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mussel-inspired delivery system for enhancing self-healing property of epoxy coatings
No full textDopamine (DA), one type of mussel-inspired biological molecules with adhesive nature and corrosion inhibitor property, are often used to functionalize the surfaces of various materials. Herein, we report the application of polydopamine (PDA) microcapsules as novel nanocontainers for the purpose, loading corrosion inhibitor (benzotriazole) in its shell structure, and then were embedded into epoxy coatings to provide self-healing and anti-corrosion protection for carbon steel. Fast release of benzotriazole in acidic environment caused by local corrosion and the chelating effect of PDA-Fe3+ can synergistically promote the formation of protective film on bare steel surface, which endows coatings with self-healing functionality. Electrochemical impedance spectroscopy (EIS), local electrochemical impedance spectroscopy (LEIS), and spray tests were conducted to evaluate the active inhibition and corrosion resistance of the loaded coatings. The scratched coating with incorporation of nanocontainers presented better protection performance, exhibiting increased Ro (oxide layer resistance) and Rct (charge transfer resistance) during initial immersion periods. The EIS tests in long-term immersion were also performed to confirm the anti-corrosion effect of composited coatings. These results demonstrated that benzotriazole-decorated PDA capsules dramatically enhanced the self-healing properties and anti-corrosion performance of epoxy coatings with the synergistic help of PDA and benzotriazole. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology
Supersized Graphitic Tube@MoS2 Pipelines with Abundant Ion Channels Synthesized by Selective Deposition toward High-Performance Anodes
No full textMolybdenum disulfide (MoS2) has been regarded as a promising anode material in lithium-ion batteries (LIBs) due to its high theoretical capacity. However, the poor conductivity and collapse of the structure upon cycling lead to poor stability, impeding the application of MoS2 in LIBs. Here, a novel strategy was reported to selectively deposit MoS2 nanosheets on a supersized graphitic tube (SGT) to obtain an SGT@MoS2 pipeline to tackle these problems. Compared with a conventional carbon nanotube (CNT), SGT has not only a graphitic wall but also a pipeline structure, which can act as an ion channel after immersion of an electrolyte. Additionally, the selective deposition of MoS2 on the outer surface effectively prevents the pipelines from being crammed by MoS2 nanosheets. Resultantly, diffusion efficiencies of both an electron and an ion are enhanced. Additionally, the shortened ion diffusion distance can boost pseudocapacitive behavior, contributing to high specific capacity and excellent rate performance. The results manifest that the specific capacity of the SGT@MoS2 pipeline reached 942 mAh g(-1) at 100 mA g(-1) after 200 cycles, 4 times higher than that of pure MoS2
Electric Field Control of the Magnetic Weyl Fermion in an Epitaxial SrRuO3 (111) Thin Film
No full textThe magnetic Weyl fermion originates from the time reversal symmetry (TRS)-breaking in magnetic crystalline structures, where the topology and magnetism entangle with each other. Therefore, the magnetic Weyl fermion is expected to be effectively tuned by the magnetic field and electrical field, which holds promise for future topologically protected electronics. However, the electrical field control of the magnetic Weyl fermion has rarely been reported, which is prevented by the limited number of identified magnetic Weyl solids. Here, the electric field control of the magnetic Weyl fermion is demonstrated in an epitaxial SrRuO3 (111) thin film. The magnetic Weyl fermion in the SrRuO3 films is indicated by the chiral anomaly induced magnetotransport, and is verified by the observed Weyl nodes in the electronic structures characterized by the angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations. Through the ionic-liquid gating experiment, the effective manipulation of the Weyl fermion by electric field is demonstrated, in terms of the sign-change of the ordinary Hall effect, the nonmonotonic tuning of the anomalous Hall effect, and the observation of the linear magnetoresistance under proper gating voltages. The work may stimulate the searching and tuning of Weyl fermions in other magnetic materials, which are promising in energy-efficient electronics
Theoretical Insights into Transplutonium Element Separation with Electronically Modulated Phenanthroline-Derived Bis-Triazine Ligands
No full textIn the process of spent fuel reprocessing, it is highly difficult to extract transplutonium elements from adjacent actinides. A deep understanding of the electronic structure of transplutonium complexes is essential for development of steady ligands for in-group separation of transplutonium actinides. In this work, we have systematically explored the potential in-group separation ability of transplutonium elements of typical quadridentate N-donor ligands (phenanthroline-derived bis-triazine, BTPhen derivatives) through quasi-relativistic density functional theory (DFT). Our calculations demonstrate that ligands with electron-donating groups have stronger coordination abilities, and the substitutions of Br and phenol at the 4-position of the 1,10-phenanthroline have a higher effect on the ligand than those at the 5-position. Bonding analysis indicates that the covalent interaction of An(3+) complexes becomes stronger from Am to Cf apart from Cm, which is because the energy of the 5f orbital gradually decreases and becomes energy-degenerate with the 2p orbitals of ligands. The most negative values of binding energies indicate the higher stability of Cf3+ complexes, in line with the larger covalency in the Cf-L bonds compared with An-L (An = Am, Cm, Bk). In addition, electron-donating group phenol can enhance the covalent interaction between ligands and heavy actinides. Consequently, the extraction ability of ligands with electron-donating substituents for heavy actinides is generally stronger than other ligands. Nevertheless, these ligands exhibit diverse separation abilities to in-group actinide recovery. Therefore, the enhancement of covalency does not necessarily lead to the improvement of separation ability, which may be caused by different extraction abilities. Compared with the tetradentate N, O-donor ligands (2,9-diamide-1,10-phenanthrolinel, DAPhen derivatives), species with BTPhen ligands display stronger covalent interaction and higher extraction capacity. In terms of in-group separation ability, the BTPhen ligands seem to have advantages in separation of californium from curium, while the DAPhen ligands possess stronger abilities to separate americium from curium. These results may afford some afflatus for the development of effective agents for in-group separation of transplutonium elements
Proximity Effect in Uranyl Coordination of the Cucurbit[6]uril-Bipyridinium Pseudorotaxane Ligand for Promoting Host-Guest Synergistic Chelating
No full textbehavior of cucurbituril-bipyridinium pseudorotaxane ligand by utilizing meta-functionalized bipyridinium dicarboxylate guest. A tailored pseudorotaxane precursor involving 1,1'-(hexane-1,6-diyl)bis(3-cyanopyridin-1-ium) bromide (C6BPCN3) and cucurbit[6]uril (CB[6]) has designed and synthesized. Through in situ hydrolysis of the pseudorotaxane ligands and their coordination assembly with uranyl cations, seven new uranyl-rotaxane coordination polymers URCP1-URCP7 have been obtained under hydrothermal conditions in the presence of different anions. It is demonstrated that the variation of carboxylate groups from para- to meta-position greatly affected the coordination behaviors of the metafunctionalized pseudorotaxane linkers, which are enriched from simple guest-only binding to host-guest simultaneous coordination and synergistic chelating. This effective regulation on uranyl coordination of supramolecular pseudorotaxane can be attributed to the proximity effect, which refers to the meta-position carboxyl group being spatially closer to the portal carbonyl group of CB[6]. Moreover, by combining other regulation methods such as introducing competing counterions and modulating solution acidity, the nuclearity of the uranyl center and the coordination patterns of the pseudorotaxane ligand can be diversely tuned, which subsequently exert great influence on the final dimensionality of resultant uranyl compounds. This work presents a large diversity of uranyl-based coordination polyrotaxane compounds with fascinating mechanically interlocked components and, most importantly, provides a feasible approach to adjust and control the metal coordination behavior of the pseudorotaxane ligand that might expand the scope of application of such supramolecular ligands
Shielded electric field-boosted lithiophilic Sites: A Janus interface toward stable lithium metal anodes
No full textUncontrolled volume expansion with spiky lithium (Li) deposits is the major challenge for high-energy?density Li metal batteries to achieve long-term and safe cycling. The roughness or protrusion induced uneven electric field on the Li plating substrate is the main cause for the Li deposition heterogeneity. Lithiophilic sites are widely employed to guide Li deposition with high Li affinity, however also suffer from the restricted electrochemical regions by the uneven electric field for Li plating/stripping. Herein, a strategy of shielding the interfacial electric field to boost the functionality of lithiophilic sites is proposed beyond the single use of lithiophilic sites. A Janus composite of nanodiamond (ND) particles imbedded lithiophilic copper oxides (CuxO) is used to decorate the Li deposition substrate. The evenly distributed ND particles play a critical role to readjust the electric field on the electrode surface, and in turn homogenize the conversion process of CuxO sites to guide uniform Li deposition throughout the entire electrode surface. Consequently, the Li cyclability on the CuxO/ND decorated electrode significantly outperforms those on bare or CuxO decorated electrodes for practical cycling conditions, proving the designing principle of the shielded electric field-boosted lithiophilic sites interface for stable Li metal anodes
Effect of crystalline structure on the cell morphology and mechanical properties of polypropylene foams fabricated by core-back foam injection molding
No full textFoam injection molding (FIM) is an advanced technology for preparing lightweight plastic foams, but its inferior mechanical performance remains a challenge. In this study, microcellular injection-molded beta-polypropylene (beta-PP) foams with high ductility were successfully prepared by combing the beta-nucleating agent with controllable temperature field. Foaming results showed that the microcellular beta-PP foams exhibiting a cell size of about 8 mu m and cell density over 10(8) cells/cm(3) were prepared with a crystalline diameter approximately 5 mu m, while PP foams had a rather large cell size approximately 150 mu m and low cell density of 10(5) cells/cm(3) with 30 mu m crystalline size. As a result, this significant improvement in cell structure as well as the crystalline size lead to a significant increment of 86% for the ductility of beta-PP foams. This work offers a facile strategy to prepare injection-molded foams with desirable mechanical properties for their wide range of applications, such as automotive construction and consumer electronics
Facile synthesis of ultralong hydroxyapatite nanowires using wormlike micelles as soft templates
No full textAs a powerful self-assembly process, the soft-template method has attracted considerable scientific interest, but there is a challenge associated with ultralong hydroxyapatite nanowires (HAPNWs) with length of tens of micrometers. In this study, we report a novel three-phase oleic acid-ethanol-water reaction system for synthesizing ultralong HAPNWs by formation of an entangled long wormlike micelle (WLM) structure. The influence of raw materials and initial pH on the HAPNW structure has been studied. Findings showed that a HAPNW structure could only be formed with a design based on the WLM structure at pH 6.5 with oleic acid or sodium oleate as a reactant. The formation mechanism of HAPNWs was proposed and analyzed. A HAPNWs/carbon composite adsorbent was used for the removal of methyl orange from the aqueous phase, showing unique adsorption properties over broad pH and temperature range from 3 to 7 and 20 to 60 degrees C, even though solid content of HAPNWs in composite adsorbent is only 0.038%. This fundamental research will enrich the knowledge base for controlled synthesis and applications of nanocrystals that rely on ultralong WLMs
Improvement of Cyclic Stability of Na0.67Mn0.8Ni0.1Co0.1O2 via Suppressing Lattice Variation
No full textStrategies to prolong operational life are highly pursued to strengthen the advantage of cost-effectiveness on sodium-ion batteries (SIBs). We demonstrate the crucial influence of particles - internal mechanical strains on durability of cathode, which does not attract enough attentions from the community. Among the investigated samples, 2% Ti-modified-Na0.67Ni0.1Co0.1Mn0.8O2 suppresses the c-axis lattice variation by 38%, attains the reversible capacity 86% higher after 200 cycles, and still keeps intact morphology. This approach indicates that the mechanical properties could tailor cyclic stability of cathode, which is particular important to further improve competitiveness for SIBs
Fluorinated graphene film for corrosion control on copper: Experimental and theoretical studies
No full textAlthough graphene film has received considerable scientific and industrial interest, the high electrical conductivity strongly limits its corrosion protection over a long-term scale. Here we develop an effective strategy to achieve the long-term corrosion protection performance of graphene film by fluorinated treatment. The success of fluorination strategy is evident in electrochemical impedance spectroscopy, local impedance module, and corresponding corrosion morphologies and structures. Even after 14 days' immersion in 3.5 wt% NaCl solution, the low frequency impedance modulus of fluorinated graphene film with fluorinated treatment at 100 degrees C is an order of magnitude higher as compared with pristine one. The corrosion resistance over a large scale also persists in air environment. We propose that the fluorine atoms bond with carbon element on the edge of vacancy defects, inhibiting the corrosion-related molecules passing through the film via intrinsic defects, this is supported by the density functional theory calculations (DFT). In brief, through effective preparation, analysis of corrosion resistant performance, and theoretical calculation, the fluorinated graphene film with long-term anti-corrosion capability is highly expected to open a new platform for practical applications. (C) 2021 Elsevier Ltd. All rights reserved