Li2ZnTi3O8 (LZTO) anodes of lithium?ion batteries have been prepared by a sol?gel method. The effects of the calcination temperature and time on the electrochemical performance have been studied for LZTO in detailed. The optimum calcination temperature and time are 700 ℃ and 3 h, respectively. On the basis of the optimum preparation process, citric acid as the chelating agent has been introduced into the synthesis to modify LZTO. When the molar ratio of metal ions to citric acid is 2.00∶1.50, the obtained product is denoted as LZTO?2/1.50, which has small particle size, good dispersion, and then shows good electrochemical performance. The discharge specific capacity is 203.6 mA·h/g after 300 cycles at the current density of 0.5 A /g for LZTO?2/1.50.
The Fe/Mo ordering at B?sites of Ba2FeMoO6-δ (BFM) were changed by adjusting Fe/Mo amount of substance ratio (i.e., stoichiometric ratio), and then a new double?perovskite anode material Ba2Fe1.3Mo0.7O6-δ (BFM0.7) for SOFC were obtained. The results indicated that the electrical conductivity of the BFM0.7 anode is 15.0~20.0 S/cm at 600~800 ℃ in H2, which is much larger than that of the lowest target for SOFC electrode (0.1 S/cm). The peak power density and polarization resistance of the BFM0.7 anode cell attained 1 149 mW/cm2 and 0.15 Ω·cm2 at 850 ℃. Compared with BFM anode, the performance of BFM0.7 is significantly improved. In addition, the performance of BFM0.7 anode cell showed no degradation after testing for 39 h, indicating that the BFM0.7 anode possesses has excellent electrochemical stability.
Monolayer Janus transition metal disulfides have low dimension, high mobility, and peculiar electronic structure properties, which have potential applications in electronics and optoelectronic devices. In devices made of monolayer Janus transition metal disulfide and substrate materials,are usually stressed due to lattice mismatch between monolayer Janus transition metal disulfides and substrate, it is significant to study the strain effect on physical properties of monolayer Janus transition metal disulfides through Raman scattering.This paper systematically investigate the biaxial strain effect on the atomic structure, electronic structure and Raman spectra of monolayer Janus MoSSe. The results show that monolayer Janus MoSSe can exhibit a band gap transition from direct to indirect one under biaxial strain, due to both the energy shift of bonding orbitals between the top of the valence band and the bottom of the conduction band and the sensitivity to strain. This paper also thoroughly study the strain effect on the Raman shift and intensity of monolayer Janus MoSSe. It is found that under biaxial strain modulation from decreasing compressive to increasing tensile, for the Raman shift, the three peaks of E1, E2, and A 1 1 red?shift, while the peak of A 1 2 blue?shifts abnormally with decreasing compressive strain; for the intensity, the peak intensity of the doubly?degenerate modes (E1,E2) increases monotonically, while singly?degenerate modes shows the opposite trend, except for the A 1 1 which intensity decreases with decreasing compressive strain and then increases with tensile strain. This paper propose a simple model to comprehend the strain effect. This theoretical study may supply an effective means to quickly and quantitatively characterize the strain size and type in Janus materials through the frequency difference and intensity ratio between typical Raman peaks.
A new type of Ruddlesden?Popper cobalt?rich layer perovskite oxide La1.5Ca0.5Ni0.2Co0.8O4+δ (LCNC) was synthesized by a sol?gel process. The results show that the conductivity of LCNC in air at 400 ℃ to 800 ℃ is 4~58 S/cm, which is better than that of most reported SOFC cathode materials. The polarization impedance of symmetrical battery LCNC|LSGM|LCNC is 0.16 Ω·cm2 at 800 ℃. The maximum power density of the single cell supported by 300 μm thick La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) with the LCNC cathode was 527 mW/cm2, and the performance of the single cell decreases slightly after working continuously for 50 hours. The experimental results show that LCNC is a potential SOFC cathode material.
As an electrochemical inert cation, Mg2+ has an ionic radius (0.072 nm) similar to that of Li+ (0.076 nm), which is widely used to replace Li+ in Li?rich layered oxides (LLOs) materials. However, the influence of Mg2+ on the crystal structure of LLOs materials is still controversial. In this work, the Mg?doped Li?rich cathode materials Li1.2-x Mg x Mn0.54Ni0.13Co0.13O2 were synthesized by a sol?gel and high?temperature calcination method. The crystal structure, and valence state of elements in synthesized materials were systematically studied via X?ray diffraction, and X?ray photoelectron spectroscopy. These results indicated that Mg2+ doping can increase the cell parameters of LLOs materials. At the same time, compared with Li1.2Mn0.54Ni0.13Co0.13O2, Mg?doping can effectively improve the electrochemical performance of LLOs materials. After optimization, the Mg?0.03 sample exhibits anomalous electrochemical performance, that is, the initial discharge?specific capacity is 291.9 mA?h/g and the initial coulomb efficiency is 78.40%.
In this paper, a kind of composite phase change material (capric?lauric acid/expanded vermiculite) using expanded vermiculite as the matrix and capric?lauric acid binary eutectic as the adsorbent was fabricated by vacuum impregnation technology. The chemical compatibility, morphology, stability，thermal?physical properties and reliability of the prepared composite capric?lauric acid/expanded vermiculite were investigated by fourier transform infrared spectrum (FT?IR), scanning electronic microscope (SEM), thermal gravimetric analyzer (TGA), differential scanning calorimeter (DSC) and thermal cycling test. The melting and solidification phase transition temperatures of capric?lauric acid/expanded vermiculite are 18.42 ℃ and 17.51 ℃, respectively. The latent heat of melting and solidification phase transition are 66.9 J/g and 62.9 J/g, respectively. Besides, the encapsulation amount of capric?lauric acid in expanded vermiculite can reach 52.97%, and it has good thermal stability between working temperature. Moreover, the capric?lauric acid/expanded vermiculite was used to substitute for a certain proportion of fine sand to prepare thermal storage mortar, the mechanical and thermal performance of capric?lauric acid/expanded vermiculite?based mortar was evaluated. The test result shows that prepared capric?lauric acid/expanded vermiculite?based thermal storage mortar is a potential material for building heat regulation and energy saving.
A mononuclear Cu complex Cu0.5(4,4'?bipy)(H2O)·L·0.5(4,4'?bipy)·2H2O (1) was obtained by hydrothermal reaction with Cu2+ as the central ion and 4,4'?bipy as the nitrogen?containing auxiliary ligand. Its structure and composition were characterized by modern characterization methods, such as X?ray single crystal diffraction, elemental analysis and infrared spectrum. The results show that Cu2+ is six coordinated with four nitrogen atoms of 4,4'?bipy molecules and two oxygen atoms of H2O molecules, showing a distorted octahedral coordination configuration. L2- anion only balances the positive charges in compound 1 and does not participate in the coordination of metal Cu2+. Cu2+ coordinates with 4,4'?bipy and H2O molecules to form a lattice layered structure [Cu(4,4'?bipy)2(H2O)2]2+, the hydroxyl group of L2- anion and free H2O molecules form hydrogen bonds with H2O molecules in the layered structure respectively, which increases the thermal stability of H2O molecules in compound 1. The fluorescence emission of compound 1 is at 409 nm, which can be attributed to the intraligand emission state. Compared with the ligand, there is a slight red shift, which may be caused by the coordination between 4,4'? bipy ligand and Cu2+.
Metal nanomaterials with high thermal conductivity are ideal promoters for enhanced gas hydrate formation, including metal?based nanoparticles, metal oxides, and metalloid oxides. In this paper, the effects of different kinds of metal nanomaterials on the formation of gas hydrates were reviewed, and the effects of parameters such as the induction time and gas consumption of enhanced hydrate formation were introduced from the three aspects of additive concentration, particle size and surface properties. The results show that the heat transfer effect of metal?based nanoparticles is better, and some metal oxides and metalloid oxides will exhibit an inhibitory effect; the appropriate addition concentration and particle size have an important impact on the formation of hydrates. In addition, the combination of metal nanomaterials and chemical reagents can significantly improve the dispersion stability of nanoparticles, thereby promoting the efficient generation of hydrates.
The interaction between chiral molecules and plasmons plays a crucial role in regulating the circular dichroism (CD) of chiral modified nanostructures. The direct interaction between chiral molecules and metals can trigger aggregation, thereby affecting their optical properties. In this study, we experimentally synthesized a chiral Core Shell Structure (Au@molecule@SiO2）. Due to the presence of a SiO2 shell layer, the particles retain molecular and metal properties while maintaining good stability. Here the UV?Vis absorption spectra and CD spectra of the chiral?modified structure (Au@molecule@SiO2) were measured, and the CD signal induced by the chiral molecules was found at the plasmon resonance position of Au Nanoparticles (Au NPs) (530 nm). To explore the underlying physical mechanism, Mie theory was used to further reveal that the induced CD signal at 530 nm mainly comes from the interaction between electric and magnetic dipoles in the chiral core?shell structure. This work provides experimental references and an effective theoretical framework for the study of chiral core?shell structures.
