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Conformal Coating of a Carbon Film on 3D Hosts toward Stable Lithium Anodes
No full textLithium metal has the highest theoretical specific capacity and the most negative redox potential among all metals. However, the uncontrolled dendritic growth of lithium seriously hinders the practical application of Li metal batteries. Thus, great approaches have been proposed to have normal operation in the presence of dendritic lithium, such as changing the growth of lithium dendrites from vertical to lateral. However, although the lateral growth of Li dendrites does not pierce the separator to ensure the safety of the battery, it still ruptures the SEI film, resulting in poor Coulombic efficiency. Here, a coaxial non-equipotential host showing a heteroatom-doped carbon film-coated stainless steel mesh (SSM@C) is fabricated by electropolymerization and carbonization to encapsulate metallic Li underneath the carbon film and reduce the parasitic reactions between the deposited lithium and the electrolyte for dendrite-free Li deposition. Therefore, highly reversible Li plating/stripping, i.e., a high average Coulombic efficiency of similar to 99% over more than 400 cycles and stable cycling performance of symmetrical batteries for more than 1200 h, can be realized on this substrate
Transition Metal Oxide-Modified Ir Nanoparticles Supported on SBA-15 Silica for Selective Hydrogenation of Substituted Nitroaromatics
No full textModification of active metals with metal oxide modifiers has attracted considerable attention in heterogeneous catalysis due to their synergistic effect. However, a controllable synthesis of highly reactive and stable metal-metal oxide hybrid nanocatalysts is difficult. To solve this problem, presynthesized IrM (M = Fe, Co, and Ni) bimetallic nanoparticles were initially confined in the mesopores of SBA-15 and were then in situ transformed to Ir-MOx hybrids. The obtained Ir-MOx/SBA-15 nanocatalysts show superior activity and selectivity in the hydrogenation of substituted nitroaromatics to corresponding aromatic amines compared to Ir/SBA-15. Among these Ir-based catalysts, Ir-FeOx/SBA-15 exhibits the highest activity and selectivity and has a wider substrate scope due to the interaction between Ir and FeOx. Therefore, our research provides a way to design reactive and stable hydrogenation catalysts
Molten Salt Synthesis of Nanolaminated Sc2SnC MAX Phase
No full textThe MAX phases are a family of ternary layered material with both metal and ceramic properties, and it is also precursor materials for synthesis of two-dimensional MXenes. The theory predicts that there are more than 600 kinds of stable ternary layered MAX phase materials. Now, more than 80 kinds of ternary layered MAX phases that the M-site elements are mainly from early transition metal have been experimental synthesized, but few researches are reported on MAX phases where M is a rare earth element. In this study, Sc, Sn and C powders were used as raw materials to synthesize a novel ternary Sc2SnC MAX phase via molten salt method. Phase composition and microstructure of Sc2SnC were confirmed by X-ray diffraction, scanning electron microscope and X-ray energy spectrum analysis. And, structural stability, lattice parameters, mechanical and electronic properties of Sc2SnC were investigated via density functional theory. The theoretical results show that Sc2SnC is thermodynamically stable, and the Sc2SnC is metallic in nature where the contribution from Sc-3d states dominates the electronic conductivity at the Fermi level. This study provides a route to explore more unknown ternary layered rare earth compounds Ren+1SnCn (Re=Sc, Y, La-Nd, n=1) and corresponding rare earth MXenes
Ultrafast and high-efficient self-healing epoxy coatings with active multiple hydrogen bonds for corrosion protection
No full textCombining a fast self-healing action and a high barrier property remains a challenge in polymeric protective coatings. Herein, we report an intrinsic self-healing epoxy coating in which 2-ureido-4[1H]-pyrimidinone (UPy) as a quadruple hydrogen bonding unit, grafted onto the backbones of an epoxy-matrix by an amine-terminated oligo(propylene glycol) linker. Without any intervention, the epoxy-matrix performs its self-healing function in similar to 5 min, even under aqueous immersion. Besides, electrochemical impedance spectroscopy measurements demonstrate corrosion protection ability of such self-healed coating on a steel substrate, with a high vertical bar Z vertical bar(0.01Hz) value of 4.8 x 10(10) Omega.cm(2) after 60 days of immersion in NaCl solution
Nano-channel-based physical and chemical synergic regulation for dendrite-free lithium plating
No full textUncontrollable dendrite growth resulting from the non-uniform lithium ion (Li+) flux and volume expansion in lithium metal (Li) negative electrode leads to rapid performance degradation and serious safety problems of lithium metal batteries. Although N-containing functional groups in carbon materials are reported to be effective to homogenize the Li+ flux, the effective interaction distance between lithium ions and N-containing groups should be relatively small (down to nanometer scale) according to the Debye length law. Thus, it is necessary to carefully design the microstructure of N-containing carbon materials to make the most of their roles in regulating the Li+ flux. In this work, porous carbon nitride microspheres (PCNMs) with abundant nanopores have been synthesized and utilized to fabricate a uniform lithiophilic coating layer having hybrid pores of both the nano- and micrometer scales on the Cu/Li foil. Physically, the three-dimensional (3D) porous framework is favorable for absorbing volume changes and guiding Li growth. Chemically, this coating layer can render a suitable interaction distance to effectively homogenize the Li+ flux and contribute to establishing a robust and stable solid electrolyte interphase (SEI) layer with Li-F, Li-N, and Li-O-rich contents based on the Debye length law. Such a physical-chemical synergic regulation strategy using PCNMs can lead to dendrite-free Li plating, resulting in a low nucleation overpotential and stable Li plating/stripping cycling performance in both the Li parallel to Cu and the Li parallel to Li symmetric cells. Meanwhile, a full cell using the PCNM coated Li foil negative electrode and a LiFePO4 positive electrode has delivered a high capacity retention of similar to 80% after more than 200 cycles at 1 C and achieved a remarkable rate capability. The pouch cell fabricated by pairing the PCNM coated Li foil negative electrode with a NCM 811 positive electrode has retained similar to 73% of the initial capacity after 150 cycles at 0.2 C
Chemical Footprint of the Wet Processing of Cotton Fabric
No full textThe chemical footprint (ChF) can identify the harmful effects of discharged chemical pollutants, helping producers to select environmentally friendly chemicals to reduce their negative environmental impact. This paper quantified and evaluated the ChF of the wet processing of cotton fabric with data collected from a dyeing enterprise. The results showed that the discharged sodium hydroxide caused the most severe impact in terms of both human toxicity and ecotoxicity due to the extensive usage and its high toxicity. The discharged sodium carbonate and dimethyl silicone oil also had a greater environmental impact. Comprehensive evaluation of human toxicity and ecotoxicity with a multi-objective grey target decision-making model indicated that the pretreatment process had the most significant impact, followed by the finishing process and dyeing process. More attention should be paid to the pretreatment process, such as the selection of environmentally friendly textile chemicals, in order to reduce the native impacts of the wet processing of cotton fabric
Anticorrosion Performance of Epoxy Coating Containing Phytic Acid-Doped Tetraaniline Nanoparticle
No full textIn this work, epoxy coatings containing phytic acid-doped tetraaniline (PATA) nanoparticles for Q235 steel were prepared and their anticorrosive properties were investigated. Synthesized PATA nanoparticles were characterized by scanning electron microscope (SEM), scanning probe microscope (SPM), photoelectronic spectroscopy (XPS), and Raman test. The anti-corrosion properties of coating were studied by the open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and scanning vibrating electrode technique (SVET). The experimental results showed that the content of the PATA nanoparticle has a positive effect on the barrier ability of the epoxy matrix. The epoxy coating containing 0.25 wt% of PATA nanoparticles has superior corrosion protection property and a satisfactory self-healing effect. The self-healing effect of PATA/EP coating ascribes to the synergistic effect of the passivation of phytic acid ions and tetraaniline. As an effective anticorrosion filler, the PATA nanoparticle has the potential to apply to the field of corrosion protective coating
A green fabricati on method of poly (lactic acid) perforated membrane via tuned crystallization and gas diffusion process
No full textPoly (lactic acid) (PLA) perforated membrane is typically obtained through the solvent-volatilization-induced or non-solvent-induced phase separation (NIPS) method. However, the residual organic solvents would unavoidably limit the application of PLA perforated membrane in biomedical and high-end water purification fields. Herein, an innovative solution-free method was proposed for preparing the PLA perforated membrane via a simple and environmentally friendly way. We have successfully fabricated the PLA perforated membrane using a physical foaming technique with CO2 as the blowing agent. By tuning the primary film thickness, saturation pressure, and foaming temperature, PLA perforated membrane's cell morphology could be accordingly adjusted. The PLA perforated membrane with a highly-ordered straight pore channel and high open cell content (OCC) approximately 72% was obtained under a mild condition. The formation mechanism of the PLA perforated membrane was discussed via the interaction of crystallization behavior and gas diffusion process. This green and solvent-free PLA perforated membrane possesses great potential for use in areas like the tissue engineering and high-end water purification. (C) 2021 Elsevier B.V. All rights reserved
First-Principles-Based Prediction of Electrochemical Oxidation and Corrosion of Copper under Multiple Environmental Factors
No full textWe present the broadly important immunity, passivation, and corrosion behavior of copper subjected to multiple environmental factors, e.g., solution pH, electrode potential, temperature, and pressure, assessed through density functional theory-calculated electrochemical Pourbaix diagrams. The existing discrepancies between thermodynamically predicted and electrochemically observed behaviors of copper in aqueous electrochemical conditions are addressed. Corrosion phases are found to compete with solid copper precipitates at small applied potentials near neutral pHs. Elevated temperatures initiate driving forces that increasingly favor corrosion products over passivating oxides. We predict the prolonged stability of solid phases at non-standard-state conditions below similar to 200 degrees C. At temperatures close to 300 degrees C and above, corrosion should progress at all pHs for neutral and positive applied potentials. Moreover, we report the pressure dependence of our Pourbaix diagrams at 500 and 5000 bar, which shows that pressure alters the predominance of specific ionic species. Finally, to reduce the needed computational resources and utilize high-fidelity density functional theory (DFT) methods, we introduce a revised correct relative chemical potential (CRCP) scheme that leverages highly accurate hybrid density functionals that include nonlocal Fock exchange. Our results and discussion of the methodology provide insight into using first-principles calculations to obtain non-standard-state Pourbaix diagrams for understanding oxidation and corrosion under extreme conditions
