查看更多>>摘要：? 2021 Elsevier B.V.The intrinsic thermal distribution during the arc deposition can induce metastable microstructural characteristics and anisotropic properties. In this study, H13 buildups with different deposition structures were manufactured by cold metal transfer (CMT) technology. The defect distribution, phase constitution, and microstructural characteristics were investigated to explore the anisotropic mechanism of mechanical properties. The X-ray computed tomography results revealed that only microscopic globular pores were randomly retained within deposit. Compared to other structures, a minor amount of γ-Fe for single-layer single-track buildup was primarily attributed to the special thermal history. Equiaxed ferrite grains comprised dense needle-like martensites with homogeneous distribution. Martensitic growth orientation was roughly parallel to the adjacent ones inside individual ferrite grain, but exhibited no preferred crystallographic orientation. Anisotropy in mechanical properties was primarily determined by the effect of porosity and microstructures. The negligible anisotropy in micro-hardness and ultimate tensile strength was accounted for the non-directional martensitic growth direction inside different ferrite grains. The anisotropy in tensile plasticity could be attributed to microscopic pores underneath dimples during the tensile process. These findings reveal that CMT can fabricate crack-free buildups with homogeneous microstructures, resulting in insignificant anisotropic behavior in mechanical performances. The results of this study could provide a guidance for the arc deposition of large-sized martensitic steel parts.
查看更多>>摘要：? 2021The plasmonic Ag@AgBr nanoparticles on a well-ordered TiO2 nanorod array (TNR) matrix were successfully constructed by a secondary hydrothermal strategy. Effects of different crystallization time of Ag@AgBr on crystallinity, size and optical properties of the ternary arrays were discussed. The results showed that the crystalline behavior of Ag@AgBr was improved significantly with the increasing crystallization time. The average size of Ag@AgBr nanoparticles attached to top and side of TiO2 nanorods was 15 nm, and increased up to 55 nm at longer time. The surface plasmon resonance (SPR) bands were evident in the Ag@AgBr/TNR (ABT) arrays, and a significant redshift was observed with crystallization time. Especially when the crystallization time is 12 h, 12ABT photoelectrode had the lowest transfer resistance for interfacial charges and the highest transient photocurrent intensity of 130 μA/cm2, which was about 13 times that of bare TNR. In the degradation of methyl orange, 12ABT showed the highest photocatalytic efficiency of 95.6% and rate constant of 0.0167 min?1 under full spectral irradiation, which was 18.6 times of TNR. The favorable sunlight-driven photocatalytic activity originated from synergistic effect of three components in Ag@AgBr/TNR array, such as the improved solar light response through surface plasmon resonance (SPR) and photosensitive effect of Ag and AgBr co-sensitizers, as well as the high-efficiency carrier transfer in the unique heterojunction.
查看更多>>摘要：? 2021A novel hive-like Co3O4 @C composite is synthesized solvothermally and calcinated using Manila grass as an interesting precursor of porous carbonous skeleton with self-doped phosphorus and oxygen, anchored by Co3O4 nanocryclusters through the sites rich in doped atoms. The capacitance of the as-fabricated materials is 767.6 F·g?1 (1 A·g?1) with long life of 96.2% retention after 12,000 cycles, according with the phosphorus content in composites. Moreover, the supercapacitor is assembled by KC-600 (+) and active-carbon (–) delivers an energy density of 81.42 Wh·kg–1 at 875 W·kg–1 and satisfactory cycling stabilities (9.17% lost after 24,000 cycles), owing to its unique microstructure and the self-doped phosphorus of Manila grass. Therefore, the porous hive-like Co3O4 @C composite can better achieve as an electrode material through an easy and eco-friendly process based on biocarbon for the energy storage devices in the future.
查看更多>>摘要：? 2021Herein, the effect of electrodeposition time on the super-capacitive performance of three-dimensional (3D) MnO2/g-C3N4 heterostructured electrodes was investigated. MnO2 nanoparticles were electrodeposited on the g-C3N4 nanosheets drop-casted on the Ni foam substrate. The microstructural analysis, carried out by FE-SEM and TEM, confirmed the homogeneous distribution of MnO2 nanoparticles on g-C3N4 nano-sheet layers. The electrochemical capacitive performances of the MnO2/g-C3N4 electrodes were evaluated by cyclic voltammetry (CV), galvanostatic charge/discharge tests, and electrochemical impedance spectra (EIS). The obtained results suggested that the supercapacitor (SC) performance of all prepared g-C3N4/MnO2 composite electrodes is higher than pure MnO2 and pure g-C3N4 electrodes. The effect of electrochemical deposition time on the electrochemical performances of the fabricated electrodes was investigated as well. The specific capacitance of synthesized g-C3N4/MnO2 electrodes was measured as 87.6, 67, and 49.5 Fg-1 for 1, 2, and 3 min deposition time respectively at the current density of 0.5 Ag-1, indicating the electrode obtained with shorter deposition time delivers maximum specific capacity. Therefore, this deposition time has been validated as the optimum time for electrochemical energy storage application.
查看更多>>摘要：? 2022 Elsevier B.V.In this paper, two-dimensional titanium carbide (Ti3C2Tx) and vanadium carbide (V2CTx) MXene with appropriate mass content are incorporated into PbI2 precursor solution to fabricate perovskite film via one-step coating method. The effects of the addition of MXene with different mass ratio on the morphology, crystallinity, light absorption property and stability of the CH3NH3PbI3 film and the photovoltaic performance and stability of the corresponding devices are further investigated. The results demonstrate that the introduction of Ti3C2Tx and V2CTx additive can improve the morphology of perovskite film, increase the grain size of perovskite film, enhance the hydrophobicity of the perovskite layer. As a result, improved photovoltaic performance can be achieved. By modifying the proportion of additives, the power conversion efficiency (PCE) of V2CTx MXene modified solar cells is better than those of the devices with Ti3C2Tx additive and the pristine one. Compared with the control device without additive, perovskite solar cells incorporating V2CTx additive with an optimized concentration of 0.0013 wt% achieve a PCE of 17.61% (increased by 17%). Moreover, for perovskite film incorporating V2CTx additive, unique morphology with uniform grain size and ordered layered crystal particle can be noted. This means the V2CTx additive can regulate the perovskite crystal film growth. In addition, the V2CTx additive incorporated devices can retain 68.29% of the initial PCE after 15 days, which is higher than the devices without additives (by 9.69%) and with Ti3C2Tx as additive (by 47.16%), owing to the better crystallinity and higher quality of perovskite film. Our work provides an effective method for improving performance of perovskite solar cells and expands the applications areas of V2CTx in photovoltaics.
查看更多>>摘要：? 2022Transition Metal Dichalcogenides (TMDs) especially molybdenum disulfide (MoS2) benefited from its low thermal conductivity and a variety of transport behavior are highly preferred as a candidate for thermoelectric (TE) application. However, MoS2 has a low electrical conductivity that hinders the thermoelectric performance which can be overcome by several factors. In this work, we have grown MoS2 on carbon fabric (CF) and decorated it with copper oxide (CuO) using the hydrothermal method followed by the subsequent facile spray deposition method. The structural and morphological analysis confirmed the formation of pristine MoS2/CF and CuO decorated MoS2/CF. The TE properties of pristine MoS2/CF and CuO decorated MoS2/CF has been investigated from the temperature ranging from 303 to 373 K. The analysis showed that the Seebeck coefficient is gradually increasing with an increase in the concentration of CuO. The electrical conductivity, Seebeck coefficient, and power factor of the sample C3 (15 mg of CuO) is around 95.67 Sm?1, 16.5 μV/K, 0.026 μW cm?1 K?2 at 373 K, which was 4.37, 1.15, and 6.5 times higher than that of pristine MoS2/CF, respectively.
查看更多>>摘要：? 2022 Elsevier B.V.Based on pseudo-ternary phase diagram and microscopic observation, Al20.45Co10Cr10Ni59.55, Al17.5Co20Cr20Ni52.5 and Al16.3Co25Cr25Ni33.7 eutectic high entropy alloy (EHEAs) were designed. The experimental results showed that the designed EHEAs all have uniform alternating BCC/FCC lamellar microstructure. Among them, the as-cast Al17.5Co20Cr20Ni52.5 alloy exhibits better tensile property at room temperature. The ultimate tensile strength and total elongation are 1272 MPa and 14.4%, respectively. We verified that the formation of AlCoCrNi EHEAs is related to the ratio of (Co, Ni) to Al, and proposed a new method to design AlCoCrNi EHEAs by fixing the ratio of (Co, Ni) to Al in the alloy. According to the thermo-physical parameters and the ratio of (Co, Ni) to Al of the AlCoCrFeNi EHEAs (FCC/BCC) reported so far, the formation rules of this type of EHEAs were summarized. This can provide useful guidance for future design of the AlCoCrFeNi EHEAs.
查看更多>>摘要：? 2022 Elsevier B.V.Porous and ultrathin polymetric carbon nitride has recently emerged as a promising photocatalyst. However, the complex synthesis strategy of porous ultrathin carbon nitride (PTCN) impedes its further application in photocatalytic water splitting. It is a challenge to find a facile and powerful synthesis strategy of porous ultrathin polymetric carbon nitride. In this work, we demonstrate a bubble-assisted strategy for porous ultrathin polymetric carbon nitride. The thermal polymerization process under the blowing effect of NH4Cl endows PTCN with the porous and ultrathin structure. The larger accessible specific surface area (SSA) provides abundant active edges and sites, decreasing the diffusion distance of reactants and carriers. Compared to the bulk carbon nitride (bulk CN), PTCN possesses higher SSA, a broader bandgap, and improved photogenerated carriers transfer efficiency. In addition, the calculation of Gibbs free energy manifests the improved hydrogen absorption ability. As a result, a remarkable hydrogen evolution rate at 22.0 mmol h?1 g?1 is achieved, which is 6 times higher than that of bulk carbon nitride.
查看更多>>摘要：? 2022Yttrium-stabilized zirconia@reduced graphene oxide (YSZ@rGO) nanofibers with uniform porous structure were prepared by electrospinning and thermal reduction process. On this basis, PEDOT/YSZ@rGO electrode was fabricated via the electrodeposition for sensitive detection of methyl parathion (MP). Among this, YSZ exhibited outstanding adsorption, rGO improved electron mobility and PEDOT enhanced electrocatalytic properties. The electrochemical impedance spectroscopy (EIS), square wave voltammetry (SWV) and cyclic voltammetry (CV) demonstrated the successful preparation of the sensor. The pH value of the buffer, the pre-deposition time of the working electrode, and the adsorption time have been optimized. Under the optimum condition, the detection limit of the sensor is 1.57 ng·mL?1 (S/N = 3), and the linear detection ranges from 5 to 4000 ng·mL?1, which is superior to most related electrochemical sensors. Furthermore, the sensor exhibits good anti-interference, reproducibility, stability, and satisfactory recovery in real sample, indicating wide commercial applications in detecting food safety and monitoring wastewater emission.
查看更多>>摘要：? 2022Owing to the fast kinetics of the precipitation, the formation mechanism of the δ′ phase in Al-Li alloys is still open to question. Using ab initio calculations, here, we reported two continuous precipitate modes (Bulk and Planar modes based on Li atoms arrangements) to complete the ordered δ′ phase through progressive Al-Li solid solutions. Under the vacancy-dependent solid-state precipitation mechanism, we found that these intermediate solid solutions were dominated by sequent Al-Li-vacancy complex structures that exhibit strong binding effects from Li atoms to vacancies. In turn, vacancies located in different sub-lattices exert short- and long-range effects to tailor the bonding strength of the constituted atoms. Based on the diffusion activation energy calculations, we suggested that the ordering transition of the δ′ phase prefers the Planar mode. In later stages of precipitation, the kinetics of precipitation accelerates, resulting in great difficulties in capturing this structural performance in experiments. Our findings are informative for understanding the energetic and phase transformation mechanism behind continuous precipitate for the precipitated phases with fast kinetics.
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