Latest ArticlesFe-based compounds with good environmental friendliness and high reversible capacity have attracted considerable attention as anode for lithium-ion batteries. But, similar to other transition metal oxides (TMOs), it is also affected by large volume changes and inferior kinetics during redox reactions, resulting in the destruction of the crystal structure and poor electrochemical performance. Here, Fe3O4/C nanospheres anchored on the two-dimensional graphene oxide as precursors are phosphated and sintered to build the multiphasic nanocomposite. XRD results confirmed the multiphasic nanocomposite composed of Fe2O3, Fe3O4 and Fe3PO7, which will facilitate the Li+ diffusion. And the carbonaceous matrix will buffer the volume changes and enhance electron conduction. Consequently, the multiphasic Fe-based anode delivers a large specific capacity of 1086 mAh/g with a high initial Coulombic efficiency of 87% at 0.1 C. It also has excellent cycling stability and rate property, maintaining a capacity retention of ~87% after 300 cycles and a high reversible capacity of 632 mAh/g at 10 C. The proposed multiphasic structure offers a new insight into improving the electrochemical properties of TMO-based anodes for advanced alkali-ion batteries.
As a close relative of ferroelectricity, antiferroelectricity has received a recent resurgence of interest driven by technological aspirations in energy-efficient applications, such as energy storage capacitors, solid-state cooling devices, explosive energy conversion, and displacement transducers. Though prolonged efforts in this area have led to certain progress and the discovery of more than 100 antiferroelectric materials over the last 70 years, some scientific and technological issues remain unresolved. Herein, we provide perspectives on the development of antiferroelectrics for energy storage and conversion applications, as well as a comprehensive understanding of the structural origin of antiferroelectricity and field-induced phase transitions, followed by design strategies for new lead-free antiferroelectrics. We also envision unprecedented challenges in the development of promising antiferroelectric materials that bridge materials design and real applications. Future research in these directions will open up new possibilities in resolving the mystery of antiferroelectricity, provide opportunities for comprehending structure-property correlation and developing antiferroelectric/ferroelectric theories, and suggest an approach to the manipulation of phase transitions for real-world applications.
In this paper, the ammonia leaching process and high-energy ball milling method were adapted to recover spent LiCoO2 material. The ammonia reduction leaching mechanism of LiCoO2 material in the ammonia-sodium sulfite-ammonium chloride system was elucidated. Compared with untreated LiCoO2 material, the leaching equilibrium time of LiCoO2 after ball-milled for 5 h was reduced from 48 h to 4 h, and the leaching efficiency of lithium and cobalt was improved from 69.86% and 70.80% to 89.86% and 98.22%, respectively. Importantly, the apparent activation energy and leaching kinetic equation of the reaction was calculated by the shrinking core reaction model, indicating that the reaction was controlled by the chemical reaction.
Aqueous supercapacitors (SCs) have attracted more and more attention for their safety, fast charge/discharge capability and ultra-long life. However, the application of aqueous SCs is limited by the low working voltage due to the narrow electrochemical stability window (ESW) of water. Herein, we report a new "water in salt" (WIS) electrolyte by dissolving potassium bis (fluorosulfonyl) amide (KFSI) in water with an ultra-high mass molar concentration of 37 mol/kg. The highly concentrated electrolyte can achieve a wide ESW of 2.8 V. The WIS electrolyte enables a safe carbon-based symmetrical supercapacitor to operate stably at 2.3 V with an ultra-long cycle life and excellent rate performance. The energy density reaches 20.5 Wh/kg at 2300 W/kg, and the capacity retention is 83.5% after 50, 000 cycles at a current density of 5 A/g. This new electrolyte will be a promising candidate for future high-voltage aqueous supercapacitors.
A novel GO modified g-C3N4 nanosheets/flower-like BiOBr hybrid photocatalyst is fabricated by a facile method. The characterization results reveal that wrinkled GO is deposited between g-C3N4 nanosheets and flower-like BiOBr forming a Z-scheme heterojunction. As a mediator, plicate GO plays a positive role in prompting photogenerated electrons transferring through its sizeable 2D/2D contact surface area. The g-C3N4/GO/BiOBr hybrid displays a superior photocatalytic ability to g-C3N4 and BiOBr in photodegrading tetracycline (TC), whose removal efficiency could reach 96% within 2 h. Besides, g-C3N4/GO/BiOBr composite can reduce Cr(Ⅵ), and simultaneously treat TC and Cr(Ⅵ) combination contaminant under the visible light. The g-C3N4/GO/BiOBr ternary composite also exhibits satisfactory stability and reusability after four cycling experiments. Further, a feasible mechanism related to the photocatalytic process of g-C3N4/GO/BiOBr is put forward. This study offers a ternary hybrid photocatalyst with eco-friendliness and hopeful application in water pollution.
Molybdenum disulfide (MoS2) has excellent trapping ability for lead ions whereas its micro-/nanoscale size has greatly impeded its practical applications in the flow-through systems. Herein, a millimeter-sized nanocomposite MoS2−001 was synthesized for Pb2+ removal by loading MoS2 nanosheets into a polystyrene cation exchanger D-001 by a facile hydrothermal method. The proposed structure and adsorption mechanism of MoS2−001 was confirmed by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis. The nanocomposite showed outstanding adsorption capacity and rapid adsorption kinetic for Pb2+ removal, and the adsorption behavior followed the Langmuir adsorption model and pseudo-first-model kinetic model. Pb2+ uptake by MoS2−001 still maintains a high level even in the presence of extremely highly competitive ions (Ca(Ⅱ) and Mg(Ⅱ)), suggesting its high selectivity for Pb2+ adsorption. Besides, the fixed-bed column experiments further certified that MoS2−001 is of great potential for Pb2+ removal from the wastewater in practical engineering applications. Even more gratifying is that the exhausted MoS2−001 can be regenerated by NaCl-EDTANa2 solution without any significant adsorption capacity loss. Consequently, all the results indicated that MoS2−001 is a promising candidate adsorbent for lead-containing wastewater treatment.
Nucleic acids with G4 elements play a role in the formation of aggregates involved in intracellular phase transitions. Our previous studies suggest that different forms of DNA could act as an accelerating template in Cu/Zn superoxide dismutase (SOD1) aggregation. Here, we examined the regulation of formation and cytotoxicity of the SOD1 aggregates by single-stranded 12-mer deoxynucleotide oligomers (dN)12 (N = A, T, G, C; ssDNAs) under acidic conditions. The ssDNAs can be divided into two groups based on their roles in SOD1 binding, exposure of hydrophobic clusters in SOD1, accelerated formation, morphology and cytotoxicity of SOD1 aggregates. G-quadruplexes convert SOD1 into fibrillar aggregates as a template, a fact which was observed for the first time in the nucleic acid regulation of protein aggregation. Moreover, the fibrillar or fibril-like SOD1 species with a G-quadruplex provided by (dG)12 were less toxic than the amorphous species with (dN)12 (N = A, T). This study not only indicates that both morphology and cytotoxicity of protein aggregates can be regulated by the protein-bound DNAs, but also help us understand roles of nucleic aid G-quadruplexes in the formation of aggregates and membraneless organelles involved in intracellular phase transitions.
Borylative cyclization of E-3-arylallyl carbamoyl chlorides is achieved through copper catalyzed intramolecular carboboration with B2pin2. 2-Aryl-3-boryl-γ-lactams are formed with exclusive cis-diastereoselectivity. CuBr-Dppp combination gives the best outcomes. The substrate scope is profiled.
Nowadays, Cu-based materials have attracted extensive attention as electrocatalysts, while the inherent reason of the filling of high anti-bonding state of Cu d band (3d104s1) makes it difficult to hybridize with O 2p band of oxygen intermediates during the adsorption process of oxygen evolution reaction (OER). To increase the efficiency of Cu-based electrocatalysts, efforts have been made to optimize the electronic structures and to create surface defects and hierarchical nanostructures with more exposed accessible active sites. Herein, we report a facile method for preparing CuO electrocatalysts with hierarchical nanostructures using the Cu-alanine complex as a precursor through room-temperature chemical precipitation and subsequent calcination in air. Investigations of products obtained at different calcination temperatures reveal the relationship between OER activities and the material characteristics such as specific surface areas, crystal growth orientations, and element components. The product obtained at 500 ℃ exhibits the smallest overpotential of 290 mV in 1.0 mol/L KOH for electrocatalyzing OER. Combining with various characterizations of CuO electrocatalysts after OER activities, the possible catalytic mechanism and the influence factors of their OER performance are also discussed.
A heterojunction of Sm-doped g-C3N4/Ti3C2 MXene (SCN/MX) was constructed via prepolymerization and solid mixture-calcination method. The modified g-C3N4 presented a hollow porous seaweed-like shape which can increase its specific area and active sites. In SCN/MX composite, the optical properties, no matter optical absorption ability or separation performance of photo-induced electrons and holes, were enhanced. Among them, Sm-doping may play an important role on transferring the photogenerated electrons to suppress their recombination, and Ti3C2 MXene would broaden light absorption and further improve the carrier migration efficiency. The SCN/MX presented higher photocatalytic degradation efficiency (> 99%) of ciprofloxacin under visible light irradiation. The quenching experiments and electron spin-resonance spectroscopy confirmed that the dominated active materials were superoxide radical and holes. The degradation mechanisms of ciprofloxacin (CIP) over the SCN/MX were attacking of the active materials on the piperazine ring and quinolone ring, and the final products were CO2, H2O and F−.
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