Modifying the Morphology, Doping, and Electroanalytical Performance of Carbon Nanofibers by Varying the Ratio of Etchant and Feedstock Gases

Ammonia (NH₃) is a widely used etchant gas in the plasma-enhanced chemical vapor deposition (PECVD) synthesis of carbon nanofibers (CNFs). In addition to being an effective etchant, NH₃ also serves as a dopant by providing N heteroatoms. However, this secondary role has not been comprehensively investigated. Moreover, the influence of N-doping on the electroanalytical performance of CNFs has not been thoroughly assessed. In this work, we have prepared CNFs of two varieties by altering the ratio of etchant and feedstock gases (NH₃ and C₂H₂, respectively), resulting in N-doped CNFs with different doping levels. Differences were also observed in the morphology and electrochemical characteristics of the CNFs. While inner sphere redox (ISR) characteristics were not significantly affected, a significant shift between the peak potentials of ascorbic acid (AA) and dopamine (DA) was detected in the higher doped CNFs, resulting in enhanced selectivity towards DA. Our results demonstrate a simple yet effective method for enhancing the electroanalytical properties of CNFs.