bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Different Functional Groups on Photocatalytic Hydrogen Evolution in Covalent‐Organic Frameworks
Authors: Sheng Jing‐Li , Dong Hong , Meng Xiang‐Bin , Tang Hong‐Liang , Yao Yu‐Hao , Liu Dan‐Qing , Bai Lin‐Lu , Zhang Feng‐Ming , Wei Jin‐Zhi , Sun Xiao‐Jun 
Published: March 2019

AbstractCovalent‐organic frameworks (COFs) have been recognized as a new type of promising photocatalysts for hydrogen evolution. To investigate how different functional groups attached in the backbone of COFs affect the overall photocatalytic H2 evolution, for the first time, we selected and synthesized a series of ketoenamine‐based COFs with the same host framework as model system. It includes TpPa−COF−X (X=−H, −(CH3)2, and −NO2) with three different groups attached in the backbone of TpPa−COF. We systematically investigated the differences in morphology, light‐absorption intensity and band gap of these 2D COFs. The results of photocatalytic H2 evolution measurements indicate that the TpPa−COF−(CH3)2 shows the best activity, while the activity of TpPa−COF−NO2 is relatively low compared to that of other two COFs in the system. Moreover, the separation ability of photogenerated charge was also followed the order of TpPa−COF−(CH3)2>TpPa−COF>TpPa−COF−NO2. The best photocatalytic H2 production performance of TpPa−COF−(CH3)2 in these systems should be mainly attributed to the better electron‐donating ability of −CH3 groups compared to −H or −NO2 group, which result in more efficient charge transferring in the inner of the material. This work demonstrates that reasonably adding electron‐donating group in TpPa−COFs can lead to a better photocatalytic H2 evolution activity, and which is meaningful for further design of efficient COF‐based photocatalysts for H2 evolution.
Controlled Formation of Defective Shell on TiO2 (001) Facets for Enhanced Photocatalytic CO2 Reduction
Authors: Shi Rui , Chen Yong 
Published: March 2019

AbstractDefective black TiO2 has attracted considerable attention as photocatalyst for highly efficient solar energy conversion. However, it still remains a challenge to understand the basic role of defective shell on the basis of crystal facet engineering, due to the difficulty in generating defects merely on a specific facet. Herein, we develop a novel strategy to precisely control the formation of defective shell only on {001} facets of TiO2 nanocrystals due to the anisotropic effect of the crystal facets, which enables the investigation of defective shell on a specific facet to be achieved. It is found that the defective shell, middle interface layer and crystalline core together constitute a homojunction (TiO2‐homojunction). The defective shell of TiO2‐homojunction realizes the effective spatial separation of photogenerated electrons and holes. Moreover, the presence of Ti3+ ion and oxygen vacancies in defective shell can induce high free electron concentration and serve as active sites to promote the adsorption and activation of CO2 molecules. As a result, the TiO2‐homojunction exhibits significant photocatalytic behavior for CO2 reduction in a gas‐solid system. More interestingly, the position of redox reaction is reversed due to the controlled formation of defective shell, where {001} facets act as reduction sites and {101} facets as oxidation sites during photocatalytic process.
Rapid, Room‐Temperature and Template‐Free Synthesis of Metal‐Organic Framework Nanowires in Alcohol
Authors: Shi Jinbiao , Zhang Jianling , Tan Dongxing , Cheng Xiuyan , Tan Xiuniang , Zhang Bingxing , Han Buxing , Liu Lifei , Zhang Fanyu , Liu Meirong , Xiang Junfeng 
Published: March 2019

AbstractThe well‐defined one‐dimensional nanostructures of metal‐organic frameworks (MOFs) are hard to obtain, especially for the MOF nanowires with small diameters and large lengths. Here we report a rapid, room‐temperature and template‐free route for the synthesis of MOF nanowires in alcohol. The crystallized MOF nanowires have a diameter of ∼25 nm and a length of ∼5 μm, which are highly active in catalyzing the selective aerobic oxidation of benzylic alcohol under mild conditions. The formation process and mechanism for MOF nanowires were investigated by in‐situ Fourier transformed infrared spectra and 1H nuclear magnetic resonance spectra, as well as fluorescence probe techniques. It was found that the alcohol molecules direct the assembly of MOF nanowires by hydrogen bonding with organic ligands.
Janus Interphase Organic‐Inorganic Hybrid Materials: Novel Water‐Friendly Heterogeneous Catalysts
Authors: Vafaeezadeh Majid , Breuninger Paul , Lösch Philipp , Wilhelm Christian , Ernst Stefan , Antonyuk Sergiy , Thiel Werner R. 
Published: March 2019

AbstractIn this work, amphiphilic silica‐based Janus‐type acid and base catalysts are introduced as heterogeneous analogues of surfactants. The new interphase organic‐inorganic hybrid catalysts comprise of two different groups (−C8H17, −C2H4Ph) on the hydrophobic and two different groups (−C3H6SO3H, −C3H6NH2) on the hydrophilic side. The hydrophobic sides of the catalysts are responsible for the diffusion of the organic substrates to the catalytically active sites while the hydrophilic sides carry catalytic centers being oriented towards the aqueous phase and thus providing sufficient connection between water (solvent) and the organic substrates. Catalyst preparation is based on simple synthetic procedures and leads in a first step to hollow silica spheres with hydrophobic groups on the inner and hydrophilic groups on the outer surface. After crushing the hollow spheres, acid resp. base functionalized Janus nano‐sheets are obtained. The basic catalyst was tested for the Knoevenagel condensation of a series of benzaldehydes with malononitrile in water, while the acid catalyst was used for Fischer esterification of acetic acid with ethanol.
Direct Conversion of Methanol to Ethanol on the Metal‐Carbon Interface
Authors: Li Yunhua , Lu Junfeng , Wang Xihui , Zhang Hua , Wu Xuee , Zhang Kelvin H. L. , Ye Jinyu , Zhan Dongping 
Published: March 2019

AbstractDirect conversion of one‐carbon (C1) compounds to two‐carbon (C2) and multi‐carbon compounds remains a critical challenge for converting non‐petroleum resources to valuable chemicals or fuels. The key issue is the selective activation of C1 compounds, methanol, as well as the controlled formation of carbon‐carbon (C−C) bonds. Herein, we achieve the direct electrocatalytic methanol to ethanol, an important chemical and energy candidate, with methanol conversion, ethanol selectivity, and faradic efficiency of 257.0 g ⋅ m−2 ⋅ h−1, 95.1 %, and 12.5 %, respectively. Furthermore, the appropriate participation of water, as a by‐product from methanol electrocatalysis, in hydrogen evolution reaction (HER) facilitates electrocatalytic reaction of methanol. Mechanistic studies reveal hydroxymethyl and methyl radicals are formed on the electropositive low‐valent metal sites and electronegative carbon vacancies, respectively, and then combined with each other to form ethanol at the metal/carbon interface. This work opens a unique route for high‐efficient concerted redox conversion of methanol reactant to ethanol.
Ultrasonic Irradiation during the Calcium Sulfate Hemihydrate to Dihydrate Transformation Process
Authors: Polat Sevgi , Sayan Perviz 
Published: March 2019

AbstractThe ultrasound‐assisted transformation of calcium sulfate hemihydrate (CSH) to calcium sulfate dihydrate (CSD) was studied using three ultrasonic power settings. In addition to continuously measuring the variation in the conductivity value with time, the process was followed by X‐ray diffraction and scanning electron microscopy (SEM) analysis. Thermogravimetric analysis, Fourier transform infrared, mass spectrometry, and filtration analyses helped to determine the physicochemical properties of the as‐obtained crystals. The morphological changes in the surface morphology were observed by SEM. The experimental results indicate that ultrasonic irradiation and its intensity have a significant effect on the crystal size, morphology, adsorption, and filtration characteristics. Mandelic acid in combination with ultrasonic irradiation can be used as an accelerator for the transformation process from CSH to CSD.
Reducing the Interfacial Resistance in All‐Solid‐State Lithium Batteries Based on Oxide Ceramic Electrolytes
Authors: Jiang Zhouyang , Han Qingyue , Wang Suqing , Wang Haihui 
Published: March 2019

AbstractAll‐solid‐state lithium batteries (ASSLBs) are regarded as next‐generation advanced energy‐storage devices, owing to their high energy density and safety. The interfacial resistance is a crucial factor affecting the practical application of ASSLBs. ASSLBs based on oxide‐based ceramic electrolytes (OCEs) still exhibit poor electrochemical performance, owing to the large interfacial resistance. Area‐specific resistance values at the interfaces ranging from thousands of ohms to several ohms per square centimeter have been achieved using multiple strategies. This Review summarizes multiple existing advanced strategies used to reduce the interfacial resistance between OCEs and electrodes through interfacial engineering. We also propose some perspectives for the future development of ASSLBs based on OCEs.
Porous Isomeric Li2.5Na0.5V2(PO4)3 Wide Voltage Cathode for High‐Performance Lithium‐Ion Batteries Synthesized Through a Colloid Chemical Method
Authors: Wang Yaoyao , Zhang Xudong , He Wen , Yang Wenhao , Wei Chuanliang 
Published: March 2019

AbstractThe synthesis of highly active and stable cathode materials for lithium‐ion batteries (LIBs) is a major challenge for electrochemical energy storage. Herein, we report an isomeric Li2.5Na0.5V2(PO4)3 porous nanoparticle composite synthesized through a colloid chemical strategy. This composite is composed of monoclinic Li3V2(PO4)3 (M–LVP), rhombohedral Li3V2(PO4)3 (R‐LVP) and rhombohedral Na3V2(PO4)3 (R‐NVP). Benefiting from the porous structure and synergistic effects between the stable M−LVP and highly conductive R‐LVP, this composite cathode exhibits outstanding electrochemical performance for LIBs. It shows a high discharge capacity of 228.1 mAh g−1 at 0.1 C rate (1 C=150 mA g−1) and 108.9 mAh g−1 at 10 C rate in a wide potential range between 1.5 and 4.3 V. Moreover, even in a high current density of 10 C, it still exhibits a stable cycle performance and retains a discharge capacity of 80 mAh g−1 after 500 cycles.
Electrochemical Properties of 9,9′‐Spiro‐Bifluorenes Containing Group 14 Elements (C, Si, Ge, Sn)
Authors: Golub‐Sedinkin Tatiana , Herath Ajith C. , West Robert , Becker James Y. 
Published: March 2019

AbstractCyclic voltammograms of four spiro‐bifluorenes involving C (I), Si (II), Ge (III) and Sn (IV) as the central atom were recorded in acetonitrile‐dichloromethane. Each substrate afforded one irreversible oxidation wave (between 1.7 to 1.9 V, vs. Ag/AgCl) and one irreversible reduction wave between −2.0 to −2.3 V (except for the Ge derivative III that showed a second irreversible reduction wave). Controlled potential anodic oxidation was executed for II–IV on a Pt anode. Surprisingly, each one of the substrates behaved differently: II yielded biphenyl (92 %) as the major product; III afforded moderate yields of a germafluorene dimer containing Ge−Ge bond (35 %) and 1,3,5‐triphenylbenzene 10 (22 %), and IV formed the aromatic derivative 10 as the major product (76 %). In all cases, chlorinated products were formed too. A plausible mechanism for the formation of the variety of products is suggested.
Cross‐Linking Tin‐Based Metal‐Organic Frameworks with Encapsulated Silicon Nanoparticles: High‐Performance Anodes for Lithium‐Ion Batteries
Authors: Zhou Xiangyang , Yu Yawen , Yang Juan , Wang Hui , Jia Ming , Tang Jingjing 
Published: March 2019

AbstractA simple one‐pot strategy is proposed to attach encapsulated Si nanoparticles to rod‐like Sn‐based metal‐organic frameworks (MOFs) through an in situ self‐assembly method. The active Sn‐MOFs amalgamating with Si nanoclusters perform their part by coordinating their individual functionalities in a complementary way. 1) As a superior capacity contributor, the rod‐like Sn‐MOFs, externally, function as a structural reinforcement that maintains the electrode integrity and mitigates the agglomeration of materials; internally, they can serve as a host material to provide inherent open channels and sufficient reserved expansion space, thus alleviating the capacity fading and further increasing the cyclability of electrodes. 2) The encapsulated Si nanoparticles not only facilitate access to a high specific capacity, but also enhance the connection between the electrode and the substrate to enable efficient electron transport upon cycling. These remarkable synergies, combined with the hybridization design, ensure that the Si@Sn‐MOF composite delivers a superior capacity as high as 1360.4 mAh g−1 at 200 mA g−1 after 250 cycles and an exceptional rate capability. When utilized as an anode material for the full cell, it exhibits a discharge capacity up to about 117.7 mAh g−1 after 150 cycles. These results reveal that such a Si@Sn‐MOF composite could be an ideal alternative anode material for high‐energy lithium‐ion batteries.
Introducing Pseudocapacitive Bioelectrodes into a Biofuel Cell/Biosupercapacitor Hybrid Device for Optimized Open Circuit Voltage
Authors: Alsaoub Sabine , Conzuelo Felipe , Gounel Sébastien , Mano Nicolas , Schuhmann Wolfgang , Ruff Adrian 
Published: March 2019

AbstractWe report the fabrication of a polymer/enzyme‐based biosupercapacitor (BSC)/biofuel cell (BFC) hybrid device with an optimized cell voltage that can be switched on demand from energy conversion to energy storage mode. The redox polymer matrices used for the immobilization of the biocatalyst at the bioanode and biocathode act simultaneously as electron relays between the integrated redox enzymes and the electrode surface (BFC) and as pseudocapacitive charge storing elements (BSC). Moreover, owing to the self‐charging effect based on the continuously proceeding enzymatic reaction, a Nernstian shift in the pseudocapacitive elements, that is, in the redox polymers, at the individual bioelectrodes leads to a maximized open circuit voltage of the device in both operating modes. Comparison with a conventional fuel cell design, that is, using redox mediators with redox potentials that are close to the potentials of the used redox proteins, indicates that the novel hybrid device shows a similar voltage output. Moreover, our results demonstrate that the conventional design criteria commonly used for the development of redox polymers for the use in biofuel cells have to be extended by considering the effect of a Nernstian shift towards the potentials of the used biocatalysts in those pseudocapacitive elements.
Ionic‐State Cobalt and Iron Co‐doped Carbon Dots with Superior Electrocatalytic Activity for the Oxygen Evolution Reaction
Authors: Yang Mingxi , Feng Tanglue , Chen Yixin , Zhao Xiaohuan , Yang Bai 
Published: March 2019

AbstractCarbon dots (CDs), with abundant functional groups and unique electrical properties, have been widely exploited as an assistant in the preparation of metal‐based nanohybrids for electrocatalytic water splitting, but complicated synthetic procedures and high power consumption restricted their practical application. In this work, novel ionic cobalt and iron co‐doped CDs (CoFe−CDs) were synthesized in a straightforward manner through the one‐step hydrothermal treatment of cobalt gluconate and ferrous gluconate salts. The CoFe−CDs exhibited superior electrocatalytic oxygen evolution reaction activity with a small overpotential of 308 mV at a current density of 10 mA/cm2, which is comparable and even lower than those of previously reported CDs/Co, Fe‐based metal composites. The activity origin of CoII sites and the synergistic effect of FeIII within CoFe−CDs were fully understood by DFT calculations and XPS analysis, respectively. This work provides a strategy to construct active metal‐ion‐doped CDs with boosted electrocatalytic activities, and such new CDs might find potential in the field of energy storage.
Role of Water in the Reaction Mechanism and endo/exo Selectivity of 1,3‐Dipolar Cycloadditions Elucidated by Quantum Chemistry and Machine Learning
Authors: Yang Xin , Zou Jun , Wang Yifei , Xue Ying , Yang Shengyong 
Published: March 2019

AbstractAsymmetric 1,3‐dipolar cycloadditions of azomethine ylides with activated olefins are among the most important and versatile methods for the synthesis of enantioenriched pyrroline and pyrrolidine derivatives. Despite both theoretical and practical importance, the role of water molecules in the reactivity and endo/exo selectivity remains unclear. To explore how water accelerates the reactions and improves the endo/exo selectivity of the cycloadditions of 1,3‐dipole phthalazinium‐2‐dicyanomethanide (1) and two dipolarophiles, an ab initio‐quality neural network potential that overcomes the computational bottleneck of explicitly considering water molecules was used. It is demonstrated that not only the nature of both the dipolarophile and the 1,3‐dipole, but also the solvent medium, can perturb or even alter the reaction mechanism. An extreme case was found for the reaction of 1,3‐dipole 1 with methyl vinyl ketone, in which the reaction mechanism changes from a concerted to a stepwise mode on going from MeCN to H2O as solvent, with formation of a zwitterionic intermediate that is a very shallow minimum on the energy surface. Thus, high stereocontrol can still be expected despite the stepwise nature of the mechanism. The results indicate that water can induce global polarization along the reaction coordinate and highlight the role of microsolvation effects and bulk‐phase effects in reproducing the experimentally observed aqueous acceleration and enhanced endo/exo selectivity.
Cobaltaelectro‐Catalyzed C—H Acyloxylation
Authors: Tian Cong , Dhawa Uttam , Struwe Julia , Ackermann Lutz 
Published: March 2019

Summary of main observation and conclusionCobaltaelectrocatalysis set the stage for sustainable C—H acyloxylations in biomass‐derived γ‐valerolactone as a renewable solvent. The sustainable electrocatalysis regime featured ample scope, along with high levels of chemo‐ and position‐selectivity.
Development of Language in the Schülerlabor – Language‐Sensitive Teaching on the Example of Sweeteners
Authors: Haberzettl Stefanie , Huwer Johannes , Bröhl Karin , Hempelmann Rolf 
Published: March 2019

AbstractUm den Herausforderungen einer heterogener werdenden Schülerschaft gerecht zu werden, müssen Unterricht und Unterrichtsmaterialien immer wieder auf den Prüfstand gestellt und aktualisiert werden. Einen solchen Ansatz bietet der sprachsensible Fachunterricht. Exemplarisch werden einige Möglichkeiten skizziert, forschendes Lernen sprachsensibel zu begleiten. Dabei liegt der Schwerpunkt auf der Vermittlung und Festigung basaler konzeptionell schriftlicher und fachsprachlicher Items und Strukturen.
Concurrent neoadjuvant chemotherapy and estrogen deprivation in patients with estrogen receptor–positive, human epidermal growth factor receptor 2–negative breast cancer (CBCSG‐036): A randomized, controlled, multicenter trial
Authors: Yu Ke‐Da , Wu Si‐Yu , Liu Guang‐Yu , Wu Jiong , Di Gen‐Hong , Hu Zhen , Hou Yi‐Feng , Chen Can‐Ming , Fan Lei , Tang Li‐Chen , Shen Zhen‐Zhou , Wu Ke‐Jin , Zhuang Zhi‐Gang , Zhang Hong‐Wei , Shao Zhi‐Ming 
Published: March 2019

BackgroundThe current randomized, controlled, multicenter clinical trial was conducted to investigate the efficacy of concurrent neoadjuvant chemotherapy (NCT) and estrogen deprivation in patients with estrogen receptor (ER)–positive, human epidermal growth factor receptor 2 (HER2)–negative breast cancer.MethodsEligible patients with AJCC stage IIB to stage IIIC, ER‐positive, HER2‐negative breast cancer were enrolled and randomly assigned to receive NCT with or without estrogen deprivation. The primary endpoint was the objective response rate (ORR).ResultsA total of 249 patients were assigned to either neoadjuvant chemoendocrine therapy (NCET) (125 patients) or the NCT group (124 patients). In the intention‐to‐treat analysis, the ORR was found to be significantly higher in the NCET group compared with the NCT group (84.8% vs 72.6%; odds ratio, 2.11 [95% CI, 1.13‐3.95; P = .02). The efficacy of NCET was more prominent in tumors with a higher Ki‐67 index (>20%), with an ORR of 91.2% reported in the NCET group versus 68.7% in the NCT group (P = .001). The pathologic complete response and pathological response rates did not differ significantly between the 2 groups. Although there was no significant difference with regard to progression‐free survival (PFS) between the 2 groups (P = .188), patients with a higher baseline Ki‐67 index appeared to derive a greater PFS benefit from NCET (2‐year PFS rate of 91.5% in the NCET group vs 76.5% in the NCT group; P = .058). Adding endocrine agents to NCT did not result in significant differences in adverse events (grade 3 or 4; graded according to National Cancer Institute Common Terminology Criteria for Adverse Events [version 3.0]) between the 2 groups.ConclusionsThe addition of estrogen deprivation to NCT appears to improve the clinical response in patients with ER‐positive, HER2‐negative breast cancer, especially for those individuals with a higher Ki‐67 index. Patients with a higher Ki‐67 index might derive more PFS benefit from concurrent neoadjuvant treatment.
1H NMR Chemosensing of Potassium Ions Enabled by Guest‐Induced Selectivity Switch of a Gold Nanoparticle/Crown Ether Nanoreceptor
Authors: Sun Xiaohuan , Rosa‐Gastaldo Daniele , De Biasi Federico , Rastrelli Federico , Mancin Fabrizio 
Published: March 2019

AbstractA sensing protocol to detect potassium ions in water by 1H NMR spectroscopy is described. The method exploits the K+‐modulated affinity of 18‐crown‐6 functionalized gold nanoparticles towards organic ions, combined with NOE magnetization transfer. Binding of K+ to the crown ether moieties switches the nanoreceptor preference (and its ability to transfer magnetization) from organic cations (tyramine) to organic anions (phloretate). In this way, a ratiometric NMR signal is produced with a detection limit of 0.6 mM. Detection can be performed in 20 min with standard instruments and with little interference from other alkali and alkaline earth metal ions present in the sample.
Highly Polarized Benzo[k]fluoranthene Imide Derivatives: Large Solvatofluorochromism, Dual Fluorescence and Aggregation Induced Emission Associated with Excited‐State Intramolecular Charge Transfer
Authors: Katayama Kohji , Kawajiri Ikumi , Okano Yotaro , Nishida Jun‐ichi , Kawase Takeshi 
Published: March 2019

AbstractThe highly conjugated imides, 9‐diphenyl‐aminobenzo[k]fluoranthene imide and N‐phenylcarbazo[2,3‐k]fluoranthene imide, were produced by Buchwald‐Hartwig reaction of N‐octyl‐9,10‐dibromobenzo[k]fluoranthene imide with diphenylamine. In a similar manner, reaction of the N‐ethylhexyl‐9,10‐dibromo derivative with carbazole leads to formation of 9‐(N‐carbazoyl)benzo[k]fluoranthene imide. All the benzo[k]fluoranthene imide (BFI) derivatives in solution show remarkable solvatofluorochromism. Diphenylamino and 9‐(N‐carbazoyl) derivatives, having twisted structures, exhibit fluorescence bands at short wavelengths in highly polar solvents, and they emit dual fluorescence in acetone. Moreover, the 9‐(N‐carbazoyl) derivative displays aggregation‐induced emission in highly aqueous acetone solutions. The results of density functional theory calculations demonstrate that a considerable spatial separation exists between the HOMO and LUMO coefficients of the N‐arylamine substituted BFIs. The results indicate that the ground‐to‐excited state transitions of these compounds have intramolecular charge transfer character.