Combustion-Induced Endothermic Process in Carbon Dots Synthesized on Magnetite Nanoparticle Substrate

Carbon dots are synthesized alone and in the presence of commercial magnetite nanoparticles using a simple hydrothermal reaction. The spectroscopic and structural characteristics of CDot and CDot–magnetite materials are presented and their behaviors under combustion conditions are studied. A careful examination of their combustion behaviors reveals interesting results for the CDot–magnetite material: it undergoes early catalytic combustion at ~200 °C and a strong endothermic process that quenches combustion. By investigating the physical mixtures of pre-formed CDots and magnetite and the starting material ascorbic acid and magnetite, it is determined that the strong endothermic behavior requires intimate interactions between the carbon source and the magnetite, highlighting the importance of the nano-interface of the CDots being synthesized onto the magnetite substrate. The results are discussed in the context of the fuels used for low-temper combustion, materials with stored endothermic potential, and the use of combustion-quenching materials for fire control.