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Insight into the Active Site in Electrochemical CO2 Reduction of Self-Supported Cobalt Phthalocyanine Anchored on ZnIn2S4 Nanoarrays
No full textElectrocatalytic CO2 reduction into value-added fuels is a promising and economical strategy to mitigate CO2 emissions. Herein, a self-supported cobalt phthalocyanine anchored on chrysanthemum-like ZnIn2S4 nanoarray electrode was prepared. By integration of experimental analysis and density functional theory calculation, the CoPc molecule was anchored with hexagonal ZnIn2S4 (ZIS) via S-C and Co-S interaction. The active site for CO2RR in ZIS-CoPc was attributed to Co sites. For hydrogen evolution reaction, the active site was mainly ascribed to the S site on the surface of ZIS
Exchange-coupled nanocomposites with novel microstructure and enhanced remanence by a new approach
No full textExchange-coupled nanocomposites with hard/soft magnetic phases are promising for the next generation of permanent magnets. Chemical methods have an advantage in controlling the nanoscale size of both phases. The nanocomposites obtained by the chemical method generally consist of a hard phase core and a soft phase shell. However, the soft-phase shell is easily oxidized leading to small enhancement of remanence. Here, a novel microstructure of Fe@FePt nanocomposites with Fe soft phase core and FePt hard phase shell has been synthesized by replacement reaction, in which the size of core and shell can be controlled below 10 nm by adjusting the ratio of Fe nanoparticles to PtCl4. Excellent exchange-coupling (single-phase-like demagnetization curves) between soft-hard phases was observed due to the precise size control of both phases, and substantial enhancements both in remanence (32 %) and saturation magnetization (81 %) were obtained in optimal nanocompistes. This work provides an alternative routine to prepare heterostructure materials with various applications. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology
Evolution of ordered structure of TPU in high-elastic state and their influences on the autoclave foaming of TPU and inter-bead bonding of expanded TPU beads
No full textDifferent from the melt foaming of extrusion and injection molding, polymer is in high-elastic state during autoclave foaming. In this study, the critical parameters used to describe the high-elastic state of polymer, i.e., softening temperature (Ts) and viscous flow temperature (Tv), were introduced to explain the autoclave foaming of thermoplastic polyurethane (TPU) and the inter-bead bonding mechanism of expanded TPU (ETPU) beads. Evolution of ordered structure of TPU in high-elastic state was characterized by different methods. The steamchest molding was used to manufacture the ETPU parts, and the molding temperature window was compared with the Ts and Tv of TPU resin, and the endothermic peaks of ETPU beads. The melting of ordered hard segments structure, interface-diffusion of polymer chains, cooling-induced formation of new ordered structure among the diffused polymer chains were the possible mechanism of strong inter-bead bonding in the molded ETPU parts
Green synthesis of Konjac glucomannan templated palladium nanoparticles for catalytic reduction of azo compounds and hexavalent chromium
No full textPalladium nanomaterials (PdNPs) have drawn significant attention due to their fascinating catalytic, optical, and electrical properties. PdNPs-catalytic hydrogenation is considered as an efficient way for the remediation of inorganic and organic pollutants. Thus, a simple Konjac glucomannan (KGM) reduced and stabilized PdNPs-catalysts were green synthesized without using any toxic reagents. The maximization of PdNPs production was investigated using a factorial design of experiments, where one variable (precursor ratio, solution pH, reaction time, and temperature) was studied at a time. The surface plasmon resonance (SPR), morphology, crystallinity, particle size distribution, composition spectra, and stability of as-synthesized PdNPs were explored in detail. Results revealed that the particles are mostly in spherical shapes, smaller in size (6.48 +/- 2.19 nm) with a narrow distribution, highly crystalline (d-spacing = 0.224 nm), well stabilized (zeta potential = -17.89 mV), and coated by thin KGM layer of cladding. The type of oxidant and temperature-dependent catalytic degradation of six azo dyes and detoxification of hexavalent chromium [Cr (VI)] was studied. The as-synthesized PdNPs-catalyst demonstrate excellent performance in the formic acid (HCOOH)-induced catalytic reduction of such pollutants with the optimum at 45 degrees C temperature. We are optimistic that the insights on the behavior of reactant adsorption and reaction kinetics revealed in this study could be readily extended to other reaction systems and practically applied to wastewater treatment
Asymmetric bilayer CNTs-elastomer/hydrogel composite as soft actuators with sensing performance
No full textLiving creatures have the nature of actuating and sensing under external stimuli to better adapt to the environment. For instance, the combination of muscles actuation and skin sensing ensures our intelligent interaction with external environments. In terms of the soft robot, implanting sensation and actuation in one system can assist us to control it better and more efficiently. However, in the development of biomimetic materials, the simultaneous realization of actuating and sensing performance in bionic soft robots is still a great challenge. Here, we propose a novel asymmetric bilayer CNTs-elastomer/PNIPAm hydrogel composite with integrated actuating and sensing performances. Due to the excellent photothermal effect of CNTs and thermo-responsiveness of PNIPAm, under the NIP irradiation, the PNIPAm hydrogel layer would shrink and the bilayer composite would thus perform a bending deformation. At the same time, based on a piezoresistive sensing mechanism of the CNTs-elastomer, the actuating procedure can be recorded. This work may open up a new insight in the designing and fabricating intelligent biomimetic hydrogel soft robots with integrated self-sensing capacity
Fabrication of Manganese Oxide/PTFE Hollow Fiber Membrane and Its Catalytic Degradation of Phenol
No full textP-aminophenol is a hazardous environmental pollutant that can remain in water in the natural environment for long periods due to its resistance to microbiological degradation. In order to decompose p-aminophenol in water, manganese oxide/polytetrafluoroethylene (PTFE) hollow fiber membranes were prepared. MnO2 and Mn3O4 were synthesized and stored in PTFE hollow fiber membranes by injecting MnSO4 center dot H2O, KMnO4, NaOH, and H2O2 solutions into the pores of the PTFE hollow fiber membrane. The resultant MnO2/PTFE and Mn3O4/PTFE hollow fiber membranes were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and thermal analysis (TG). The phenol catalytic degradation performance of the hollow fiber membranes was evaluated under various conditions, including flux, oxidant content, and pH. The results showed that a weak acid environment and a decrease in flux were beneficial to the catalytic degradation performance of manganese oxide/PTFE hollow fiber membranes. The catalytic degradation efficiencies of the MnO2/PTFE and Mn3O4/PTFE hollow fiber membranes were 70% and 37% when a certain concentration of potassium monopersulfate (PMS) was added, and the catalytic degradation efficiencies of MnO2/PTFE and Mn3O4/PTFE hollow fiber membranes were 50% and 35% when a certain concentration of H2O2 was added. Therefore, the manganese oxide/PTFE hollow fiber membranes represent a good solution for the decomposition of p-aminophenol
The Ballistic Performance of Laminated SiC Ceramics for Body Armor and the Effect of Layer Structure on It
No full textLaminated ceramics with weak interface layers have been proven to be effective in toughening ceramics. The energy absorption ability of laminated ceramics may also benefit their ballistic performance. However, the effect of the layer structure on the ballistic performance of laminated ceramics has not been studied. Focusing on the application for body armor, this paper studied the effect of the different layer structures on the ballistic performance of laminated SiC ceramics. The laminated SiC ceramics with different layered structures were designed and prepared by tape-casting and hot-pressing. When used for the 'in conjunction with' armor system, the laminated SiC ceramics with a gradual-layered structure had the backface signature depth of 30% less than the laminated SiC with no interface structure and 50% less than the commercial solid-state sintered SiC. However, when used stand-alone, the laminated SiC had a similar ballistic performance regardless of the layer structure, which was likely due to the weak back support. In conclusion, the ballistic performance of the laminated ceramics was related to the back support of the armor system. When used for the 'in conjunction with' armor system, the laminated SiC had a better ballistic performance than that of the solid-state sintered SiC
Poly(ethylene glycol) brush on Li6.4La3Zr1.4Ta0.6O12 towards intimate interfacial compatibility in composite polymer electrolyte for flexible all-solid-state lithium metal batteries
No full textPolyethylene oxide (PEO)/Li6.4La3Zr1.4Ta0.6O12 (LLZTO) composite solid electrolyte is considered as a promising electrolyte for lithium batteries. However, LLZTO nanoparticles tend to agglomerate in PEO/LLZTO composite polymer electrolyte due to interfacial incompatibility between PEO and LLZTO nanoparticles, which leads to low ionic conductivity, poor interface stability with the electrode, and inferior batteries cycling stability. In order to enhance interfacial compatibility, herein, LLZTO nanoparticles are modified through firstly surface-functionalizing by dopamine coating and then grafting poly (ethylene glycol) (PEG) brush on it via amino and epoxy reaction. As a consequence, the ionic conductivity of LLZTO/PEO composite polymer electrolyte filled with 2 wt% modified LLZTO increases up to 1.1 x 10(-4) S cm(-1), which is about twice and 20 times in comparison with LLZTO/PEO filled with 2 wt% unmodified LLZTO and PEO electrolytes, respectively. Moreover, high oxidation potential of around 4.8 V and ionic transference number of 0.34 as well as good interface stability with lithium anode are also achieved. Thus, LiFePO4 parallel to Li all-solid-state lithium metal batteries based on LLZTO/PEO composite polymer electrolyte filled with 2 wt% modified LLZTO exhibit excellent cyclic stability of 152.3 mAh g(-1) with capacity retention of 90.35% at 0.5 C after 500 cycles under 60 degrees C
Flexible Sulfide Electrolyte Thin Membrane with Ultrahigh Ionic Conductivity for All-Solid-State Lithium Batteries
No full textAll-solid-state lithium batteries (ASSLBs) employing Li-metal anode, sulfide solid electrolyte (SE) can deliver high energy density with high safety. The thick SE separator and its low ionic conductivity are two major challenges. Herein, a 30 mu m sulfide SE membrane with ultrahigh room temperature conductivity of 8.4 mS cm(-1) is realized by mechanized manufacturing technologies using highly conductive Li5.4PS4.4Cl1.6 SE powder. Moreover, a 400 nm magnetron sputtered Al2O3 interlayer is introduced into the SE/Li interface to improve the anodic stability, which suppresses the short circuit in Li/Li symmetric cells. Combining these merits, ASSLBs with LiNi0.5Co0.2Mn0.3O2 as the cathode exhibit a stable cyclic performance, delivering a discharge specific capacity of 135.3 mAh g(-1) (1.4 mAh cm(-2)) with a retention of 80.2% after 150 cycles and an average Coulombic efficiency over 99.5%. The high ionic conductivity SE membrane and interface design principle show promising feasible strategies for practical high performance ASSLBs
An Azobenzene-Modified Photoresponsive Thorium-Organic Framework: Monitoring and Quantitative Analysis of Reversible trans-cis Photoisomerization
No full textMonitoring and quantification of the photoresponsive behavior of metal-organic frameworks that respond to a light stimulus are crucial to establish a clear structure-activity relationship related to light regulation. Herein, we report the first azobenzene-modified photoresponsive thorium-organic framework (Th-Azo-MOF) with the formula [Th6O4(OH)(4)(H2O)(6)L-6] (H2L = (E)-2 '-p-tolyldiazenyl-1,1':4',4'-terphenyl-4,4-dicarboxylic acid), in which the utilization of a thorium cluster as a metal node leads to one of the largest pore sizes among all the azobenzene-containing metal-organic frameworks (MOFs). The phototriggered transformation of the trans isomer to the cis isomer is monitored and characterized quantitatively by comprehensive analyses of NMR and UV spectroscopy, which reveals that the maximum isomerization ratio of Th-cis-Azo-MOF in the solid state is 19.7% after irradiation for 120 min, and this isomerization is reversible and can be repeated several times without apparent performance changes. Moreover, the isomerization-related difference in the adsorption of the Rhodamine B guest is also illustrated and a possible photoregulated mechanism is proposed. This work will shed light on new explorations for constructing functionalized actinide porous materials by the elegant combination of actinide nodes with tailored organic ligands and furthermore will provide a comprehensive understanding of photoisomerization processes in MOF solids and insight into the mechanism on photoregulated cargo adsorption and release by photoactive MOFs