查看更多>>摘要：Molybdenum diselenide (MoSe2) has been drawing increasingly more attention due to its natural abundance, larger interlayer space (~ 6.5 ?) and higher theoretical capacity (422 mA h/g). Nevertheless, the low capacity and the poor cycling stability greatly hinder their application. Here, microstructures constructed by MoSe2/C nanoplates sheathed in N-doped carbon (MoSe2/C@NC) were synthesized by co-precipitation approach and subsequent annealing treatment with selenium powder. MoSe2/C@NC electrode shows the reversible sodium/potassium ion storage capacity of 362 and 310 mA h/g at 0.1 A/g, respectively. In SIBs, the capacity retains 237 mA h/g after a long-term cycling (500 cycles) at 1 A/g. In addition, it is worth noting that the capacity also retains 212 mA h/g at 1 A/g over 100 cycles in PIBs. The excellent performances for sodium and potassium ions storage are credited to the synergistic effect of unique assembly structure of MoSe2/C@NC, which can effectively alleviate volume expansion, and improve the electrical conductivity of MoSe2.
查看更多>>摘要：Single-step thermal chemical vapor deposition was optimized at 400 °C for the growth of CoFe2O4 spinel thin films starting from the corresponding metal acetylacetonate precursors. Enhanced magnetization was observed for conditions leading to a columnar growth with a preferred (100) orientation. The implemented liquid precursor delivery secured a reliable films’ composition control and a straightforward dosage of acetylacetone, as a molecular growth inhibitor, to enhance the film conformality on structured surfaces. The optimized conditions enabled an efficient micro-pore filling, and the fabricated ordered micropillar arrays feature a coercivity of 1.8 kOe and a saturation magnetization of 350 emu/cm3. The implemented state-of-the-art up-scalable microfabrication technology, the reasonable thermal budget and the resulting high magnetic performance pave the way towards the development of innovative magnetoelectric devices.
查看更多>>摘要：A recently investigated HT-Ce2Rh2Ga was found to exhibit a magnetic phase transition at 128.5 K. A comprehensive multi-temperature investigation in the 85–400 K temperature range showed that the compound undergoes a structural phase transition as well. Upon cooling below 123.2 K its crystal symmetry changes from Cmce to C2/m being accompanied by non-merohedral twinning. Both structural transformations are reversible with a small hysteresis furthermore. The temperature of the structural phase transition was detected by anomalies in temperature dependences of unit cell dimensions, interatomic distances, and atomic displacement parameters. Negative thermal expansion along the c-axis was revealed in the range 92.7–170 K. When cooled to 200 K, Ce and Rh atoms converge to a distance sufficient for structural changes to become qualitative. Upon further cooling to 145 K, this interaction affects positions of all the atoms in the structure, leading to anisotropy of earlier equivalent interatomic distances and a sharp anomalous increase in atomic displacement parameters, the dynamics of which deviates more and more from the theoretical dependences in the Einstein and Debye approximations.
查看更多>>摘要：To comprehensively understand the relationship between substrate type and boron doped diamond (BDD) electrode structure, performance and antibiotic tetracycline mineralization, this work made a systematic evaluation of BDD electrodes prepared by the same process but based on different substrates, namely Si/BDD, Ta/BDD, Nb/BDD and Ti/BDD, in terms of microstructure, electrochemical properties, antibiotic tetracycline mineralization and accelerated service life. The results show that the physical and chemical properties of substrates have significant impacts on BDD film growth and microstructure. The substrate and film surface characteristics determined the physicochemical properties of BDD electrode. The growth rate of BDD film follows the sequence order as Si > Ta > Nb ? Ti. Ti/BDD electrode shows the higher oxygen evolution potential, lower background current, smaller electron transfer resistance, lower surface activity and shorter service life. Tetracycline can be completely removed by direct electron transfer or free radical mediated oxidization. On Ti/BDD electrode tetracycline removal and current efficiency are the second only to Si/BDD and the lowest electricity consumption can be obtained. Nb/BDD electrode shows slightly better performance than Ta/BDD electrode. Furthermore, the anode failure mode of Ti/BDD electrode was revealed.
查看更多>>摘要：The electrodeposition of Ni-Cu and Ni-Cu-P was performed over steel electrodes using baths containing aspartate as a complexing agent for the metallic cations. Through the rotating disk electrode technique and the measurement of the deposition potentials, it was found that the electrodeposition is controlled by activation at current densities (jdep) equal or lower than 10 mA cm?2 and suffers limitations on diffusion for jdep>10 mA cm?2. The hydrogen evolution reaction during the electrodeposition was more intense over Ni-Cu-P films leading to a lower efficiency compared to the Ni-Cu films. The composition of the amount of Cu in the Ni-Cu films varied from 13.7% to 21.5%, while the amount of Cu in the Ni-Cu-P films varied from 24.4% to 43.1%. The P incorporation was low, varying from 1.2% to 2.8%. For the Ni-Cu films, globular, dendritic, and smooth films were obtained depending on the deposition control and the efficiency. The Ni-Cu-P presented dendritic and smooth morphology depending on the efficiency.
查看更多>>摘要：The reaction mechanism of a spinel-type sodium titanium oxide (Na3LiTi5O12) was investigated using in situ XRD during the Na insertion/extraction process. The XRD profiles gradually shifted to lower and higher angles during the sodiation and de-sodiation processes, respectively, while maintaining a spinel-type structure and no new peaks were observed, indicating a solid-solution reaction according to the following reaction; (Na)38a(Li1Ti5)16dO12192i + 3Na+ + 3e? ? (Na)616c(Li1Ti5)16dO12192i. The evolution of the XRD profile was confirmed to be highly reversible, which explains the high cycling stability of the NTO electrode. There are two possible sites for Na to occupy: 8a and 16c. The Na ion initially occupies only the 8a site, as confirmed by the 220 peak. The intensity of the 220 peak gradually decreased with increasing SOC and was hardly detected at an SOC of 50%, indicating that all the Na ions at the 8a sites moved to the 16c sites. Topological analysis combined with XRD revealed that the Na ion at the 8a site is stable with one other Na ion at an adjacent 16c site despite the interatomic distance being too short.
查看更多>>摘要：Recent advances have presented a promising p-n heterostructure strategy to develop highly ionic conducting electrolytes for low-temperature solid oxide fuel cells (LT-SOFCs). In this study, a p–n–n heterostructure approach is further proposed to develop new electrolytes for LT-SOFCs based on p-type Ni0.8Co0.15Al0.05LiO2?δ (NCAL), n-type ZnO, and n-type SnO2. Material characterization reveals that the developed NCAL-ZnO-SnO2 electrolyte gains a desirable heterostructure with homogenous distribution and hetero-interface as well as enriched oxygen vacancies. Electrochemical studies find that the electrical conductivity and fuel cell performance are significantly correlated with the mass ratios of p/n phases in the samples. The 2NCAL-1(ZnO-SnO2) exhibits a highest ionic conductivity of 0.389 S cm?1 at 530 ℃ along with a remarkable fuel cell power density of 1267 mW cm?2, which are apparently superior to those of p–n heterostructure electrolytes of NCAL-ZnO and NCAL-SnO2. By considering the semiconductor features of the used materials, further investigation in terms of energy band structure and rectifying characteristic studies indicate the possible existence of p-n-n heterojunction in the NCAL-ZnO-SnO2 fuel cell with rectifying behavior for charge carrier modulation. On basis of which, an energy band alignment effect is propounded to illustrate the electronic blocking and ionic acceleration processes of the p–n–n heterostructure electrolyte. The successful demonstration of 2NCAL-1(ZnO-SnO2) thus provides a new approach to develop advanced electrolytes for LT-SOFCs.
查看更多>>摘要：This work focuses on the nanomolar-level detection of the antihistamine, promethazine hydrochloride (PMTZ), based on a novel ternary nanocomposite sonochemically prepared using a zinc-graphene oxide (GO-Zn) complex and a nanosheets-stacked spherical ZnO. The efficient detection of PMTZ is very important because of its critical side effects when overdosed and its high toxicity to aquatic life. Morphologically varied ZnO nanostructures (spindle-like, nanosheets-stacked spherical, nanoplates-based spherical, and rod-flower) were synthesized using a new aqueous solution approach by regulating the concentration of base in the reaction mixture. Characterization techniques including SEM, TEM, elemental mapping, XRD, Raman spectroscopy, and XPS were utilized for analyzing the properties of synthesized materials. Electrochemical investigations employing cyclic voltammetry and differential pulse voltammetry techniques showcased outstanding electrocatalytic activity of the proposed ternary nanocomposite-modified screen-printed carbon electrode towards PMTZ detection. The PMTZ sensor attained ultra-low detection limit of 0.3 nM, broad linear range from 0.05 to 177.45 μM, and a sensitivity of 5.29 μAμM?1cm?2. Furthermore, good operational stability, anti-interference, repeatability, and reproducibility was exhibited by the developed sensor. The real sample analysis provided excellent recovery results indicating outstanding practicability of PMTZ detection.
查看更多>>摘要：In the present study, aluminum metal matrix composites (AMCs) reinforced with Al-Cr-Fe quasicrystal (AlQC) nanoparticles (3 and 5 wt%) and monolithic Al were produced by the accumulative roll bonding (ARB) process up to 8 cycles. X-ray diffraction (XRD) and scanning electron microscopy were employed for structural evaluation. XRD results confirmed the presence of AlQC nano-powders in the Al matrix and the decrease of the matrix crystallite size to a nanometric scale (105 nm) after eight cycles. Microstructural studies showed an improvement in the distribution of the AlQC nanoparticles in the matrix, as well as the connection improvement between Al layers by increasing ARB cycles. Density measurements also showed that theoretical density of the composite samples was greater than the measured density, which is attributed to the presence of voids and pores. Also, corrosion behavior investigations in 3.5 wt% NaCl solution showed that corrosion potential decreases and corrosion rate increases in the presence of AlQC nanoparticles as the reinforcement in comparison to monolithic Al. Finally, a decrease in the corrosion rate of the samples was realized by increasing ARB cycles to the 4 cycle and then an increase was detected by further increasing cycles up to 8 cycles.
查看更多>>摘要：In the present work we study the polar properties of domain walls using a recently developed method of combining layer group analysis with order parameter symmetry [Schranz et al. PRB 100 (2019) 184105]. Using this method we obtain a detailed overview on the microscopic and macroscopic properties of domain walls which we can quantify with results from Landau-Ginzburg-Devonshire theory. Recently, we have applied [Schranz et al. PRB 102 (2020) 184101] the method to analyse the symmetry and polar properties of ferroelastic twin walls and antiphase boundaries in SrTiO3. Here we discuss the elastic anomalies observed in SrTiO3 at various temperatures in the light of these findings.
NSTL
Elsevier