查看更多>>摘要：? 2022 Elsevier B.V.The high-performance formaldehyde sensor is an ideal choice for industrial gas detection and environmental gas analysis. In this article, the 3D Ti3C2Tx MXene/rGO/SnO2 aerogle was successfully fabricated via a simple one-step solvothermal route. The composite structures and morphology were characterized by an array of testing techniques. According to the gas measurement, the 3D Ti3C2Tx MXene/rGO/SnO2 sensor exhibited 54.97% sensing response in 10 ppm formaldehyde at room temperature (RT). Not only that, the 3D Ti3C2Tx MXene/rGO/SnO2-based sensor indicated an excellent sensing selectivity, short response and recovery times (2.9 and 2.2 s, separately), good repeatability and stability. A general formaldehyde sensing mechanism with a ternary architectural was proposed and supported through density functional theory (DFT) calculations data, which has been sufficiently shown to be a promising candidate for the design of efficient formaldehyde sensor.
查看更多>>摘要：? 2022 Elsevier B.V.The construction of a hybrid hierarchical architecture is a promising strategy for optimizing the electrocatalytic activity and the performance of flexible Zn-air battery. However, it still remains a challenging task. This study reports on the use of a simple approach in the preparation of a flexible 3D self-supporting bifunctional catalyst. Ultrathin NiFe-based layered double hydroxide nanosheets (NiFe-LDH) have in this approach been strongly coupled to a metal-organic framework (MOF)-derived carbon nanoflake array, to be used in flexible Zn-air batteries. Importantly, the introduction of Co nanoparticles that were anchored onto the nitrogen-doped porous carbon (Co-NC) nanoflakes provided an abundance of active sites for the oxygen reduction reaction (ORR). Moreover, the catalytic oxygen evolution reaction (OER) process was improved by altering the local electronic structure of the Ni and Fe species in NiFe-LDH. The 3D interconnected conductive network structure, in addition to the strong coupling between NiFe-LDH and Co-NC, was found to give a catalyst with superior electrocatalytic OER performances. The overpotential was only 284 mV at 50 mA cm?2 in an alkaline medium, which is a result that outperforms the commercial RuO2 catalyst. This bifunctional catalyst did also exhibit a good catalytic performance that is comparable to that of commercial Pt/C towards ORR. Interestingly, when this catalyst was used as binder-free air cathode, the assembled flexible solid-state Zn-air battery demonstrated a favorable power density, cycling stability, and mechanical flexibility. The present work offers a facile and efficient strategy for the development and construction of self-supporting bifunctional OER/ORR electrocatalysts, to be used in wearable and flexible electronic devices.
查看更多>>摘要：? 2022 Elsevier B.V.How to effectively use the structural design on poly para-phenylene terephthalamide (PPTA) fabric to provide superior electromagnetic interference (EMI) shielding performance while giving it hydrophobicity and comprehensive functions remains a significant issue. Herein, a layered assembly technique is demonstrated to construct a hollow hybrid separated structure with gradient electrical conductivity on PPTA fabric for achieving efficient electromagnetic radiation attenuation and excellent hydrophobic properties. Due to the difference in electrical conductivity between Ni and polyaniline (Pani), gradient conductivity is generated from top to bottom that highly conductive core-shell Ni provides excellent electromagnetic reflection capability, and Pani-Fe3O4 forms a separated electromagnetic absorption network to achieve an “absorption-reflection-reabsorption” shielding mode. The EMI shielding effectiveness (SE) of the composite fabric is more than 65 dB, and the normalized specific SE (SSE) is as high as 2153 dB·cm2/g at a thickness of 0.221 mm, more than 20% of electromagnetic waves are absorbed, which can effectively alleviate the secondary contamination caused by reflection. The constructed hydrophobic structure enables the fabric to reach a large contact angle (CA) of 156.4° with excellent self-cleaning and antifouling properties. More, integrated functionalities are discovered in the composite fabric including flexibility, thermal stability and corrosion resistance, offering great potential for EMI shielding in complex environments.
查看更多>>摘要：? 2022 Elsevier B.V.This work discussed a straightforward approach to manufacture Co-, La-, and Co/La-doped BiVO4 nanoporous films. The effect of doping in the photoelectrochemical (PEC) water splitting performance was evaluated through PEC test and the strong electronic correlation of the framework in the density functional theory (DFT) calculation was taken into account. It was shown that replacing Bi atoms with Co would decrease the bandgap of BiVO4, but doping with La shifted the bandgap from indirect to direct and resulted in the negative shift of onset potential. Furthermore, doping Co and La ions into BiVO4 also introduced deep levels into the BiVO4 bandgap. After the optimization of the mole ration of Co to La, the (0.7/0.3)Co/La:BiVO4 photoanode achieved a high photocurrent density of 3.65 mA cm?2 under the simulated solar irradiation with a bias of 1.23 VRHE, resulting in an H2/O2 production rate of 57.6/25.8 μmol cm?2 h?1. More importantly, without any co-catalysts and hole scavengers, the photoanode presented a favorable stability during 16 h test. The enhanced PEC performance was mainly due to improved visible light absorption and carrier separation ability. Both the experimental and theoretical demonstrations proved that the dual-element doping strategy shed light on designing efficient and stable photoelectrodes for solar energy conversion.
查看更多>>摘要：? 2022 Elsevier B.V.Layered double hydroxide (LDH) has attracted extensive attention as the potential electrode materials used in asymmetric supercapacitor (ASC) because of its adjustable elemental composition and microstructure. In this work, a series of NiCoFe-LDH with different element ratios and morphology was synthesized by a facile hydrothermal treatment. A special interlaced structure assembled by nanorods and nanosheets surprisedly emerged. The nanorods and nanosheets have same chemical composition. The corresponding NiCoFe-LDH with interlaced structure exhibits much excellent electrochemical performance than that with single structure. Especially, the Ni2Co1Fe1-LDH material has the highest specific capacitance of 1772.26 F g?1 at 1 A g?1 due to the suitable specific surface area and pore structure, faster electron transportation and dynamic Faradaic redox reactions. The Ni2Co1Fe1-LDH//AC ASC based on the Ni2Co1Fe1-LDH and active carbon (AC) reveals a better specific capacitance of 256.19 F g?1 at 1 A g?1 and an excellent energy density of 91.09 Wh kg?1 at the power density of 809.68 W kg?1. The change of metal element proportion effectively adjusted the interlaced structure of NiCoFe-LDH and extremely enhanced the electrochemical performance of the resulted electrode materials.
查看更多>>摘要：? 2022Ca1-xBaxWO4 (x = 0–0.25, CBWO) composite microwave dielectric ceramics were obtained after sintering at 1200 °C for 4 h. X-ray diffraction and X-ray photoelectron spectroscopy were used to determine their complex phase structures. The lattice vibrational properties were revealed by Raman scattering and Fourier-transform infrared (FTIR) spectroscopy. The Raman spectra showed that phase-pure CaWO4 had eight active vibrational modes when x = 0.15–0.25. A new vibrational mode appeared near 927 cm?1, which was attributed to BaWO4. The intrinsic properties were fitted and simulated by the four-parameter semi-quantum model according to the FTIR spectra. The low-frequency vibrational modes made a greater contribution to the intrinsic properties than the high-frequency modes. Structure-property relationships of the CBWO ceramics were obtained using Raman spectroscopy, and their dielectric responses were elucidated. The CBWO ceramic at x = 0.25 had excellent dielectric properties with εr = 7.43 and Q × f = 56,929 GHz.
查看更多>>摘要：? 2022 Elsevier B.V.The microstructural evolution and mechanical properties of Ti35 alloy applied in nuclear industry with lamellar microstructure during high-temperature straining were systematically investigated. Ti35 alloy plates were subjected to hot rolling down to 20 %, 50 % and 80 % reduction in thickness. Results showed that {101?2}<101?1?>, {112?2}<112?3?>and {101?1}<101?2?>twins were developed during hot rolling and their proportion varied with the amount of deformation. The fraction of twinning boundary reached peak value in the 50 % reduction sample, which dominated by {101?2}<101?1?>and {112?2}<112?3?>twins. After annealing, the deformation twins in>50 % reduction samples were nearly annihilated. The twins and substructures acted as nucleation point for static recrystallization, resulting in twins annihilated and grain refinement during annealing. Micro-hardness and tensile tests revealed that deformation twinning improved strength and plasticity of the Ti35 alloy by introducing extra interfaces and reorientation.
查看更多>>摘要：? 2022 Elsevier B.V.In the typical hydrometallurgy-based recycling process of spent Li-ion batteries (LIBs), excessive amounts of Na ions are inevitably incorporated in leachate through a discharging process with salt solutions and a purification step for impurity removal. In this study, a facile Al3+ doping strategy is realized ranging from impurity level to usual doping levels for improving the LIB performance of Na-incorporated Li[Ni0.8Co0.1Mn0.1]O2 (N-NCM). We synthesize Na-incorporated hydroxide precursor via a coprecipitation reaction using a metal solution containing excess amounts of Na (12.6 mol%), simulating the resynthesis of NCM from purified leachate. The Na and Al co-doped NCM811 (NA-NCM) cathode materials are successfully synthesized by subsequent solid-state reactions with various concentrations of Al. The physicochemical and electrochemical properties of NA-NCM are systematically investigated, with N-NCM as a control sample. Notably, the trace amount of Al (0.05 mol%)-doped cathode material reveals the highest cyclability of 93.9% after 80 cycles at 1 C and more than six times higher discharge capacity (115 mAh g?1) at 20 C than N-NCM. Overall, the small amount of Al doping (0.05 mol%) makes the host structures stable and more favorable for Li+ diffusion, whereas the excessive Al (4 mol%) doping lead to the sluggish kinetics on rate capability due to thick A2O3 film layers formed on the particle surface. This work suggests the rational design for upgrading the resynthesized Ni-rich NCM cathode materials for the sustainable recycling of spent LIBs.
查看更多>>摘要：? 2022 Elsevier B.V.Due to its considerable theoretical capacity and high availability through conversion reaction, CoP is regarded as a promising candidate for potassium-ion batteries (PIBs). However, huge volume change and low intrinsic conductivity seriously impede the further development of CoP anode in PIBs. Generally, structural design and composition regulation can well improve potassium storage performance of CoP via increasing capacitive contribution rate, but are unfavorable for realizing a high energy density in a K-full cell. Therefore, how to optimize the bulk phase diffusion ability of CoP to enhance the diffusion-dominated potassium storage is of great importance. Herein, CoP nanoparticles (about 20–40 nm) with enormous voids embedded in carbon-cage structure encapsulated in N-doped amorphous carbon are reported (CoP/C@NC-PDA), in which CoP particles with appropriate nano-size benefit the bulk phase diffusion process. Besides, the existence of amorphous carbon coating layer and voids can provide sufficient space to buffer volume expansion, while carbon-cage architecture and its high graphitization degree accelerate fast ions/electrons transfer, respectively. As a result, CoP/C@NC-PDA achieves an excellent diffusion-controlled capacity ratio (77.5% at 0.05 A g?1, 75.0% at 1.0 A g?1), and a good cycle lifespan over 1000 cycles with nearly 100% Coulombic efficiency.
查看更多>>摘要：? 2022In recent years, bifunctional electrocatalysts derived from zeolite imidazole framework (ZIF) as a carbon substrate have been a hot research topic. In addition, one-component catalyst cannot achieve the efficient catalysis of oxygen reduction reaction(ORR) and oxygen evolution reaction( OER). At the same time, this paper reports a bifunctional catalyst with a bimetallic three-dimensional porous structure using silicon spheres as a hard template and ZIF as a carbon substrate. The inherent porosity of pie-shaped ZIF, the use of silica templates to generate an ordered macroporous structure, and the synergy between metal activity sites, which together promote the mass transfer and electrocatalytic activity of the battery. The synthesized catalyst showed excellent electrocatalytic activity toward ORR and OER including a half-wave potential (E1/2 =0.80 V) which is 20 mv less than Pt/C, and its overpotential (0.321 V) and voltage gap (ΔE=0.751 V) surpasses commercial Pt/C+RuO2 catalyst (0.368 V, ΔE=0.778 V). Moreover, primary and rechargeable Zn-air battery is assembled based on this catalyst delivered preferable performance, including a high power density (98.7 mw cm-2),batter charge/discharge cycling stability (220 h) exceeds commercial Pt/C+RuO2 catalyst (160 h）. Given its unique pore structure and good electrical conductivity, this derived material has scope for expansion in bifunctional catalysis and other energy technologies for rechargeable Zn-air batteries.
NSTL
Elsevier