Molten aluminum-mediated production of carbon nanomaterials from hydrocarbon streams: Morphology and energy storage

The sustainable synthesis of carbon nanomaterials (CNMs) from hydrocarbons has gained significant attention for their potential in energy storage applications. In this work, we investigate the morphology, properties, and applications of carbon nano-onions (CNOs) produced by a catalyst-free molten aluminum-based reactor. This reactor decomposes hydrocarbon feedstock into high-quality CNOs while simultaneously generating hydrogen gas, a valuable green energy byproduct (H₂ gas), and preventing the emission of greenhouse gases. The synthesized CNOs were extensively characterized using SEM, TEM, XRD, Raman spectroscopy, and TGA analysis, revealing their graphitic, defect-rich structure and good thermal stability. Electrochemical studies demonstrated the efficacy of CNOs as conductive additives in conventional supercapacitors, achieving higher capacitance and cycling stability compared to commercial alternatives. Furthermore, the CNOs were successfully employed as active materials for printed flexible micro-supercapacitors (MSCs), exhibiting excellent electrochemical performance, mechanical flexibility, and long-term stability. Notably, these MSCs operated effectively without metal current collectors, offering a scalable and cost-effective solution for flexible energy storage devices. The results highlight the promise of hydrocarbon-derived CNOs as sustainable materials for advanced energy storage technologies.