Designing 3D Oxygen–Diffusion Scaffolds for High-performance Metal Fuels

Metal fuels are central to energetic materials because of their high energy density and intense heat-release capability. However, early-stage formation of passivating oxide shells severely restricts oxygen diffusion, resulting in incomplete oxidation and limited energy utilization. Here, we report a grain-boundary engineering strategy to overcome this long-standing diffusion barrier by constructing three-dimensional oxygen-diffusion scaffolds within aluminum-based fuels through trace cerium addition. Rapidly solidified Al– x Ce powders develop a continuous Al ₁₁ Ce ₃ network along grain boundaries, which is in situ transformed into oxygen-ion-conductive CeO ₂ during combustion. This scaffold enables sustained inward oxygen transport following a “surface triggering–boundary conduction–core activation” pathway, extending the combustion duration of aluminum by nearly an order of magnitude (up to 6760 ms) while achieving complete oxidation. This work establishes a general and scalable design principle for enhancing metal-fuel combustion through rare-earth-enabled oxygen-diffusion networks.