Tuning the crystal morphology and catalytic behavior of graphene-templated energetic bis-tetrazole copper coordination polymers

The addition of graphene-based energetic catalysts to the solid propellants may improve the combustion efficiency, and meantime maintain its energy level and high thermal stability, which are of great importance for the solid propellant applications. Various new energetic coordination polymers (ECPs), based on the graphene oxide (GO) copper(II) complex, have been synthesized using 5,5′-bis-tetrazole (H₂BT) or 5,5-bis-tetrazole-1,1-dioldehydrate (DHBT) as the ligands, by hydrothermal and solvothermal methods. It has been shown that crystal structure and morphologies could be changed by regulation of the synthetic methods, resulting in a series of the graphene-based bis-tetrazole complexes using the same starting materials. The graphene-based energetic azole-based ECPs showed higher thermostability than the pristine metal complexes due to stabilization effect of graphene, and change in crystal forms also makes thermostability different. The heat releases from AP have been increased by three to four times under the catalytic effects of these GO-based ECPs, where two exothermic peaks of AP merged into one at 290.5 °C for GO-Cu-DBT/AP and 316.2 °C for GO-Cu-BT/AP. A shoulder peak is shown after the main exothermic peak of RDX due to the post-effect of the catalysts on its condensed products with secondary reactions. [Figure not available: see fulltext.]