Enhancing Heat Performances Of Metastable Intermolecular Composites Through Incorporation With Graphene Quantum Dots

Metastable intermolecular composites?MICs?,one class of energetic composites with high energy density and proper energy?heat?releasing rate hold great promises for many applications.So far,a vary kinds of MICs have been successfully fabricated through different methodologies.However,the MICs with high heat release of thermite reaction show usually relatively low reaction rate,which is hard to satisfy the demand in practical applications.Owing to the limitations of novel fuel and oxidant components,and also the efficient assembly strategy,the mass scale fabrication of MICs assuming both high heat release and reaction rate is still challenging.Graphene quantum dots?GQDs?,as a derivative of graphene,have the same single atom layer structure and abundant functionalities,which afford it well dispersing ability in water and the possibility for chemically bonding with certain nanoparticles?NPs?.Thus,GQDs should have the potential to mediate the self-assembling MICs.In this work,GQDs were employed as the media to assemble MICs.The morphology,chemical compositions and heat performance have been systematically studied.Frist,Al/GQDs/CuO MICs were prepared through a two-step method with isopropanol as solvent.The as-assembled MICs exhibit 1942.1 J g^-1 of heat release and 5.2 mW mg^-1 of peak heat flow,owing to more intimate surface contact between Al and CuO NPs.The reaction rate evaluated from peak heat flow was further enhanced by etching the Al₂O₃passivation layer on Al NPs with acetic acid.The results show a remarkably enhancement with 2203 J g^-1 of heat release and 53.3 mW mg^-1 of peak heat flow,suggesting the quick thermite reaction of the as-assembled MICs.Second,considering the passivation Al₂O₃ shell on Al NPs can hinder the interaction between the fuel and oxidizer,Si NPs are further utilized as the fuel.Si/GQDs/Fe₂O₃ MICs were prepared and the effects of dispersant,GQDs contents and ratio of the components on heat performance have been elaborated.The results show the heat release can reach to 1817.5 J g^-1 even when the MICs were prepared in water/IPA dispersant with the GQDs content of 0.5%?in weight?and the optimized ratio between Si and Fe₂O₃should be 1.4.Given the relatively high heat release and thermite reaction rate,the strategy described in this work can be developed as a simple and facile route to prepare MICs for practical application.