Self-assembly preparation of advanced metastable MCo2O4/GO/Al (M=Cu, Mg, Zn, Ni) nanothermites to realize large heat release, stable combustion and high safety

Abstract

Metal/oxide-based nanothermite is a kind of metastable intermolecular composites (MICs) whose application performance can be adjusted purposefully by varying properties of oxidizers. Herein, four new MCo2O4/GO/Al (M = Cu, Mg, Zn, Ni) nanothermites were prepared in this work, in which the bimetallic composite oxides of spinel MCo2O4 were employed to replace single metal oxides as oxidizer. The positively charged MCo2O4 and Al nanoparticles were successfully self-assembled by the encapsulation of negatively charged GO. MCo2O4/GO/Al nanothermites present a dense layer stacked structure and uniform distribution, with a favorable interfacial contact between the bimetallic oxide and fuel at the nanoscale. MCo2O4/GO/Al nanothermites release higher energy of about 2500–3400 J g−1, much higher than that of corresponding thermite with single metal oxide. CuCo2O4/GO(2.5 wt%)/Al has the shortest pressure rise time (27.18 ms), largest energy output (3422 J g−1) and peak pressure (6.03 MPa), exhibiting a more violent combustion reaction and higher reactivity. The introduction of GO significantly improves the safety, and the electrostatic discharge sensitivity (EDS) of CuCo2O4/GO(5 wt%)/Al can reach 0.56 mJ, largely higher than that of CuCo2O4/Al without GO (0.04 mJ). MCo2O4/GO/Al nanothermites also have different catalytic performances on energetic components of cyclotrimethylenetrinitramine (RDX), ammonium perchlorate (AP) and dihydroxy-lammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50), indicating the selectivity of catalyst. This study proves that spinel MCo2O4 is a superior oxidizer for Al-based nanothermite system.