Encapsulation of aluminum nanoparticles within copper oxide matrix for enhancing their reactive properties

- Al nanoparticles (NPs) are significantly oxidized by calcination process.
- CuO-encapsulated Al NPs are fabricated using a spray pyrolysis.
- CuO matrices protect Al NPs from thermal oxidation in the calcination process.
- The reactive properties of CuO-encapsulated Al NPs are much better than those of Al/CuO composites.

Simple and easy spray pyrolysis and subsequent calcination processes were employed in this study to fabricate nanoenergetic materials (nEMs) composed of Al as the fuel and CuO as the oxidizer. Al nanoparticles (NPs) and Cu(NO3)2 as the CuO precursor were first dissolved in ethanol, and then they were pyrolized in the gas phase. After the subsequent calcination process, Cu(NO3)2 and its intermediate matrix covering Al NPs were completely transformed to the CuO matrix by thermal decomposition, and thus, the CuO-encapsulated Al NPs were successfully fabricated. The burn rate of the CuO-encapsulated Al NPs fabricated in this study was found to be much higher than that of Al/CuO composite NPs, which were fabricated for comparison by traditional sonication mixing and subsequent calcination processes. The ignition delay time and total burning time of CuO-encapsulated Al NPs were also much shorter than those of Al/CuO composite NPs. This suggests that the combination of spray pyrolysis and subsequent calcination processes can be a versatile and effective method to form the homogeneous and intimate nEMs composed of fuel materials (i.e., Al NP core) and oxidizers (i.e., CuO matrix) with high reactivity and excellent combustion properties.