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Matthew J Gilkey, Alexander V Mironenko, Leerang Yang, Dionisios G Vlachos, Bingjun Xu
The selective ring-opening of cellulose-derived furanic molecules is a promising pathway for the production of industrially relevant linear oxygenates, such as 1,6-hexanediol. 2,5-Dimethylfuran (DMF) is employed as a model compound in a combined experimental and computational investigation to provide insights into the metal-catalyzed ring-opening. Ring-opening to 2-hexanol and 2-hexanone and ring-saturation to 2,5-dimethyltetrahydrofuran (DMTHF) are identified as two main parallel pathways. DFT calculations and microkinetic modeling indicate that DMF adsorbs on Ru in an open-ring configuration, which is potentially a common surface intermediate that leads to both ring-opening and ring-saturation products...
October 14, 2016: ChemSusChem
Chaohe Xu, Meihua Lu, Binggong Yan, Yi Zhan, Palani Balaya, Li Lu, Jim Yang Lee
The rational design of nonprecious-metal electrocatalysts with activities comparable to or greater than that of platinum is extremely valuable to the development of high energy density metal-air batteries. Herein, the two-step preparation of a highly active oxygen electrocatalyst based on ultrasmall cobalt nanoparticles stabilized in a nitrogen-doped graphene matrix is reported. The catalyst performs as well as the commercial Pt/C catalyst in the oxygen reduction reaction, and better than the Pt/C catalyst in the oxygen evolution reaction...
October 14, 2016: ChemSusChem
Tuula Selkälä, Juho Antti Sirviö, Gabriela S Lorite, Henrikki Liimatainen
Deep eutectic solvents (DESs) are green chemicals that have the potential to replace traditional solvents in chemical reactions. In this study, urea-LiCl DES was used successfully as a reaction medium in the anionic functionalization of wood cellulose with succinic anhydride. The effects of reaction temperature and time on the carboxyl content and yield were evaluated. The analyses of the degree of polymerization and crystallinity revealed that the DES was a nondegrading and nondissolving reaction medium. Three samples with the highest carboxyl contents were further nanofibrillated with a microfluidizer to diameters of 2-7 nm, as observed by atomic force microscopy...
October 14, 2016: ChemSusChem
Enrique Ruiz-Trejo, Milla Puolamaa, Brian Sum, Farid Tariq, Vladimir Yufit, Nigel P Brandon
A simple chemical bath deposition is used to coat a complex porous ceramic scaffold with a conformal Ni layer. The resulting composite is used as a solid oxide fuel cell electrode, and its electrochemical response is measured in humidified hydrogen. X-ray tomography is used to determine the microstructural characteristics of the uncoated and Ni-coated porous structure, which include the surface area to total volume, the radial pore size, and the size of the necks between the pores.
October 14, 2016: ChemSusChem
Giacomo M Lari, Olivier G Gröninger, Qiang Li, Cecilia Mondelli, Núria López, Javier Pérez-Ramírez
Sugar alcohols are applied in the food, pharmaceutical, polymer, and fuel industries and are commonly obtained by reduction of the corresponding saccharides. In view of the rarity of some sugar substrates, epimerization of a readily available monosaccharide has been proposed as a solution, but an efficient catalytic system has not yet been identified. Herein, a molybdenum heteropolyacid-based catalyst is developed to transform glucose, arabinose, and xylose into less-abundant mannose, ribose, and lyxose, respectively...
October 14, 2016: ChemSusChem
Florentina Neaţu, Geanina Culică, Mihaela Florea, Vasile I Parvulescu, Fabrizio Cavani
The synthesis of terephthalic acid from biomass remains an unsolved challenge. In this study, we conducted the selective oxidation of p-cymene (synthesized from biodegradable terpenes, limonene, or eucalyptol) into terephthalic acid over a Mn-Fe mixed-oxide heterogeneous catalyst. The impact of various process parameters (oxidant, temperature, reaction time, catalyst amount, oxygen pressure) on the selectivity to terephthalic acid was evaluated, and some mechanistic aspects were elucidated. An unprecedented synthesis of biobased terephthalic acid (51 % yield) in the presence of O2 is reported...
October 12, 2016: ChemSusChem
Alessandro Chieregato, Claudia Bandinelli, Patricia Concepción, M Dolores Soriano, Francesco Puzzo, Francesco Basile, Fabrizio Cavani, José M López Nieto
The design of suitable catalysts for the one-pot conversion of glycerol into acrylic acid (AA) is a complex matter, as only fine-tuning of the redox and acid properties makes it possible to obtain significant yields of AA. However, fundamental understanding behind the catalytic phenomenon is still unclear. Structure-reactivity correlations are clearly behind these results, and acid sites are involved in the dehydration of glycerol into acrolein with vanadium as the main (or only) redox element. For the first time, we propose an in-depth study to shed light on the molecular-level relations behind the overall catalytic results shown by several types of V-containing catalysts...
October 12, 2016: ChemSusChem
Daochuan Jiang, Rana Muhammad Irfan, Zijun Sun, Dapeng Lu, Pingwu Du
Photocatalytic production of hydrogen by water splitting is a promising pathway for the conversion of solar energy into chemical energy. However, the photocatalytic conversion efficiency is often limited by the sluggish transfer of the photogenerated charge carriers, charge recombination, and subsequent slow catalytic reactions. Herein, we report a highly active noble-metal-free photocatalytic system for hydrogen production in water. The system contains a water-soluble nickel complex as a molecular cocatalyst and zinc sulfide on 1D cadmium sulfide as the heterojunction photocatalyst...
October 12, 2016: ChemSusChem
Marta Haro, Claudia Solis, Vicente M Blas-Ferrando, Olivier Margeat, Sadok Ben Dhkil, Christine Videlot-Ackermann, Jörg Ackermann, Fabio Di Fonzo, Antonio Guerrero, Sixto Gimenez
Here, we have developed an organic photocathode for water reduction to H2 , delivering more than 1 mA cm(-2) at 0 V versus RHE and above 3 mA cm(-2) at -0.5 V versus RHE with moderate stability under neutral pH conditions. The initial competitive reduction of water to H2 and ZnO to metallic Zn is responsible for the dynamic behaviour of both photocurrent and Faradaic efficiency of the device, which reaches 100 % Faradaic efficiency after 90 min operation. In any case, outstanding stable H2 flow of approximately 2 μmol h(-1) is measured over 1 h at 0 V versus RHE and at neutral pH, after equilibrium between the Zn(2+) /Zn(0) concentration in the AZO film is reached...
October 12, 2016: ChemSusChem
S Fleischmann, M Mancini, P Axmann, U Golla-Schindler, U Kaiser, M Wohlfahrt-Mehrens
A series of Li2 MnSiO4 samples with various Li, Mn, and/or Si concentrations are reported to study for the first time the effect of impurities and deviation from ideal stoichiometry on electrochemical behavior. Carbon-coated and nanosized powders are obtained at 600 °C and compared with those synthetized at 900 °C. Samples are investigated using XRD, SEM, high-resolution TEM, attenuated total reflection infrared spectroscopy and Brunauer-Emmett-Teller surface area to characterize crystal structure, particle size, impurity amount, morphology, and surface area...
October 6, 2016: ChemSusChem
Ângelo Rocha, Raquel Teixeira, Nuno M T Lourenço, Carlos A M Afonso
We developed a method for the resolution of secondary alcohols using an ionic anhydride acylating agent prepared directly in the reaction medium containing the biocatalyst Candida antarctica lipase B (CALB). NMR studies showed that mixing all components at the same time does not interfere with the coupling reaction or the enzymatic activity. After optimization of the reaction conditions, the method allowed the resolution of a number of substrates in very high conversions (46-48 %) and enantiomeric ratios (E>170) along with an easy recovery of both enantiomers without the need for preparative chromatographic separation...
October 6, 2016: ChemSusChem
Xu-Dong Wang, Yang-Fan Xu, Bai-Xue Chen, Ning Zhou, Hong-Yan Chen, Dai-Bin Kuang, Cheng-Yong Su
Cupric oxide (CuO), a narrow-bandgap semiconductor, has a band alignment that makes it an ideal photocathode for the renewable production of solar fuels. However, the photoelectrochemical performance of CuO is limited by its poor conductivity and short electron diffusion lengths. Herein, a three-dimensional (3D) architecture consisting of CuO nanosheets supported onto transparent conducting macroporous antimony-doped tin oxide (mpATO@CuONSs) is designed as an excellent photocathode for promoting the hydrogen evolution reaction (HER)...
October 5, 2016: ChemSusChem
Mariia V Pavliuk, Edgar Mijangos, Valeriya G Makhankova, Vladimir N Kokozay, Sonja Pullen, Jia Liu, Jiefang Zhu, Stenbjörn Styring, Anders Thapper
The heterometallic complexes (NH4 )2 [Co(H2 O)6 ]2 [V10 O28 ]⋅4 H2 O (1) and (NH4 )2 [Co(H2 O)5 (β-HAla)]2 [V10 O28 ]⋅4 H2 O (2) have been synthesized and used for the preparation of mixed oxides as catalysts for water oxidation. Thermal decomposition of 1 and 2 at relatively low temperatures (<500 °C) leads to the formation of the solid mixed oxides CoV2 O6 /V2 O5 (3) and Co2 V2 O7 /V2 O5 (4). The complexes (1, 2) and heterogeneous materials (3, 4) act as catalysts for photoinduced water oxidation...
September 30, 2016: ChemSusChem
Tanja Ivanovska, Claudio Quarti, Giulia Grancini, Annamaria Petrozza, Filippo De Angelis, Alberto Milani, Giampiero Ruani
The dynamic evolution of the vibrational interactions in the prototypical CH3 NH3 PbI3 was studied through a comprehensive experimental and theoretical investigation with a focus on the interactions between the organic cations and the inorganic cage. To date, no clear picture has emerged on the critical and fundamental interactions between the two perovskite components, despite the relevance of phonons to the electronic properties of several classes of perovskites. For the first time, we have monitored the IR and nonresonant Raman response in the broad frequency range 30-3400 cm(-1) and in the temperature interval 80-360 K...
September 28, 2016: ChemSusChem
Yinyu Xiang, Junsheng Li, Jiaheng Lei, Dan Liu, Zhizhong Xie, Deyu Qu, Ke Li, Tengfei Deng, Haolin Tang
Li-ion and Li-S batteries find enormous applications in different fields, such as electric vehicles and portable electronics. A separator is an indispensable part of the battery design, which functions as a physical barrier for the electrode as well as an electrolyte reservoir for ionic transport. The properties of the separators directly influence the performance of the batteries. Traditional polyolefin separators showed low thermal stability, poor wettability toward the electrolyte, and inadequate barrier properties to polysulfides...
September 26, 2016: ChemSusChem
Yunqian Dai, Eric Formo, Haoxuan Li, Jiajia Xue, Younan Xia
Precious metals are widely used as catalysts in industry. It is of critical importance to keep the precious metal ions leached from catalysts at a level below one part per million (ppm) in the final products and to recycle the expensive precious metals. Here we demonstrate a simple and effective method for scavenging precious metal ions from an aqueous solution and thereby reduce their concentrations down to the parts per billion (ppb) level. The key component is a filtration membrane comprised of titania (TiO2 ) nanofibers whose surface has been functionalized with a silane bearing amino or thiol group...
September 23, 2016: ChemSusChem
Kyung Taek Cho, Giulia Grancini, Yonghui Lee, Dimitrios Konios, Sanghyun Paek, Emmanuel Kymakis, Mohammad Khaja Nazeeruddin
In this work we systematically investigated the role of reduced graphene oxide (rGO) in hybrid perovskite solar cells (PSCs). By mixing rGO within the mesoporous TiO2 (m-TiO2 ) matrix, highly efficient solar cells with power conversion efficiency values up to 19.54 % were realized. In addition, the boosted beneficial role of rGO with and without Li-treated m-TiO2 is highlighted, improving transport and injection of photoexcited electrons. This combined system may pave the way for further development and optimization of electron transport and collection in high efficiency PSCs...
September 22, 2016: ChemSusChem
Michael J Pellin, Shannon C Riha, Eric C Tyo, Gihan Kwon, Joseph A Libera, Jeffrey W Elam, Soenke Seifert, Sungsik Lee, Stefan Vajda
The complexity of the water oxidation reaction makes understanding the role of individual catalytic sites critical to improving the process. Here, size-selected 27-atom cobalt clusters (Co27 ) deposited on hematite (Fe2 O3 ) anodes were tested for water oxidation activity. The uniformity of these anodes allows measurement of the activity of catalytic sites of well-defined nuclearity and known density. Grazing incidence X-ray absorption near-edge spectroscopy (GIXANES) characterization of the anodes before and after electrochemical cycling demonstrates that these Co27 clusters are stable to dissolution even in the harsh water oxidation electrochemical environment...
September 22, 2016: ChemSusChem
Huy Quang Lê, Anna Zaitseva, Juha-Pekka Pokki, Marina Ståhl, Ville Alopaeus, Herbert Sixta
The solubility of lignin in a mixture of γ-valerolactone (GVL) and water at different weight ratios was measured using the Hildebrand solubility parameters. Based on the molecular structure of lignin, its solubility parameter (δ-value) was calculated as 25.5 MPa(1/2) . The δ-value for aqueous GVL solvent increased from 23.1 MPa(1/2) for pure GVL to 45.6 MPa(1/2) for pure water. Therefore, the lignin solubility was predicted to increase with increasing GVL concentration in the aqueous mixture up to approximately 92-96 wt % of GVL...
September 22, 2016: ChemSusChem
Marc Ledendecker, Xiaofei Yang, Markus Antonietti, Menny Shalom
Here, we elucidate the activity origin of ceramic nickel electrocatalysts in the oxygen evolution reaction (OER), ranging from nitrides, sulfides, and phosphides, as a case study that may be projected on almost any ceramic metallic. Our results show that regardless of the starting material, the formation of an active (oxy)hydroxide layer, acting as the real electrocatalyst during the OER, is unavoidable. Nevertheless, the in situ transformation into highly active (oxy)hydroxides leads to the formation of active catalysts for various applications...
September 21, 2016: ChemSusChem
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