Synthesis of magnetic particles with superparamagnetism, high magnetization, excellent biocompatibility and small particle size is highly desirable for biomedical applications. Herein, we report that sub-100 nm biocompatible Fe3O4 nanocrystal clusters can be prepared via a solvothermal method by using water as a size-control agent and sodium citrate as a stabilizer. The resultant Fe3O4 particles have uniform spherical shape, superparamagnetic properties, high magnetization values, excellent colloidal stability and good biocompatibility. Notably, the particle size can be tuned over a range of 70–180 nm by changing the content of H2O in the system. Moreover, the T2-weighted magnetic resonance imaging (MRI) experiments show that 85 nm Fe3O4 particles have an ultra-high r2 relaxivity of 175.4 mM−1 s−1, suggesting a great potential as MRI probes. In addition, the labeling efficiency of mesenchymal stem cells with as-obtained Fe3O4 particles is much higher than that of commercial superparamagnetic iron oxide nanoparticles, which further indicates their promising in biomedicine.

Here, we develop a novel and cost-effective design of hierarchical Co3O4/SnO2@MnO2 core–shell nanostructures to serve as high-performance electrodes for supercapacitors. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) measurements indicate that ultrathin MnO2 nanosheets uniformly deposit on the surface of the Co3O4/SnO2 nanobox, as a result, forming a core–shell structure. These unique well-designed electrodes exhibit a high specific capacitance (225 F g−1 at a current density of 0.5 A g−1), a good rate capability (62.2% capacitance retention), and an excellent cycling stability (90.7% retention after 6000 cycles). We believe that this facile strategy to fabricate the core–shell structure with significantly improved electrochemical properties opens up new opportunities to design a high-performance MnO2-based nanocomposite for constructing next-generation supercapacitors.

Development of anode materials with high capacity and long cycle life, while maintaining low production cost is crucial for achieving high-performance lithium-ion batteries (LIBs). Herein, we report a simple and cost-effective one-pot solvothermal method to synthesize graphene@Fe3O4@C core–shell nanosheets as a LIB anode with improved electrochemical performances. In this case, ferrocene was used as the precursor for both Fe3O4 and carbon, while graphene oxide was used as a template for the resultant two-dimensional nanostructure and conductive graphene backbone. The obtained graphene@Fe3O4@C core–shell nanosheets have a unique core–shell nanostructure, ultrasmall Fe3O4 nanoparticles (∼6 nm), and a high surface area of ∼136 m2 g−1, as well as show a high reversible capacity of ∼1468 mA h g−1, an excellent rate capability and long cycle life, which reflects the ability of graphene backbone to enhance the conductivity and carbon coating to prevent agglomeration of iron oxide nanoparticles. These findings provide a new approach to the design and synthesis of high-performance anode materials.

Graphene-based hybrids have been well studied as advanced catalysts and high-performance electrode materials. In this Article, we have fabricated a novel graphene@mesoporous TiO2 nanocrystals@carbon nanosheet by a simple one-step solvothermal method. We have found that titanocene dichloride can act as an extraordinary source with multiple roles for forming TiO2 nanocrystals, ultrathin carbon outer shells, and cross-linkers to binding TiO2 nanocrystals on graphene surface. Moreover, it also serves as a controlling agent to produce mesoporous structure on TiO2 nanocrystals. The loading-concentration of mesoporous TiO2 nanocrystals on graphene sheets can be well controlled by adjusting the initial content of titanocene dichloride. The as-obtained graphene@mTiO2@carbon nanosheets possess a uniform sandwich-like structure, highly crystalline mesoporous TiO2 nanocrystals, a high surface area of ∼209 m2/g, and a large pore volume of ∼0.68 cm3 g–1. When used as anodes for LIBs, the resultant nanosheets show a high reversible capacity (∼145 mAh/g), good rate capability, and long cycling life (capacity remains 110 mAh/g after 100 cycles at a current density of 0.2 A/g). We believe that our method represents a new path way to synthesize novel nanostructured graphene-based hybrids for future applications.Keywords: carbon; graphene; lithium-ion batteries; mesoporous; TiO2 nanocrystals;

In this research, hierarchical porous TiO2 ceramics were successfully synthesized through a camphene-based freeze-drying route. The well-dispersed TiO2 slurries were first frozen and dried at room temperature, followed by high-temperature sintering. The ceramics were analyzed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Results indicated that the obtained TiO2 ceramics could inhibit undesirable anatase-to-rutile phase transformation and grain growth even at temperatures as high as 800 °C. In this experiment, optimal compressive strength and porosity of the TiO2 ceramics were produced with the initial TiO2 slurry content of ∼15 wt %. The resultant TiO2 ceramics performed excellently in the photodegradation of atrazine and thiobencarb, and the total organic carbon removal efficiency was up to 95.7% and 96.7%, respectively. More importantly, the TiO2 ceramics were easily recyclable. No obvious changes of the photocatalytic performance were observed after six cycles. Furthermore, the ceramics also effectively degraded other pesticides such as dimethoate, lindane, dipterex, malathion, and bentazone. These hierarchical porous TiO2 ceramics have potential applications in environmental cleanup.Keywords: floating photocatalyst; pesticide micropolluted water; photocatalysis; porous TiO2 ceramics; room-temperature freeze-drying

Here, we develop a novel and cost-effective design of hierarchical Co3O4/SnO2@MnO2 core–shell nanostructures to serve as high-performance electrodes for supercapacitors. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) measurements indicate that ultrathin MnO2 nanosheets uniformly deposit on the surface of the Co3O4/SnO2 nanobox, as a result, forming a core–shell structure. These unique well-designed electrodes exhibit a high specific capacitance (225 F g−1 at a current density of 0.5 A g−1), a good rate capability (62.2% capacitance retention), and an excellent cycling stability (90.7% retention after 6000 cycles). We believe that this facile strategy to fabricate the core–shell structure with significantly improved electrochemical properties opens up new opportunities to design a high-performance MnO2-based nanocomposite for constructing next-generation supercapacitors.

Development of anode materials with high capacity and long cycle life, while maintaining low production cost is crucial for achieving high-performance lithium-ion batteries (LIBs). Herein, we report a simple and cost-effective one-pot solvothermal method to synthesize graphene@Fe3O4@C core–shell nanosheets as a LIB anode with improved electrochemical performances. In this case, ferrocene was used as the precursor for both Fe3O4 and carbon, while graphene oxide was used as a template for the resultant two-dimensional nanostructure and conductive graphene backbone. The obtained graphene@Fe3O4@C core–shell nanosheets have a unique core–shell nanostructure, ultrasmall Fe3O4 nanoparticles (∼6 nm), and a high surface area of ∼136 m2 g−1, as well as show a high reversible capacity of ∼1468 mA h g−1, an excellent rate capability and long cycle life, which reflects the ability of graphene backbone to enhance the conductivity and carbon coating to prevent agglomeration of iron oxide nanoparticles. These findings provide a new approach to the design and synthesis of high-performance anode materials.