Nanoscale Characterization of Energetic Core-Shell Carbon-coated Aluminum Nanoparticles Produced via Atmospheric Plasma Surface Treatment

Aluminum nanoparticles (nAl) have received considerable attention as metallic fuels due to their high heat of combustion, enhanced oxidation reactivity and large specific surface area to volume ratio. However, nAl are usually covered with a passivated amorphous oxide shell, which is detrimental for their intended applications. In this work, the key characterization results will be presented for our new reactive carbon coated nAl (nAl@C) samples produced by a two-step atmospheric plasma surface treatment process. This involved initial helium (He) plasma treatment of commercial nAl particles, followed by He/carbon monoxide (CO) plasma treatment for different durations. The resulting nAl@C were comprehensively studied utilizing advanced microscopy, Fourier transform  infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy. High-resolution transmission electron microscopy (HRTEM) images revealed a distinct faceted core/shell structure with significantly reduced oxide shell of nAl after the He plasma treatment at the first step. An evenly distributed carbonaceous material on the surface of Al@C was confirmed. The carbonaceous materials was determined to be aluminum carboxylate via Fourier transform infrared spectroscopy. The results from the reactive molecular simulation will be discussed in relevance to some our experimentally observed results.