Electrocatalytic activity of electrospun carbon nitride-polyacrylonitrile nanofiber towards oxygen reduction reactions

• CNx nanoparticles successfully dispersed on PAN nanofibers.
• Pyridinic N of CNx nanoparticles in PAN responsible for ORR activity
• SECM confirms good electronic conductivity of CNx/PAN nanofibers.
• LSV onset potential of CNx/PAN nanofibers for ORR is slightly lower than Pt/C.
• ORR takes place via 4-electron pathway in CNx/PAN nanofibers.

Oxygen reduction reaction (ORR) activity of carbon nitride (CNx) is improved upon dispersing it on polyacrylonitrile (PAN) nanofiber using electrospinning technique. Transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy are used to study the morphology, size, form of nitrogen group present and bond structure of CNx/PAN nanofibers. Improvement in ORR activity of CNx/PAN nanofibers is observed compared to native CNx nanoparticles as per cyclic and linear sweep voltammetries. Onset potential and current density of CNx/PAN nanofibers for ORR is slightly lesser than that of commercial Pt/C (40:60% by weight). Rotating ring disk electrode (RRDE) voltammetry employed to study ORR mechanism on CNx/PAN nanofibers confirms four-electron pathway for ORR and water formation. In-situ FTIR coupled with voltammetry reveals continuous water formation, which is the ORR product, within the active potential range. Stability of the ORR catalytic activity of CNx/PAN is ascertained by 6000 repetitions of linear sweep voltammetry studies coupled with FTIR.

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