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The reaction kinetics of CO2 methanation over a highly active 8.5% Ni/CeO2 catalyst was determined in a fixed-bed reactor, in the absence of heat- and mass-transfer limitations. Once the catalyst activity was stabilized, more than 120 kinetic experiments (with varying values of reaction temperature, total pressure, space velocity (GHSV), and partial pressure of products and reactants) were performed. From initial reaction rates, an apparent activation energy of 103.9 kJ mol–1 was determined, as well as the effect of reactants (positive) and water partial pressures (negative) on CO2 methanation rate. Three mechanistic models reported in the literature, in which CO2 is adsorbed dissociatively (carbon and formyl routes) or directly (formate route), were explored for modeling the entire reaction kinetics. For that, the corresponding rate equations were developed through the Langmuir–Hinshelwood–Hougen–Watson (LHHW) approach. In agreement with DRIFTS experiments, formate route, in which the hydrogenation of bicarbonate to formate is considered to be the rate-determining step, reflects the kinetic data accurately, operating from differential conversion to thermodynamic equilibrium. In fact, this mechanism results in a mean deviation (D) of 10.38%. Based on previous own mechanistic studies, the participation of two different active sites has been also considered. Formate route on two active sites maintains a high fitting quality of experimental data, providing kinetics parameters with a higher physical significance. Thus, the LHHW mechanism, in which Ni0 sites as well as oxygen vacant near to Ni-CeO2 interface participate in CO2 methanation, is able to predict the kinetics of Ni/CeO2 catalyst accurately for a wide range of operational conditions. Support for this study was provided by the Spanish Ministry of Science and Innovation (Project Nos. PID2019-105960RB-C21 and PID2019-105960RB-C22) and the Basque Government (Project No. IT1297-19). J.A.O.-C. acknowledges the Postdoctoral research grant (No. DOCREC20/49) provided by the University of the Basque Country. A.Q. also acknowledges University of the Basque Country for his Ph.D. grant (No. PIF-15/351).

Solid polymer electrolytes (SPEs) could play a major role in the transition to safer and high-energy-density potassium-based batteries. However, most polymeric K-ion electrolytes are based on fluorine-containing anions and flammable organic solvents, whose safety is nowadays in question. Herein, we report a facile solvent-free synthesis of a series of several poly(ethylene oxide) (PEO)-based SPE solid solutions with KBPhsalt as potassium-ion source, including the formation of two crystalline (PEO)/KBPhcomplexes. The ionic conductivity of these novel K-ion SPEs above and below the melting point of PEO is rationalized in light of their glass-transition temperature and chemical composition. We highlight that below the melting point of PEO, the crystalline complexes may not be intrinsically ionically conducting, but they act as ion sinks preventing the polymer cross-linking and the formation of contact ion pairs and lower the glass-transition temperature leading to a conductivity of 1.1 × 10S cmat 55 °C. A high ionic conductivity of 1.8 × 10S cmis achieved at 80 °C for the optimum (PEO)/KBPhcomposition (3.2 mol % KBPh). Besides, the SPE compositions were found to be stable up to 4 V vs Kmetal electrode at 60 °C. The (PEO)/KBPhcomposite electrolyte employed in an all-solid-state symmetric cell with Prussian Blue electrodes showed reversible K-ion (de)intercalation, where a reversible capacity of 20 mAh gand low voltage hysteresis were achieved for 20 cycles. Considering the material availability, ease of synthesis, and promising electrochemical properties, this work may encourage future research on fluorine-free polymer electrolytes for K-ion batteries., The authors acknowledge financial support from the Ministry of Science and Innovation of Spain (ANOKIB; RTI2018-094550-A-I00). J.C.-G. acknowledges support from the Spanish Ministry of Economy, Industry, and Competitiveness (MINECO) through a Ramon y Cajal Fellowship (RYC-2015-17722). O.K. acknowledges support from the Erasmus+ grantthrough Eskisehir Technical University. M.E. acknowledges financial support from the Erasmus+ grant for mobility through the Université de Picardie Jules Verne and the Erasmus Mundus Program “MESC+” of the European Commission

The reverse water–gas shift reaction (RWGS) reaction represents a direct route for CO2 conversion whose selectivity significantly depends on the selected catalyst. In this work, a new family of bimetallic iron–copper oxide catalysts supported on ceria-alumina with various Fe/Cu oxides ratios were investigated for the RWGS reaction. Additionally, bare Fe-based and Bare Cu-based catalysts were synthesized for comparison. Our results demonstrate that the developed bimetallic Fe–Cu catalysts present a remarkable enhancement of catalytic performance when compared to monometallic systems, especially at the so-called “low-temperature range” for RWGS. Characterization results evidence that Cu species undergo different states on the catalytic surface during the reaction, wherein the formed metallic Cu is linked to the catalytic activity via the strength of the interaction with the multioxide phases, such as Fe3O4/CeO2, while the copper-dopped ceria could contribute to the promotion of CO selectivity. Besides, we identify that the Fe/Cu oxides mass ratio of 0.25/0.75 is an optimal formulation rendering highly commendable CO2 conversion levels at 450 °C with excellent selectivity and stability for long-term runs. Very importantly, without preactivation, our multicomponent materials still display an optimum performance which have a potential realistic application from cost perspective than other Cu-based catalysts. Overall, this work showcases a strategy to design highly effective multicomponent Fe–Cu catalysts for CO2 conversion via RWGS. Financial support for this work was also provided by the EPSRC grant EP/R512904/1 as well as the Royal Society Research Grant RSGR1180353. Furthermore, this work was also partially sponsored by the CO2Chem UK through the EPSRC grant EP/P026435/1.

Cryptomelane is an abundant mineral manganese oxide with unique physicochemical features. This work investigates the real capabilities of cryptomelane as an oxidation catalyst. In particular, the preferential CO oxidation (CO-PROX), has been studied as a simple reaction model. When doped with copper, the cryptomelane-based material has revealed a great potential, displaying a comparable activity to the high-performance CuO/CeO2. Despite stability concerns that compromise the primary catalyst reusability, CuO/cryptomelane is particularly robust in the presence of CO2 and H2O, typical components of realistic CO-PROX streams. The CO-PROX reaction mechanism has been assessed by means of isotopic oxygen pulse experiments. Altogether, CuO/CeO2 shows a greater oxygen lability, which facilitates lattice oxygen enrolment in the CO-PROX mechanism. In the case of CuO/cryptomelane, in spite of its lower oxygen mobility, the intrinsic structural water co-assists as active oxygen species involved in CO-PROX. Thus, the presence of moisture in the reaction stream turns out to be beneficial for the stability of the cryptomelane structure, besides aiding into the active oxygen restitution in the catalyst. Overall, this study proves that CuO/cryptomelane is a promising competitor to CuO/CeO2 in CO-PROX technology, whose implementation can bring the CO-PROX technology and H2 purification processes a more sustainable nature. The authors thank the financial support of the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-67597-C2-2-R and grant FJCI-2015-23769), the Spanish Ministry of Science and Innovation (PID2019-105960RB-C22), Spanish Ministry of Education (FPU14/01178), Generalitat Valenciana (Project PROMETEO/2018/076), and the EU (FEDER funding).

The evaluation of the flexibility in zeolitic imidazolate frameworks (ZIFs) has been very useful to understand their performance in gas adsorption and separation applications. Here, we have evaluated the adsorption properties of a nanoporous mixed-linker ZIF-62 using a combination of gas adsorption measurements, grand canonical Monte Carlo simulations, and synchrotron X-ray powder diffraction under operando conditions. While adsorption studies in nanoporous ZIF-62 at 77 K and atmospheric pressure predict a large O2/N2 separation ability, computational studies anticipate that the observed differences must be attributed to kinetic restrictions of N2 to access the internal porosity at cryogenic temperatures. Interestingly, upon a small increase in the adsorption temperature (90 K vs 77 K), both N2 and O2 are able to access the inner porous structure through the promotion of a phase transition (ca. 3.8% volume expansion) upon gas adsorption. This narrow phase (np) to expanded phase (ep) structural transition in ZIF-62 is completely suppressed above 150 K. Based on the excellent molecular sieve properties of nanoporous ZIF-62 for O2/N2 at cryogenic temperatures, we extended our study to the adsorption of linear and branched hydrocarbons. This study predicts the preferential adsorption of alkanes over alkenes in ZIF-62 for small hydrocarbons (C2), while in the case of C3 hydrocarbons and above, the adsorption process is mainly defined by kinetic restrictions. J.S.-A. acknowledges financial support from the MINECO (Projects MAT2016-80285-p and PID2019-108453GB-C21). The authors acknowledge ALBA for providing beamtime (Project No. 2019023264). Computational work was supported by the Cambridge High-Performance Computing Service, the Cambridge Service for Data-Driven Discovery (CSD3).

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.0c08942., L.H.W. acknowledges the Fonds Wetenschappelijk Onderzoek (FWO) - Vlaanderen for a senior postdoctoral research fellowship and International Mobility fellowship under contract numbers of 12M1418N and V402319N, respectively. S.V.D.B., S.M.J.R., and J.W. acknowledge Fonds Wetenschappelijk Onderzoek (FWO) - Vlaanderen for Grants 11U1914N, 12T3519N, and 1103618N as well as the Research Board of Ghent University (BOF). J.A.R.N. acknowledges generous funding from the Spanish Ministry of Economy (CTQ2014- 53486-R) and FEDER from the European Union. Funding was also received from the European Union’s Horizon 2020 Research and Innovation Programme [ERC Consolidator Grant Agreement 647755 - DYNPOR (2015−2020)]. J.A.M. and C.E.A.K. gratefully acknowledge financial support from the Flemish Government (Long-term structural funding Methusalem and FWO support). Collaboration among universities was supported by the Belgian Government (IAP-PAI network)., Molecular separation of carbon dioxide (CO2) and methane (CH4) is of growing interest for biogas upgrading, carbon capture and utilization, methane synthesis and for purification of natural gas. Here, we report a new zeolitic-imidazolate framework (ZIF), coined COK-17, with exceptionally high affinity for the adsorption of CO2 by London dispersion forces, mediated by chlorine substituents of the imidazolate linkers. COK-17 is a new type of flexible zeolitic-imidazolate framework Zn(4,5-dichloroimidazolate)(2) with the SOD framework topology. Below 200 K it displays a metastable closed-pore phase next to its stable open-pore phase. At temperatures above 200 K, COK-17 always adopts its open-pore structure, providing unique adsorption sites for selective CO2 adsorption and packing through van der Waals interactions with the chlorine groups, lining the walls of the micropores. Localization of the adsorbed CO2 molecules by Rietveld refinement of X-ray diffraction data and periodic density functional theory calculations revealed the presence and nature of different adsorption sites. In agreement with experimental data, grand canonical Monte Carlo simulations of adsorption isotherms of CO2 and CH4 in COK-17 confirmed the role of the chlorine functions of the linkers and demonstrated the superiority of COK-17 compared to other adsorbents such as ZIF-8 and ZIF-71., FWO 12M1418N V402319N 11U1914N 12T3519N 1103618N, Spanish Ministry of Economy CTQ201453486-R, FEDER from the European Union, European Union's Horizon 2020 Research and Innovation Programme [ERC] 647755 - DYNPOR, Flemish Government (Long-term structural funding Methusalem), FWO, Belgian Government (IAP-PAI network)

This study addresses the yet unresolved CO2 methanation mechanism on a Ru/CeO2 catalyst by means of near-ambient-pressure X-ray photoelectron spectroscopy (NAP–XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) complemented with periodic density functional theory (DFT) calculations. NAP–XPS results show that the switch from H2 to CO2 + H2 mixture oxidizes both the Ru and CeO2 phases at low temperatures, which is explained by the CO2 adsorption modes assessed by means of DFT on each representative surface. CO2 adsorption on Ru is dissociative and moderately endergonic, leading to polybonded Ru-carbonyl groups whose hydrogenation is the rate-determining step in the overall process. Unlike on Ru metal, CO2 can be strongly adsorbed as carbonates on ceria surface oxygen sites or on the reduced ceria at oxygen vacancies as carboxylates (CO2–δ), resulting in the reoxidation of ceria. Carboxylates can then evolve as CO, which is released either via direct splitting at relatively low temperatures or through stable formate species at higher temperatures. DRIFTS confirm the great stability of formates, whose depletion relates with CO2 conversion in the reaction cell, while carbonates remain on the surface up to higher temperatures. CO generation on ceria serves as an additional reservoir of Ru-carbonyls, cooperating to the overall CO2 methanation process. Altogether, this study highlights the noninnocent role of the ceria support in the performance of Ru/CeO2 toward CO2 methanation. The authors thank the financial support of the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-67597-C2-2-R and grant FJCI-2015-23769), the Spanish Ministry of Science and Innovation (PID2019-105960RB-C22), Generalitat Valenciana (Project PROMETEO/2018/076), and the EU (FEDER funding). A.D.-Q. and M.G.-M. acknowledge the financial support from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 713567 and Science Foundation Ireland Research Centre award 12/RC/2278_P2. F.C.H. acknowledges the Argentinian National Research Council (CONICET) for the financial support. C.E. acknowledges funding from the MICINN/FEDER RTI2018-093996-B-32 project. The computational results of this research have been achieved using the DECI resource Salomon based in the Czech Republic at the IT4Innovations National Supercomputing Center with support from the PRACE aisbl. The DJEI/DES/SFI/HEA Irish Centre for High-End Computing (ICHEC) is also acknowledged for the provision of computational facilities.

7 pags., 3 figs., 1 tab., Phasing agents enabling de novo protein structure determination at ca. 1 Å, the wavelength corresponding to the maximum intensity of the synchrotron facilities applied in biomacromolecular crystallography, have been long sought-after. The first phasing agent designed for solving native protein structures at 0.97934 Å is described herein. The agent consists of a neutral ytterbium(III)-caged complex that exhibits higher anomalous signals at shorter wavelengths when compared to the best, currently applied lanthanide-based phasing agents, all of them based on gadolinium or terbium. As a proof of principle, the complex allows determining the 3D structure of a 36 kDa protein without setting the incident beam wavelength at the metal absorption edge, the strategy followed to date to gain the strongest anomalous signal even at the expense of crystallographic resolution. The agent becomes nondisruptive to the diffraction quality of the marked crystals and allows determining accurate phases, both leading to high-quality electron-density maps that enable the full tracing of the protein structure only with one agent unit bound to the protein. The high phasing power, efficient binding to the protein, low metal-macromolecule ratio, and easy handling support the developed Yb(III) complex as the best phasing agent for X-ray crystallography of a complex biomacromolecule without using modified analogues., Financial support from Spanish Ministry of Science and Innovation (MAT2017-83856-C3-1 and C3-2, BFU2017- 90030-P, PID2020-114755GB-C3 and PID2020-115331GBI00 grants) is gratefully acknowledged. Technical support provided by staff at the ALBA Synchrotron facility (Barcelona, Spain) is also acknowledged. A.P.-C. thanks Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid, and Fondo Social Europeo for a predoctoral contract (CT2/ 17/CT3/17/PEJ16/MED/AI-1598).

Three-dimensional (3D)-printed catalysts are being increasingly studied; however, most of these studies focus on the obtention of catalytically active monoliths, and thus traditional channeled monolithic catalysts are usually obtained and tested, losing sight of the advantages that 3D-printing could entail. This work goes one step further, and an advanced monolith with specifically designed geometry has been obtained, taking advantage of the versatility provided by 3D-printing. As a proof of concept, nonchanneled advanced monolithic (NCM) support, composed of several transversal discs containing deposits for active phase deposition and slits through which the gas circulates, was obtained and tested in the CO-PrOx reaction. The results evidenced that the NCM support showed superior catalytic performance compared to conventional channeled monoliths (CMs). The region of temperature in which the active phase can work under chemical control, and thus in a more efficient way, is increased by 31% in NCM compared to the powdered or the CM sample. Turbulence occurs inside the fluid path through the NCM, which enhances the mass transfer of reagents and products toward and from the active sites to the fluid bulk favoring the chemical reaction rate. The nonchanneled monolith also improved heat dispersion by the tortuous paths, reducing the local temperature at the active site. Thus, the way in which reactants and products are transported inside the monoliths plays a crucial role, and this is affected by the inner geometry of the monoliths. The authors are grateful for the financial support of the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-67597-C2-2-R), The University of Alicante (Project GRE18-01A), Generalitat Valenciana (Project PROMETEO/2018/076, Ph.D. grant GRISOLIAP/2017/177, and contract APOSTD/2019/030), Junta de Andalucía (Project P18-RTJ-2974), and the UE (FEDER funding).

Excellent Pd supported on carbon catalysts for the dehydrogenation of formic acid were synthesized from a lignocellulosic biomass residue. The preparation of the carbon support consisted of a H3PO4-assisted hydrothermal carbonization (HTC) and activation of a hemp residue and subsequent nitrogen functionalization. It was observed that the presence of nitrogen groups influenced both the size and the electronic properties of the Pd nanoparticles, which ultimately affected their catalytic properties. Furthermore, the catalytic performance also depended on the synthesis conditions used in the preparation of the catalysts (i.e., reduction of the Pd nanoparticles with NaBH4 prior to the catalytic test or in situ reduction). The best-performance catalysts (Pd/N-HTC (n.r.)), which were prepared by in situ reduction of the nanoparticles, displayed a remarkable catalytic activity with a very high TOF number of 8365 h–1 (TOF value calculated for the 2nd catalytic run and expressed per surface Pd atom) and outstanding stability during 6 consecutive reaction cycles, although the initial activity is maintained for 12 cycles. The catalytic system studied is among the most stable ever reported Pd-based heterogeneous catalysts for the dehydrogenation of formic acid. This work was financed by the MICINN, FEDER (RTI2018-095291-B-I00). J.C.-G. acknowledges her predoctoral scholarship (GRISOLIA/2018/105) funded by the Generalitat Valenciana. M.N.-G. thanks the Plan GenT project (CDEIGENT/2018/027) for the financial support. D.S.-T. thanks the MICINN for the “Juan de la Cierva” contract (IJCI-2016-27636).

A large number of inorganic and organic materials have been postulated to grow via nonclassical pathways involving the assembly of amorphous precursors that serve as growth units for crystallization. Elucidating the assembly, microstructure, and mechanism(s) by which precursors are involved in processes of nucleation and growth is nontrivial because of the lack of available techniques that are capable of monitoring amorphous-to-crystal transformations with sufficient spatiotemporal resolution. Here we propose an elemental mapping method employing field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FE-SEM-EDX) as a versatile tool to characterize morphological and compositional properties of precursors during the crystallization of five zeolites (MER, MFI, MOR, TON, and LTL) that are used in commercial applications that include (but are not limited to) catalysis, ion exchange, separations, drug delivery, and adsorption. Time-resolved ex situ elemental mapping images of extracted solids during several stages of zeolite crystallization reveal that a sufficient disparity in the chemical composition (e.g., alkali metal content) between amorphous precursors and crystals can be exploited for (i) tracking the early stages of zeolite crystallization, (ii) locating where it happens, and (iii) resolving residual amorphous material among crystalline domains. In this study, we also show that FE-SEM-EDX elemental mapping is a highly sensitive technique to detect the onset of nucleation, the completion of crystallization, and the existence of impurities. Given the ubiquitous presence of amorphous precursors during nonclassical crystallization, we expect that elemental mapping may prove valuable for understanding and tracking the growth of other zeolites, minerals, and related materials. J.D.R. acknowledges funding from the Welch Foundation (Award E-1794). J.G.M. and N.L. acknowledge funding from the Spanish Ministry of Science and Innovation (RTI2018-099504-B-C21). N.L. acknowledges funding from the University of Alicante (UATALENTO17-05).

The effect of the three-dimensionally ordered macroporous (3DOM) structure and the Ni doping of CeO2 on the physicochemical properties and catalytic activity for soot combustion was studied. Moreover, the way in which Ni is introduced to the ceria support was also investigated. For this, CeO2 supports were synthesized with uncontrolled (Ref) and 3DOM-structured morphology, and their respective Ni/CeO2 catalysts were prepared by impregnation of the previously synthesized supports or by successive impregnation of both precursors (Ni and Ce) on the 3DOM template. Conclusions reached in this study are: (1) the 3DOM structure increases the surface area of the catalysts and improves the catalyst–soot contact. (2) The doping of CeO2 with Ni improves the catalytic activity because the NiO participates in the catalytic oxidation of NO to NO2, and also favors the production of active oxygen and the catalyst oxygen storage capacity. (3) Ni incorporation method affects its physicochemical and catalytic properties. By introducing Ni by successive infiltration in the solid template, the CeO2 crystal size is reduced, Ni dispersion is improved, and the catalyst reducibility is increased. All of these characteristics make the catalyst synthesized by successive infiltration to have higher catalytic activity for soot combustion than the Ni-impregnated CeO2 catalyst. The authors thank the financial support from the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-67597-C2-2-R and Grant FJCI-2015-23769), the Spanish Ministry of Education, Culture and Sports (Grant FPU14/01178), Generalitat Valenciana (Project PROMETEO/2018/076), and the UE (FEDER funding).

Porous metal–organic frameworks (MOFs) capable of storing a relatively high amount of dry methane (CH4) in the adsorbed phase are largely explored; however, solid CH4 storage in confined pores of MOFs in the form of hydrates is yet to be discovered. Here we report a rational approach to form CH4 hydrates by taking advantage of the optimal pore confinement in relatively narrow cavities of hydrolytically stable MOFs. Unprecedentedly, we were able to isolate methane hydrate (MH) nanocrystals with an sI structure encapsulated inside MOF pores with an optimal cavity dimension. It was found that confined nanocrystals require cavities slightly larger than the unit cell crystal size of MHs (1.2 nm), as exemplified in the experimental case study performed on Cr-soc-MOF-1 vs smaller cavities of Y-shp-MOF-5. Under these conditions, the excess amount of methane stored in the pores of Cr-soc-MOF-1 in the form of MH was found to be ≈50% larger than the corresponding dry adsorbed amount at 10 MPa. More importantly, the pressure gradient driving the CH4 storage/delivery process could be drastically reduced compared to the conventional CH4-adsorbed phase storage on the dry Cr-soc-MOF-1 (≤3 MPa vs 10 MPa). G.M., M.E., and Y.B. thank the Aramco sponsored research fund (contract. 66600024505). We would like also to acknowledge the support by King Abdullah University of Science and Technology. J.S.A. would like to acknowledge financial support from the MINECO (MAT2016-80285-p), Generalitat Valenciana (PROMETEOII/2014/004), Oak Ridge beam time availability (Project IPTS-20859.1), and Spanish ALBA synchrotron (Project 2020014008). INS experiments were conducted at the VISION beamline (IPTS-20859) at the Spallation Neutron Source, Oak Ridge National Laboratory (ORNL), which is supported by the Scientific User Facilities Division, Office of Basic Energy Sciences (BES), U.S. Department of Energy (DOE), under contract no. DE-AC0500OR22725 with UT Battelle, LLC. The computing resources were made available through the VirtuES and the ICE-MAN projects, funded by the Laboratory Directed Research and Development programme and by Compute and Data Environment for Science (CADES) at ORNL.

Cationic fac-[Re(CO)3(pz*H)(pypzH)]OTf (pz*H = pyrazole, pzH; 3,5-dimethylpyrazole, dmpzH; indazole, indzH; 3-(2-pyridyl)pyrazole, pypzH) were obtained from fac-[ReBr(CO)3(pypzH)] by halide abstraction with AgOTf and subsequent addition of the corresponding pyrazole. Successive deprotonation with Na2CO3 and NaOH gave neutral fac-[Re(CO)3(pz*H)(pypz)] and anionic Na{fac-[Re(CO)3(pz*)(pypz)]} complexes, respectively. Cationic fac-[Re(CO)3(pz*H)(pypzH)]OTf, neutral complexes fac-[Re(CO)3(pz*H)(pypz)], and fac-[Re(CO)3(pypz)2Na] were subjected to photophysical and electrochemical studies. They exhibit phosphorescent decays from a prevalently 3MLCT excited state with quantum yields (Φ) in the range between 0.03 and 0.58 and long lifetimes (τ from 220 to 869 ns). The electrochemical behavior in Ar atmosphere of cationic and neutral complexes indicates that the oxidation processes assigned to ReI → ReII occurs at lower potentials for the neutral complex compared to cationic complex. The reduction processes occur at the ligands and do not depend on the charge of the complexes. The electrochemical behavior in CO2 saturated media is consistent with CO2 electrocatalyzed reduction, where the values of the catalytic activity [icat(CO2)/icat(Ar)] ranged from 2.7 to 11.5 (compared to 8.1 for fac-[Re(CO)3Cl(bipy)] studied as a reference). Controlled potential electrolysis for the pyrazole cationic (3a) and neutral (4a) complexes after 1 h affords CO in faraday yields of 61 and 89%, respectively. These values are higher for indazole complexes and may be related to the acidity of the coordinated pyrazole., Spanish MINECO, Spain (PGC2018-099470–B-I00) and Junta de Castilla y León (VA130618), and the authors in Burgos gratefully acknowledge financial support from the Junta de Castilla y León, Consejería de Educación y Cultura y Fondo Social Europeo (Project BU263P18). E.C. thanks the UVa for her grant. We also thank the ICIQ Foundation, AGAUR 2017-SGR-1647 (J.L.-F.) and the Spanish MINECO (CTQ2016-80038-R; J.L-F.), and the Spanish Ministry of Science is acknowledged for a FPU fellowship to S.F.

The preferential CO oxidation (CO-PROX) reaction is paramount for the purification of reformate H2-rich streams, where CuO/CeO2 catalysts show promising opportunities. This work sheds light on the lattice oxygen recovery mechanism on CuO/CeO2 catalysts during CO-PROX reaction, which is critical to guarantee both good activity and selectivity, but that is yet to be well understood. Particularly, in situ Raman spectroscopy reveals that oxygen vacancies in the ceria lattice do not form in significant amounts until advanced reaction degrees, whereas pulse O2 isotopic tests confirm the involvement of catalyst oxygen in the CO and H2 oxidation processes occurring at all stages of the CO-PROX reaction (Mars–van Krevelen). Further mechanistic insights are provided by operando near-ambient pressure X-ray photoelectron spectroscopy (NAP–XPS) and near edge X-ray absorption fine structure (NEXAFS) experiments, which prove the gradual CuO reduction and steady oxidized state of Ce ions until the very surface reduction of CeO2 at the point of selectivity loss. Experiments are complemented by density functional theory (DFT) calculations, which reveal a more facile oxygen refill according to the trend CuO > CeO2 > Cu2O. Overall, this work concludes that the oxygen recovery mechanism in CO-PROX switches from a direct mechanism, wherein oxygen restores vacancy sites in the partially reduced CuO particles, to a synergistic mechanism with the participation of ceria once CuxO particles reach a critical reduction state. This mechanistic switch ultimately results in a decrease in CO conversion in favor of the undesired H2 oxidation, which opens-up future research on potential strategies to improve oxygen recovery. The authors thank the financial support of the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-67597-C2-2-R and grant FJCI-2015-23769), the Spanish Ministry of Education, Culture and Sports (grant FPU14/01178), the Generalitat Valenciana (Project PROMETEO/2018/076) and the EU (FEDER funding). F.C.H. acknowledges the Argentinian National Research Council (CONICET) for financial support.

The design of multifunctional materials is a current demand for high-end technological applications that need to combine different functions unable to be accomplished by a single material. The aim of this work is to present, at first glance, a new family of recently patented multifunctional porous materials developed by locating granular phases with specific functionality (guests) within the cavities of open-pore cellular materials (hosts) and, at second glance, the use of a set of these materials for the preconcentration and management of volatile organic compounds (VOCs). These materials (herein known as Guefoams, acronym for Guest-containing foams), present host foams and guest phases that are not bonded and therefore allow fluids to pass through. The processing method is the gas pressure infiltration of a host precursor into preforms containing particulate guest phases covered by a NaCl martyr coating, which is later dissolved in water. The manuscript shows the manufacture and characterization of a specific set of Guefoams composed of aluminum foams that incorporate both steel particles and activated carbon particles as guest phases into the same material. These guest phases make the materials highly adsorbent and susceptible to rapid desorption by magnetic induction, two properties never achieved with traditional foams that transform these materials into perfect candidates for preconcentration and energy-efficient management of VOCs. The manuscript concludes with a discussion on advisible properties to consider when exploring the use of these materials in the mentioned applications. The author acknowledges financial support from the Spanish “Agencia Estatal de Investigación” (AEI) and European Union (FEDER funds) through grant MAT2016-77742-C2-2-P.

In this work, we reported the preparation of composites based on titania (TiO2) and Zeolite Socony Mobil-5 (ZSM-5) nanozeolite, following two approaches (i.e., incorporating the presynthesized zeolite in the synthesis medium of TiO2 and incorporating presynthesized TiO2 in the synthesis medium of ZSM-5). The materials synthesized were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), nitrogen adsorption, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible spectroscopy (UV–vis), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectrometry analysis, and their photocatalytic activities were assessed in the oxidation of propene in the gas phase. It was observed that the synthesis methodology affects the final properties of the composite, which ultimately affected their photocatalytic performance in the studied application. It was found that the Nano-ZSM5/TiO2 composite was the most active among the investigated samples, which was attributed to the intimate contact between the two components of the composite, the preserved properties of the photocatalytic active phase in the final material, and the positive contribution of the nanozeolite by increasing the local concentration of propene. The authors thank Ministerio de Ciencia Innovación y Universidades and FEDER (Project RTI2018-095291-B-I00) and the Generalitat Valenciana (PROMETEOII/2018/076) for financial support. J.F.-C. thanks MINECO for a researcher formation grant (BES-2016-078079). M.N.-G. gratefully acknowledges Generalitat Valenciana and Plan GenT (CDEIGENT/2018/027) for the postdoctoral grant.

New cis-(1,2-azole)-aquo bis(2,2′-bipyridyl)ruthenium(II) (1,2-azole (az*H) = pzH (pyrazole), dmpzH (3,5-dimethylpyrazole), and indzH (indazole)) complexes are synthesized via chlorido abstraction from cis-[Ru(bipy)2Cl(az*H)]OTf. The latter are obtained from cis-[Ru(bipy)2Cl2] after the subsequent coordination of the 1,2-azole. All the compounds are characterized by 1H, 13C, 15N NMR spectroscopy as well as IR spectroscopy. Two chlorido complexes (pzH and indzH) and two aquo complexes (indzH and dmpzH) are also characterized by X-ray diffraction. Photophysical and electrochemical studies were carried out on all the complexes. The photophysical data support the phosphorescence of the complexes. The electrochemical behavior of all the complexes in an Ar atmosphere indicate that the oxidation processes assigned to Ru(II) → Ru(III) occurs at higher potentials in the aquo complexes. The reduction processes under Ar lead to several waves, indicating that the complexes undergo successive electron-transfer reductions that are centered in the bipy ligands. The first electron reduction is reversible. The electrochemical behavior in CO2 media is consistent with CO2 electrocatalyzed reduction, where the values of the catalytic activity [icat(CO2)/ip(Ar)] ranged from 2.9 to 10.8. Controlled potential electrolysis of the chlorido and aquo complexes affords CO and formic acid, with the latter as the major product after 2 h. Photocatalytic experiments in MeCN with [Ru(bipy)3]Cl2 as the photosensitizer and TEOA as the electron donor, which were irradiated with >300 nm light for 24 h, led to CO and HCOOH as the main reduction products, achieving a combined turnover number (TONCO+HCOO–) as high as 107 for 2c after 24 h of irradiation., Junta de Castilla y León (ref. VA130618). E.C. thanks the UVa for her grant. The authors in Valladolid gratefully acknowledge financial support from the Spanish MINECO, Spain (PGC2018-099470-B-I00) and Junta de Castilla y León (VA130618), and the authors in Burgos gratefully acknowledge financial support from the Junta de Castilla y León, Consejería de Educación y Cultura and Fondo Social Europeo (Project BU263P18). A.M.A.-B. is grateful for support from the National Science Foundation CAREER Grant (CHE-1652606).

The design of advanced N-doped carbon materials towards oxygen reduction reaction (ORR) catalysis is only possible if the nature of the active sites is fully understood. There is an important piece of research seeking to overcome this challenge through experimental or theoretical results. However, the combination of both approaches is necessary to deepen the knowledge about this subject. This work presents excellent agreement between experimental results and computational models, which provides evidence of the nature of the most active sites in N-doped carbon materials. N-doped carbon materials have been experimentally obtained through double stage treatment of polyaniline in distinct atmospheres (both oxygen-containing and inert atmospheres) at different temperatures (800–1200 °C). According to temperature programmed desorption (TPD), Raman spectroscopy, N2-adsorption isotherms at −196 °C and X-ray photoelectron spectroscopy (XPS), this synthesis method results in the selective formation of nitrogen species, without significant changes in structural order or porosity. ORR catalytic tests evidence the highly efficient catalysis, with platinum-like performance in terms of the current density and onset potential, of N-doped carbon materials selectively containing graphitic-type nitrogen species. Computational chemistry, through DFT calculations, shows that edge-type graphitic nitrogen is more effective towards ORR catalysis than pyridinic, pyrrolic, pyridonic, oxidized and basal-type graphitic nitrogen species. The authors thank Ministerio de Ciencia, Innovación y Universidades and FEDER for financial support (Project RTI2018-095291-B-I00, ENE2017-90932-REDT and FIS2015-64222-C2-2-P). MMF acknowledges support from the Portuguese Foundation for Science and Technology (FCT), under the projects IF/00894/2015, and FCT Ref. UID/CTM/50011/2019 for CICECO - Aveiro Institute of Materials.

This work showcases an innovative route for biocompound upgrading via hydrodeoxygenation (HDO) reactions, eliminating the need for external high-pressure hydrogen supply. We propose the use of water as reaction media and the utilization of multifunctional catalysts that are able to conduct multiple steps such as water activation and HDO. In this study, we validate our hypothesis in a high-pressure batch reactor process using guaiacol as a model compound and multicomponent Ni-based catalysts. In particular, a comparison between ceria-supported and carbon/ceria-supported samples is established, the carbon-based materials being the suitable choice for this reaction. The physicochemical study by X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray diffraction, and temperature-programmed reduction reveals the greater dispersion of Ni clusters and the strong metal-support interaction in the carbon/ceria-based samples accounting for the enhanced performance. In addition, the characterization of the spent samples points out the resistance of our catalysts toward sintering and coking. Overall, the novel catalytic approach proposed in this paper opens new research possibilities to achieve low-cost bio-oil upgrading processes. Financial support for this work was provided by the Department of Chemical and Process Engineering of the University of Surrey and the EPSRC grants EP/J020184/2 and EP/R512904/1 as well as the Royal Society Research grant RSGR1180353. Authors would also like to acknowledge the Ministerio de Economía, Industrial Competitividad of Spain (project MAT2016-80285-P) and the Chinese Scholarship Council (CSC). L.P.-P. also thanks Comunitat Valenciana for her postdoctoral fellow APOSTD2017.

[EN] Silica mesoporous microparticles loaded with both rhodamine B fluorophore (S1) or hydrocortisone (S2), and capped with an olsalazine derivative, are prepared and fully characterized. Suspensions of Si and S2 in water at an acidic and a neutral pH show negligible dye/drug release, yet a notable delivery took place when the reducing agent sodium dithionite is added because of hydrolysis of an azo bond in the capping ensemble. Additionally, olsalazine fragmentation induced 5-aminosalicylic acid (5-ASA) release. In vitro digestion models show that S1 and S2 solids are suitable systems to specifically release a pharmaceutical agent in the colon. In vivo pharmacokinetic studies in rats show a preferential rhodamine B release from Si in the colon. Moreover, a model of ulcerative colitis is induced in rats by oral administration of 2,4,6-trinitrobenzenesulfonic acid (TNBS) solutions, which was also used to prove the efficacy of S2 for colitis treatment. The specific delivery of hydrocortisone and 5-ASA from S2 material to the colon tissue in injured rats markedly lowers the colon/body weight ratio and the clinical activity score. Histological studies showed a remarkable reduction in inflammation, as well as an intensive regeneration of the affected tissues., We thank the Generalitat Valenciana (Project PROMETE02018/024) and the Spanish Government (Projects AGL2015-70235-C2-2-R and MAT2015-64139-C4-1-R (MINECO/FEDER)) for support. A.H.T. thanks the Spanish MEC for his FPU fellowship. The authors also thank the support of the Electron Microscopy Service at the UPV. The SCSIE (of the Universitat de Valencia) is also gratefully acknowledged for all the equipment used. NMR spectra were measured at the U26 facility of ICTS "NANBIOSIS" at the Universitat de Valencia.

The treatment of zeolites with surfactants in alkaline media is an effective and versatile technique to impart intracrystalline well-defined mesoporosity in these materials. In this study, the dynamics of surface reconstruction that occurs during the treatment of USY zeolite by surfactant-templating was monitored in situ by atomic force microscopy. The development of surfactant-templated mesoporosity and the concurrent healing of defects that are characteristic of steamed zeolites occur in less than 1 h at room temperature, which emphasizes the low energy barriers needed to reorganize the crystalline structure of this zeolite. This transformation was also followed by X-ray diffraction, N2 adsorption, and transmission electron microscopy analysis of ultramicrotomed samples to confirm that the rapid formation of surfactant-templated mesoporosity and the reconstruction of the zeolite crystals occur not only on the surface of the zeolite but also homogeneously throughout the whole zeolite. This process involves a significant and rapid breaking and re-formation of bonds; however, the zeolite does not dissolve during this process as solid recovery at any given time of the treatment is approximately 100% and the concentration of soluble Si or Al species in the liquid is negligible. Parametric analysis revealed that excessive NaOH leads to the partial transformation of zeolite into an amorphous mesoporous solid, while insufficient quantity of base and/or treatment time can lead to an incomplete mesostructuring of the zeolite, which highlights the importance of judiciously selecting the treatment conditions for every given zeolite. N.L. acknowledges funding from the University of Alicante, through the “Programa de retención y captación de talento” (ref. UATALENTO17-05). J.D.R. acknowledges funding from the Welch Foundation (Award E-1794).

Materials able to produce the reduction of nitrate from water without the need of a metal catalyst and with avoiding the use of gaseous hydrogen have been developed by combining the synergistic properties of titania and two conducting polymers. Polymerization of aniline and pyrrol on titanium dioxide in the presence of two different oxidants/dopants (iron trichloride or potassium persulfate) has been evaluated. The resulting hybrid materials have good thermal stability imparted by the titania counterpart, and a considerable conductivity provided by the conducting polymers. The capability of the hybrid materials of reducing aqueous nitrate has been assessed and compared to the catalytic hydrogenation of nitrate using a platinum catalyst supported on these hybrid synthesized materials. The mechanism of nitrate abatement implies adsorption of nitrate on the polymer by ion exchange with the dopant anion, followed by the reduction of nitrate. The electron transfer from titania to the conducting polymer in the hybrid material favors the reductive ability of the polymer, in such a way that nitrate is selectively reduced with a very low production of undesirable side products. The obtained results show that the activity and selectivity of the catalytic reduction of nitrate with dihydrogen in the presence of a platinum catalyst supported on the hybrid materials are considerably lower than those of the metal-free nanocomposites. Financial support from Generalitat Valenciana, Spain (PROMETEOII/2014/004) and Ministry of Economy and Competitivity (MAT2016-80285-P) is gratefully acknowledged. E.S. acknowledges the Spanish MINECO and AEI/FEDER (ref CTQ2015-74494-JIN) and the University of Alicante (ref UATALENTO16-03).

The microporous nature of monodisperse Stöber silica spheres is demonstrated in the literature, although usually via indirect evidence. Contradictorily, there also exist numerous reports of nonporosity based on conventional N2 adsorption isotherms, leading to a confusing scenario and questioning the evaluation methodology. Thus, there is the strong need of straight measure of microporosity in Stöber spheres, at best by available adsorption techniques, which must be further directly confronted with the standard nitrogen method. Here, for the first time, microporosity detection by N2 and CO2 adsorption is compared in Stöber spheres. We demonstrate that CO2 isotherms at 273 K allow direct detection and quantification of the microporosity (about 0.1 cm3/g in our samples), while N2 at 77 K cannot probe adequately the internal volume. We also show that a large amount of water fills the micropores under usual ambient conditions, also revealing the presence of small mesoporosity. Thus, the porous nature of Stöber spheres is investigated by a simple combination of adsorption isotherms, and the different accessibility of N2, CO2, and H2O molecules is discussed. We emphasize the inadequacy of standard N2 isotherms for micropore detection in Stöber silica, as the access of nitrogen molecules at cryogenic temperatures is kinetically restricted and may lead to erroneous conclusions. Instead, we propose CO2 isotherms as a simple and direct means for evaluation of microporosity. This work was funded by Spanish MINECO Projects MAT2014-58731-JIN, MAT2015-68075-R, MAT2016-80285-p, and SIFE2; Comunidad de Madrid Projects S2013/MIT-2740 and PHAMA_2.0; Generalitat Valenciana Project PROMETEOII/2014/004, and Project EU H2020 MSCARISE-2016/NanoMed.

High-resolution, multiple temperature adsorption isotherms of ten adsorptives classified into highly polar (1.7 ± 0.1 D) and nonpolar (0 D) probes with increasing kinetic diameters were measured on a well-characterized poly(furfuryl alcohol)-based microporous carbon. The Clausius–Clapeyron equation was applied to each, resulting in isosteric heats of adsorption. Fluid–fluid interactions, nonspecific fluid–solid interactions, and specific fluid–high energy site interactions were identified and discussed as variables contributing to the total isosteric heat of adsorption. Each isosteric heat was compared against its position relative to adsorption heat by a flat surface, twice this heat, and adsorptive latent heat of condensation. The shape of each curve was analyzed via the contribution of each interaction to the total across the fractional filing range, leading to identification of fillings as Zero Coverage, Low Coverage, and High Coverage. This systematic investigation provided a detailed analysis of the influences of adsorptive size, its conformation, and polarity effects on micropore filling, and tabulation of the analyses gave a clear and comprehensive insight into the adsorption mechanisms. The authors thank the Australian Research Council discovery program (DP110101293) for funding support.

[EN] Biocompatible ZnS-based nanocrystals capped with 4-mercaptophenylboronic acid (ZnS@B) have been size-designed as excellent pH responsive gatekeepers on mesoporous silica nanoparticles (MSNs), which encapsulate fluorophore safranin O (S2-Sap or anticancer drug epirubicin hydrochloride (S2-Epi) for delivery applications in cancer cells. In this novel hybrid system, the gate mechanism consists of reversible pH-sensitive boronate ester moieties linking the nanocrystals directly to the alcohol groups from silica surface scaffold, avoiding tedious intermediate functionalization steps. The similar to 3 nm size of the ZnS@B nanocrystals was tailored to allow efficient sealing of the pore voids and achieve a "zero premature cargo release" at neutral pH (7.4). The system selectively released the cargo in acidic conditions (pH 5.4 and 3.0) because of the hydrolysis of the boronate esters, which unblocked the pore voids. Delivery of the cargo by off-on cycles was demonstrated by changes in pH from 7.4 to 3.0, showing its potential pH-switching behavior. Cellular uptake of these nanocarriers within human cervix adenocarcinoma (HeLa) cells was achieved and the controlled release of the chemotherapeutic drug epirubicin was shown to occur within the endogenous endosomal/lysosomal acidified cancer cell microenvironment and further diffused into the cytosol. Cytotoxicity tests done on the mesoporous support without cargo and covalently linked with ZnS@B nanocrystals as caps were negative, suggesting that the proposed system is biocompatible and can be considered as a very promising drug nanocarrier., The authors acknowledge P. Oberhumer from Centre for Nano- and Surface Analytics (ZONA) for the SEM and TEM measurements; Prof. A. Rastelli from Semiconductor Physics Division, Institute of Semiconductor and Solid State Physics, for helping in the Bohr radius calculations for excitons in ZnS; and the Prof. G. Knor from Institut fur Anorganische Chemie, for the access to the fluorescence spectrometer, all located at Johannes Kepler University Linz. M. Kleindienst is acknowledged for her drawing contribution (Scheme 1,,). R.M.-M. and F.S. express their gratitude to the Spanish government (MAT2015-64139-C4-1-R (MINECO/FEDER)) and the Generalitat Valencia (PROMETEOII/2014/047) for support. A.G-F. is grateful to the Spanish government for an FPU grant.

The assembly and structural evolution of amorphous precursors during zeolite crystallization is an important area of interest owing to their putative roles in the nucleation and growth of aluminosilicate microporous materials. Precursors range in complexity from oligomeric molecules and colloidal particles to gels comprised of heterogeneous silica and alumina domains. The physical state of precursors in most zeolite syntheses is generally not well understood; however, it is evident that the physicochemical properties of precursors depend on a wide range of conditions that include (but are not limited to) the selection of reagents, the composition of growth mixtures, the methods of preparation, and the use of inorganic and/or organic structure-directing agents. The fact that precursors evolve in size, shape, and/or microstructure during the course of nucleation and potentially throughout crystallization leads to questions pertaining to their mode of action in the formation of zeolites. This also highlights the diversity of species that are present in growth media, thus rendering the topic of zeolite synthesis essentially a black box to those attempting to better understand the fundamental role(s) of precursors. In this Article, we discuss the wide variety of precursors encountered in the synthesis of various framework types, emphasizing their complex physical states and the thermodynamic and kinetic factors that govern their heterogeneity. J.D.R. acknowledges financial support from the National Science Foundation (DMREF Award 1629398), the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0014468, and the Welch Foundation (Award E-1794). N.L. acknowledges support from the University of Alicante under the project GRE15-07. Work done at Argonne and use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory, were supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357.

In the present study, 20 wt % K2CO3 was added to coal and coal/biomass blends in a 20:80 wt % ratio and subsequently were heating-treated at 600 °C using CO2 or N2 atmospheres. The reactivity under oxy-combustion conditions (21% O2 + 79% CO2) was studied by thermogravimetry, and characterization of chars was carried out by N2 adsorption, scanning electron microscopy, and Raman and X-ray photoelectron spectroscopy. Higher activation energy for impregnated coal/biomass blends compared to impregnated coal was observed, likewise, for materials thermally treated with CO2. It is demonstrated that CO2 gasification takes place together with O2 combustion under oxy-combustion conditions. Isotopically labeled 13C18O2 was used to confirm the participation of CO2 gasification reactions at 450, 500, 550, and 600 °C in both catalyzed and uncatalyzed systems under O2 + CO2. The catalytic effect of potassium promotes CO2 gasification, and the highest CO (12C18O) desorption was obtained with impregnated samples. It is possible to suggest that CO2 gasification reactions follow different reaction pathways in the presence or absence of potassium. The catalytic gasification reaction proceeded preferentially through a molecular CO2 (13C18O2) adsorption route, while the noncatalyzed systems advanced using a dissociative adsorption pathway. The authors thank the “Departamento Administrativo de Ciencia, Tecnología e Innovación”- COLCIENCIAS (Administrative Department of Science, Technology and Innovation from Colombia) through the program “Research and Innovation on Advanced Combustion in Industrial Use”, code No. 1115-543-31906, contract No. 0852-2012.

When exposed to body fluids, mesoporous bioactive glasses (MBGs) of the CaO-SiO2-P2O5 system develop a bone-bonding surface layer that initially consists of amorphous calcium phosphate (ACP), which transforms into hydroxy-carbonate apatite (HCA) with a very similar composition as bone/dentin mineral. Information from various 1H-based solid-state nuclear magnetic resonance (NMR) experiments was combined to elucidate the evolution of the proton speciations both at the MBG surface and within each ACP/HCA constituent of the biomimetic phosphate layer formed when each of three MBGs with distinct Ca, Si, and P contents was immersed in a simulated body fluid (SBF) for variable periods between 15 min and 30 days. Directly excited magic-angle-spinning (MAS) 1H NMR spectra mainly reflect the MBG component, whose surface is rich in water and silanol (SiOH) moieties. Double-quantum-single-quantum correlation 1H NMR experimentation at fast MAS revealed their interatomic proximities. The comparatively minor H species of each ACP and HCA component were probed selectively by heteronuclear 1H-31P NMR experimentation. The initially prevailing ACP phase comprises H2O and "nonapatitic" HPO42-/PO43- groups, whereas for prolonged MBG soaking over days, a well-progressed ACP → HCA transformation was evidenced by a dominating O1H resonance from HCA. We show that 1H-detected 1H → 31P cross-polarization NMR is markedly more sensitive than utilizing powder X-ray diffraction or 31P NMR for detecting the onset of HCA formation, notably so for P-bearing (M)BGs. In relation to the long-standing controversy as to whether bone mineral comprises ACP and/or forms via an ACP precursor, we discuss a recently accepted structural core-shell picture of both synthetic and biological HCA, highlighting the close relationship between the disordered surface layer and ACP.

In the present study, wood biomass from Acacia mangium and its main components (hemicellulose (xylan), cellulose, and lignin) were blended with a sub-bituminous coal in 20:80 wt % ratio and subsequently were heat-treated at 900 °C using CO2 or N2 atmospheres. The reactivity (ignition temperature and activation energy) under oxy-fuel conditions (21% O2–79% CO2) was studied by thermogravimetry (TGA). It has been observed that adding biomass or its main components to coal improved the combustion efficiency. Coal/biomass and coal/xylan/cellulose/lignin char blends showed lower ignition temperatures when they were devolatilized using CO2 instead of N2. In addition, the activation energies were lower for blends thermally treated with CO2. Differences in reactivity are discussed considering changes in physical-chemical properties characterized by SEM, N2 adsorption at −196 °C, Raman spectroscopy, and XPS. The authors thank the “Departamento Administrativo de Ciencia, Tecnología e Innovación” - COLCIENCIAS (Administrative Department of Science, Technology and Innovation from Colombia) through the program “Research and Innovation on Advanced Combustion in Industrial Use,” code nos. 1115-543-31906 contract 0852-2012. The authors also thank the Universidad de Antioquia, Universidad Nacional de Colombia - Sede Medellín and Universidad de Alicante- Departamento de Química Inorgánica.

Climate change, global warming, urban air pollution, energy supply uncertainty and depletion, and rising costs of conventional energy sources are, among others, potential socioeconomic threats that our community faces today. Transportation is one of the primary sectors contributing to oil consumption and global warming, and natural gas (NG) is considered to be a relatively clean transportation fuel that can significantly improve local air quality, reduce greenhouse-gas emissions, and decrease the energy dependency on oil sources. Internal combustion engines (ignited or compression) require only slight modifications for use with natural gas; rather, the main problem is the relatively short driving distance of natural-gas-powered vehicles due to the lack of an appropriate storage method for the gas, which has a low energy density. The U.S. Department of Energy (DOE) has set some targets for NG storage capacity to obtain a reasonable driving range in automotive applications, ruling out the option of storing methane at cryogenic temperatures. In recent years, both academia and industry have foreseen the storage of natural gas by adsorption (ANG) in porous materials, at relatively low pressures and ambient temperatures, as a solution to this difficult problem. This review presents recent developments in the search for novel porous materials with high methane storage capacities. Within this scenario, both carbon-based materials and metal–organic frameworks are considered to be the most promising materials for natural gas storage, as they exhibit properties such as large surface areas and micropore volumes, that favor a high adsorption capacity for natural gas. Recent advancements, technological issues, advantages, and drawbacks involved in natural gas storage in these two classes of materials are also summarized. Further, an overview of the recent developments and technical challenges in storing natural gas as hydrates in wetted porous carbon materials is also included. Finally, an analysis of design factors and technical issues that need to be considered before adapting vehicles to ANG technology is also presented. Support from the Ministerio de Ciencia e Innovacion (Joint Japan−Spain Project PLE2009-0052) is acknowledged. K.V.K. thanks the European Commission for an EU-FP7 Intra European Marie Curie Research Fellowship (PIEF-GA-2013-623227) through Project BIOADSORB, an IAPP Fellowship through the ATLAS-H2 FP7 Marie Curie Project (PIAP-GA-251562), and Ministerio de Ciencia e Innovación (Spain) for a Juan de la Cierva fellowship.

Perovskite-related GdBaMnFeO5 and the corresponding oxidized phase GdBaMnFeO6, with long-range layered-type ordering of the Ba and Gd atoms have been synthesized. Oxidation retains the cation ordering but drives a modulation of the crystal structure associated with the incorporation of the oxygen atoms between the Gd layers. Oxidation of GdBaMnFeO5 increases the oxidation state of Mn from 2+ to 4+, while the oxidation state of Fe remains 3+. Determination of the crystal structure of both GdBaMnFeO5 and GdBaMnFeO6 is carried out at atomic resolution by means of a combination of advanced transmission electron microscopy techniques. Crystal structure refinements from synchrotron X-ray diffraction data support the structural models proposed from the TEM data. The oxidation states of the Mn and Fe atoms are evaluated by means of EELS and Mö ssbauer spectroscopy, which also reveals the different magnetic behavior of these oxides.

[EN] A new catalytic process to produce alkyl 5-benzyl-2-furoates has been performed through two step process that involves: a) selective oxidative esterification of 5-hydroxymethylfurfural (HMF) to 5-hydroxymethyl furoic acid methyl ester (HMFE) using Au/TiO2 as catalyst and oxygen as oxidant and b) alkylation of benzene derivatives with HMFE using zeolites as acid catalysts. The alkylation process has been carried out using large pore tridimensional zeolites such as Beta and USY, a mesoporous aluminosilicate (MCM-41), and a 2D delaminated ITQ-2 zeolite. The results showed that ITQ-2 zeolite which combines an easy product diffusion and adequate acitidy was the most active and selective catalyst to produce alkyl 5-benzyl-2-furoates. Finally, we have presented a simple protocol to prepare 5-(4-fluorobenzyl)-2-furyl methyl ketone, a key intermediate in the synthesis of S-1360, an antiviral for the treatment of AIDS, in good yield through a more sustainable method that the existing ones, starting from biomass platform molecules., Spanish MICINN Project CTQ:2015-67592-P, Generalitat Valenciana (Prometeo program) and Program Severo Ochoa are gratefully acknowledged.

Ru(Me3[9]aneN3)(bpy)(NO)](BF4)2 ([1](BF4)2) was explored by single-crystal X-ray diffractometry, leading to the first crystal structure of an octahedral {RuNO}7 complex. The metal resides on the center of a distorted octahedron, with dN-O and Ru-N-O at 1.177(3) Å and 141.6(2)°, respectively. [1](BF4)2 can be stored indefinitely under argon. Solutions of [1]2+ show no signs of decomposition when protected from air and light. The electron paramagnetic resonance X-band spectrum at 85 K in vitrified acetonitrile (MeCN) shows signals consistent with an S = 1/2 spin state, better described as RuIINO• (g = [2.030, 1.993, 1.880] and A = [11.0, 30.4, 3.9]/10-4 cm-1). In water, the {RuNO}7 species reacts with O2 in a 1:4 stoichiometry. The reaction is first-order in both reactants with k = (1.9 ± 0.2) M-1 s-1 at 25 °C (ΔH‡ = 11.5 ± 0.3 kJ mol-1 ΔS‡ = -189 ± 1 J K-1 mol-1). Solutions of [1]2+ evolve NO when irradiated a 365 nm with øNO = 0.024 and 0.090 mol einstein-1 in H2O and MeCN, respectively. Fil: Levin Rojas, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina Fil: Osa Codesido, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina Fil: Bill, Eckhard. Max-Planck Institut für Chemische Energiekonversion; Alemania Fil: Weyhermüller, Thomas. Max-Planck Institut für Chemische Energiekonversion; Alemania Fil: Segantin Gaspari, Ana Paula. Universidade de Sao Paulo; Brasil Fil: Da Silva, Roberto Santana. Universidade de Sao Paulo; Brasil Fil: Olabe Iparraguirre, Jose Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina Fil: Slep, Leonardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina

Model CuO/Ce0.8X0.2Oδ catalysts (with X = Ce, Zr, La, Pr, or Nd) have been prepared in order to obtain CuO/ceria materials with different chemical features and have been characterized by X-ray diffraction, Raman spectroscopy, N2 adsorption, and H2 temperature-programmed reduction. CO-PROX experiments have been performed in a fixed-bed reactor and in an operando DRIFTS cell coupled to a mass spectrometer. The CO oxidation rate over CuO/ceria catalysts correlates with the formation of the Cu+–CO carbonyl above a critical temperature (90 °C for the experimental conditions in this study) because copper–carbonyl formation is the rate-limiting step. Above this temperature, CO oxidation capacity depends on the redox properties of the catalyst. However, decomposition of adsorbed intermediates is the slowest step below this threshold temperature. The hydroxyl groups on the catalyst surface play a key role in determining the nature of the carbon-based intermediates formed upon CO chemisorption and oxidation. Hydroxyls favor the formation of bicarbonates with respect to carbonates, and catalysts forming more bicarbonates produce faster CO oxidation rates than those which favor carbonates. The authors thank the financial support of Generalitat Valenciana (Project PROMETEOII/2014/010 and Grant BEST/2014/250), the Spanish Ministry of Economy and Competitiveness (Projects CTQ2012-30703, CTQ2012-31762, MAT2014-61992-EXP, and Grant PRX14/00249), and the UE (FEDER funding).

Proton conduction in solids attracts great interest, not only because of possible applications in fuel cell technologies, but also because of the main role of this process in many biological mechanisms. Metal−organic frameworks (MOFs) can exhibit exceptional proton-conduction performances, because of the large number of hydrogen-bonded water molecules embedded in their pores. However, further work remains to be done to elucidate the real conducting mechanism. Among the different MOF subfamilies, bioMOFs, which have been constructed using biomolecule derivatives as building blocks and often affording water-stable materials, emerge as valuable systems to study the transport mechanisms involved in the proton-hopping dynamics. Herein, we report a versatile chiral threedimensional (3D) bioMOF, exhibiting permanent porosity, as well as high chemical, structural, and water stability. Moreover, the choice of this suitable bioligand results in proton conductivity, and allows us to propose a proton-conducting mechanism based on experimental data, which are displayed visually by means of quantum molecular dynamics simulations.

Silica nanoparticles functionalized with thiol reactive units and bulky polar polyamines were used for the selective colorimetric detection of formaldehyde. The reaction of thiols groups in the nanoparticles surface with a squaraine dye resulted in loss of the pi-conjugation of the chromophores, and the subsequent bleaching of the solution. However, when formaldehyde was present in the suspension, the thiol-squaraine reaction was inhibited and a chromogenic response was observed. A selective response to formaldehyde was observed only when the thiol and polyamine groups were anchored to the silica surface. The observed selective response was ascribed to the fact that bulky polyamines generate a highly polar environment around thiols, which were only able to react with the small and polar formaldehyde, but not with other aldehydes. The sensing nanoparticles showed a limit of detection (LOD) for formaldehyde of 36 ppb in water., Spanish Government (Project MAT2015-64139-C4-1-R, MINECO/FEDER) Generalitat Valencia (Project PROME-TEOII/2014/047)

[EN] Multidisciplinary research at the forefront of the field of hybrid materials has paved the way to the development of endless examples of smart devices. One appealing concept in this fertile field is related to the design of gated materials. These are constructed for finely tuning the delivery of chemical or biochemical species from voids of porous supports to a solution in response to predefined stimuli. Such gated materials are composed mainly of two subunits: (i) a porous inorganic support in which a cargo is loaded and (ii) certain molecular or supramolecular entities, generally grafted onto the external surface, which can control mass transport from pores. On the basis of this concept, a large number of imaginative examples have been developed. This review intends to be a comprehensive analysis of papers published until 2014 on hybrid mesoporous gated materials. The molecules used as gates, the opening mechanisms, and controlled release behavior are detailed. We hope this review will not only help researchers who work in this field but also may open the minds of related ones to develop new advances in this fertile research area., The authors gratefully acknowledge financial support from the Spanish Government (Project MAT2012-38429-C04-01) and the Generalitat Valenciana (Project PROMETEOII/2014/047). Ll.P. and M.O. also thank the Universidad Politecnica de Valencia for their predoctoral grants.