Search

A series of nanoporous carbons was obtained by physical activation of polyethylene terephthalate and investigated for the separation of CO2 from flue gas. The prepared carbons exhibited extremely low functionalization—negligible content in oxygen and other heteroatoms—accompanied by well-developed porous networks consisting of gradually increasing surface areas and micropore volumes. Such features allowed to study the role of nanopore confinement in the separation of carbon dioxide in CO2/N2 gas mixtures. The analysis of the adsorption isotherms of individual gases and their mixtures revealed different trends for the CO2 uptake and the selectivity. Whereas CO2 uptake was larger in the carbons with higher burn-off degree, the selectivity of CO2 over N2 was favored in the carbons with a higher fraction of narrow micropores. The differential adsorption enthalpy curves are typical of highly microporous samples reaching values close to those found in zeolites for low loadings. Data also show that the choice of the best adsorbent for cyclic gas adsorption and separation processes should consider a broad context, taking into account various parameters simultaneously such as gas selectivity, working capacity, adsorption enthalpy and energy consumption in the synthesis of the adsorbent.

The photocatalytic activity of a series of novel KSrNbO materials was studied using the photooxidation of methylene blue as model reaction. The influence of the calcination time upon the crystalline structure and photoactivity was verified. Characterization was performed by XRD, SEM, FTIR, UV–Vis/DR, Helium picnometry, and N and CO adsorption-desorption isotherms. The diffraction line profile and the refinement of the structural parameters of KSrNbO were obtained from the XRD patterns by the Rietveld method. Data showed that samples were photoactive under UV irradiation, regardless the synthesis conditions. However, the calcination time had a clear influence upon the photocatalytic activity of the samples, being more efficient towards the degradation of the dye those obtained at a lower calcination time. Indeed, the sample calcined for 4 h showed up to 4 times higher photocatalytic activity than commercial TiO. Additionally, a correlation between the photocatalytic activity and the displacement of the Nb ion from the central position in the [NbO] octahedron was found. It is suggested that this fact causes an important polarization of the niobate structure. The apical oxygen in these samples is very reactive and can lead to the formation of superoxoradical anions (O ) showing that KSrNbO can be potentially used in photocatalytic reactions under UV irradiation., J. Matos thanks to the Chilean grants (Basal ProgramPFB-27, FAE-829, FONDEF-IDEA #ID15I10321, CORFO15IPPID-45676, FONDECYT1161068), for their financial support. S. Lanfredi thanks FAPESP (grants 2007/03510-9, 2014/11189-0, CNPq and UNESP/PROPe), for their financial support. C.O. Ania thanks the financial support of the Spanish MINECO (grant CTM2011/56770-R).

This work provides new insights in the field of applied photoelectro chemistry based on the use of nanoporous carbons as additives to tungsten oxide for the photooxidation of water under potential bias. Using a nanoporous carbon of low surface functionalization as additive to WO3 we have shown the dependence of the photochemical oxidation of water with the wavelength of the irradiation source. Photoelectrochemical responses obtained under monochromatic illumination show a significant increase in the incident photon-to-current conversion efficiency (IPCE) values for electrodes featuring up to 20 wt% carbon additive. Photoelectrochemical transient responses also show a sharp potential dependence, suggesting that the performance of the electrodes is strongly influenced by the carrier mobility and recombination losses. Despite the modest IPCE values of the W/NC electrodes (due to high bulk recombination and poor electron transport properties of the electrodes), our data shows that the incorporation of an optimal amount of nanoporous carbon additive to WO3 can enhance the carrier mobility of the semiconductor, without promoting additional recombination pathways or shadowing of the photoactive oxide., COA thanks the financial support of the European Research Council through a Consolidator Grant (ERC-CoG-648161-PHOROSOL) and the Spanish MINECO (grants CTM2014/56770-R, CTQ2013-48280-C3-3-R). VC and DJF kindly thank the UK Catalysis Hub for resources and support provided via the membership of the UK Catalysis Hub Consortium and funded by EPSRC (grants EP/ K014706/1, EP/K014668/1, EP/K014854/1, EP/K014714/1 and EP/M013219/1). AGB thanks her PhD fellowship (BES-2012-060410) and VC thanks the UK National Academy and the Royal Society by the support though the Newton International Fellows program.

We propose the use of siliceous diatomite as an antishrinkage additive for the synthesis of monolithic carbon aerogel electrodes with enhanced electrochemical response for capacitive deionization of NaCl solutions. Hybrid N- and Mn-doped carbon aerogels with improved electrical conductivity and wettability in the aqueous electrolyte are prepared by introducing modifications in the synthesis (carbon black and/or diatomite loading before the polymerization sol–gel polycondensation of the monomers, followed by manganese infiltration). The textural and morphological characterizations of the materials reveal that the presence of the additives does not impede the cross-linking of the monomers to form branched clusters and colloidal aggregates leading to a highly porous structure. Furthermore, the aerogel materials display an open macroporous network inherited by the diatomite, even after its lixiviation. As a result, the monolithic carbon aerogel electrodes present good electrochemical performance in terms of low polarization resistance, high capacitance, and fast electroadsorption., The authors are indebted to the MINECO (Contract IPT-2011-1450-310000 (ADECAR) and FEDER cofunding, and CTM2014-56770-R) for the financial support. We also thank the fruitful collaboration of Isolux Ingeniería, S.A., Fundación Imdea Energía and Proingesa.University of Cordoba thanks to SCAI and IUIQFN for technical support and Junta de Andalucía (FQM-288) for financial support.

International audience

A glassy carbon electrode (GCE) was surface-modified with carbon quantum dots (CQDs) and applied for the effective enhancement of the electrochemical signal for dopamine and uric acid determination. CQDs were prepared from graphite by a green modification of the Hummers method. They were characterized by FTIR-ATR, XPS, solid-state NMR, fluorescence and Raman spectroscopies. TPD-MS analysis was applied to characterize the functionalization of the surface. The CQDs were assembled on the glassy carbon electrode by adsorption because of the large number of carboxy groups on their surface warrants effective adsorption. The modified GCE exhibits a sensitivity that is almost 10 times better than of the bare GCE. The lower limits of detection are 1.3 μM for uric acid and 2.7 μM for dopamine. Fil: Algarra, M.. Universidad de Málaga; España Fil: González Calabuig, A.. Universitat Autònoma de Barcelona; España Fil: Radotić, K.. University Of Belgrade; Serbia Fil: Mutavdzic, D.. University Of Belgrade; Serbia Fil: Ania, C.O.. Universite D'orleans; Francia Fil: Lazaro Martinez, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina Fil: Jiménez Jiménez, J.. Universidad de Málaga; España Fil: Rodríguez Castellón, Enrique. Universidad de Málaga; España Fil: del Valle, M.. Universitat Autònoma de Barcelona; España

Activated carbons with different textural and chemical surface characteristics were synthesized from waste biomass and low rank coals, and furthermore used as a host matrix for cobalt species, varying the preparation and modification methods. The obtained activated carbons and modified samples were characterized by complex of various physicochemical methods, such as: low temperature physisorption of nitrogen, XRD, EPR, XPS, UV–Vis and TPR with hydrogen. Boehm method was applied for qualitative and quantitative determination of oxygen-containing groups on the carbon surface before and after cobalt deposition. The catalytic properties of cobalt modifications were tested in methanol decomposition. The dominant effect of activated carbon texture over the surface chemistry on the state and catalytic behavior of cobalt species was discussed., Financial support from Bulgarian Academy of Sciences and Bulgarian Ministry of Education (Projects DFNI-Е01/7/2012 and DFNI-E02/2/2014) is gratefully acknowledged.

A new hybrid Cu/rGO catalyst obtained by a thermal treatment of the composite of a copper-based MOF with graphite oxide exhibited a marked catalytic activity for oxygen reduction reaction (ORR) in an alkaline medium, high tolerance to methanol oxidation and superior long-term stability over 20 h. The unique architecture of the copper atoms in the 3D framework of the pristine MOF coupled with the excellent electron transfer properties of rGO lead to materials with a homogenous distribution of copper nanoparticles of specific chemistry assembled within the graphene sheets. Fast O2 adsorption and charge transfer owing to the strong interactions between copper atoms and graphite oxide resulted in highly stable and active Cu/rGO electrodes, compared to the carbonized MOF. The synergistic effect of copper and rGO in the composite leads to a superior ORR activity in terms of long-term stability and high current densities, close to the best performance reported for Pt and other metal-free electrocatalysts., COA thanks the Spanish MECD for her Salvador de Madariaga mobility action (CTM2011/23378 and PRX12/00290).

A novel set-up has been designed and used for synchrotron radiation X-ray high-resolution powder diffraction (SR-HRPD) in transmission geometry (spinning capillary) for in situ solid–gas reactions and processes in an isobaric and isothermal environment. The pressure and temperature of the sample are controlled from 10−3 to 1000 mbar and from 80 to 1000 K, respectively. To test the capacities of this novel experimental set-up, structure deformation in the porous material zeolitic imidazole framework (ZIF-8) by gas adsorption at cryogenic temperature has been studied under isothermal and isobaric conditions. Direct structure deformations by the adsorption of Ar and N2 gases have been observed in situ, demonstrating that this set-up is perfectly suitable for direct structural analysis under in operando conditions. The presented results prove the feasibility of this novel experimental station for the characterization in real time of solid–gas reactions and other solid–gas processes by SR-HRPD., The authors are grateful to the SpLine staff for their assistance. Financial support under grant PIE 201060E013 of the Consejo Superior de Investigaciones Científicas-CSIC and the Spanish Ministry of Economy and Competitiveness MINECO is also acknowledged.

This work reports a green and fast approach to the synthesis of nanoporous carbon materials based on the UV-assisted condensation of organic compounds as precursors. This new approach offers several improvements over the classical soft template and sol-gel routes for the synthesis of materials: versatility of organic precursors, shorter synthesis time, and ambient conditions. Owing to the specificity of the UV-assisted reactions mechanisms, organic compounds of varied chemical composition can be used as precursors in the preparation of nanoporous carbons with tuned porous features. The method consisted in the exposure of an aqueous solution of the organic precursors to UV light for 60 min at room temperature in the absence of a catalyst, allowing an outstanding shortening of the synthesis time compared to sol-gel routes. Furthermore, UV irradiation promoted the cross-linking of the polymer chains of precursors at room temperature, as opposed to classical methods that require an additional step at mild/high temperatures. By changing the chemistry of the organic compound used as precursor, it was possible to modulate the surface area (from 10 to 720 m2 g−1) and the porosity of the synthesized carbons within the micro-/mesopore range. The obtained carbons also presented varied morphology depending on the precursor, from dense aggregates to ordered hexagonal arrangements of nanometric dimensions., This study was supported by the European Research Council through a ERC-Consolidator Grant (648161-PHOROSOL) and the Spanish MINECO (grant CTM2014-56770-R).

Since the seminal work by Pekala in 1989, polycondensation of phenol derivatives with formaldehyde and subsequent carbonization has been one of the most used procedures for preparation of porous carbons. Nitrogen-doped carbons have also been obtained through this approach only by using nitrogen-rich precursors. The list of the most commonly used nitrogen-rich precursors includes melamine, urea, 3-hydroxypyridine, 3-aminophenol and lysine, and despite a few of them can be used in a single fashion, they typically need to be co-condensed with a second precursor. Nitrogen-rich precursors different from these ones have been used rarely because their molecular structure does not favor the nucleophilic substitution through which polycondensation takes place-e.g. p-nitrophenol. This is by no means a trivial issue because, on the one hand, these precursors cannot form a cross-linked network by themselves, and on the other hand, it may be difficult to encompass their different reaction kinetics when combined with more reactive precursors. This is also the situation for other precursors with an amphiphilic molecular structure that could be of interest to control the structure of the resulting porous carbons-e.g. 4-hexylresorcinol. In this work, we have used deep eutectic solvents composed of resorcinol, 4-hexylresorcinol, p-nitrophenol and choline chloride for the preparation of nitrogen-doped carbon monoliths with a hierarchical porous structure. Carbon conversions ranged from 64 to 50%-depending on the carbonization temperature-despite using three different carbon precursors for co-condensation and two of them were uncommon. The nitrogen content ranged from 4.9 to 3.0 wt%, revealing an excellent nitrogen-doping efficiency for p-nitrophenol when used in the form of DES. Finally, the use of 4-hexylresorcinol controlled the formation of a narrow microporosity that, in combination with the nitrogen functionalities, provided a remarkable CO2-sorption capability to the resulting carbons., This work was supported by the MINECO (MAT2012-34811 and MAT2011-25329). NLS acknowledges the MINECO for a FPI contract.

Physisorption on microporous materials has emerged as a promising strategy to store hydrogen for use as an energy carrier. Here, we investigate adsorption of hydrogen in all-silica zeolites ITQ-29 and MFI at low temperatures using molecular simulations. Out of five existing models for hydrogen and its interactions with the zeolite, we determine that a model with hydrogen as a single uncharged Lennard-Jones center best reproduces experimental adsorption isotherms. We present a new set of Lennard-Jones parameters for this model and find that small variations in the parameters have a large impact on computed hydrogen adsorption at 77 K. Preferential adsorption sites of hydrogen in the two zeolite structures are analyzed. We investigate the effect of incorporating quantum corrections via use of a Feynman–Hibbs effective interaction potential and determine that quantum corrections are important at 25 K.

The combined effect of resorcinol/catalyst (100≤R/C≤800) and resorcinol/water (0.04≤R/W≤0.13) molar ratio on the textural and capacitive properties of carbon aerogels with potential application for capacitive deionization has been evaluated. Activated and pyrolyzed aerogels were synthesized by the sol-gel polymerization of resorcinol-formaldehyde mixtures and dried in supercritical conditions. Data show that high R/C and R/W molar ratios lead to materials with large pores in the mesopore range, whereas the surface area and micropore volumes remain somewhat the same. The activation of the aerogels increased the differences in the specific surface and micropore volumes due to the development of microporosity. This effect was more remarkable for the samples with low R/C whatever the R/W ratio, indicating that the carbon aerogel obtained using high amounts of catalyst are more prone to be activated. Regarding the electrochemical features of the aerogels, low capacitance values were measured in aerogels combining low R/W and high R/C and reciprocally low R/C and high R/W molar ratios, due to their higher resistance. Polarization resistances were found to be slightly higher for the pyrolyzed than for activated aerogels, and followed a decreasing trend with the mesoporosity, indicating the outstanding contribution of the mesoporous network to provide a good kinetic response. The desalting capacity of monolithic aerogels showed a simultaneous dependence with the surface area and the resistivity of the electrodes, pointing out the importance of performing electrochemical measurements in adequate cell configurations (i.e., desalting units) upon the intended application., The authors are indebted to the Spanish MICINN (contract IPT-2011-1450-310000 (ADECAR) and CTM2014/56670-R) for the financial support. We also thank the fruitful collaboration of Isolux Ingeniería, S.A., Fundación Imdea Energia and Proingesa.

Phenolic-formaldehyde resins aged at 85, 90 and 95 °C were used as ammonia adsorbents at dynamic conditions in dry and moist air. To avoid pressure drops 10% bentonite was added as a binder. The initial and hybrid materials (before and after ammonia adsorption) were extensively characterized from the point of view of their porosity and surface chemistry. The results showed that the addition of the binder had various effects on materials’ properties depending on the chemistry of their surface groups. When the phenolic acidic groups were predominant, the largest increase in surface acidity upon the addition of the binder was found. It was linked to the exfoliation of bentonite by polar moieties of the resins, which made acidic groups from aluminosilicate layers available for ammonia adsorption. On this sample, a relatively high amount of ammonia was strongly adsorbed in dry conditions. Insensitivity to moisture is a significant asset of ammonia adsorbents, This work was partially supported by the Spanish MINECO (CTM2014/56770-R). COA thanks her Salvador de Madariaga Mobility Action (PRX12/00290).

In a combined experimental and theoretical study, the first transferable set of charges of imidazolate linkers has been derived specifically to model zeolitic imidazolate frameworks (ZIFs). The validity of the charges is demonstrated by comparing experimental and computed results of CH4 and CO2 adsorption on ZIF-7, ZIF-8, ZIF-69, and ZIF-71. The sets of charges obtained with this method provide values of isosteric heats of adsorption and adsorption isotherms of similar accuracy as those obtained using specific sets of charges derived for each individual structure, with the great advantage of being readily transferable to a wide range of ZIFs.

Infrared spectra (IR) of a great variety of zeolite frameworks in the limit of pure silica composition are calculated by molecular dynamics and also recorded experimentally. This enables us to study and assess the effect of three flexible force fields from the literature developed for zeolites in reproducing the IR spectra: the force fields by Demontis (J. Phys. Chem.1988, 92, 867), Nicholas (J. Am. Chem. Soc.1991, 113, 4792), and Hill (J. Phys. Chem.1995, 99, 9536). On one side, a qualitative comparison is undertaken; on the other, a similarity index is introduced to perform a quantitative assessment of the similarity of spectra. It is applied to experimental spectra and enables us to arrange the frameworks in three different sets. It can also be applied to study the agreement of the spectra obtained with the three force fields with experimental spectra on a quantitative basis. The force field by Nicholas performs best, followed by the force field by Demontis. Frameworks are therefore analyzed purely theoretically with the Nicholas force field to investigate the dependency on frameworks. This yields a new classification in sets, which is found to be related to the topology of the frameworks. Surprisingly, these sets do not agree with the sets obtained with experimental spectra. As a consequence, it is found that none of the force fields is good enough to enable the identification of frameworks based on their experimental spectra. In a comparison of spectra generated by different force fields, it is found that the Nicholas and Hill force fields generate the most similar IR spectra.

By using monochromatic light the ability of semiconductor-free nanoporous carbons to convert the low-energy photons from the visible spectrum into chemical reactions (i.e. phenol photooxidation) is demonstrated. Data shows that the onset wavelength of the photochemical activity can be tuned by surface functionalization, with enhanced visible-light conversion upon introducing N-containing groups.

The removal of thiocyanate, a toxic anion originating in a large number of industrial processes, from aqueous solutions was investigated using adsorbents of different natures (activated carbon, zeolite, diatomite, sepiolite, hydrotalcite, steel-making residues). The uptake of thiocyanate anions did not seem to be directly related to the porous features of the adsorbents, but rather connected to the ion-adsorbent affinity. The highest retention in synthetic solutions was obtained with hydrotalcite, followed by activated carbon, zeolite and the steel-making slags. In real wastewater, the removal efficiency of hydrotalcite relative to industrial wastewater was largely suppressed due to the organic matter present. In contrast, the retention ability of the activated carbon and the slags was less modified in real wastewater due to their open porous networks. These results indicate that steel-making slag could be used as a potential adsorbent for the removal of thiocyanate anions from real wastewater produced in coke-making processes without any additional processing., The authors thank FICYT for financial support (PEST08-07, PEST08-14). COA thanks CSIC for financial support (200980I131).

A series of activated carbons with varied surface chemistry, obtained by wet oxidation and thermal treatment, was used for the removal of penicillin from low concentration aqueous solution. It was found that the carbon surface chemistry favors the degradation of the antibiotic, giving rise to various intermediates detected both in solution and in the adsorbed phase (deposited with the pore structure of the activated carbons). The confinement of penicillin molecules entrapped in the nanopores of activated carbons of acidic nature accelerates their degradation compared to that one in the bulk solution, which can be linked the strong local pH fall inside the pores. Degradation also takes place in activated carbons of basic pH, although the nature and partition of the intermediates formed differ from those in the acidic carbons. In both cases most of the breakdown products do not present therapeutic activity., This work was supported by the Spanish Ministry of Science and Innovation, MICINN (project CTM2008-01956). COA thanks Dr. Vix from IS2M (France) for providing the TPD-MS. COA and TJB are grateful to the Spanish Council for Scientific Research (CSIC) for their Mobility Actions (grants PA1001122 and PA2001393).

The goal of this study is to investigate the preparation of low-cost activated carbon from bean pods waste and to explore their potential application for the removal of heavy metals from aqueous solutions. Conventional physical (water vapor) activation was used for synthesizing the adsorbent. The obtained carbon was employed for the removal of As (III) and Mn (II) from aqueous solutions at different initial concentrations and pH values. Adsorption for both ions follows Langmuir-type isotherm, the maximum loading capacities for arsenic (III) and Mn (II) ions being 1.01 and 23.4 mg g −1 , respectively. According to the experimental data, it can be inferred that the basic character of the surface, i.e. the high content of basic groups, favors adsorption of ions. Arsenic adsorption capacity on the carbon obtained from agricultural waste was found to be similar to this of more expensive commercial carbons showing high adsorption capability. Regarding manganese adsorption, herein obtained carbon presented higher uptake adsorption than that of activated carbons reported in the literature.

We have developed a complete force field that accurately reproduces the adsorption properties of carbon dioxide in a variety of zeolites with different topologies and compositions. The force field parameters were obtained by fitting to our own experimental data and validated with available data taken from the literature. The novelty of this force field is that it is fully transferable between different zeolite framework types, and therefore, it is applicable to all possible Si/Al ratios (with sodium as extra-framework cation) and for the first time affording the prediction of topology-specific and chemical composition-specific adsorption properties.

The understanding of adsorption isotherms is important for the solution of a large class of industrial problems, many of which are of current research interest. The existence of stepped adsorption isotherms is often observed in some particular adsorption processes, being a distinction of mesoporous materials reflecting capillary condensation effects. However, such singularity is less observed at very low relative pressures. For instance, the presence of a substep on the argon adsorption isotherm of MFI at cryogenic temperature has been corroborated with a variety of experimental studies, but its origin is still unclear, and the interpretations are even contradictory. In this work, a new insight into this process is proposed by a combined approach using both experiments and molecular simulations.

In this work a series of commercial carbons with different structural and textural properties were characterised and evaluated for their application in hydrogen storage. The results showed that temperature has a greater influence on the storage capacity of carbons than pressure. The highest H2 storage capacity at 298 K and 90 bar was 0.5 wt%, while at 77 K and atmospheric pressure it was 2.9 wt%. It is also showed that, in order to predict the hydrogen storage capacity of carbon material both at cryogenic and ambient temperature, the only use of BET surface area or total micropore volume obtained from N2 adsorption isotherm may be insufficient, the characterization of the narrow microporosity is needed due to its high contribution to hydrogen adsorption capacity. The process involved in hydrogen storage in pure carbon materials seems to be physisorption. Morphological or structural characteristics have no influence, at least on gravimetric storage capacity.

Soft-template approaches have been frequently applied for the preparation of porous carbons. Most of these processes proved highly effective for the preparation of mesoporous carbons with pore diameters below 10 nm but less explored has been the preparation of carbons with mesopores larger than 10 nm. The lack of syntheses providing large and well-interconnected mesopores is by no means a trivial issue because it limits the achievement of materials suitable for applications where pore surface accessibility is crucial – e.g. electrodes in supercapacitors or adsorbents in flow-through systems, among others. In this work, we have used deep eutectic solvents (DESs, a sort of ionic liquid, that are obtained by complexation of quaternary ammonium salts with hydrogen-bond donors) composed of resorcinol, urea and choline chloride for the preparation – via formaldehyde polycondensation and subsequent carbonization – of hierarchical porous carbons with micropores and large mesopores within the 10 to 20 nm range. The formation of large mesopores took place at the polycondensation stage via a spinodal decomposition process where some components forming the DES acted as precursors of the polymer phase, while some other ones were segregated into a polymer depleted phase. Thus, the ultimate dimension of the mesopores was controlled by the mass ratio between the segregated and condensed phases, and this mass ratio by the molar ratio of the components forming the original DES. We have finally demonstrated that carbons with larger mesopores exhibited better performance as electrodes in supercapacitor cells., The authors thank Spanish MINECO (grants MAT2012‐34811 and CTM2014‐56770‐R) for financial support. N. López‐Salas also acknowledges MINECO for a FPI research contract.

Deep eutectic solvents (DESs) composed of resorcinol, either 2-cyanophenol or 4-cyanophenol, and choline chloride were used for the synthesis of hierarchical nitrogen-doped carbon molecular sieves. Carbons were obtained with high conversions by polycondensation of resorcinol and either 2-cyanophenol or 4-cyanophenol with formaldehyde, and subsequent carbonization at 800 °C in nitrogen atmosphere. The nitrogen content was ca. 2.4 wt%, revealing an excellent nitrogen-doping efficiency for cyanophenol derivatives when used in the form of DES. The use of either 2-cyanophenol or 4-cyanophenol modified the contribution of quaternary-Nvalley groups in the resulting carbons, being larger in carbons coming from 4-cyanophenol than in those coming from 2-cyanophenol. The hierarchical porous structure was composed of micro-, meso- and macropores, and the diameter distribution of mesopores was also related to the use of either 2-cyanophenol or 4-cyanophenol. These structural and compositional differences were critical for the use of the resulting hierarchical nitrogen-doped carbons as efficient metal-free electrocatalysts. In particular, the carbons coming 4-cyanophenol proved particularly effective in the direct reduction of oxygen to OH− (H2O in acidic solution) through a four-electron (4e−) process with high catalytic activity and selectivity, and longer stability and stronger tolerance to crossover effects than platinum-based electrocatalysts.

18 pages, 11 figures, 4 tables.-- Available online 17 November 2006.-- Issue title: TSOP 2005 - Papers from the 22nd Annual Meeting of TSOP (Louisville, Kentucky, USA, 11–15 Sep 2005)., The goal of this work is to study the ability of two immature Carboniferous coals from Donets Basin (Ukraine) to act as source for oil. Heating experiments in confined medium were performed to compare the thermal behavior of these coals, 1l1 Dim (%Rr = 0.55; H/C at. = 0.79) and 2c10YD (%Rr = 0.65; H/C at. = 0.80), relative to a mature Cretaceous coal from Sabinas Basin (Olmos, %Rr = 0.92, H/C at. = 0.77). Macerals analysis carried out on starting materials showed that Olmos is exhausted in liptinite contrary to 2c10YD (20 vol.%) and 1|1Dim (6 vol.%). The vitrinite content is lower for 2c10YD (59 vol.%) than for Olmos (84 vol.%) and 1|1Dim (80 vol.%). Solid bitumen occurs often dispersed in the raw coals. Both petrographic and geochemical analyses on starting materials revealed that the selected Carboniferous Donets coals have better potentialities for bitumen generation than the Cretaceous Sabinas coal. The presence of long chain n-alkanes (> n-C8) in the pyrolysis-GC chromatograms indicates that the two raw Carboniferous coals from Donets Basin can yield non-volatile hydrocarbons under further thermal maturation. It is speculated that some vitrinite macerals present in hydrogen-rich Carboniferous coals from Donets Basin can act as source rocks for oil. As a matter of fact, results showed that the ‘oil window’ occurs between ~ 1.0%Rr and ~ 2.0%Rr for both Cretaceous Sabinas and Carboniferous Donets coals during confined pyrolysis. As expected from geochemical and petrographic analyses of starting samples, the Carboniferous Donets coals yielded more bitumen and hydrocarbons than Cretaceous Sabinas coal during artificial maturation. Low proportions of solid bitumen (< 12 vol.%) are also formed between 1.1%Rr and 1.5%Rr during confined pyrolysis of coals. Two solid bitumen groups have been identified, which correspond to distinct phases of neo-formation. The drop in the solid bitumen content at higher ranks indicates that it contributes to generation of gas during experimental simulation. Moreover, their morphology and porosity change with the level of maturity. The porosity of the vitrinite matrix increases as well as the pore size with increasing maturity. A relationship has been observed between the porosity and the weight loss: the higher pore content of Carboniferous Donets coals is correlated with a higher generation of gas compared to Cretaceous Sabinas coal., The authors wish to acknowledge the CREGU (France) and the Syria Government for their financial support. This research was also supported by a CSIC-CNRS (Spain-France) Bilateral Agreement (Collaboration Cooperation Accord CNRS/CSIS Project Conjoint 16226).

We report the dependence of the photochemical activity of titania/carbon hybrid catalysts toward the degradation of phenol from solution using polychromatic light and filters. In all cases larger photooxidative efficiencies were obtained using light at 200 nm < λ < 600 nm. The incorporation of a carbon additive to TiO2 increased the photocatalytic performance regardless the illumination conditions, although, the effect was more pronounced at λ > 200 nm. The photocatalytic runs carried out with the nonporous carbon alone confirmed a certain level of intrinsic photoactivity under both irradiation conditions. Nevertheless, a clear deactivation was evident after 60 min of irradiation suggesting that the photoactive sites in the carbon are either consumed or deactivated in the course of the reaction. The composition of the catalyst and the illumination conditions also have a strong effect on the nature of the degradation intermediates, with a marked regioselectivity toward ortho-substitution at high energy photons and when the carbon component is added to the catalyst composition., The authors thank Cordex (Portugal) for kindly supplying sisal. The financial support of the pluriannual funding to CQB (UID/MULTI/00612/2013), and MINECO (CTM2014/56770-R, AIB2010-PT00209) is also acknowledged. MAA and ASM thank FCT for their PhD (SFRH/BD/71673/2010) and Post-Doc (SFRH/BPD/86693/2012) fellowships, respectively. RJC thanks PCTI Asturias Fondos Feder for her Severo Ochoa fellowship. The authors thank Dr. Matos for fruitful discussion.

Knowledge of the pore structure of carbon materials including micropores is crucial for applications such as double layer supercapacitors, gas separation, and other applications requiring high specific surface area materials. High surface area is always associated with fine micropores. The pore size distribution (PSD) of microporous carbons is usually evaluated from nitrogen adsorption isotherms measured at 77 K in the relative pressure range from 10−7 to 1. Due to the very slow gas diffusion into fine pores at cryogenic temperatures and low pressures, the adsorption measurements may be extremely time consuming and sometimes inaccurate when the adsorption equilibrium is difficult to achieve during the measurement. In this work, we discuss an approach in which the carbon PSD is calculated from the combined N2 and CO2 data measured in the pressure range from 1 to 760 Torr. Under such conditions, the diffusion into micropores is usually fast and equilibration times are short for both measurements. In the PSD calculations we use 2D-NLDFT models for carbons with heterogeneous surfaces (J. Jagiello and J.P. Olivier, Adsorption19, 2013, 777–783). We show that both isotherms can be fitted simultaneously with their corresponding models and as a result the unified PSD can be obtained., J.J. would like to thank Dr. Ani Nikova of Cabot Corporation for providing a sample of carbon BP280 and Dr. William Betz of Sigma–Aldrich Corporation for providing Supelco samples of carbon molecular sieves.

Highly micro-mesoporous carbon electrodes have been synthesized by the polycondensation of resorcinol-formaldehyde-melamine mixtures in the presence of a carbon conductive additive. The materials showed high surface functionalization (N- and O- groups) provided by the precursors. Despite the low amount used, the conductive additive had a marked effect on the porosity of the aerogels; for a given series, the carbon black loaded materials showed similar micropore volumes and a more developed mesoporosity than the pristine aerogels. Furthermore, the activation treatment under CO2 atmosphere led to an increase in the surface area along with a widening of the mesoporosity. The synthesized aerogels were explored as electrodes for the electro-assisted removal of sodium chloride from saline water. A desalting capacity of 7.3 mg/g was obtained for monolith electrodes of sample MRF-Act/CB, along with an excellent chemical stability upon charge and discharge at high polarization voltages. Such good electrochemical performance is due to the combination of an adequate pore network and surface functionalization with an enhanced electrical conductivity achieved upon the incorporation of the carbon black additive during the polycondensation of the aerogel precursors., The authors are indebted to the MICINN (Contract IPT-2011-1450-310000 (ADECAR), and CTM2011/23378) for the financial support. We also thank the fruitful collaboration of Isolux Ingeniería, S.A., Fundación Imdea Energia and Proingesa. University of Córdoba thanks to SCAI for technical and FEDER and Junta de Andalucía (FQM-288) for financial supports.

The sol–gel polymerization of resorcinol/formaldehyde mixtures to obtain porous gels is typically a long process performed throughout several days. In this work, we have explored an experimental approach to reduce the time necessary to obtain porous gels based on mild polymerization conditions and direct drying. We have analyzed the effects of the temperature and time of the gelation/aging step on the porosity of the gels, as well as the impact on the overall energetic cost of the process. Data have shown that well-developed micro–mesoporous architectures can be obtained within less than a day. The temperature of the gelation/aging step mainly affects the mesopore network, whereas the microporosity is determined by the composition of the precursor’s mixture. The exclusion of the solvent exchange step yields soft mechanically fragile porous gels with structural limitations upon carbonization at high temperature in inert atmosphere, due to the surface tensions applied to the backbone during the evolution of volatiles. The mesopore structure lost during carbonization is not recovered upon activation in CO2 atmosphere, but it is preserved upon chemical activation in K2CO3 and the resulting gel exhibits a bimodal micro–mesoporous distribution. Furthermore, the energy savings of this route are similar to those obtained using microwave-heating in terms of grams of xerogel per kilowatt hour of energy consumed for similar textural properties. The correlation between the energy power consumed and the textural parameters is a useful tool to optimize the synthesis., The authors thank the financial support of the Spanish MINECO (grant CTM2011/023378) and Fondos Feder PCTI Asturias (grant PC10-002). EDIP and RJC are grateful to CONACyT and PCTI Asturias for the mobility grant (290674) and Severo Ochoa fellowship, respectively. COA acknowledges Dr. Jacek Jagiello for the fruitful discussion on 2D-NLDFT-HS model.

N-doped carbon aerogels were synthesized by the polycondensation of resorcinol–formaldehyde–melamine mixtures. The prepolymerization of the precursors was determinant for the preparation of meso/macroporous aerogels with varied nitrogen content, regardless the solution pH and M/R molar ratio. The effect was more pronounced at pH 6, as the hydrogels prepared by the one-step route displayed essentially a microporous character, as opposed to the mesoporous network after prepolymerization. The prepolymerized carbon aerogels presented large capacitance values due to the optimum balance between pore structure, improved wettability and low polarization resistance for the highly doped materials. Salt deionization capacity revealed the importance of the macropore structure in the monolithic configuration of the aerogels for a fast electrosorption of ions., The authors are indebted to the MINECO – Spain (Contract IPT-2011-1450-310000 (ADECAR), and CTM2011/23378) for the financial support. We also thank the fruitful collaboration of Isolux Ingeniería, S.A., Fundación Imdea Energia and Proingesa. University of Córdoba thanks to SCAI for technical support and Junta de Andalucía (FQM-288) for financial support.

On the basis of the results described in the literature on the reactivity of sodium toward DBT and its derivates, the effect of sodium dispersed on the surface of a carbonaceous support on the removal of DBT from hexane solution at ambient conditions has been investigated. Since the main objective of this paper is to demonstrate the effect of sodium on the reactive adsorption of DBT from an organic solvent, hexane was chosen as a model solvent. As adsorbents, two carbons with and without sodium on the surface were investigated. The carbons are obtained by carbonization of polystyrene−sulfonic acid−co-maleic acid in sodium salt at 800 °C in nitrogen. The results show that sodium present on the surface of carbon takes part in the reaction with DBT in which sodium metalates and sodium sulfides are formed., This work was supported by FICYT and PSC CUNY (PSC CUNY 66382-0035). The authors thank Dr. Martin Gorbaty of ExxonMobil for inspiration and fruitful discussion. Dr. Alvarez is kindly acknowledged for his help in SEM.

[EN] Thermal regeneration of activated carbons (AC) was carried out at 1123 K and under N2 atmosphere. Experiments have been carried out using a single mode microwave device operating at 2450 MHz and a conventional electric furnace (EF) so as to compare the effect of the different heating mechanisms on the adsorptive capacities of the regenerated AC. The adsorbents were saturated with phenol in columns. Adsorptive capacities after subsequent regeneration cycles were evaluated from the breakthrough curves. Additionally, a complete textural and chemical characterization of the regenerated samples was also carried out in order to study the influence of the subsequent regeneration cycles on the texture and the adsorptive capacities of the AC. Textural characterization of the regenerated samples was carried out by means of N2 adsorption isotherms at 77 K., The authors thank the European Commission, the Spanish Ministry of Science and Technology (research Project 1FD 1997 400 CO2 01) and Química Farmaceútica Bayer for financial support.

We have explored the role of the physicohemical properties of carbon materials as additives to bismuth tungstate on its structure, optical properties, and photocatalytic activity for the degradation of rhodamine B under visible light. For this purpose, C/Bi2WO6 hybrid composites were prepared following two different routes: (i) physical mixture of the catalyst components, and (ii) one-pot hydrothermal synthesis of the semiconductor in the presence of the carbon additive. Three carbons with different properties were selected as additives: biomass-derived activated carbon, carbon nanotubes and carbon spheres obtained from polysaccharides. Data has shown the outstanding role of the acidic/basic nature of the carbon additive, and of the synthetic method on the photocatalytic performance of the resulting composites. For a given additive, the degradation rate of RhB is greatly improved for the catalysts prepared through a one-step hydrothermal synthesis, where there is low shielding effect of the carbon matrix. Carbon additives of acidic nature boost the surface acidity of the hybrid photocatalyst, thereby enhancing the photodegradation of RhB under visible light via a coupled mechanism (photosensitization, semiconductor photocatalysis and carbon-photon mediated reactions)., The authors thank the financial support of MINECO (grants CTM2011/23378 and CTQ2011/26617) and PCTI Asturias (Fondos Feder 2007-2013, grant PC10-002). RJC thanks PCTI Asturias for her Severo Ochoa fellowship

We showed the effect of surface oxidation on the conversion of light into a chemical reaction in the confined pore space of nanoporous carbons. The photoactivity of carbons is caused by the combination of high porosity and the presence of photoreactive sites that favor the splitting of the exciton inside the pores, which boosts its efficient use in chemical reactions. The incorporation of O-containing groups in the carbon matrix decreased the photoconversion inside the pores, although values were higher than those attained in solution. This is attributed to the lower stabilization of the exciton through the delocalization within the conjugated sp2 network of the basal planes because of the electron-withdrawing effect of the O-containing groups. The photochemical conversion of light inside the pores is very sensitive to the acidic/basic nature of the O-containing groups of the carbon matrix, and can be enhanced by balancing the surface composition, porosity, and electronic mobility., The financial support of the Spanish MINECO (grant CTM2014- 56770-R) is acknowledged.

A simple modification of the sol–gel polymerization of resorcinol–formaldehyde mixtures allowed the preparation route of homogeneously dispersed carbon black-activated carbon aerogel composites with high pore volumes and improved electrical conductivity. These materials showed good performance as electrodes for the electro-assisted removal of sodium chloride from saline water using high voltages. Besides the effect of the carbon black additive, we have investigated the influence of resorcinol–water ratio on the textural and electrochemical properties of the resulting materials. Data has shown a slight dependence on the structural order of the aerogels with the R/W ratio, regardless the incorporation of the conductive additive. The effect of the carbon black on the textural features was also negligible, due to the low amount incorporated. Nonetheless, the samples showed higher capacitance values for the removal of ions from solution, due to the enhanced conductivity provided by the carbon black, being the effect more evident for the materials prepared using a low R/W ratio., The authors are indebted to the MICINN (Contract IPT-2011-1450-310000 (ADECAR), and CTM2011/23378) for the financial support. We also thank the fruitful collaboration of Isolux Ingeniería, S.A., Fundación Imdea Energia and Proingesa. University of Córdoba thanks to SCAI and IUIQFN for technical support and Junta de Andalucía (FQM-288) for financial support.

We report on a facile and rapid microwave-assisted method for preparing a sodium–cadmium metal–organic framework (having coordinatively unsaturated sodium ions) that considerably shortens the conventional synthesis time from 5 days to 1 hour. The obtained (Na,Cd)-MOF showed an excellent volumetric CO2 adsorption capacity (5.2 mmol cm−3 at 298 K and 1 bar) and better CO2 adsorption properties than those shown by the same metal–organic framework when synthesized following a more conventional procedure. Moreover, the newly prepared material was found to display high selectivity for adsorption of carbon dioxide over nitrogen, and good regenerability and stability during repeated CO2 adsorption–desorption cycles, which are the required properties for any adsorbent intended for carbon dioxide capture and sequestration (CSS) from the post-combustion flue gas of fossil fuelled power stations., The Spanish Ministerio de Economía y Competitividad (MINECO) and the European Funds for Regional Development (FEDER) are gratefully acknowledged for financial support through Project CTQ2013-47461-R. Financial support from Programa Pont la Caixa per a grups de recerca de la UIB is also acknowledged. C.P. acknowledges the Spanish Ministerio de Educación y Ciencia (pre-doctoral fellowship).

We have analyzed the effects of CO2 activation on the porosity of ultrahigh pore volume carbon aerogels. Data obtained from the new 2D-NLDFT-HS model for carbons has been compared to the results of conventional methods (BJH, t-plot, DR); all the models were applied to the desorption branch of the isotherms. Physical activation of the carbon aerogel at different burn-off degrees resulted in materials showing increasing volume of micropores and alteration of mesopore structure. The later effect manifested itself by a characteristic inflection in the desorption branch of the nitrogen isotherm at high relative pressures. Such curvatures are attributed to a non uniform activation of the carbon matrix with CO2 that in some parts carves the surface of the precursor deeper than in others, creating bimodal/multimodal pore size distributions. The different methods applied for the assessment of the textural properties of the aerogels with ultrahigh micro-/mesoporosity showed excellent agreement in terms of pore volumes, surface areas and average pore size., The authors thank the financial support of the Spanish MINECO (grant CTM2011/02338). REFERENCES

Three microporous commercial activated carbons (AC) were used for the adsorption of phenol and salicylic acid from aqueous solution. Equilibrium adsorption data were obtained by the bottle-point technique. Long periods of time were needed to reach the equilibrium between the active carbon and the aqueous solution. Adsorptive capacities obtained from the isotherms were calculated following the ASTM 3860 procedure. Carbons with a high oxygen content were found to present lower adsorptive capacities for both phenol and salicylic acid. Column tests were also used for the uptake of phenol and salicylic acid, and adsorptive capacities were calculated from the breakthrough curves. Adsorptive capacities calculated from the breakthrough curves were found to be significantly lower than those evaluated from the equilibrium isotherms.

A nanoporous carbon was prepared from sulfonic acid based water soluble polymer. Its direct one step carbonization followed by air oxidation led to a porous material whose surface was rich in N-, O- and S-containing groups. TEM images showed the presence of 10 nm graphitic domains in the carbon matrix. When the carbon was used as a photoanode under visible light irradiation, oxygen evolution occurred at overpotentials as low as +0.8 V vs. Ag/AgCl. The ability of the carbon to oxidize water was linked to the presence of sulfur and nitrogen containing groups working as chromophores whose electrons are excited by irradiation leaving reactive vacancies (holes) that are able to accept electrons from oxygen in water molecules. The conductivity of the carbon matrix and the presence of small pores were found of paramount importance. While the former helps in electron transfer within the carbon matrix, strong adsorption of water molecules in micropores close to chromophores enhances the electron transfer from oxygen to the vacancy on the chromophore promoting water splitting and oxygen evolution. This work provides the first direct experimental evidence of water photooxidation reactions using metal-free nanoporous carbons exposed to visible light., This work was partially supported by the Spanish MINECO (Grants CTM2011/23378 and CTQ2012-37925-C03-03 and FEDER funds). COA thanks her Salvador de Madariaga Mobility Action (PRX12/00290).

We use a combination of experiments and molecular simulations to address the discrepancies of the force fields available in the literature to accurately reproduce CO2 adsorption in zeolites with high density of aluminum atoms and extra framework cations. We attribute these discrepancies to the fact that previous force fields are not parametrized to take into account the formation of carbonate-like complexes in these zeolites during CO2 adsorption. Our data show that the formation of carbonate-like complexes has a marked effect on the accessible porous structure of the zeolite, and the strength is controlled by the density and nature of extra framework cations. Strong carbonate-like complexes are formed in zeolite topologies containing high density of sodium, whereas bivalent cations give rise to more labile complexes. We provide a new set of parameters capable to reproduce the experimental adsorption in these systems. Our approach consists of the modification of the partial charges of the atoms of the zeolite that are directly involved in the formation of the surface complexes (oxygen atoms and cations). The new set of charges combined with our previous transferable force field reproduces the experimental adsorption in structures containing carbon dioxide–cation complexes., This work was supported by the Spanish “Ministerio de Educacion, Cultura y Deporte” (CTQ2010-16077/BQU), and the European Research Council through an ERC Staring Grant (ERC-StG-279520-RASPA). A. Martín-Calvo thanks the Spanish “Ministerio de Educación” for her predoctoral fellowship.

The photocatalytic performance of titania/Cu-carbon composites was investigated towards phenol degradation under visible light. The approach consisted on the incorporation of the transition metal on the carbon component of the hybrid composite via impregnation of the carbon precursor with a metal salt followed by activation. Data showed a homogeneous dispersion of copper particles within the carbonaceous matrix, predominantly as copper (II) species. The synthesized carbons displayed a well developed nanoporous texture, although comparatively the impregnation of copper caused a marked inhibition of the textural development of the carbon precursor. The phenol photooxidation tests carried out on 1:1 titania/carbon composites showed the outstanding role of copper under visible light, with an increased efficiency in terms of phenol conversion, mineralization degree and degradation rate. This is important, since similar overall conversions were obtained with half of the amount of the photoactive semiconductor (1:1 composites). The beneficial effect of copper loading was also observed in the marked regioselectivity towards the preferential formation of catechol. Furthermore, the copper-loaded photocatalyst was found to be stable with no lixiviation or photorreduction of the copper species after illumination., The authors thank Cordex (Portugal) for kindly supplying sisal. The financial support of the pluriannual funding to CQB (PEst-OE/QUI/UI0612/2013), MINECO (CTM2008/01956, CTM2011/23378, AIB2010-PT00209) and PCTI Asturias (Fondos Feder 2007-2013, grant PC10-002) is also acknowledged. MAA and ASM thank FCT for their PhD (SFRH/BD/71673/2010) and postdoc (SFRH/BPD/86693/2012) fellowships, respectively. RJC thanks PCTI Asturias for her Severo Ochoa fellowship.

The long term performance of semiconductor-free activated carbons showing photochemical activity was explored by monitoring the photodegradation of phenol from aqueous solution along 20 h of illumination in consecutive photocatalytic cycles. The efficiency of the process was evaluated in terms of phenol conversion, mineralization degree and evaluation of degradation intermediates upon cycling. Data showed a strong dependence of the photooxidation efficiency on the hydrophobic/hydrophilic nature of the carbons. The outstanding role of dissolved oxygen as a promoter of phenol photodegradation through the formation of O-radicals upon illumination of the carbons was also demonstrated. The excess of oxygen not only improved phenol conversion and mineralization, but delayed the clogging of the carbon’s porosity upon cycling. This is important since a fraction of the photooxidation reaction also takes place inside the porous network of the carbon materials. Overall, the performance of the activated carbons, especially in conditions of excess of oxygen, is comparable to that of commercial titania., The authors thank the financial support of the Spanish MINECO (Grants CTM2008/01956, CTM2011/23378) and PCTI Asturias (Fondos Feder 2007–2013, Grant PC10-002). L.F.V. and R.J.C. thank CSIC and PCTI Asturias for their JAE-Pre and Severo-Ochoa fellowships, respectively. The authors are grateful to Dr. Maurino and Dr. Laurenti from the University of Torino for the ESR measurements and to Ms. Querejeta-Montes for her help in the adsorption kinetics.

Three-activated carbon aerogels were synthesized by CO2 activation of the materials prepared by the polycondensation of resorcinol and formaldehyde mixtures followed by supercritical drying. The obtained carbon aerogels were characterized and used as electrode materials for the electrosorption of sodium phosphate and nitrate. X-ray diffraction and Raman spectroscopy showed the dependence of the structural ordering of the aerogels with the resorcinol/catalyst ratio and the extent of activation. The electrosorption capacitance evaluated by cyclic voltammetry revealed large values for the activated samples containing a large contribution of mesopores, regardless the electrolyte salt. Due to an adequate combination of chemical and porous features, the desalting capacity of the activated carbon aerogel electrodes exceeded that of the as-prepared materials. The evaluation of the kinetic properties by chronocoulometric relaxation and impedance spectroscopy showed a decrease of time constant and resistances for highly mesoporous activated samples. A high deionization capacity and fast electrode discharge was detected for the deionization of sodium nitrate on the highly mesoporous activated aerogel. Data also showed the efficient electrosorption of ionic species on consecutive charge/discharge cycles, confirming the stability of the aerogel electrodes at the high applied potentials., The authors are indebted to the MICINN (Contract IPT-2011-1450-310000 (ADECAR), and CTM2011/23378) for the financial support. We also thank the fruitful collaboration of Isolux Ingeniería, S.A., Fundación Imdea Energia and Proingesa.

Carbon aerogels doped with manganese or iron oxides were prepared by the resorcinol-formaldehyde method as potential electrodes for the capacitive deionization of sodium chloride from saline water. The solution containing the metal precursors was mixed with the hydrogel before the supercritical drying step ensuring a highly homogeneous dispersion of the nanometric metal oxides as determined by X-ray diffraction and electron microscopy. XPS spectra revealed the increased contribution of hydroxyl and carboxylic groups after the activation process. Also, an enhanced metal oxidation at the outer particle surface was observed. Nitrogen isotherms have revealed a decrease of the pore volume in doped samples ascribed to the partial blocking of the pore structure by the embedded nanometric metal oxide particles. Capacitance values as large as 99 F/g and 91 F/g were respectively recorded for CAGDFeAct and CAGDMnAct by cyclic voltammetry. The large capacitance detected for the iron containing activated aerogel was confirmed by deionization experiments. An electrosorption capacity of 0.133 mmol/g was recorded for CAGDFeAct in a 0.025 M NaCl solution when 1.5 V were applied during the charge period. The study of the kinetic response of the electrodes showed a poor behavior for CAGDMnAct and was correlated to the partial blocking of pore structure exerted by the embedded nanometric metal oxide particles., The authors are indebted to the MICINN (Contract IPT-2011-1450-310000 (ADECAR) and CTM2011-23378) and Junta de Andalucía (Research group FQM-288) for the financial support. We also thank the fruitful collaboration of Isolux Ingeniería, S.A., Fundación Imdea Energia and Proingesa.

Herein, we explore the immobilization of nickel on various carbon supports and their application as electrocatalysts for the oxidation of propargyl alcohol in alkaline medium. In comparison with massive and nanoparticulated nickel electrode systems, Ni-doped nanoporous carbons provided similar propargyl alcohol conversions for very low metallic contents. Nanoparticulated Ni on various carbon supports gave rise to the highest electrocatalytic activity in terms of product selectivity, with a clear dependence on Ni content. The results point to the importance of controlling the dispersion of the Ni phase within the carbon matrix for a full exploitation of the electroactive area of the metal. Additionally, a change in the mechanism of the propargyl alcohol electrooxidation was noted, which seems to be related to the physicochemical properties of the carbon support as well. Thus, the stereoselectivity of the electrooxidative reaction can be controlled by the active nickel content immobilized on the anode, with a preferential oxidation to (Z)-3-(2-propynoxy)-2-propenoic acid with high Ni-loading, and to propiolic acid with low loading of active Ni sites. Moreover, the formation of (E)-3-(2-propynoxy)-2-propenoic acid was discriminatory irrespective of the experimental conditions and Ni loadings on the carbon matrixes., This work was funded by the Spanish MINECO (grants CTQ2010-20347, CTM2011- 23378).

Bifunctional Pt-HMOR catalysts were prepared by incipient wetness impregnation of various desilicated MOR obtained by alkaline treatment using NaOH concentrations ranging from 0.1 to 0.5 M. The zeolite structural changes upon modification were investigated by several techniques including powder X-ray diffraction, 27Al and 29Si MAS-NMR spectroscopy, N2 adsorption, pyridine adsorption followed by infrared spectroscopy and the catalytic model reaction of m-xylene transformation. For low alkaline concentration the zeolite acidity is preserved, along with a slight increase of the volume correspondent to the larger micropores due to the removal of extra-framework debris already existent at the parent zeolite. At higher NaOH concentrations there is a significant loss of crystalinity and acidity as well as the formation of mesoporosity. The characterization of the metal function shows similar patterns for Pt-HMOR and Pt-M/0.1 samples, with Pt particles located mainly inside the inner porosity. In contrast, large Pt particles become visible at the intercrystalline mesoporosity of MOR crystals developed during the desilication treatments at severe alkaline conditions. The catalytic results obtained for n-hexane hydroisomerization showed an improved selectivity for dibranched over monobranched isomers for Pt-M/0.1 sample, likely due to the preservation of the support acidity and the slight enlargement of the micropores. This work is a new example in which the mesoporous development does not improve the catalytic efficiency of the zeolites, whereas mild alkaline desilication might be considered as an effective solution to produce customized catalysts with enhanced performance for a given application., This work was financially supported by FCT (Portugal) through strategic projects PEst- OE/QUI/UI0612/2013 (CQB), and PEst-C/CTM/LA0011/2013, Portuguese NMR Network (RNRMN)

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Sustainable Chemistry and Engineering, copyright © American Chemical Society after peer review and technical editing by the publisher.To access the final edited and published work see http://dx.doi.org/10.1021/sc500069h, Carbon nanotubes have been successfully coated with a N-doped carbon layer via hydrothermal carbonization in the presence of a nitrogen-containing carbohydrate, i.e., glucosamine hydrochloride. By controlling the amount of glucosamine added, it was possible to tune the N content of the composites N-doped carbon/CNT between 1.8–2.5 wt %. The prepared composites exhibited superior supercapacitor performance in comparison to bare CNTs even though they possess lower textural properties. Thus, a 2- to 4-fold increase in specific capacitance per surface area was registered at low current densities and sweep rates and a 2-fold increase in energy density, while keeping the power density. Besides, the composites possess superb long-term stability, losing only 4–6% of specific capacitance after 10,000 cycles at 10 A g–1., This research work was supported by Spanish MINECO (MAT2012-31651 and CTM2011- 23378). M.S. acknowledges the award of the Ramón y Cajal contract.

A comparative study of slow crack propagation in alumina, zirconia and zirconia toughened alumina (ZTA) ceramics is presented keeping in mind the option that ZTA materials offer to improve the lifetime and reliability of ceramic joint prostheses. Different ZTA composites, using either unstabilized or yttria stabilized zirconia, have been tested. The materials were prepared in the range 0 - 15 ZrO2 vol. %, by two different processing methods: powder-mixing and a modified colloidal route. Crack propagation tests have been conducted for crack velocities from 10-12 to 10-2 m/s by means of double torsion method. The influence of the processing conditions on the microstructure development, and the effect of these microstructures on the slow crack-growth behaviour, have been studied.

Deep eutectic solvents (DESs) composed of resorcinol, 3-hydroxypyridine and tetraethylammonium bromide were used for the synthesis of hierarchical nitrogen-doped carbon molecular sieves. DESs played multiple roles in the synthetic process, as the liquid medium that ensures reagent homogenization, the structure-directing agent responsible for the achievement of the hierarchical structure, and the source of carbon and nitrogen for the solid sorbent obtained after carbonization. Thus, the synthesis offers an economy of reagents that emphasizes the green nature and low cost of conventional polycondensation. Interestingly, while macropores facilitated mass transport and access to the surface area, the combination of the molecular sieve structure and nitrogen functionalization provided, respectively, excellent CO2 adsorption capacities of up to 3.7 mmol g-1, and outstanding CO 2-N2 selectivities of up to 14.4 from single component gas data. Nonetheless, the CO2-N2 selectivity in the Henry law regime-representative of post-combustion flue-gas streams-of some of our carbons was particularly remarkable (e.g. 96), comparable to or even higher than those described for most recent carbons, and only surpassed by those of certain zeolites. This journal is © the Partner Organisations 2014., This work was supported by MINECO (MAT2009-10214, MAT2011-25329, CTM2011-23378, and MAT2012-34811). DC thanks CSIC for a JAE-Doc postdoctoral contract co-funded by the European Social Fund. JP thanks MINECO for a FPI fellowship.