Jianmei Lu

Graphene-Encapsulated Hollow Fe3O4 Nanoparticle Aggregates As a High-Performance Anode Material for Lithium Ion Batteries

Graphene-encapsulated ordered aggregates of Fe(3)O(4) nanoparticles with nearly spherical geometry and hollow interior were synthesized by a simple self-assembly process. The open interior structure adapts well to the volume change in repetitive Li(+) insertion and extraction reactions; and the encapsulating graphene connects the Fe(3)O(4) nanoparticles electrically. The structure and morphology of the graphene-Fe(3)O(4) composite were confirmed by X-ray diffraction, scanning electron microscopy, and high-resolution transmission microscopy. The electrochemical performance of the composite for reversible Li(+) storage was evaluated by cyclic voltammetry and constant current charging and discharging. The results showed a high and nearly unvarying specific capacity for 50 cycles. Furthermore, even after 90 cycles of charge and discharge at different current densities, about 92% of the initial capacity at 100 mA g(-1) was still recoverable, indicating excellent cycle stability. The graphene-Fe(3)O(4) composite is therefore a capable Li(+) host with high capacity that can be cycled at high rates with good cycle life. The unique combination of graphene encapsulation and a hollow porous structure definitely contributed to this versatile electrochemical performance.

Synthesis, characterization, and nonvolatile ternary memory behavior of a larger heteroacene with nine linearly fused rings and two different heteroatoms.

To achieve ultrahigh density memory devices with the capacity of 3(n) or larger, organic materials with multilevel stable states are highly desirable. Here, we reported a novel larger stable heteroacene, 2,3,13,14-tetradecyloxy-5,11,16,22-tetraaza-6,10,17,21-tetrachloro-7,9,18,20-tetraoxa-8,19-dicyanoenneacene (CDPzN), which has two different types of heteroatoms (O and N) and nine linearly fused rings. The sandwich-structure memory devices based on CDPzN exhibited excellent ternary memory behaviors with high ON2/ON1/OFF current ratios of 10(6.3)/10(4.3)/1 and good stability for these three states.

A Small-Molecule-Based Ternary Data-Storage Device

High-density data storage (HDDS) is urgently required to address ongoing rapid increases in amounts of information. Here we present a prototype sandwich device that has ternary data-storage performance. Three characteristic currents can be read out using a certain constant voltage after removal of the applied voltage. Two electron pull groups and one electron push group are identified as the species responsible for electron flow. We believe that our observation will offer an interesting and useful theoretical approach for a huge increase in the memory density of potential future devices.

Tailoring of Molecular Planarity to Reduce Charge Injection Barrier for High‐Performance Small‐Molecule‐Based Ternary Memory Device with Low Threshold Voltage

By introducing a coplanar fluorenone into the center of an azo molecule, the turn-on voltages of the ternary memory devices are significantly decreased to lower than -2 V due to the improved crystallinity and the reduced charge injection barrier. The resulting low-power consumption devices will have great potential applications in high-performance chips for future portable nanoelectronic devices.

Study on controlled free-radical polymerization in the presence of 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN)

Abstract Polymerization of methyl methacrylate was carried out in the presence of 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN). The results exhibit controlled polymerization characters: well-controlled molecular weight, narrow polydispersity (minimal value: 1.09), molecular weight linearly increasing with conversion and first-order kinetics of polymerization. The polymer can be used to synthesize methyl methacrylate–styrene copolymer with narrow polydispersity (minimal value: 1.22). The polymers were characterized by 1H NMR and GPC. The effect of molar ratio among MMA/CNDB/AIBN on polymerization was investigated.

High-Temperature Solid-State Dye-Sensitized Solar Cells Based on Organic Ionic Plastic Crystal Electrolytes

Organic ionic plastic crystal, 1-ethyl-1-methyl pyrrolidinium iodide (P(12) I), is employed as the solid-state electrolytes for dye-sensitized solar cells. The fabricated solid-state devices show an overall power conversion efficiency of ~5.8% under AM 1.5 radiation (50 mW/cm(2) ) and excellent long-term stability at 80 °C.

A Robust and Cost‐Effective Superhydrophobic Graphene Foam for Efficient Oil and Organic Solvent Recovery

Water pollution caused by chemical reagent leaking, industrial wastewater discharging, and crude oil spills has raised global concerns on environmental sustainability, calling for high-performance absorbent materials for effective treatments. However, low-cost materials capable of effectively separating oils and organic solvents from water with a high adsorption capacity and good recyclability are rare on the market. Here, a cost-effective method is reported to fabricate high-performance graphene modified absorbents through the facile thermal reduction of graphene oxide on the skeletons of melamine foam. By integrating the high porosity, superior elasticity, and mechanical stability of raw sponge with the chemical stability and hydrophobicity of graphene sheets, the as-fabricated graphene foam not only possesses a rough and superhydrophobic surface, but also exhibits an excellent adsorption performance and extraordinary recyclability for various oils and organic solvents. It is worth mentioning that the superhydrophobic surface also endows the graphene foam with an excellent efficiency for oil/water separation. More importantly, the cost-effective fabrication method without involving expensive raw materials and sophisticated equipment permits a scale-up of the graphene foam for pollution disposal. All these features make the graphene foam an ideal candidate for removal and collection of oils and organic solvents from water.

Synthesis, physical properties, and light-emitting diode performance of phenazine-based derivatives with three, five, and nine fused six-membered rings.

Realizing the control of emission colors of single molecules is very important in the development of full-color emitting materials. Herein, three novel phenazine derivatives (2,3,7,8-tetrakis(decyloxy)phenazine (2a), 2,3-didecyloxy-5,14-diaza-7,12-dioxo-9,10- dicyanopentacene (2b), and 2,3,13,14-tetradecyloxy-5,11,16,22-tetraaza-7,9,18,20-tetraoxo-8,19-dicyanoenneacene (2c)) have been successfully synthesized and fully characterized. Compound 2c can emit blue light in toluene solution (450 nm), green light in the powder/film state (502/562 nm), and red light in the 2c/TFA state (610 nm). The OLED with 2c emits a strong green light at a peak of 536 nm with a maximum luminance of the OLED of about 8600 cd m(-2), which indicates that 2c could be a promising fluorescent dye for OLED applications.

Modification of magnetic silica/iron oxide nanocomposites with fluorescent polymethacrylic acid for cancer targeting and drug delivery

Biocompatible and water-soluble magnetic nanoparticles with mesoporous core-shell structure were prepared and successfully modified with a fluorescent polymer chain as a labelling segment and folic acid as the cancer targeting moiety and loaded with a drug for directional release. The porous silica oxide structure and long molecular chains of polymethacrylic acid embedded the drug efficiently in the nanocomposites and did not affect the magnetic properties of the carrier. Sustained release of the loaded drug was observed over 100 h under in vitro conditions. Furthermore, the drug carrier is able to drill into the cell membranes and obtain a sustained release of the anticancer drug into the cytoplasm. The in vitro cellular uptake of the drug demonstrated that the drug-loaded nanocomposites could effectively target the tumor cells. Our model experiments indicated that this multifunctional mesoporous core-shell magnetic nanoparticle can be exploited as an anticancer drug delivery vehicle for targeting and therapy applications.

A highly active nano-palladium catalyst for the preparation of aromatic azos under mild conditions.

A worm-like Pd nanocatalyst has been prepared and used in the preparation of azo compounds from nitroaromatics under mild reaction conditions. This highly dispersible nano-Pd catalyst shows high activity toward the synthesis of both symmetric aromatic azo compounds and a range of asymmetric aromatic azo compounds.