查看更多>>摘要：? 2022 Elsevier B.V.Designing novel NiO/porous carbon nanocomposites is an effective strategy to improve poor conductivity and rapid capacity fading of NiO in lithium-ion batteries (LIBs). Covalent organic frameworks (COFs) are attractive materials for LIBs as they have large specific surface areas, well-ordered structure, and controllable pore size. Here, we designed a COFTpPa nanoflower as templates for the preparation of porous carbon and a carrier for NiO to obtain NiO/nitrogen-oxygen co-doped carbon nanoflower (NiO/NCF) composites. NiO nanostructures have a smaller volume effect, and the coating of carbon nanoflowers can further buffer the volume expansion of NiO nanostructures, which effectively slow down the capacity decay. In addition, the NCF derived from COFTpPa provide a larger specific surface area and more pores, which not only increases the capacity of nanocomposites but also improves the electrical conductivity of the electrodes. When applied to the anode of LIBs, NCF and NiO/NCF exhibit excellent performance (with first-cycle capacities of 1038.2 and 1685.9 mAh g?1, respectively, and high first coulomb efficiencies of 61.5 % and 60.9 %, respectively). The designed NiO/NCF nanocomposites is a promising anode material for LIBs.
查看更多>>摘要：? 2022 Elsevier B.V.The effect of composition, grain sizes (GSs), and cutting depths on the deformation behaviors and subsurface damages of scratched NiCoCrFe high entropy alloys are investigated using molecular dynamics (MD) simulation. The ability to remove atoms during the cutting process depends on the alloy composition and GSs. When Ni, Co compositions are kept constant, the maximum tangential force-Fx and average friction coefficient-μ increase as decreasing Fe composition from 40% to 24%, then that inverse increase as continuous decrease Fe composition to 20%. Maximum normal force-Fz and average VMS increase with increasing percentage composition of Fe. Besides, the dislocation increases with the Co composition increase leading to a reduction in the efficiency of the cutting process or reducing the number of worn atoms. The reason is that the higher Co content results hinder dislocation movement and reduce the stacking fault energy of the material. The deformation mechanism presents that GBs keep a vital act in barring the propagation dislocation and the development of stacking fault. The GBs also act as an intermediary path to release thermal residual stresses to help reduce cutting force. Interestingly, the number of worn atoms clearly increases as increasing average GS to 81 ?, then decreases as continuously increasing GS to 108 ?.
查看更多>>摘要：? 2022 Elsevier B.V.Cobalt-based perovskites are widely used as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) due to their excellent catalytic activities. In this paper, a series of Nb-doped La0.5Sr0.5Co0.8Cu0.2-xNbxO3–δ (LSCCu0.2-xNbxO3-δ, x = 0.00 ≤ x ≤ 0.075) cathode materials with excellent electrochemical performance are prepared by a Pechini method, and the critical Nb-doping effect is studied in detail. In the new cathode material, the surface oxygen content increases with the Nb doping, while the segregation of Sr and the coefficient of thermal expansion (TEC) is reduced. The optimum LSCCu0.15Nb0.05O3-δ shows the highest surface oxygen content, the lowest surface Sr content, and the highest oxygen reduced reaction (ORR) catalytic activity. At 700 °C, the polarization resistance (Rp) is 0.065 Ω cm2, and the peak power density (PPD) of single cells supported by the electrolyte is 518 mW cm?2, which are promising for the IT-SOFCs. Therefore, the LSCCu0.15Nb0.05O3-δ should be a promising cathode material for the high-performance IT-SOFCs.
查看更多>>摘要：? 2022The redox of anions can be realized by the Li-rich manganese-based (LRM) cathode materials at high voltage, which provides a high specific capacity application prospect for lithium-ion batteries. However, the anion redox reaction brings problems such as poor cycling performance and serious voltage decay, which can be improved by the doping method. Herein, Al3+ cation and (BO3)3-/(BO4)5- polyanion are introduced into the LRM cathode materials to achieve double site occupation and charge regulation of the structure. It results in excellent electrochemical properties, especially in terms of cycling stability. The doped sample shows a discharged capacity of 239 mAh g?1 at 0.01 C after 100 cycles and a capacity retention rate of 92.0 % (higher than 77.9 % of the pristine sample). Through the brand newly-developed in-situ electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy analysis, the joint regulation of Al3+ and (BO3)3-/(BO4)5- inhibits the attack of singlet oxygen on the electrolyte and makes the cathode electrolyte interphases (CEI) film more uniform. First-principles calculations show that the introduction of electron holes and the reduction of the covalency between transition metal and O are key factors in the improvement of electrochemical property and structural stability of the modified materials.
查看更多>>摘要：? 2022 Elsevier B.V.Herein, Li1.0Nb0.6Ti0.5O3 + x wt% BaCu(B2O5) (0 ≤ x ≤ 0.8) ceramics were synthesized via the traditional solid-state reaction method. The sintering behavior, phase, Raman spectra, microwave dielectric characteristics, and chemical compatibility with Ag of the Li1.0Nb0.6Ti0.5O3 + x wt% BaCu(B2O5) samples were comprehensively analyzed. The results show that doping the Li1.0Nb0.6Ti0.5O3 ceramics with BaCu(B2O5) can not only reduce the sintering temperature from 1100 °C to 950 °C but also effectively improve the density and quality factor (Q×f) of the Li1.0Nb0.6Ti0.5O3 samples. Additionally, Li1.0Nb0.6Ti0.5O3 + 0.4 wt% BaCu(B2O5) samples, which were sintered at 950 °C for 4 h, exhibit excellent microwave dielectric properties (εr= 61.4, Q×f = 6423 GHz, and τf= 27.5 ppm/°C) and excellent chemical compatibility with Ag, which makes these ceramics potential candidate materials in the low-temperature co-fired ceramic technology.
查看更多>>摘要：? 2022 Elsevier B.V.Magnetic anisotropy in magnetic nanostructures is highly desirable for the manufacturing of magnetic data storage devices. Therefore, in the present work, the effective magnetic anisotropy is investigated in α-FeCo nanoparticles (NPs) and nanowires (NWs) prepared using hydrazine reduction method. The growth of the NWs was manifested by applying external static magnetic field using bar magnets during synthesis which promoted the continuous growth up to 4 μm of average length and an average diameter of ~ 294 nm. The NP-formation as well as NW-growth adopted the phenomena of Ostwald ripening. The NWs demonstrated the enhanced saturation magnetization, enhanced effective magnetic anisotropy and reduced coercivity as compared to the corresponding NPs. The enhanced magnetic properties of the NWs have been associated with the magnetic force exerted by the external magnetic field during growth which aligned the crystallites along the direction of magnetic field together with the reorientation of the easy axis< 100 > of FeCo along the long axis of the wire. The assistance of the magnetic field during growth enhanced the ease of magnetization along the long axis of the wire. Additionally, the growth induced shape magnetic anisotropy via induced the dipolar interactions lead to the enhanced effective magnetic anisotropy. Thereby, it can be suggested that the external magnetic field applied during synthesis not only plays a primary role in the growth of NWs but also enhances the intrinsic magnetic properties of the material.
查看更多>>摘要：? 2022 Elsevier B.V.In this paper, aluminum alloy doped with Mg, In, Sn and Bi (Al-0.02Mg-0.01Sn-0.004Bi-0.003In) is prepared via melting and casting process. The influence of rare earth elements Bi and In on electrochemical performance of aluminum alloy anode is studied. The self-corrosion of hydrogen evolution and the electrochemical performance are investigated for the prepared alloy in 4 M NaOH electrolyte. The scanning electron microscope is used to study the surface morphology of the prepared alloy after discharge. It shows that synergistic effect between the alloy elements significantly reduces the self-corrosion rate of aluminum anode. Discharge experiments display that the prepared alloy outputs high capacity density and energy density of 2857.14 A h kg?1 and 4805.71 W h kg?1 at a high discharge rate (50 mA cm?2), respectively. It can also obtained considerable anodic utilization of 95.94 %. The prepared aluminum alloy is a desirable candidate anode material for the high-performance Al-air battery.
查看更多>>摘要：? 2022 Elsevier B.V.We have optimized the photovoltaic properties of active ZnO/p-GaAs heterojunction solar cells by pulsed laser deposition method by varying the oxygen pressure from 0 to 50 mTorr during the fabrication process. We observed the crystallinity and grain size of ZnO enhanced with increasing oxygen pressure from 0 to 30 mTorr. In addition, with this increase of oxygen flux, the intensity of E1(LO) modes obtained by Raman measurements declines significantly and almost disappears under an oxygen pressure of 50 mTorr. The change of intensity is assumed to be the change of oxygen vacancy and zinc interstitial concentrations in ZnO films with oxygen pressures. Current-voltage measurements and extractions show that ZnO grown at 30 mTorr displays the best performance with the ISC of 24.3 mA/cm2, the efficiency of 8.746 %, and FF0 of 68.73 %. The high performance of the heterojunction solar cell grown at the oxygen partial pressure of 30 mTorr might be due to the reduction of oxygen vacancies by increasing oxygen during the deposition. The results reveal the importance of the oxygen processing gas in promoting devices performance.
查看更多>>摘要：? 2022 Elsevier B.V.Increasing the oxygen reduction reaction (ORR) electrocatalytic performance of cobalt-nitrogen carbon (Co-NC) materials is highly desired for promoting their widespread application. Yet, it remains challenging due to the existence of activity gap between Co-NC and commercial Pt/C catalyst. Herein, an in-situ decoration strategy was proposed to construct a series of manganese tailored Co-NC (CoxMn-NC, where x represents the molar ratio of Co/Mn) electrocatalysts, which not only increased the content of active metal-Nx sites but also enhanced the graphitized degree of carbon skeleton. The optimal Co0.2Mn-NC exhibited higher half-wave potentials (0.868 V; 0.594 V) than Pt/C (0.838 V; 0.580 V) and robust catalytic stability in alkaline and neutral electrolytes, which was attributed to the tailored nitrogen doping and enhanced graphitized degree. Impressively, a magnesium-air battery driven by Co0.2Mn-NC exhibited better discharging performance than one driven by Pt/C, with a high open circuit voltage (1.61 V), a large peak power density of 83.17 mW cm?2, and a long discharge time of> 87 h at 20 mA cm?2. This work highlighted the promising potential of Mn decorated Co-NC for ORR related energy conversion.
查看更多>>摘要：? 2022 Elsevier B.V.There is a high demand for photocatalysts that can efficiently degrade antibiotics; however, there are challenges in technological development related to charge transfer and light capture ability. In this study, ternary Bi2MoO6/GQDs/TiO2 (denoted as BGT; GQDs refer to graphene quantum dots) heterojunction photocatalysts with high ciprofloxacin (CIP) photodegradation efficiency were successfully prepared. BGT with a 0.20 mL GQD dispersion solution (BGT-2) exhibited the highest CIP photodegradation efficiency (90.21 %). The rate constant of BGT-2 was 15.49 × 10?3 min?1, which was 4.01, 4.16, and 9.22 times higher than those of Bi2MoO6/TiO2 (3.86 × 10?3 min?1), Bi2MoO6 (3.72 × 10?3 min?1), and TiO2 (1.68 × 10?3 min?1), respectively. The degradation efficiencies of amoxicillin and tetracycline hydrochloride were 78.98 % and 92.49 %, respectively. The effects of pH values, water sources, and inorganic anions on CIP degradation were systematically explored. In addition, three environmentally friendly degradation pathways were proposed based on liquid chromatography-mass spectrometry (LC-MS) results and the toxicity evaluation of the various intermediates. Testing the optical and electrochemical properties of the catalysts showed that the synthesized dual Z-scheme heterojunctions can significantly improve the light capture ability and reduce the photogenerated electron-hole recombination rate, effectively addressing the challenges encountered with the use of photocatalysts.
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