Ferrocene functionalized graphene: preparation, characterization and application as an efficient catalyst for the thermal decomposition of TKX-50.

Novel ferrocene functionalized graphene with different molecular structures were designed, fabricated and characterized via SEM, EDS, FTIR, XPS and RAMAN methods. SEM results show the two-dimensional structure of the as-prepared catalysts, and the active metal Fe is uniformly distributed on the surface of graphene. The FTIR, XPS and RAMAN results confirmed the successful preparation of ferrocene functionalized graphene. The catalytic effects of the as-synthesized catalysts for the thermal decomposition of energetic TKX-50 were monitored by DSC, and the corresponding kinetic parameters were calculated using multi kinetic methods including traditional and nonlinear models. The results showed that the as-prepared ferrocene functionalized graphene can effectively promote the thermal decomposition of TKX-50 with the reduced decomposition peak temperatures and activation energies. In addition, the effects of ferrocene functionalized graphene for TKX-50 decomposition are reflected in both high and low temperature stages, and the effect on the high temperature stage is more significant. The outstanding catalytic activity of ferrocene functionalized graphene is related not only to the good dispersion of active Fe, but also to the enhanced interaction of small molecule products on two-dimensional graphene. Among the ferrocene functionalized graphene studied, G-792-Fe and G-902-Fe exhibit better catalytic effects on the thermal decomposition of TKX-50, which can be used as candidate catalysts for TKX-50-based solid propellants.

Catalytic Effects of rGO-MFe2O4 (M = Ni, Co, and Zn) Nanocomposites on the Thermal Decomposition Performance and Mechanism of Energetic FOX-7.

Thermal decomposition performance of the insensitive energetic compound 1,1-diamino-2,2-dintroethene (FOX-7) is essential for its application in the field of solid propellants. This study seeks to reveal the catalytic effects of reduced graphene oxide-bimetallic oxide nanocomposites (rGO-MFe2O4, M = Ni, Co, and Zn) on the thermal decomposition, kinetic parameters, and pyrolysis mechanism of energetic FOX-7. The results showed that the catalytic activities of the bimetallic iron oxide (NiFe2O4, CoFe2O4, and ZnFe2O4) increased obviously after anchoring on the surface of graphene. Particularly, the rGO-NiFe2O4 nanocomposite possessed the best catalytic activity for FOX-7 thermal decomposition. The high thermal decomposition peak temperature (THDP) and the apparent activation energy (Ea) of FOX-7 were decreased by 57.4 °C and 54.27 kJ mol-1 after mixing with the rGO-NiFe2O4 nanocomposite. The excellent catalytic activity of rGO-NiFe2O4 can be attributed to the synergistic interaction between rGO and NiFe2O4, which is beneficial for the reduction of activation energy and a high thermal decomposition peak temperature of FOX-7. This study is helpful for the rational design of a solid propellant containing FOX-7 and to understand the thermal decomposition kinetics and mechanism of FOX-7.

Growth of colloidal PbS nanosheets and the enhancement of their photoluminescence.

Dual photoluminescence peaks observed during the synthesis of colloidal PbS nanosheets reveal their growth mechanism - two-dimensional attachments of the quantum dots. Well-grown nanosheets show the photoluminescence linewidth of 95 meV at room temperature. Aged nanosheets in toluene have enhanced photoluminescence with intensity improved by an order of magnitude.

Colloidal Nanoribbons: From Infrared to Visible.

Using the cation-exchange method, colloidal PbS nanoribbons are converted completely into CdS nanoribbons. This process expands the emission spectrum of the nanoribbons from infrared to visible. The morphology of nanoribbons remains the same after cation exchange, but the crystal structure changes from rock salt to zincblende. CdS nanoribbons exhibit blue band-edge photoluminescence under ultraviolet-light excitation. Cathodoluminescence spectroscopy of the CdS nanoribbons shows multicolor (blue, green, and red) emissions. Further time-resolved photoluminescence spectroscopy studies show that the lifetime of the midgap states is more than 2 orders of magnitude longer than that of the band-edge states.

Using Interaction of Nano Dipoles to Control the Growth of Nanorods.

Charged facets of a nanocrystal can form an intrinsic nanometer-size electric dipole. When the spacing between these nano dipoles is adjusted, the dipolar interaction energy is tuned from a fraction to a multiple of the thermal energy. Consequently, the one-dimensional oriented attachment can be switched on or off, as is the growth of nanorods. This kinetically controlled growth is achieved at relatively low reaction temperatures while the thermodynamically controlled growth dominates at higher temperatures. The synthesized PbSe nanorods are branchless, exhibiting a single-exponential photoluminescence decay trace with an e-folding lifetime of 1.3 µs and a photoluminescence quantum yield of 35%.

Facile and rapid synthesis of RGO-In2S3 composites with enhanced cyclability and high capacity for lithium storage.

A sheet-on-sheet reduced graphene oxide-ß-In(2)S(3) (RGO-In(2)S(3)) composite, was successfully synthesized via a one-step mild method. This fresh composite used as an anode material exhibits enhanced cyclability and specific capacity for lithium storage. These results are linked with the intrinsic layered structure of ß-In(2)S(3) sheets and the effective combination of ß-In(2)S(3) and RGO sheets. This results in a high specific surface area and good conductivity of RGO-In(2)S(3) composites, with higher transport rates of electrolyte ions and electrons, and a more effective electrochemical reaction of the active material. This facile and rapid synthesis method is a promising route for a large-scale production of graphene-based metal sulfides, which could be used as electrode materials for Li-ion batteries.