Green low-sensitivity energetic materials which can be stored under laboratory conditions and do not ignite spontaneously at room temperature are currently of high relevance due to their multiple energy applications in propulsion, pyrotechnics or civil engineering. In this context, we report a gram-scale synthesis of copper oxide (Cu2O) nanoparticles interfaced at the surface of 2D aluminum (Al) nanosheets. This synthesis is mild, cheap, and environmentally friendly, allowing us to obtain a stable and homogeneous product with high crystallinity. The burst heat released was estimated to be 6841 ± 272 J g-1 under air, and 2946 ± 306 J g-1 under a nitrogen (N2) atmosphere, which are the largest values reported so far. We attribute this superior performance to the intimate interfacing between Al and Cu2O nanoparticles. The complex reactivity of this material was thoroughly studied, permitting to account for the branching of reactions occurring in the material under different conditions, which is essential for the understanding of the factors governing the reactivity.