Pyridinic nitrogen induced compressed bilayer graphene for oxygen reduction reaction

• Published in: Materials today energy 2023-07, Vol.35 (C), p.101323, Article 101323
• Main Authors: Solati, Navid, Çankaya, Mehmet, Kahraman, Abdullah, Şimşek, Kaan, Titus, Charles James, Lee, Sang Jun, Nordlund, Dennis, Ogasawara, Hirohito, Tekin, Adem, Kaya, Sarp
• Format: Article
• Language: English
• Subjects: DFT; Functionalized graphene; Nitrogen doping; ORR; X-ray spectroscopy
• ISSN: 2468-6069; 2468-6069
• DOI: 10.1016/j.mtener.2023.101323

Despite the emergence of nitrogen-doped graphene as a noble-metal free electrocatalyst for oxygen reduction reaction, its participation in the electrochemical conversion mechanism is not well-established. In the present study, functionalities of the nitrogen species on the oxygen reduction activity of bilayer graphene were investigated by combining atom-specific X-ray spectroscopy, Raman spectroscopy, and density functional theory calculations with electrochemical activity tests in alkaline media. Among various nitrogen species, pyridinic nitrogen as the dominant species improved the electrochemical activity of bilayer graphene, which was followed by graphene bilayers doped with graphitic nitrogen in majority. Polarization curves revealed a significantly high electrocatalytic oxygen reduction activity of the nitrogen-doped bilayer graphene where the pyridinic nitrogen was the major dopant. This improved activity was confirmed by the lowest overpotential and Tafel slope (78.9 mV/dec). The enhanced interaction of graphene bilayers doped with pyridinic nitrogen is shown to be the main reason for this improvement. [Display omitted] •Bilayer N-doped graphene with a controlled content and configurations of N dopants can be prepared via chemical vapor deposition.•The co-presence of pyridinic and graphitic N enhances the π-π interactions of bilayer graphene.•Atom-specific X-ray spectroscopy findings agree well with the calculated density of states.•The ORR activity increases with the number of active sites and enhanced interlayer interactions in pyridinic N-rich bilayer graphene.