Dongzhi Yang

Graphene Oxide/Chitosan Aerogel Microspheres with Honeycomb-Cobweb and Radially Oriented Microchannel Structures for Broad-Spectrum and Rapid Adsorption of Water Contaminants

Multifunctional graphene oxide (GO)/chitosan (CS) aerogel microspheres (GCAMs) with honeycomb-cobweb and radially oriented microchannel structures are prepared by combining electrospraying with freeze-casting to optimize adsorption performances of heavy metal ions and soluble organic pollutants. The GCAMs exhibit superior adsorption capacities of heavy metal ions of Pb(II), Cu(II), and Cr(VI), cationic dyes of methylene blue (MB) and Rhodamine B, anionic dyes of methyl orange and Eosin Y, and phenol. It takes only 5 min to reach 82 and 89% of equilibrium adsorption capacities for Cr(VI) (292.8 mg g-1) and MB (584.6 mg g-1), respectively, much shorter than the adsorption equilibrium time (75 h) of a GO/CS monolith. More importantly, the GCAMs maintain excellent adsorption capacity for six cycles of adsorption-desorption. The broad-spectrum, rapid, and reusable adsorption performance makes the GCAMs promising for highly efficient water treatments.

Highly Efficient High-Pressure Homogenization Approach for Scalable Production of High-Quality Graphene Sheets and Sandwich-Structured α-Fe2O3/Graphene Hybrids for High-Performance Lithium-Ion Batteries

A highly efficient and continuous high-pressure homogenization (HPH) approach is developed for scalable production of graphene sheets and sandwich-structured α-Fe2O3/graphene hybrids by liquid-phase exfoliation of stage-1 FeCl3-based graphite intercalation compounds (GICs). The enlarged interlayer spacing of FeCl3-GICs facilitates their efficient exfoliation to produce high-quality graphene sheets. Moreover, sandwich-structured α-Fe2O3/few-layer graphene (FLG) hybrids are readily fabricated by thermally annealing the FeCl3 intercalated FLG sheets. As an anode material of Li-ion battery, α-Fe2O3/FLG hybrid shows a satisfactory long-term cycling performance with an excellent specific capacity of 1100.5 mA h g-1 after 350 cycles at 200 mA g-1. A high reversible capacity of 658.5 mA h g-1 is achieved after 200 cycles at 1 A g-1 and maintained without notable decay. The satisfactory cycling stability and the outstanding capability of α-Fe2O3/FLG hybrid are attributed to its unique sandwiched structure consisting of highly conducting FLG sheets and covalently anchored α-Fe2O3 particles. Therefore, the highly efficient and scalable preparation of high-quality graphene sheets along with the excellent electrochemical properties of α-Fe2O3/FLG hybrids makes the HPH approach promising for producing high-performance graphene-based energy storage materials.

FeCl3 intercalated few-layer graphene for high lithium-ion storage performance

We report a facile and efficient approach to prepare graphene and FeCl3-intercalated few-layer graphene (FeCl3-FLG) with stage 1 FeCl3-graphite intercalation compounds (GICs) as a precursor by a non-oxidation process. The enlarged interlayer spacing by the intercalation of FeCl3 greatly weakens the interaction among graphite sheets and thus facilitates the exfoliation of FeCl3-GICs. By ultrasonic treatment, FeCl3-GICs are well exfoliated to graphene sheets (<2 nm) with a high yield of 100%, while the ultrasonication of pristine graphite is less efficient with a low yield (about 32%) of graphene sheets. By simply controlling the sonication time, FeCl3-FLG consisting of graphene sheets and sandwiched FeCl3 is also prepared, which exhibits a high capacity of 989 mA h g−1 after 50 cycles, fairly higher than that of the sonicated graphite (503 mA h g−1) and the theoretical value of graphite (372 mA h g−1). Furthermore, FeCl3-FLG still retains a reversible capacity as high as 539 mA h g−1 even at a current density of 1000 mA g−1. Therefore, the high reversible capacity, remarkable cycling stability and superior capability make FeCl3-FLG promising as anode materials for large-scale and high-capacity lithium ion batteries.