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Reduced graphene-oxide (RGO)-based electrodes in supercapacitors deliver high energy/power capacities compared to typical nanoporous carbon materials. However, extensive critical analysis of literature reveals enormous discrepancies (up to 250 F g-1 ) in the reported capacitance (variation of 100-350 F g-1 ) of RGO materials synthesized under seemingly similar methods, inhibiting an understanding of capacitance variation. Here, the key factors that control the capacitance performance of RGO electrodes are demonstrated by analyzing and optimizing various types of commonly applied electrode fabrication methods. Beyond usual data acquisition parameters and oxidation/reduction properties of RGO, a substantial difference of more than 100% in capacitance values (with change from 190 ± 20 to 340 ± 10 F g-1 ) is found depending on the electrode preparation method. For this demonstration, ≈40 RGO-based electrodes are fabricated from numerous distinctly different RGO materials via typically applied methods of solution (aqueous and organic) casting and compressed powders. The influence of data acquisition conditions and capacitance estimation practices are also discussed. Furthermore, by optimizing electrode processing method, a direct surface area governed capacitance relationship for RGO structures is revealed.

Partially dissolved crystals of curcumin grow faster and exhibit an accelerated growth rate hysteresis.

Crystallization experiments performed with highly supercooled solutions produced highly pure (>99 wt %) and highly crystalline mesocrystals of curcumin from impure solutions (∼22% of two structurally similar impurities) in one step. These mesocrystals exhibited a crystallographic hierarchy and were composed of perfectly or imperfectly aligned nanometer-thick crystallites. X-ray diffraction and spectroscopic analysis confirmed that the spherulites are a new solid form of curcumin. A theoretical hypothesis based on particle aggregation, double nucleation, and repeated secondary nucleation is proposed to explain the spherulite formation mechanism. The experimental results provide, for the first time, evidence for an organic molecule to naturally form spherulites without the presence of any stabilizing agents. Control experiments performed with highly supercooled pure solutions produced spherulites, confirming that the formation of spherulites is attributed to the high degree of supercooling and not due to the presence of impurities. Likewise, control experiments performed with a lower degree of supercooling produced impure crystals of curcumin via classical molecular addition mechanisms. Collectively, these experimental observations provide, for the first time, evidence for particle-mediated crystallization as an alternate and efficient method to purify organic compounds.

The binding affinity distribution is a fingerprint of the adsorbent heterogeneity. In chromatographic separations, the affinity distribution determines the molecular recognition capability of the stationary phases. In gas storage and separation applications, the affinity distribution decides the selectivity towards a target molecule. The end application of almost every molecular recognizing material like molecularly imprinted polymers (MIPs) critically depend on their affinity distribution. In this work, we develop two simple analytical expressions by coupling a numerical technique with the widely used Toth isotherms. These models are universally applicable and can accurately characterize different classes of industrially-important adsorbents that include metal organic frameworks, carbon allotropes and chromatographic stationary phases for their selectivity, binding affinity and adsorption site heterogeneity. The models require only the Toth isotherm parameters to characterize both homogeneous or heterogeneous adsorbents.

Metal-organic frameworks/zeolitic imidazolate frameworks (MOFs/ZIFs) and their post-synthesis modified nanostructures, such as oxides, hydroxides, and carbons have generated significant interest for electrocatalytic reactions. In this work, a high and durable oxygen evolution reaction (OER) performance directly from bimetallic Zn100-x Cox -ZIF samples is reported, without carrying out high-temperature calcination and/or carbonization. ZIFs can be reproducibly and readily synthesized in large scale at ambient conditions. The bimetallic ZIFs show a systematic and gradually improved OER activity with increasing cobalt concentration. A further increase in OER activity is evidenced in ZIF-67 polyhedrons with controlled particle size of 50 %, OER activity is obtained with ZIF-67/carbon black, which shows a low overpotential of approximately 320 mV in 1.0 m KOH electrolyte. Such activity is comparable to or better than numerous MOF/ZIF-derived electrocatalysts. The optimized ZIF-67 sample also exhibits increased activity and durability over 24 h, which is attributed to an in situ developed active cobalt oxide/oxyhydroxide related nanophase.

Metal-organic framework (MOF)-related derivatives have generated significant interest in numerous energy conversion and storage applications, such as adsorption, catalysis, and batteries. However, such materials' real-world applicability is hindered because of scalability and reproducibility issues as they are produced by multistep postsynthesis modification of MOFs, often with high-temperature carbonization and/or calcination. In this process, MOFs act as self-sacrificial templates to develop functional materials at the expense of severe mass loss, and the resultant materials exhibit complex process-performance relationships. In this work, we report the direct applicability of a readily synthesized and commercially available MOF, a zeolitic imidazolate framework (ZIF-8), in a rechargeable zinc-air battery. The composite of cobalt-based ZIF-8 and platinum carbon black (ZIF-67@Pt/CB) prepared via facile solution mixing shows a promising bifunctional electrocatalytic activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), the key charge and discharge mechanisms in a battery. ZIF-67@Pt/CB exhibits long OER/ORR activity durability, notably, a significantly enhanced ORR stability compared to Pt/CB, 85 versus 52%. Interestingly, a ZIF-67@Pt/CB-based battery delivers high performance with a power density of >150 mW cm-2 and long stability for 100 h of charge-discharge cyclic test runs. Such remarkable activities from as-produced ZIF-67 are attributed to the electrochemically driven in situ development of an active cobalt-(oxy)hydroxide nanophase and interfacial interaction with platinum nanoparticles. This work shows commercial feasibility of zinc-air batteries as MOF-cathode materials can be reproducibly synthesized in mass scale and applied as produced.

Supercapacitors have shown extraordinary promise for miniaturized electronics and electric vehicles, but are usually limited by electrodes with rather low volumetric performance, which is largely due to the inefficient utilization of pores in charge storage. Herein, we design a freestanding graphene laminate film electrode with highly efficient pore utilization for compact capacitive energy storage. The interlayer spacing of this film can be precisely adjusted, which enables a tunable porosity. By systematically tailoring the pore size for the electrolyte ions, pores are utilized optimally and thereby the volumetric capacitance is maximized. Consequently, the fabricated supercapacitor delivers a stack volumetric energy density of 88.1 Wh l−1 in an ionic liquid electrolyte, representing a critical breakthrough for optimizing the porosity towards compact energy storage. Moreover, the optimized film electrode is assembled into an ionogel-based, all-solid-state, flexible smart device with multiple optional outputs and superior stability, demonstrating enormous potential as a portable power supply in practical applications. The volumetric performance of supercapacitors needs to be improved, but the usual trade-off between porosity and density is a problem. Here the authors develop a graphene laminate film with tunable porosity that leads to a volumetric energy density of 88.1 Wh l−1 at the device level.

Covalent triazine-based frameworks (CTFs), a group of semiconductive polymers, have been identified for photocatalytic water splitting recently. Their adjustable band gap and facile processing offer great potential for discovery and development. Here, we present a series of CTF-0 materials fabricated by two different approaches, a microwave-assisted synthesis and an ionothermal method, for water splitting driven by visible-light irradiation. The material (CTF-0-M2) synthesized by microwave technology shows a high photocatalytic activity for hydrogen evolution (up to 7010 μmol h-1 g-1), which is 7 times higher than another (CTF-0-I) prepared by conventional ionothermal trimerization under identical photocatalytic conditions. This leads to a high turnover number (TON) of 726 with respect to the platinum cocatalyst after seven cycles under visible light. We attribute this to the narrowed band gap, the most negative conduction band, and the rapid photogenerated charge separation and transfer. On the other hand, the material prepared by the ionothermal method is the most efficient one for oxygen evolution. CTF-0-I initially produces ca. 6 times greater volumes of oxygen gas than CTF-0-M2 under identical experimental conditions. CTF-0-I presents an apparent quantum efficiency (AQY) of 5.2% at 420 nm for oxygen production without any cocatalyst. The activity for water oxidation exceeds that of most reported CTFs due to a large driving force for oxidation and a large number of active sites. Our findings indicate that the band positions and the interlayer stacking structures of CTF-0 were modulated by varying synthesis conditions. These modulations impact the optical and redox properties, resulting in an enhanced performance for photocatalytic hydrogen and oxygen evolution, confirmed by first-principles calculations.

We propose a new synthetic route towards nanoporous functional carbon materials based on salt templating with pore-padding approach (STPP). STPP relies on the use of a pore-padding agent that undergoes an initial polymerisation/ condensation process prior to the formation of a solid carbon framework. The pore-padding agent allows tailoring hierarchically the pore-size distribution and controlling the amount of heteroatom (nitrogen in this case) functionalities as well as the type of nitrogen (graphitic, pyridinic, oxides of nitrogen) incorporated within the carbon framework in a single-step-process. Our newly developed STPP method offers a unique pathway and new design principle to create simultaneously high surface area, microporosity, functionality and pore hierarchy. The functional carbon materials produced by STPP showed a remarkable CO2/N2 selectivity. At 273 K, a carbon with only micropores offered an exceptionally high CO2 adsorption capacity whereas a carbon with only mesopores showed promising CO2-philicity with high CO2/N2 selectivity in the range of 46–60 %, making them excellent candidates for CO2 capture from flue gas or for CO2 storage.

Characterization of the guest–host interactions and the heterogeneity of porous materials is essential across the physical and biological sciences, for example for gas sorption and separation, pollutant removal from wastewater, biological systems (protein–ligand binding) and molecular recognition materials such as molecularly imprinted polymers. Information about the guest–host interactions can be obtained from calorimetric experiments. Alternatively, more detailed information can be obtained by properly analysing the experimentally acquired adsorption equilibrium data. Adsorption equilibrium is usually interpreted using theoretical adsorption isotherms that correlate with the equilibrium concentration of the adsorbate in the solid phase and in the bulk fluid at a constant temperature. Such theoretical isotherms or expressions can accurately predict the adsorbent efficiency (at equilibrium) as a function of process variables such as the initial adsorbate concentration, adsorbent mass, reactor volume and temperature. Detailed analysis of the adsorption isotherms permits the calculation of the number density of the adsorbent sites, their binding energy for the guest molecules and information about the distribution of adsorption site binding energies. These analyses are discussed in this review. A critical evaluation of the analytical and numerical methods that can characterize the heterogeneity and guest–host interactions involved in terms of discrete or continuous binding site affinity distribution was performed. Critical discussion of the limitations and the advantages of these models is provided. An overview of the experimental techniques that rely on calorimetric and chromatographic principles to experimentally measure the binding energy and characteristic properties of adsorbent surfaces is also included. Finally, the potential use of site energy distribution functions and their potential to provide new information about the binding energy of adsorbents for a specific guest molecule application is discussed. We thank the EU for the Intra European Marie Curie Research Fellowship (PIEF-GA-2013-623227).

peer-reviewed Characterization of the guest-host interactions and the heterogeneity of porous materials is essential across the physical and biological sciences, for example for gas sorption and separation, pollutant removal from wastewater, biological systems (protein-ligand binding) and, molecular recognition materials such as molecularly imprinted polymers. Information about the guest-host interactions can be obtained from calorimetric experiments. Alternatively, more detailed information can be obtained by properly interrogating the experimentally acquired adsorption equilibrium data. Adsorption equilibrium is usually interpreted using the theoretical adsorption isotherms that correlate the equilibrium concentration of the adsorbate in the solid phase and in the bulk fluid at a constant temperature. Such theoretical isotherms or expressions can accurately predict the adsorbent efficiency (at equilibrium) as a function of process variables such as initial adsorbate concentration, adsorbent mass, reactor volume and temperature. Detailed analysis of the adsorption isotherms permits the calculation of the number density of the adsorbent sites, their binding energy for the guest molecules and information about the distribution of adsorption site binding energies. These analyses are discussed in this review. A critical evaluation of the analytical and numerical methods that can characterize the heterogeneity; guest-host interactions involved in terms of discrete or continuous binding site affinity distribution was performed. Critical discussion of the limitations and the advantages of these models is provided. An overview of the experimental techniques that rely on calorimetric and chromatographic principles to experimentally measure the binding energy and characteristic properties of the adsorbent surfaces is also included. Finally, the potential use of the site energy distribution functions and their potential to bring new information about the adsorbents binding energy for a specific guest molecule application is discussed.

We report a purposely designed route for the synthesis of a promising carbon-based electrocatalyst for both ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) from zeolitic imidazolate frameworks (ZIFs). Firstly, precursor ZIFs are rationally designed with a blend of volatile zinc to induce porosity and stable cobalt to induce graphitic domains. Secondly, the self-modulated cobalt–nitrogen–carbon system (SCNCS) is shown to be an effective ORR catalyst after graphitization at mild temperatures. Finally, the best OER catalyst is developed by enhancing graphitization of the SCNCS. For the first time, solely by switching the graphitization conditions of SCNCS, excellent ORR or OER performance is realized. This approach not only opens up a simple protocol for simultaneous optimization of nitrogen doping and graphitization at controlled cobalt concentrations, but also provide a facile method of developing such active catalysts without the use of extensive synthesis procedures.

Nanoporous carbons (NPCs) with engineered specific pore sizes and sufficiently high porosities (both specific surface area and pore volume) are necessary for storing energy in the form of electric charges and molecules. Herein, NPCs, derived from biomass pine‐cones, coffee‐grounds, graphene‐oxide and metal‐organic frameworks, with systematically increased pore width ( 50 Wh kg−1 at high power density, 1000 W kg−1) are achieved to form the highest reported values among the range of carbons in the literature. The noteworthy energy storage performance of the NPCs for all five cases (CO2, H2, H2O, and capacitance in aqueous and organic electrolytes) is highlighted by direct comparison to numerous existing porous solids. A further analysis on the specific pore type governed physisorption capacities is presented.

The room temperature synthesis of perovskite nanocrystals (NCs) is typically achieved by employing a ligand‐assisted reprecipitation (LARP) method, which can be handled in air, and its products are comparable to what is obtained using the traditional hot‐injection method. However, the LARP method typically requires the use of coordinating polar solvents such as dimethylformamide, which are not appropriate for large‐scale production due to toxicity concerns and can also degrade or form defective perovskite NCs. Herein, an amine and oleic‐acid‐free room temperature synthesis of lead bromide perovskite NCs is reported that uses a combination of trioctylphosphine oxide and diisooctylphosphinic acid ligands. This combination of ligands provides a stable platform for the polar‐solvent‐free synthesis in air of fully inorganic CsPbBr3 (fwhm ≈ 14 nm, emission = 519 nm) and hybrid organic‐inorganic FAPbBr3 (fwhm ≈ 19 nm) NCs with photoluminescence emission between 530 and 535 nm, which is in line with the Rec. 2020 color standards. In addition, it is shown that compared to a traditionally used ligand combination, phosphine ligands can be easily removed from the surface of the NCs, which is important for the future development of this technology in optoelectronic devices.

In article number https://doi.org/10.1002/advs.201901517, Srinivas Gadipelli and co‐workers present direct evidence of carbon nanoparticle size–dependent electrochemical activity for the supercapacitors and oxygen reduction reaction. For this, the carbon polyhedrons with size between few tens of nanometers to microns are designed from a zeolitic imidazolate framework (ZIF‐8), and all other parameters, such as surface area, microporosity, pore‐size distribution, nitrogen‐doping and graphitization are maintained identically.

Metal–organic framework–derived carbon nanostructures have generated significant interest in electrochemical capacitors and oxygen/hydrogen catalysis reactions. However, they appear to show considerably varied structural properties, and thus exhibit complex electrochemical–activity relationships. Herein, a series of carbon polyhedrons of different sizes, between 50 nm and µm, are synthesized from zeolitic imidazolate frameworks, ZIF‐8 (ZIF‐derived carbon polyhedrons, ZDCPs) and their activity is studied for capacitance and the oxygen reduction reaction (ORR). Interestingly, a well‐correlated performance relationship with respect to the particle size of ZDCPs is evidenced. Here, the identical structural features, such as specific surface area (SSA), microporosity, and its distribution, nitrogen doping, and graphitization are all strictly maintained in the ZDCPs, thus allowing identification of the effect of particle size on electrochemical performance. Supercapacitors show a capacity enhancement of 50 F g−1 when the ZDCPs size is reduced from micrometers to ≤200 nm. The carbonization further shows a considerable effect on rate capacitance—ZDCPs of increased particle size lead to drastically reduced charge transportability and thus inhibit their performance for both the charge storage and the ORR. Guidelines for the capacitance variation with respect to the particle size and SSA in such carbon nanostructures from literature are presented., Carbon‐based nanostructures are indispensable for supercapacitors, fuel cells, and batteries. Advancement in this area requires critical understanding of the form and function. Here, a well‐correlated relationship is demonstrated for the performance of supercapacitors and the oxygen reduction reaction with respect to particle size of metal–rganic frameworks–derived carbon. Surface area, pore‐size distribution, nitrogen doping, and graphitization are all maintained identical.

Noble‐metal‐free electrocatalysts are attractive for cathodic oxygen catalysis in alkaline membrane fuel cells, metal–air batteries, and electrolyzers. However, much of the structure–activity relationship is poorly understood. Herein, the comprehensive development of manganese cobalt oxide/nitrogen‐doped multiwalled carbon nanotube hybrids (MnxCo3−xO4@NCNTs) is reported for highly reversible oxygen reduction and evolution reactions (ORR and OER, respectively). The hybrid structures are rationally designed by fine control of surface chemistry and synthesis conditions, including tuning of functional groups at surfaces, congruent growth of nanocrystals with controllable phases and particle sizes, and ensuring strong coupling across catalyst–support interfaces. Electrochemical tests reveal distinctly different oxygen catalytic activities among the hybrids, MnxCo3−xO4@NCNTs. Nanocrystalline MnCo2O4@NCNTs (MCO@NCNTs) hybrids show superior ORR activity, with a favorable potential to reach 3 mA cm−2 and a high current density response, equivalent to that of the commercial Pt/C standard. Moreover, the hybrid structure exhibits tunable and durable catalytic activities for both ORR and OER, with a lowest overall potential of 0.93 V. It is clear that the long‐term electrochemical activities can be ensured by rational design of hybrid structures from the nanoscale.

Carbon monoliths of ultrahigh pore volume (5.35 cm(3) g(-1) ) and high surface area (2700 m(2) g(-1) ) accommodate a record high level of amine(tetraethylenepentamine), up to 5 g g(-1) within its hierarchically networked micro-/mesopores over a wide range. Thus, this solid-amine@carbon shows exceptional CO2 sorption and stable cyclic capacities at simulated flue-gas conditions.

A highly effective and facile synthesis route is developed to create and tailor metal-decorated and nitrogen-functionalized active microporous carbon materials from ZIF-8. Clear metal- and pyrrolic-N-induced enhancements of the cyclic CO2 uptake capacities and binding energies are achieved, particularly at a much lower carbonization temperature of 700 °C than those often reported (1000 °C). The high-temperature carbonization can enhance the porosity but only at the expense of considerable losses of sample yield and metal and N functional sites. The findings are comparatively discussed with carbons derived from metal–organic frameworks (MOFs) reported previously. Furthermore, the porosity of the MOF-derived carbon is critically dependent on the structure of the precursor MOF and the crystal growth. The current strategy offers a new and effective route for the creation and tuning of highly active and functionalized carbon structures in high yields and with low energy consumption.

Utilising the hugely abundant waste from spent coffee grounds (CGs), KOH activated highly microporous carbons with surface areas of 2785 m2 g−1 and micropore volumes of 0.793 cm3 g−1 were synthesised that are capable of uptake capacities near 3 mmol g−1 at 50 °C and 1 bar. Importantly such uptake capacities are achieved though the material's superior microporous character and without doping within the carbon matrix, thereby ensuring facile regeneration with a binding enthalpy of only 26 kJ mol−1 and therefore being capable of energy unintensive cycleable adsorption processes. Furthermore, excellent tunability of pore-size is demonstrated from narrow micropores through to narrow mesopores, enabling optimised adsorption over a range of pressures.

Graphene-oxide (GO) based porous structures are highly desirable for supercapacitors, as the charge storage and transfer can be enhanced by advancement in the synthesis. An effective route is presented of, first, synthesis of three-dimensional (3D) assembly of GO sheets in a spherical architecture (GOS) by flash-freezing of GO dispersion, and then development of hierarchical porous graphene (HPG) networks by facile thermal-shock reduction of GOS. This leads to a superior gravimetric specific capacitance of ≈306 F g

We report a new, simple and versatile method to obtain highly active MOF structures by carefully controlled post-synthesis thermal annealing. The active ZIF-8 structure shows highly enhanced CO2/N2 selectivity and a stable cyclic CO2 uptake of ≥1.5 mmol g−1 at 1 bar and 25 °C with a heat of adsorption of ≥30 kJ mol−1, which is over 100% greater than ≈0.7 mmol g−1 and ≈17 kJ mol−1, respectively of ZIF-8.

A hybrid membrane of superacid sulfated Zr-MOF (SZM) and Nafion shows much superior performance to Nafion, particularly for fuel cell operating under low humidity. The Brønsted acidic sites in SZM networks retain an ample amount of water which facilitated proton conduction under low humidity. The water retention properties of Nafion-SZM hybrid membranes with 1 wt % loading of SZM increased at 35% relative humidity and outperformed commercial unfilled Nafion membrane. The proton conductivity increases by 23% for Nafion-SZM hybrid compared to unfilled Nafion membrane. The Nafion-SZM membrane also shows higher performance stability at 35% relative humidity than Nafion, as confirmed by close monitoring of the change of open circuit voltage for 24 h.

The addition of cations to TiO2 photoelectrodes is routinely accepted as a route to enhance the performance of conventional n‐i‐p solar cells. However, this is typically achieved in multiple steps or by the incorporation of expensive and hydroscopic cationic precursors such as lithium bis(trifluoromethanesulfonyl)imide. In addition, it is often unclear as to whether the incorporation of such cation sources is inducing “doping” or simply transformed into cationic oxides on the surface of the photoelectrodes. In this study, TiO2 nanofibers were produced through a simple electrospinning technique and modified by introducing lithium and lanthanum precursors in one step. Our results show that the addition of both cations caused minimal substitutional or interstitial doping of TiO2. Brunauer‐Emmett‐Teller measurements showed that lanthanum‐treated TiO2 nanofibers had an increase in surface area, which even exceeded that of TiO2 P25 nanoparticles. Finally, treated and untreated TiO2 nanofibers were used in n‐i‐p solar cells. Photovoltaic characteristics revealed that lanthanum treatment was beneficial, whereas lithium treatment was found to be detrimental to the device performance for both dye‐sensitized and perovskite solar cells. The results discuss new fundamental understandings for two of the commonly incorporated cationic dopants in TiO2 photoelectrodes, lithium and lanthanum, and present a significant step forward in advancing the field of materials chemistry for photovoltaics.

© 2016 by Taylor & Francis Group, LLC. Nanoporous solids with high accessible specific surface area and pore volume, high chemical and mechanical stability are considered as one of the key materials to solve many energy and environment-related problems. Abundant porous carbon materials have attracted great attention in hydrogen/meth-ane storage, and carbon capture. Graphene-based materials are relatively new members of the carbon family and opened up great scope for molecular sorption, storage and separa tion due to the flexibility in designing functionalized surfaces and tuneable porosities. In this chapter, we describe recent research efforts to synthesize a variety of graphene-based structures, starting with layered, expanded graphite, interca lation, exfoliation, chemical reduction, pillaring layers, self assembly, surface functionalization, doping, metal dispersion, porous template, chemical activation, and hierarchical pore structures for hydrogen/methane storage and carbon capture. Graphene oxide (GO, also known as graphite/graphitic oxide) was first prepared by Brodie (1859). It is an oxidized graphite compound, with a nominal C:O ratio between 2 and 3, usually obtained by treating graphite with strong oxidizers: Mixtures of nitric/sulfuric acid, sodium nitrate, and potassium/chlo-rate/permanganate (Dreyer et al. 2010, 2012; Hummers and Offeman 1958). Structurally, GO is a layered structure with an interlayer spacing of about 0.7 nm, twice that of graphite (Barroso-Bujans et al. 2010; Burress et al. 2010; Dreyer et al. 2010). The GO structure contains abundant oxygen-rich func tional groups: Hydroxide and epoxide groups on basal planes, and carbonyl and carboxyl groups on the edges of graphene sheets. This makes GO hydrophilic in nature and soluble in water and several solvents (Dreyer et al. 2010). GO with its lamellar water, a largely expanded and tunable layered struc ture provides a rich platform for a wide range of functional ity and reaction sites for chemical modifications. Thus, GO becomes a more popular and versatile precursor for the syn thesis of large-scale graphene-related materials (Aboutalebi et al. 2012; Chandra et al. 2012; Li and Shi 2012; Liu et al. 2013; Srinivas et al. 2010, 2011, 2012; Yang et al. 2013). A variety of GO-based porous network structures are discussed in this chapter, particularly for hydrogen/methane storage and carbon (dioxide) capture. These include simple, single- to few-layer randomly arranged graphenes through thermal exfoliation of GO, well-ordered and pillared layer structures of GO, and chemically activated GO, with tunable and functional pore structures and large internal surface area.

On page 4903, S. Gadipelli, Z. Guo, and co-workers describe solidamine@carbon monoliths of ultrahigh hierarchical pore volume (5.35 cm(3) g(-1) ) that have a wide-range pore-size distribution (up to 50 nm) and high specific surface area (2700 m(2) g(-1) ). They also show exceptional CO2 sorption kinetics and stable cyclic capacities (over 200 mg g(-1) ) at simulated flue-gas conditions (75 °C and 15% CO2 , humidified and balanced with N2 ).

The first example of a mixed-metal amidoborane Na(2)Mg(NH(2)BH(3))(4) has been successfully synthesized. It forms an ordered arrangement in cation coordinations, i.e., Mg(2+) bonds solely to N(-) and Na(+) coordinates only with BH(3). Compared to ammonia borane and monometallic amidoboranes, Na(2)Mg(NH(2)BH(3))(4) can release 8.4 wt% pure hydrogen with significantly less toxic gases.

Ammonia borane (NH3BH3, AB) has recently received much attention as a promising hydrogen-storage medium among a very large number of candidate materials because of its satisfactory air stability, relatively low molecular mass (30.7 gmol ), and remarkably high energy-storage densities (gravimetric and volumetric hydrogen capacities are 19.6wt% and 140 gL , respectively). However, the direct use of pristine AB as a hydrogen energy carrier in onboard/fuel-cell applications is prevented by its very slow dehydrogenation kinetics below 100 8C and the concurrent release of detrimental volatile by-products such as ammonia, borazine, and diborane. Many different methods have been adopted to promote efficient H2 generation from AB, including catalytic hydrolysis in aqueous solution, ionic liquids, organic solvents, and thermodynamic modifications by formation of hybrid structures with transition metals, alkali-, or alkaline-earth metal/hydrides, 12] or nanoconfined phases using porous scaffolds. However, many of these methods rely on the usage of heavy metal catalysts, aqueous or nonaqueous solutions, and ionic liquids, all of which make the hydrogen density of the systems unacceptably low for practical applications. Furthermore, the vigorous reactions, hygroscopic properties, and water solubility of borohydrides have negative impacts on the dehydrogenation performance and make it difficult to control the release of hydrogen. The other approach is made, in particular, nanocomposition of AB within porous scaffoldings. However, systems still suffers one or more of the followings: either the nanocomposite is heavier or cannot prevent the generation of all the volatile by-products. Hence, more work needs to be done to explore the potential role that catalysts can play to further improve the controllable H2-release kinetics under moderate conditions while at the same time preventing the generation of detrimental byproducts. Over the past few years, porous metal–organic frameworks (MOFs) have emerged as promising multifaceted materials, combining such functions as catalytic activity, 24] shape-selectivity, templating, and purification. Crystalline MOF structures are composed of metal sites linked to organic ligands, yielding three-dimensional extended frameworks that often possess considerable porosity. In principle, the combination of nanoporosity and active metal sites in MOFs makes them potentially useful materials for promoting the decomposition of AB. However, until now, such a use of MOFs has been rare and any future success would depend crucially on the particular choices of a suitable metal center, pore structure, and thermal stability. For instance, Li et al. were the first to show that Y-based MOF as a solid state decomposition agent for AB. The main drawback of AB-Y-MOF is largely added weight due to the heavy Y metal. In addition, for the given very narrow pore structure of Y-MOF, as low as approximately 8 wt% of AB loading is achieved for the reported 1:1 mole ratio. Thus, it is highly desirable to have a light weight MOF with stable and suitable nanopore channels that can hold more than one AB molecule. Herein, we show that the porous MgMOF-74 (Mg2ACHTUNGTRENNUNG(DOBDC), DOBDC=2, 5-dioxido-1, 4-benzenedicarboxylate) is a promising candidate for nanoconfinement and catalytic decomposition of AB for clean and efficient H2 generation. Mg-MOF-74 has a rigid framework, composed of one-dimensional (1D) hexagonal channels (Figure 1a) with a nominal diameter of approximately 12 running parallel to the DOBDC ligands. In as-synthesized material, the Mg cations are coordinated with five oxygen atoms from the DOBDC ligands and one oxygen atom from a terminal water molecule. However, upon heating under vacuum, the terminal water molecules can be easily removed, leading to unsaturated (open) Mg metal sites (decorated on the edges of the hexagonal pore channels) with an open pore structure of high surface area (>1000 mg ). The open Mg metal sites play a vital role in enhanced binding of various gas molecules (H2, CH4, C2H2, NO, etc. ) and successfully used to promote molecular separation. Figure 1b represents AB confinement within the MOF pores as obtained [a] Dr. S. Gadipelli, Dr. J. Ford, Dr. W. Zhou, Dr. H. Wu, Dr. T. J. Udovic, Dr. T. Yildirim NIST Center for Neutron Research Gaithersburg MD 20899-6102 (USA) Fax: (+1)301-921-9847 E-mail : taner@seas.upenn.edu gsrini@seas.upenn.edu [b] Dr. S. Gadipelli, Dr. J. Ford, Dr. T. Yildirim Department of Materials Science and Engineering University of Pennsylvania, Philadelphia PA, 19104 (USA) [c] Dr. W. Zhou, Dr. H. Wu Department of Materials Science and Engineering University of Maryland, College Park MD, 20742 (USA) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201100090.

A series of idealized model systemswith various diboronic acid linker concentrations (and con-sequently different pore size, pore volume, and surface areas)were examined (see Supporting Information for details).Structural optimization yielded a circa 1.1 nm interlayerseparation for these ideal structures. The simulated absolute