In situ flame-synthesis of nanostructured carbon materials via facile alcohol Bunsen burner

This study aimed to investigate the in-situ synthesis of nanostructured carbon materials using alcohol flames generated by a Bunsen lamp burner and a catalytic Ni substrate, as opposed to the chemical vapor deposition method. Four different liquid fuels were utilized, including n-butanol, ethanol, n-butanol/aqueous ammonia, and ethanol/aqueous ammonia. The carbon growth, morphology, and structure caused by the parameters of sampling position, temperature distribution, and liquid fuel type were investigated using the diffusion flame produced by the atmospheric alcohol lamp burner. The results show that the additive aqueous ammonia affects not only the flame temperature but also the axial position of the highest temperature. When using n-butanol and portions of 10 %, 20 %, and 30 % of aqueous ammonia mixed fuels, carbon nanotubes (CNTs), and carbon nano-onions (CNOs) are both observed; however, using ethanol and the portions of 10 %, 20 %, and 30 % of aqueous ammonia mixed fuels, only CNTs are synthesized. Soot particles show concentrically stacked carbon layers with a diameter of around 45 ± 5 nm. CNTs have no encapsulated Ni catalytic particles at the closed tip, showing the root growth mechanism and indicating differences from the top growth mechanism. In addition, graphene could be synthesized in pure n-butanol and n-butanol/ammonia flames, but not in pure ethanol and ethanol/ammonia flames. The I_G/I_D ratio values of the raw CNOs (2.33) and CNTs (1.05) are greater than 1, where I_G/I_D is the intensity ratio of Raman G-band and D-band peaks, indicating good crystallization of the graphite layer of these nanostructured carbon materials. Notably, flame synthesis via an alcohol Bunsen lamp burner simplifies operations saves resources, and improves conventional production, demonstrating a facile and efficient method.