Enhanced Thermal Decomposition Properties of CL-20 through Space-Confining in Three-Dimensional Hierarchically Ordered Porous Carbon

High energy and low signature properties are the future trend of solid propellant development. As a new and promising oxidizer, hexanitrohexaazaisowurtzitane (CL-20) is expected to replace the conventional oxidizer ammonium perchlorate to reach above goals. However, the high pressure exponent of CL-20 hinders its application in solid propellants so that the development of effective catalysts to improve the thermal decomposition properties of CL-20 still remains challenging. Here, 3D hierarchically ordered porous carbon (3D HOPC) is presented as a catalyst for the thermal decomposition of CL-20 via synthesizing a series of nanostructured CL-20/HOPC composites. In these nanocomposites, CL-20 is homogeneously space-confined into the 3D HOPC scaffold as nanocrystals 9.2–26.5 nm in diameter. The effect of the pore textural parameters and surface modification of 3D HOPC as well as CL-20 loading amount on the thermal decomposition of CL-20 is discussed. A significant improvement of the thermal decomposition properties of CL-20 is achieved with remarkable decrease in decomposition peak temperature (from 247.0 to 174.8 °C) and activation energy (from 165.5 to 115.3 kJ/mol). The exceptional performance of 3D HOPC could be attributed to its well-connected 3D hierarchically ordered porous structure, high surface area, and the confined CL-20 nanocrystals. This work clearly demonstrates that 3D HOPC is a superior catalyst for CL-20 thermal decomposition and opens new potential for further applications of CL-20 in solid propellants

Gram-Scale Synthesis of Graphene Quantum Dots from Single Carbon Atoms Growth via Energetic Material Deflagration

Graphene quantum dots (GQDs) with quantum confinement and size effect are proposed to be applicable in photovoltaic, nanodevices, and so on, due to extraordinary electronic and optical properties. Here we report a facile approach to synthesize gram-scale GQDs from active carbon atoms, which are obtained via the deflagration reaction of polytetrafluoroethylene (PTFE) and Si, growing from high- to low-temperature zones when traveling through the deflagration flame in a short time with releasing gas as the carrier medium. The prepared GQDs were aggregated into carbon nanospheres; thus, Hummer’s method was utilized to exfoliate the GQD aggregations into individual GQDs. We show that the length of GQDs is ∼10 nm and the exfoliated GQDs solution presents an obvious fluorescence effect with a strong emission peak at 570 at 460 nm excitation. And these GQDs are demonstrated to be excellent probes for cellular imaging. Furthermore, we propose a growth mechanism based on computer simulation, which is well verified by experimental reproduction. Our study opens up a promising route for high-yield and high-quality GQDs, as well as other various quantum dots