查看更多>>摘要：? 2022 The AuthorsIn this study, Fe-Mn co-doped ceria Fe0.25Mn0.00Ce0.75O2-δ (FMDC1), Fe0.23Mn0.02Ce0.75O2-δ (FMDC2), Fe0.21Mn0.04Ce0.75O2-δ (FMDC3), and Fe0.19Mn0.06Ce0.75O2-δ (FMDC4) powders are synthesized by sol gel method and evaluated as cathode materials for intermediate temperature solid oxide fuel cell (IT-SOFC). The combination of Fe and Mn significantly enhanced the ceria catalytic activity and oxygen kinetics for redox-based reactions. The effects of the co-doping mechanism on the phase composition, optical behavior, and electrochemical performance are mainly investigated. The prepared samples are characterized by XRD, SEM, FTIR, UV–vis, and conductivity tests. X-ray diffraction analysis revealed well-developed crystallinity with a single phase cubic structure of synthesized cathode material. SEM depicted the highly porous facet for Fe0.19Mn0.06Ce0.75O2-δ (FMDC4) resulted in the large triple-phase boundaries for the reduction of ambient air. The inclusion of Mn3+and Fe3+ ions into CeO2 network created additional oxygen vacancies (Ov) and simultaneously reduced the optical band gap energy from 2.81 eV for FMDC1 (x = 0.00) to 2.54 eV for FMDC4 (x = 0.06). Among the four samples, FMDC4 possessed the highest electrical conductivity (～0.89 Scm?1) at 650 °C and corresponding low activation energy of ～0.301 eV, which lead to good catalytic activity with an enhanced electrochemical performance of the SOFC system. The open-circuit voltage (OCV) attained the value of ～0.98 V, maximum power density of ～335 mW cm?2 is obtained at 550 °C, which is comparable to previously reported electrodes. The results suggested that the combination of Fe and Mn into ceria can be used as an effective catalytic promoter for oxygen reduction reactions (ORR), and the composition of FMDC4 resulted in the peak conductivity, short term stability and highest power density as compared to other synthesized samples.
查看更多>>摘要：? 2022 Elsevier B.V.The vapor transport deposition (VTD) processing is one of the most promising techniques to fabricate quasi-one-dimensional antimony selenosulfide (Sb2(S,Se)3) photovoltaic materials with micrometer-scale grains and preferred crystal orientations. However, current researches rarely involve the effect of evaporation source on the film growth by VTD. Herein, we adopt Sb2(S,Se)3 tablets as evaporation sources to develop Sb2(S,Se)3 solar cells for the first time. We find that increasing the evaporation source area can effectively improve the deposition rate of Sb2(S,Se)3 films, leading to an enhancement of the (221) preferred orientation and columnar large grains of the absorber layers, further improves the device photovoltaic performance. With fine-tuning of the evaporation source area, the optimized Sb2(S,Se)3 solar cells show a high efficiency up to 7.6%. This study proposes a unique strategy to improving the quality of low-dimensional materials and a deeper understanding of the growth mechanism via vacuum methods.
查看更多>>摘要：? 2022 Elsevier B.V.TiO2 as one of critical anode materials for sodium ion batteries (SIBs) has excellent characteristics such as low cost, high safety, small volume expansion and high packing density. However, low conductivity and poor sodium ion diffusion ability prevent its further applications in SIBs. Thus, achieving functionalized carbon embraced TiO2 nanocrystals (NCs) becomes an alternative to boost the TiO2 performance in SIBs. Herein, using NH2-MIL-125 (Ti) and sulfur powder as template and sulfur source, N, S dual-anion doped porous carbon embraced ultrafine TiO2 NCs (TiO2@NSPC) are successfully constructed. Due to a large surface-to-volume ratio of TiO2 NCs, the transport pathway of sodium ions is greatly shortened. Meanwhile, N, S dual-anion doped porous carbon can ameliorate the electrical conductivity and transport efficiency of ions, effectively inhibiting the agglomeration of TiO2 NCs. As a result, when used as the anode of SIBs, TiO2@NSPC shows a reversible capacity of 230.2 mAh g-1 after 300 cycles at a current density of 500 mA g-1, with high capacity retention of 88.9%. Moreover, it exhibits extremely high cycling stability with a capacity of 63 mAh g-1 even at 10 A g-1 after 20000 cycles, and higher pseudocapacitive sodium storage than single heteroatom doping, causing its superior sodium ion storage capability. This strategy opens up a new situation to design new electrode materials with enhanced pseudocapacitance and superior sodium storage.
查看更多>>摘要：? 2022 Elsevier B.V.The sensing sensitivities of the Sr2InSbO6:Eu3+ phosphors with different doping concentrations were investigated based on the temperature-dependent decay curves. The crystal and electronic structure were studied by the X-ray diffractometer (XRD), Rietveld refinement, and X-ray photoelectron spectroscopy (XPS). In addition, the luminescent behaviors (e.g., photoluminescence spectra, concentration quenching, thermal stability, and luminescent dynamic) were investigated under the green light excitation (λex = 529 nm). The dominated peak was assigned to the 5D0 → 7F1 transition emitting an orange-red emission. Moreover, the obtained sample exhibited excellent thermal stability that the emission intensity remained 91.61% at 425 K. Eventually, the relative sensing sensitivity of the Sr2EuSbO6 phosphor was 0.766% K?1 and the doping concentration of Eu3+ ions greatly affected the sensing sensitivity. This work is the first time to investigate the single Eu3+-activated luminescent materials under the green light excitation.
查看更多>>摘要：? 2022 Elsevier B.V.Simple, binder free, low-cost chemical route has been employed to design CdSe@PbS core-shell surface architecture in thin film form towards electrochemical supercapacitor application. Horizontal chemical bath deposition (H-CBD) was used to grow one-dimensional (1D) Cd(OH)2 nanowires (NWs) template followed by ion exchange to get 1D CdSe NWs. Further, PbS nanoparticles were encapsulated on the surface of CdSe nanowires by using successive ionic layer adsorption and reaction (SILAR) method. Structural, compositional, and morphological studies have been used to confirm and investigate obtain surface architecture. Interestingly, design CdSe@PbS core-shell surface architecture not only offer maximum active sites but also provide smooth and fast electron transfer path exhibiting significant electrochemical performance with a specific capacity of 82 mAh g-1 and improved long-term stability. Additionally, symmetric electrochemical supercapacitor device of CdSe@PbS exhibits noticeable energy density of 16.14 Wh kg-1 at the power density of 288 W/kg.
查看更多>>摘要：? 2022 Elsevier B.V.The current research project was designed to investigate the influence of Ce3+ substitution on different properties of β-type hexagonal ferrite KCexFe11?xO17 (x = 0, 0.02, 0.06 and 0.1) and to verify the experimental obtained results through theoretical calculations/modeling by performing the curve fittings. For this purpose, the sol-gel auto-combustion route was adopted to synthesize the samples. The X-rays diffraction (XRD) analysis divulged the formation of single phase structure for all samples. It was observed that the structural parameters such as lattice constants a (?) and c (?), dislocation density (g/cm3), crystalline size (nm) and unit cell volume V (?)3 varied with Ce3+ concentration. Moreover, the results obtained from Williamson Hall (W-H) technique revealed that both the pure and Ce-substituted samples exhibited the positive tensile micro strain. The formation of single phase hexaferrite was also confirmed by Fourier transform infrared (FTIR) spectra. The dielectric constant, dielectric loss and tangent losses have large values at low frequency region and declined with increase in frequency. The ac conductivity revealed the increasing trend with enhancement in frequency. The Cole-Cole plot specified the influence of both grains and grain boundaries for the capacitive and resistive nature of the material. The P-E (Polarization vs electric field) loops indicated the increase of resistive nature of sample with Ce3+ contents. The DC electrical resistivity of the sample at voltage range (?200 to 0 V) was found to be diminished with substitution of Ce3+ content. The M-H loops for all the samples represented the alteration in saturation magnetization (Ms) and coercivity (Hc) with the substitution of Ce3+ contents. Consequently, the M-H loop of one concentration surprisingly exhibited both the ferromagnetic and diamagnetic behavior simultaneously.
查看更多>>摘要：? 2022 Elsevier B.V.To mimic the biomechanical properties of natural bone, the porous Ti45Zr10Cu31Pd10Sn4 bulk metallic glass (BMG) with bone-like mechanical characteristics was developed by one step SPS method. In this work, the introduced pore contributions to the corrosion behavior in simulated body fluid and the biocompatibility of BMG were further explored. According to the findings, the porous BMG not only outperforms commercial Ti-based orthopedic implants (CP-Ti and Ti-6Al-4V) in terms of corrosion resistance, but also ranks among the porous biomedical alloys that have been reported. Simultaneously, in vitro investigations revealed that MC3T3 cells co-cultured with porous BMGs could multiply normally, indicating the porous BMG's remarkable biocompatibility.
查看更多>>摘要：? 2022 Elsevier B.V.Motivated by fine tuning of the magnetic and topological properties of MnBi2Te4 via defect engineering, in this work, we report the crystal growth of MnBi2Te4 and related compounds using vapor transport method and crystal characterization by measuring elemental ratio, magnetic and transport properties, and scanning tunneling microscopy. For the growth of MnBi2Te4 single crystals, I2, MnI2, MnCl2, TeCl4, and MoCl5 are all effective transport agents; chemical transportation occurs faster in the presence of iodides than chlorides. We further successfully grow MnSb2Te4, MnBi2?xSbxTe4, and Sb-doped MnBi4Te7 crystals. A small temperature gradient< 20°C between the hot and cold ends of the growth ampoule is critical for the successful crystal growth of MnBi2Te4 and related compounds. Compared to flux grown crystals, vapor transported crystals tend to be Mn stoichiometric, and Sb-bearing compositions have more Mn/Sb site mixing. The vapor transport growth provides a new materials synthesis approach to fine tune the magnetic and topological properties of these intrinsic magnetic topological insulators where controlling defects is vital.
查看更多>>摘要：? 2022 Elsevier B.V.Second harmonic generation (SHG) and upconversion luminescence (UCL), as second-order nonlinear optical (NLO) effects, are crucial in modern optics and optoelectronics. Here, through the chemical engineering process we obtained a series of optically active BaTiO3: Er3+, Yb3+ perovskite materials, exhibiting temperature-dependent NLO responses. Upon 976 nm laser light irradiation, the micron-sized, polycrystalline samples show simultaneously intense UCL and SHG effects. Comparison of the thermometric features based on luminescence thermometry, i.e., band intensity ratio based on thermally-coupled levels of Er3+, and NLO thermometry, i.e., SHG/UCL intensity ratio, shows that the superior thermal sensitivity (≈ 4%/K, at ~400 K) and excellent temperature resolution (δT = 0.07 K) is achieved for the NLO thermometry approach. Furthermore, the combination of NLO spectroscopy with UCL allows rapid, more precise and clear phase transition detection (from tetragonal to cubic phase at around 386 K), compared to conventional structural methods, such as X-ray diffraction and Raman spectroscopy. Our work suggests that some non-Boltzmann, non-linear thermometers can provide much more effective temperature readouts (compared to the commonly studied Boltzmann thermometers), simultaneously working as accurate, rapid and non-invasive phase transition sensors.
查看更多>>摘要：? 2022 Elsevier B.V.Magnetic metal/carbon composites derived from metal-organic frameworks (MOFs) have shown tremendous potential for lightweight electromagnetic (EM) wave absorption. In this study, 1, 3, 5-trimethylbenzene (TMB) and dopamine (DA) are used to regulate the morphology of bimetallic MIL-53. Afterwards, the morphology of MIL-53 rods changes to spindles. The corresponding derivative of FeCo/C composite with spindle microstructure reveals better microwave absorption properties than MIL-53 rods derived FeCo@Fe3C/C composite. The high specific surface area, strong attenuation ability and good impedance matching give desirable EM waves absorption performance of FeCo/C composite. The strongest absorption intensity is ? 78.6 dB with effective absorbing bandwidth of 5.1 GHz when the matching thickness is 2.6 mm. This work provides a new idea for the modification of MOFs derivatives.
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