查看更多>>摘要：? 2022 Elsevier B.V.In this study, functionalized carbon nanotube decorated with PtFeV tri-metallic electrocatalysts (PtFeV/FCNT) by different concentrations are prepared using the ethylene glycol reduction method in order to minimize electrocatalyst load and enhance the performance of the fuel cell cathodic electrode, simultaneously. The homogeneous distribution of PtFeV catalysts on the FCNT substrate and also the change in the electronic states of Pt, Fe and V elements is confirmed with characterization analyses. Electrode half-cell tests simulating the cathodic compartment of a polymer fuel cell show that the 2 mM PtFeV/FCNT electrode increases the maximum power density by about 500% compared to the commercial Pt/C 20% wt catalyst (from 4.43 to 27.31 mW/cm2). The increase in maximum power density along with the decrease in charge transfer resistance specified by the electrochemical impedance tests confirm the synergistic effects of alloying Pt with Fe and V and the application of FCNTs. In fact, in addition to the exceptional specific surface area and electrical conductivity of FCNTs, the increase in PtFeV/FCNT electrode performance can be attributed to the improved electrocatalytic activity of PtFeV tri-metallic nanoparticle alloy, resulting from the valence alterations and the Pt network compression during alloying.
查看更多>>摘要：? 2022 Elsevier B.V.The notorious polysulfide shuttle and sluggish kinetics seriously challenge the commercialization process of lithium-sulfur (Li-S) batteries, even though their addictive theoretical energy density and specific capacity. Herein, a MOF-808-derived Ce-doped ZrOF (Ce-ZrOF) composite is constructed by the impregnation of Zr-based MOF-808 film with Ce salt and carbonization as an efficacious polysulfide inhibitor in Li-S batteries, which is anchored on carbon cloth. With a hierarchical porous structure, sufficient adsorption sites and Ce-doping, the proposed structure is qualified for efficaciously trapping polysulfides through adsorption. Meanwhile, the metal Ce and oxygen vacancies facilitate the catalytic conversion of polysulfides, enabling the accelerated redox kinetics. Based on the above synergistic effect, the developed interlayer delivers a high initial capacity of 1048 mAh g?1 with a durable cyclability of a limited decay of 0.025% per cycle for 500 cycles under 1 C, a considerable rate performance of 744 mAh g?1 at 5 C and an outstanding area capacity of 9.6 mAh cm?2 with the high sulfur loading (10.8 mg cm?2).
查看更多>>摘要：? 2022 Elsevier B.V.With the quick development of electric vehicles and grid energy storage, the demand and production of lithium ion batteries (LIBs) are rapidly increasing, and the problem of lithium resource shortage becomes more and more serious. Both in terms of economic value and environmental protection, the recycling and regeneration of the spent lithium batteries is extremely urgent. Herein, a green and efficient hydrothermal technique for direct regeneration of spent lithium iron phosphate (LiFePO4 or LFP) was proposed. LFP loses the partial lithium during the long cycle and converts to FePO4 (FP), therefore, the replacement of the lost lithium is crucial for the regeneration of spent LFP. Herein, the effects of hydrothermal conditions such as reaction temperature, Li+ concentration and reducing agent concentration on the performance of product are systemically studied. Besides, it has been found that the control of hydrothermal condition is conductive to the supplement of Li and the enhancement of electrochemical performance of the product. Under hydrothermal conditions of 200 °C for 3 h, the regenerated LFP shows the optimal electrochemical performance of 165.9, 151.93, 145.92, 133.11 and 114.96 mAh g?1 at 0.1, 0.5, 1, 2, and 5 C, respectively. In addition, the capacity retention is as high as 99.1% after 200 cycles at 1 C. Therefore, this work provides a new idea for the direct regeneration of spent LFP cathode materials.
查看更多>>摘要：? 2022 Elsevier B.V.The increasing complexity of environmental pollution posed a higher requirement for the development of environment-governed functional materials. Herein, to achieve desired synergy and multiple functionalities of eco-friendly nanomaterials, a micelle-mediated metal assembly strategy was proposed to integrate plasmonic Ag nanoparticles into MnOx modified mesoporous silica hosts by metal-modified neutral dodecyl amine surfactant, correspondingly, a multifunctional mesoporous Ag@MnOx/m-SiO2 (AMSs) nanocomposite was obtained. The characterization results revealed that the introduction of Mn and alteration in the amount of Ag mediated the formation of a special mesostructure and nanometric morphology of the silica host. Bearing a low Ag loading (r.t. of Ag/Mn = 1/2), ultrafine Ag nanoparticles were embedded in the inner core of mesoporous silica nanospheres. While assembly with a higher Ag concentration affected the morphology of the obtained AMSs and resulted in rich Ag nanoparticles on the exterior surface of mesoporous silica. By this strategy, ultrafine Ag nanoparticles and well-dispersed amorphous MnOx species were coupled into the mesoporous silica to reach a special configuration and integrated functionality. The obtained AMSs-3 can effectively inactivate bacteria (E. coli, S. aureus, and P. aeruginosa) with a prolonged inhibitory effect, rapidly reduce harmful nitrophenol, as well as photothermally assist water evaporation (evaporation rate of 1.51 kg m?2 h?1, receiver efficiency of 87%). This work provides versatile environment-governing functional nanomaterials for both highly effective antimicrobial and environmental remediation.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, a MnNiO3/Ni6MnO8 composite is synthesized under the hydrothermal condition of 120–160 ℃ through different growth time. The three-dimensional (3D) flower-like MnNiO3/Ni6MnO8 nanospheres are successfully obtained under the reaction condition of 140 ℃ for 10 h. The unique 3D spherical structure of MnNiO3/Ni6MnO8 with mesopores can facilitate the transport of electrolyte ions and generate more redox active sites. The specific capacity of MnNiO3/Ni6MnO8 can reach 70.6 mAh/g at 1 A/g, and reserve 70.1% even at 10 A/g. What's more, the MnNiO3/Ni6MnO8 composite displays excellent cycling stability that the capacity has almost no degradation after 6000 cycles at 3 A/g. In addition, the energy storage mechanism of MnNiO3/Ni6MnO8 is also studied and the results show that it is a battery type electrode material dominated by diffusion-controlled process. Moreover, the as-prepared MnNiO3/Ni6MnO8 nanospheres are further used to assemble a hybrid device. The device can provide a specific energy of 22.3 Wh/kg at a specific power of 1074.7 W/kg. The specific capacity of 122% is kept after 10000 cycles at 8 A/g, revealing its superior cycling stability. As expected, the commercial LEDs with different colors can be lit up by MnNiO3/Ni6MnO8//AC device, indicating that the as-prepared MnNiO3/Ni6MnO8 electrode has good application potential.
查看更多>>摘要：? 2022 Elsevier B.V.The black phosphorus (BP) was coordinated with molybdenum diboride (MoB2) for achieving excellent flame retardancy. The BP-MoB2 nanohybrids was fabricated by ball milling to improve the dispersion state of BP and MoB2 in graphene oxide (GO), where the BP was coordinate with MoB2 via P-Mo bonds. Based on density functional theory (DFT) calculations, the adsorption energy between BP and MoB2 is ? 1.01 eV, which suggests there exists a strong mutual adsorption. With the incorporation of 15 wt% BP-MoB2 into GO matrix, compared with neat GO, 60.28 % reduction in peak heat release rate (PHRR) was achieved. The addition of 20 wt% BP- MoB2 results in a maximum decrease of 75.00 % in total heat release (THR). TG-IR results demonstrated that the addition of 20 % BP-MoB2 into GO significantly reduces the decomposition of GO. Meanwhile, the GO/BP-MoB2 5 nanocomposites exhibited ultrafast intelligent response ability at 1 s. The four-probe experiment proved the resistance of the GO/BP-MoB2 5 composite film was decreased by 105 times after combustion. This strategy not only illustrates that BP can reduce the fire hazards of GO, and the hybridization of MoB2 can achieve better flame retarded efficiency, but also promotes the promising potentials of BP nanosheets in the fast intelligent response.
查看更多>>摘要：? 2022 Elsevier B.V.Zinc ion hybrid supercapacitors (Zn-HSCs), combined with the superiorities of supercapacitors and batteries, are regarded to have evolutive potential in devices of energy storage. Herein, the nitrogen and sulfur co-doped graphene/polyaniline nanoarrays (NSG/PANI) have been successfully compounded by in-situ polymerization. The structural characterization shows that the NSG/PANI-50 nanocomposite possess more active sites and vertically arranged PANI nanoarrays on the surface of NSG. The Zn-HSCs devices assembled by the zinc foil as anode, NSG/PANI-x (x = 30, 50, 70) as cathode and ZnSO4 as electrolyte (NSG/PANI//ZnSO4 (aq.)//Zn) show extraordinary energy storage properties. The prepared NSG/PANI-50//Zn device exhibits exceptional specific capacitance of 268.4 F g?1 at 0.1 A g?1 (the retention rate is 75.2% as the current density increased 20-times from 0.1 A g?1 to 2 A g?1), high energy density (95.4 Wh kg?1) and excellent capacitance retention rate of ~ 93% at 5 A g?1 after 10,000 cycles. The diffusion-controlled behavior (72% of the total storage charge at 5 mV s?1) suggests that the diffusion-controlled process acts a momentous role in the process of energy storage. The impressive results demonstrate that NSG/PANI nanocomposite could be a potential high-performance electrode material for Zn-ion hybrid energy systems.
查看更多>>摘要：? 2022 Elsevier B.V.Aiming to comprehensively improve the safety of energetic materials by minimizing their sensitivity to external stimuli such as impact, friction, static electricity and heat, a bionic functional layer strategy is developed to construct energetic composites with core-shell-shell structure. The morphology and structure of the samples were characterized in depth by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and X-ray photoelectron spectra (XPS). The results show that the bionic functional layer forms a dense and complete shell layer on the surface of energetic material, the two-dimensional (2D) material is uniformly and tightly coated on the surface of energetic material based on the super adhesion of the functional interface layer, and the core-shell-shell structure CL-20@Polydopamine@Graphene Oxide (CL-20@PDA@GO) is successfully prepared. The preparation process does not cause the crystalline transformation of energetic material. In addition, the impact sensitivity, friction sensitivity, electrostatic accumulation characteristics and thermal properties of the samples were also evaluated. The results indicate that the bionic functional layer and 2D material can synergistically reduce the sensitivity of energetic material to external stimuli based on their intrinsically superior properties. Therefore, synergistic effect of bionic functional layer strategy in this work has the potential to be extended for multiple properties regulation of energetic materials.
de Moura D.A.de Gouveia G.L.Spinelli J.E.Gomes L.F....
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查看更多>>摘要：? 2022 Elsevier B.V.It is critical to gain a better knowledge of the impact of varying Ni contents on the microstructural changes of the AlSi10Mg alloy solidified at various cooling severities. Understanding the combined features of Si and Al3Ni phases constituting this modified alloy may also have a significant impact on understading its properties. In order to advance in these topics, AlSi10Mg alloys modified with, 1.0, 2.0 and 3.0 wt% Ni are either directionally solidified (DS) at lower cooling rates or laser surface remelted (LSR) at higher rates. α-Al dendritic branches are found in the microstructure of all tested alloys either for DS or LSR specimens, surrounded by the eutectic constituent. Moreover, the dendritic array is defined by the secondary dendritic spacing, λ2, which is found to be 65% lower for the Ni-containing alloys than in the AlSi10Mg alloy. The microstructure of the quaternary alloys is constituted by the α-Al+Si+Al3Ni phases, with the Al3Ni phase having a prevalent fishbone shape and being found in higher proportions as a result of slow cooling and increasing Ni content. Ultimate tensile strength of the AlSi10Mg alloy is 190 MPa for a specified range of λ2 (22–30 μm), which is higher than that of Ni-containing alloys for the same range. However, Ni-containing alloys are more sensitive to λ2, and the DS AlSi10Mg-1Ni alloy, as well as a combination of samples solidified at no less than 3 °C/s, fine dendritic spacing (<18 μm) and fine fishbone+plate-like Al3Ni mixture, shows the best tensile results: 4.6% and 208 MPa. This appears to be the optimal condition for cooperative reinforcement throughout these hardening phases. The laser treated AlSi10Mg-2Ni alloy samples have a superior hardness of 145 HV, much higher than the original substrate, demonstrating the effectiveness of the laser treatment in improving the surface mechanical properties of a Ni-modified AlSi10Mg alloy.
查看更多>>摘要：? 2022 Elsevier B.V.LiNbO3 single-phase phosphors with varying single-doping and co-doping contents of Dy3+ and Sm3+ ions were fabricated via the solid phase reaction. All the X-ray diffractions of these samples revealed that they belonged to the single-phase trigonal structure of LiNbO3. LiNbO3: Dy3+ phosphors could have a neutral white light at 392 nm excitation owing to two strong emission bands (at 488 and 585 nm). Upon the excitation of 412 nm, LiNbO3: Sm3+ phosphors produced orange-red light which attributed to the biggest emission of Sm3+ at 613 nm. The most appropriate doping content of Dy3+ and Sm3+ and the concentration quenching mechanism were also examined. The PL spectra of Dy3+ matched well with the PLE spectra of Sm3+, implying that the energy might be delivered from Dy3+ to Sm3+. At 392 nm excitation, Dy3+ and Sm3+ co-doping LiNbO3 phosphors showed tunable photoluminescence from ordinary to warm white light when doped with more Sm3+ ions. The process of Dy3+ passing on the energy to Sm3+ was validated through the PL spectra of LiNbO3: Dy3+/Sm3+ phosphors. The decay lifetimes also affirmed the energy transfer process. Moreover, Li0.97NbO3: 0.02Dy3+/0.01Sm3+ phosphors exhibited admirable thermal property with the activation energy 0.15 eV. Hence, the results strongly suggested that LiNbO3: Dy3+/Sm3+ phosphors could be applied to fabricate warm white LEDs.
NSTL
Elsevier