline (PANI) by carbonization of the latter, followed by etching away the mesoporous silica template from it. The synthetic method also allowed the immobilization of different metals such as Fe and Co easily into the system. While all the resulting materials showed outstanding electrocatalytic activity toward ORR, the metal-free, PANI-derived mesoporous carbon ...
TL;DR: The uniform 3D distribution of the ultrafine AuNi nanoparticles encapsulated in the pores of MIL-101 was achieved, as demonstrated by TEM and electron tomographic measurements, which brings light to new opportunities in the fabrication of ultrafine non-noble metal-based NPs throughout the interior pores of MOFs.
Abstract: AuNi alloy nanoparticles were successfully immobilized to MIL-101 with size and location control for the first time by double solvents method (DSM) combined with a liquid-phase concentration-controlled reduction strategy. When an overwhelming reduction approach was employed, the uniform 3D distribution of the ultrafine AuNi nanoparticles (NPs) encapsulated in the pores of MIL-101 was achieved, as demonstrated by TEM and electron tomographic measurements, which brings light to new opportunities in the fabrication of ultrafine non-noble metal-based NPs throughout the interior pores of MOFs. The ultrafine AuNi alloy NPs inside the mesoporous MIL-101 exerted exceedingly high activity for hydrogen generation from the catalytic hydrolysis of ammonia borane.
TL;DR: The C60SAM functionalization of mesoporous TiO2 is used to achieve an 11.7% perovskite-sensitized solar cell using Spiro-OMeTAD as a transparent hole transporter and this strategy allows a reduction of energy loss, while still employing a "mesoporous electron acceptor".
Abstract: A plethora of solution-processed materials have been developed for solar cell applications. Hybrid solar cells based on light absorbing semiconducting polymers infiltrated into mesoporous TiO2 are an interesting concept, but generating charge at the polymer–metal oxide heterojunction is challenging. Metal–organic perovskite absorbers have recently shown remarkable efficiencies but currently lack the range of color tunability of organics. Here, we have combined a fullerene self-assembled monolayer (C60SAM) functionalized mesoporous titania, a perovskite absorber (CH3NH3PbI3–xClx), and a light absorbing polymer hole-conductor, P3HT, to realize a 6.7% efficient hybrid solar cell. We find that photoexcitations in both the perovskite and the polymer undergo very efficient electron transfer to the C60SAM. The C60SAM acts as an electron acceptor but inhibits further electron transfer into the TiO2 mesostructure due to energy level misalignment and poor electronic coupling. Thermalized electrons from the C60SAM a...
TL;DR: Lithium ion battery anodes made of the mesoporous graphene nanosheets have exhibited an excellent reversible capacity, and they can retain at 833 mAh/g even after numerous cycles at varied current densities, suggesting a remarkably promising candidate for energy storage.
Abstract: We report a new solution deposition method to synthesize an unprecedented type of two-dimensional ordered mesoporous carbon nanosheets via a controlled low-concentration monomicelle close-packing assembly approach. These obtained carbon nanosheets possess only one layer of ordered mesopores on the surface of a substrate, typically the inner walls of anodic aluminum oxide pore channels, and can be further converted into mesoporous graphene nanosheets by carbonization. The atomically flat graphene layers with mesopores provide high surface area for lithium ion adsorption and intercalation, while the ordered mesopores perpendicular to the graphene layer enable efficient ion transport as well as volume expansion flexibility, thus representing a unique orthogonal architecture for excellent lithium ion storage capacity and cycling performance. Lithium ion battery anodes made of the mesoporous graphene nanosheets have exhibited an excellent reversible capacity of 1040 mAh/g at 100 mA/g, and they can retain at 833 mAh/g even after numerous cycles at varied current densities. Even at a large current density of 5 A/g, the reversible capacity is retained around 255 mAh/g, larger than for most other porous carbon-based anodes previously reported, suggesting a remarkably promising candidate for energy storage.
TL;DR: This review summarizes the basic aspects of materials synthesis, discusses some structural properties relevant in gas sensing, and gives an overview of the literature on ordered mesoporous gas sensors.
Abstract: Ordered mesoporous materials have great potential in the field of gas sensing. Today various template-assisted synthesis methods facilitate the preparation of silica (SiO2) as well as numerous metal oxides with well-defined, uniform and regular pore systems. The unique nanostructural properties of such materials are particularly useful for their application as active layers in gas sensors based on various operating principles, such as capacitive, resistive, or optical sensing. This review summarizes the basic aspects of materials synthesis, discusses some structural properties relevant in gas sensing, and gives an overview of the literature on ordered mesoporous gas sensors.
TL;DR: This review will cover the whole field of the intersection between electrochemistry and ordered mesoporous materials, which includes the generation of mesostructured solids by electro-assisted deposition using appropriate templates and the application of these novel materials for electrochemical purposes.
Abstract: Ordered mesoporous materials prepared by the template route have attracted increasing interest from the electrochemists community due to their plenty of unique properties and functionalities that can be effectively exploited in electrochemical devices. This review will cover the whole field of the intersection between electrochemistry and ordered mesoporous materials. The latter are either electronically insulating (silica and some other metal oxides, as well as silica-based organic–inorganic hybrid materials), semi-conducting (metal oxides), or conducting (metals, carbons). The three main intersection areas are: (1) the development/use of electrochemical methods to characterize the properties of mesoporous materials (i.e., charge and mass transfer processes); (2) the generation of mesostructured solids by electro-assisted deposition using appropriate templates; and (3) the application of these novel materials for electrochemical purposes. The most common devices to date are based on a bulk composite or thin film configuration and the resulting electrodes modified with such mesoporous materials have been successfully applied in various fields, including mainly electrochemical sensing and biosensing as well as energy conversion and storage (620 references).
Eni1
TL;DR: New synthesis strategies, especially designed for preparing materials with improved physico-chemical and textural properties, together with the catalytic features of the resulting materials, are described and discussed in the second part of the review.
Abstract: The discovery of ordered mesoporous materials has opened great opportunities for new applications in heterogeneous catalysis, thanks to their hitherto unprecedented intrinsic structural features. Evidence shows that, however, these materials have not met the researchers' expectations mainly because of the severe limitations related to the strength of acid sites and to the thermal/hydrothermal stability, significantly lower than those of zeolites and due to the amorphous nature of the mesostructured materials. These features are highlighted in the first part of this review, where the peculiarities of mesostructured materials are compared with those of zeolite catalysts in some reactions of industrial interest. New synthesis strategies, especially designed for preparing materials with improved physico-chemical and textural properties, together with the catalytic features of the resulting materials, are described and discussed in the second part of the review.
TL;DR: This review presents the fundamentals and recent advances related to the field of ordered mesoporous carbon materials from the direct synthesis strategy of block copolymer soft-templating, with a focus on their controllable preparation, modification and potential applications.
Abstract: Ordered mesoporous carbon materials have recently aroused great research interest because of their widespread applications in many areas such as adsorbents, catalysts and supports, gas storage hosts, and electrode materials. The direct synthesis strategy from organic–organic self-assembly involving the combination of polymerizable precursors and block copolymer templates is expected to be more flexible in preparing mesoporous carbons, compared with the traditional nanocasting strategy of complicated and high-cost procedures using mesoporous silica materials as the hard template. In this review, we present the fundamentals and recent advances related to the field of ordered mesoporous carbon materials from the direct synthesis strategy of block copolymer soft-templating, with a focus on their controllable preparation, modification and potential applications. Under the guidance of their formation mechanism, the preparation of ordered mesoporous carbons are discussed in detail by consulting different experimental conditions, including synthetic pathways, precursors, catalysts and templates. Both the mesopore size and morphology control are introduced. The potential applications of pure mesoporous carbons, nonmetallic- and metallic-modified mesoporous carbons, and some interpenetrating carbon-based composites are demonstrated. Furthermore, remarks on the challenges and perspectives of research directions are proposed for further development of the ordered mesoporous carbons (232 references).
TL;DR: This review focuses on the relation between the progress in ordered mesoporous materials and its corresponding contribution to enzyme immobilization as well as the applications of these materials in biocatalysis.
Abstract: A short time after the discovery of ordered mesoporous materials, which possess unique features such as high specific surface area and pore volume, highly uniform pore distribution and tunable pore size, these materials have been prospected as promising carriers for enzyme immobilization. The immobilization of enzymes in ordered mesoporous materials has been studied for almost two decades. With the development of tailored ordered mesoporous materials and advances in enzyme technology, this field attracted increasing interest due to its quickly expanded functions and applications. This review focuses on the relation between the progress in ordered mesoporous materials and its corresponding contribution to enzyme immobilization as well as the applications of these materials in biocatalysis. The potential trends in the future development of this field are also pointed out.
TL;DR: In this paper, mesoporous NiCo2O4 nanoplatelets and graphene sheets are combined as a hybrid material via a one-pot synthesis process to demonstrate excellent bi-functional catalytic activity towards both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).
Abstract: Mesoporous NiCo2O4 nanoplatelets and graphene sheets (NiCo2O4–G) are combined as a hybrid material via a one-pot synthesis process to demonstrate excellent bi-functional catalytic activity towards both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Physical characterizations have confirmed the formation of NiCo2O4 nanoplatelets created by selective adsorption of PVP onto specific crystal orientations, which provides spatial confinement for an anisotropic growth into 2-dimensional nanostructures. In addition, the decomposition of surface adsorbed PVP during the calcination process creates uniformly distributed meso-sized pores in the NiCo2O4 nanoplatelets. The beneficial hybrid and PVP effects are investigated via half-cell testing with NiCo2O4–G in comparison to graphene-free NiCo2O4 and PVP-free NiCo2O4–G, respectively, where much lower activation energy and higher current densities are observed with the mesoporous NiCo2O4–G hybrid for both ORR and OER. Furthermore, the positive impact of Ni incorporation was exclusively demonstrated, whereby NiCo2O4–G outperformed Co3O4–G in terms of onset potential and current densities for both ORR and OER. This is attributed to the increased electrical conductivity and the creation of new active sites with much lower activation energy due to the incorporation of Ni cations into the octahedral sites of the spinel crystal structure. This cost effective and highly efficient bi-functional catalyst is highly suitable for rechargeable metal–air battery technologies.
TL;DR: This tutorial review will give a general overview of the diverse strategies on how to implement a secondary pore system in zeolites and distinguish top-down from bottom-up and template-assisted from 'template-free' procedures.
Abstract: Frameworks of precisely defined pores with diameters matching the size of small molecules endow crystalline zeolites with valuable size- and shape-selectivity. Being important selective adsorbers and separators, zeolites are also indispensable as solid acids in size-selective catalysis. However, despite being extremely beneficial, micropores impose restrictions on the mass transport of reactants, especially when bulky molecules are involved. The prospect to boost the catalytic power of zeolites and to extend their applications into new areas has prompted numerous efforts to synthesize mesoporous zeolitic materials that combine diffusional pathways on two different size scales. Our tutorial review will introduce the reader to this exciting recent development in zeolite science. We will give a general overview of the diverse strategies on how to implement a secondary pore system in zeolites. We will distinguish top-down from bottom-up and template-assisted from ‘template-free’ procedures. Advantages and limitations of the different methods will also be addressed.
TL;DR: Magnetite nanoparticles (Fe3O4) represent the most promising materials in medical applications and are incorporated into mesoporous materials to form a hybrid support with the consequent reduction of magnetization saturation to favor high-drug or enzyme loading.
Abstract: Magnetite nanoparticles (Fe₃O₄) represent the most promising materials in medical applications. To favor high-drug or enzyme loading on the nanoparticles, they are incorporated into mesoporous materials to form a hybrid support with the consequent reduction of magnetization saturation. The direct synthesis of mesoporous structures appears to be of interest. To this end, magnetite nanoparticles have been synthesized using a one pot co-precipitation reaction at room temperature in the presence of different bases, such as NaOH, KOH or (C₂H₅)₄NOH. Magnetite shows characteristics of superparamagnetism at room temperature and a saturation magnetization (Ms) value depending on both the crystal size and the degree of agglomeration of individual nanoparticles. Such agglomeration appears to be responsible for the formation of mesoporous structures, which are affected by the pH, the nature of alkali, the slow or fast addition of alkaline solution and the drying modality of synthesized powders.
TL;DR: Recently developed synthetic methods and strategies for ordered mesoporous silicas, metal oxides, carbons and metals which have shown superior performances for applications in various fields, including solar cells, batteries, fuel cells, and sensors are summarized.
Abstract: The self-assembly of small surfactants and Pluronic® amphiphilic copolymers has enabled the synthesis of a range of ordered mesoporous materials with high surface area, diverse compositions, variable pore structures and tunable pore sizes. It has recently been realized that non-Pluronic block copolymers can be used as robust templates for the synthesis of novel and high-performance mesoporous materials with crystalline frameworks, ultra-large pores, and abundant pore symmetries, which are not accessible using the Pluronic counterparts. In this review, we introduce the principle of self-assembly of block copolymers and their phase separations, and summarize recently developed synthetic methods and strategies for ordered mesoporous silicas, metal oxides, carbons and metals which have shown superior performances for applications in various fields, including solar cells, batteries, fuel cells, and sensors.
TL;DR: Under a strong acidic environment, a high turnover frequency (TOF) of ~2.2 × 10(-3) s(-1) per Co atom was achieved, which is more than twice the TOF of traditional hard-templated, mesoporous Co3O4.
Abstract: Oxygen evolution from water by use of earth-abundant element-based catalysts is crucial for mass solar fuel production. In this report, a mesoporous cobalt oxide with an ultrahigh surface area (up to 250 m2·g–1) has been fabricated through Mg substitution in the mesoporous Co3O4 spinel, followed by a Mg-selective leaching process. Approximately a third of Mg cations were removed in the leaching process, resulting in a highly porous cobalt oxide with a significant amount of defects in the spinel structure. The activated mesoporous cobalt oxide exhibited high oxygen evolution activities in both the visible-light-driven [Ru(bpy)3]2+–persulfate system and the Ce4+/Ce3+ chemical water oxidation system. Under a strong acidic environment, a high turnover frequency (TOF) of ∼2.2 × 10–3 s–1 per Co atom was achieved, which is more than twice the TOF of traditional hard-templated, mesoporous Co3O4.
TL;DR: A 2D mesoporous covalent organic framework featuring expanded pyrene cores and linked by imine linkages has a high surface area and exhibits significant gas storage capacities under high pressure, which make this class of material very promising for gas storage applications.
Abstract: Hole-some mixture: A 2D mesoporous covalent organic framework (see figure) featuring expanded pyrene cores and linked by imine linkages has a high surface area (SA(BET) = 2723 m(2) g(-1)) and exhibits significant gas storage capacities under high pressure, which make this class of material very promising for gas storage applications.