Frenkel Defect-modulated Anti-thermal Quenching Luminescence in Lanthanide-doped Sc2(WO4)3

Although large amount of effort has been invested in combating thermal quenching that severely degrades the performance of luminescent materials particularly at high temperatures, not much affirmative progress has been realized. Herein, we demonstrate that the Frenkel defect formed via controlled annealing of Sc₂(WO₄)₃:Ln (Ln=Yb, Er, Eu, Tb, Sm), can work as energy reservoir and back-transfer the stored excitation energy to Ln³⁺ upon heating. Therefore, except routine anti-thermal quenching, thermally enhanced 415-fold downshifting and 405-fold upconversion luminescence are even obtained in Sc₂(WO₄)₃:Yb/Er, which has set a record of both the Yb³⁺-Er³⁺ energy transfer efficiency (>85 %) and the working temperature at 500 and 1073 K, respectively. Moreover, this design strategy is extendable to other hosts possessing Frenkel defect, and modulation of which directly determines whether enhanced or decreased luminescence can be obtained. This discovery has paved new avenues to reliable generation of high-temperature luminescence.     

Rh/Cr2O3 and CoOx Cocatalysts for Efficient Photocatalytic Water Splitting by Poly (Triazine Imide) Crystals

In situ photo-deposition of both Pt and CoO_x cocatalysts on the facets of poly (triazine imide) (PTI) crystals has been developed for photocatalytic overall water splitting. However, the undesired backward reaction (i.e., water formation) on the noble Pt surface is a spontaneously down-hill process, which restricts their efficiency to run the overall water splitting reaction. Herein, we demonstrate that the efficiency for photocatalytic overall water splitting could be largely promoted by the decoration of Rh/Cr₂O₃ and CoO_x as H₂ and O₂ evolution cocatalysts, respectively. Results reveal that the dual cocatalysts greatly extract charges from bulk to surface, while the Rh/Cr₂O₃ cocatalyst dramatically restrains the backward reaction, achieving an apparent quantum efficiency (AQE) of 20.2 % for the photocatalytic overall water splitting reaction.     

Thermally Responsive Selenide-containing Materials Based on Transalkylation of Selenonium Salts

Covalent adaptable networks (CANs) possess unique properties as a result of their internal dynamic bonds, such as self-healing and reprocessing abilities. In this study, we report a thermally responsive C−Se dynamic covalent chemistry (DCC) that relies on the transalkylation exchange between selenonium salts and selenides, which undergo a fast transalkylation reaction in the absence of any catalyst. Additionally, we demonstrate the presence of a dissociative mechanism in the absence of selenide groups. After incorporation of this DCC into selenide-containing polymer materials, it was observed that the cross-linked networks display varying dynamic exchange rates when using different alkylation reagents, suggesting that the reprocessing capacity of selenide-containing materials can be regulated. Also, by incorporating selenonium salts into polymer materials, we observed that the materials exhibited good healing ability at elevated temperatures as well as excellent solvent resistance at ambient temperature. This novel dynamic covalent chemistry thus provides a straightforward method for the healing and reprocessing of selenide-containing materials.     

Comprehensive Mechanism for CO Electroreduction on Dual-Atom-Catalyst-Anchored N-Doped Graphene

Carbon neutrality has drawn increasing attention for realizing the carbon cyclization and reducing the greenhouse effect. Although the C1 products, such as CO, can be achieved with a high Faraday efficiency, the targeted production of C2 fuels as well as the mechanism have not been systematically investigated. In this work, we carry out a first-principles study to screen dual-atom catalysts (DACs) for producing C2 fuels through the electrocatalytic carbon monoxide reduction reaction (e-CORR). We find that methanol, ethanol and ethylene can be produced on both DAC−Co and DAC−Cu, while acetate can be achieved on DAC−Cu only. Importantly, methanol and ethylene are preferred on DAC−Co, while acetate and ethylene on DAC−Cu. Furthermore, we show that the explicit solvent can enhance the adsorption and influence the protonation steps, which subsequently affects the protonation and dimerization behavior as well as the performance and selectivity of e-CORR on DACs. We further demonstrate that the C−C coupling is easy to be formed and stabilized if the Integrated Crystal Orbital Hamilton Population (ICOHP) is low because of the low energy barrier. Our findings provide not only guidance on the design of novel catalysts for e-CORR, but an insightful understanding on the reduction mechanism.     

An efficient high-speed counter-current chromatography method for the preparative separation of sesquiterpenoids from the rhizomes of Cyperus rotundus L. combined with evaluation of the anti-inflammation activity in vitro and molecular docking

Cyperus rotundus L. has been extensively used in ancient medication for the treatment of different disorders worldwide, in which sesquiterpenes are the most representative components. In this study, sesquiterpenes were effectively purified by two-dimensional counter-current chromatography in combination with continuous injection and inner-recycling mode with a solvent system of n-hexane/ethyl acetate/methanol/water (1:0.2:1:0.2, v/v/v/v). For one-dimension separation, continuous injection mode was used with three times injection and the inner-recycling mode was adopted for the separation of two mixtures for two-dimensional separation. Finally, four sesquiterpenoids, including scariodione ( 1 ), cyperenoic acid ( 2 ), scariodione ( 3 ), and α-cyperone ( 4 ), were obtained with purities over 98%. Mass spectrometry and nuclear magnetic resonance were applied to identify their structures. The results from the anti-inflammation effect with zebrafish demonstrated that cyperenoic acid exhibited stronger anti-inflammation activity. Molecular docking results suggested that cyperenoic acid possessed lower binding energies –9.4545 kcal/mol with 1CX2 to form formed hydrogen bond interaction with ARG120. In general, all the obtained findings proved that the strong anti-inflammation capacity of cyperenoic acid can have the potential of being adopted for treating diseases resulting from inflammation.     

Separation,identification, and structural characterization of sucrose ester isomers from tobacco

Sucrose esters (SEs) are crucial tobacco smoke flavor precursors and play a significant role in tobacco's functionality. Due to their structural complexity, the separation and analysis of SEs in tobacco remain a major challenge, and massive structures of SEs have not yet been fully identified. In this study, the fractions enriched in SEs were obtained from oriental and flue-cured tobacco through a series of pretreatments, and two types of SEs (Types I and II) were distinguished by liquid chromatography-tandem mass spectrometry (LC-MSⁿ) analysis, with Type II SEs newly characterized in tobacco. Five groups of main SEs were further purified using preparative high-performance LC (HPLC) coupled to an evaporative light scattering detector, and their structures were characterized by nuclear magnetic resonance spectrometry techniques including ¹H, ¹³C, correlation spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond correlation. By combining LC-MSⁿ and nuclear magnetic resonance spectrometry, the structures of eight SE isomers were finally proposed, of which four were newly identified. These findings further enhance the understanding of the structural diversity of SEs in tobacco, serving as a valuable reference for future research on the elucidation, synthesis, and metabolism of SEs.     

无机固态材料中气体元素分析的现状与进展

本文介绍了气体元素分析样品表面处理的最新研究成果,综述了热导法、红外吸收法、库仑滴定法、飞行时间质谱法和火花源原子发射光谱法等分析方法在无机固态材料气体分析中的应用现状,分析了各自的特点及存在的问题,并展望了气体分析的发展方向(引用文献85篇)。     

Graphene Nanoribbons from Tetraphenylethene‐Based Polymeric Precursor: Chemical Synthesis and Application in Thin‐Film Field‐Effect Transistor

Graphene nanoribbons (GNRs) with a non‐zero bandgap are regarded as a promising candidate for the fabrication of electronic devices. In this study, large‐scale solution synthesis of narrow GNRs was firstly achieved by the intramolecular cyclodehydrogenation of kinked tetraphenylethene (TPE) polymer precursors prepared by A₂B₂‐type Suzuki‐Miyaura polymerization. After the cyclization reaction, the nanoribbons have a better conjugation than the twisted polymer precursor, resulting in obvious red shift in UV/vis absorption and photoluminescence (PL) spectra. The efficient formation of conjugated nanoribbons was also investigated by Raman, FTIR spectroscopy, and microscopic studies. Furthermore, such structurally well‐defined GNRs have been successfully developed for top‐gated field‐effect transistor (FET) by directly solution processing. The AFM images show that the prepared‐GNRs thin films form crystalline fibrillar intercalating networks, which can effectively facilitate the charge transport. These FET devices with ion‐gel gate dielectrics exhibit low‐voltage operation (<5 V) with excellent mobility up to 0.41 cm²·V^?1·s^?1 and an on‐off ratio of 3×10⁴, thus opening up new opportunities for flexible GNRs‐based electronic devices.     

Quantum-chemical study on the catalytic activity of TinRumO2(1 1 0) surfaces on chlorine evolution

Based on the generalized gradient approximation (GGA), Perdew-Wang-91 (PW91) combined with a periodic slab model has been applied to study the catalytic activity of chlorine evolution on TinRumO2(1 1 0) surface. Metal oxide model TinRumO2 has been established with pure TiO2 and RuO2 on the basis set of Double Numerical plus polarization (DNP), in which the proportion of n:m was 3:1, 1:1, or 1:3. Analysis on the reaction activity in the electrochemical reaction and the electrochemical desorption reaction was based on Frontiermolecular orbital theory. The results show that the TinRumO2 with a ratio of Ti:Ru at 3:1 is best facilitates the electrochemical reaction and electrochemical desorption reaction to produce M-Clads intermediate and precipitate Cl2. In addition, the adsorption energy of Cl on the surface of Ti3Ru1O2 possesses the minimum value of 2.514 eV, and thus electrochemical desorption reaction could occur most easily.     

Deoxygenation of methyl laurate to hydrocarbons on silica-supported Ni-Mo phosphides: Effect of calcination temperatures of precursor

SiO2-supported Ni-Mo bimetallic phosphides were prepared by temperature-programmed reduction(TPR) method from the phosphate precursors calcined at different temperatures. Their properties were characterized by means of ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis DRS), H2temperature-programmed reduction(H2-TPR), X-ray diffraction(XRD), transmission electron microscopy(TEM), CO chemisorption, H2 and NH3temperature-programmed desorptions(H2-TPD and NH3-TPD). Their catalytic performances for the deoxygenation of methyl laurate were tested in a fixed-bed reactor. When the precursors were calcined at 400 and 500?C, respectively, Ni Mo P2 phase could be formed apart from Ni2 P and Mo P phases in the prepared C400 and C500 catalysts. However, when the precursors were calcined at600, 700 and 800°C, respectively, only Ni2 P and Mo P phases could be detected in the prepared C600, C700 and C800 catalysts. Also, in C400, C500 and C600 catalysts, Mo atoms were found to be entered in the lattice of Ni2 P phase, but the entering extent became less with the increase of calcination temperature. As the calcination temperature of the precursor increased, the interaction between Ni and Mo in the prepared catalysts decreased, and the phosphide crystallite size tended to increase, subsequently leading to the decrease in the surface metal site density and the acid amount. C600 catalyst showed the highest activity among the tested ones for the deoxygenation of methyl laurate. As the calcination temperature of the precursor increased, the selectivity to C12 hydrocarbons decreased while the selectivity to C11 hydrocarbons tended to increase. This can be mainly attributed to the decreased Ni-Mo interaction and the increased phosphide particle size. In sum, the structure and performance of Ni-Mo bimetallic phosphide catalyst can be tuned by the calcination temperature of precursor.