Pure Pyridinic Nitrogen‐Doped Single‐Layer Graphene Catalyzes Two‐Electron Transfer Process of Oxygen Reduction Reaction

Abstract

A post‐treatment approach is presented to prepare nitrogen‐doped single‐layer graphene via ultraviolet/ozone (UV/O3) irradiation followed by NH3 annealing. Under optimal experimental conditions, a maximum atomic ratio (N/C) of 16.6 % can be reached. X‐ray photoelectron spectroscopy analysis reveals that only one type of pyridinic N is doped in the graphene lattice, which can be used as an ideal platform to investigate its catalytic activity toward oxygen reduction reaction (ORR). Electrochemical results demonstrate that ORR on the pyridinic N doped graphene sheet occurs via a two‐electron transfer process, indicating that the pure pyridinic N doped graphene is not an effective 4e‐process promoter.

Supercritical Deposition Coupled with Ammonia Treatment: A New Route to Co‐Promoted N‐Doped Carbon Aerogels with High Oxygen Reduction Reaction Activity

“…However, the dominance of pyridinic N sites in the catalyst will cause a high density of lone‐pair electrons, and this high density of polarized pyridinic N will largely repel O 2 molecules due to their high density of lone‐pair electrons, which hinders the electron transfer between C(ς + ) and O═O. Therefore, the high portion of pyridinic N–C configuration in a carbon plane should not be the reason for the high ORR activities, which is in accordance with the literature …”

“…On the other hand, the nature of the particular N species has caused considerable controversy because some research groups[55,62c] suggested a possible role of pyridinic N as an active site in ORR. However, Zheng et al recently showed that the ORR on pyridinic N‐doped graphene mainly occurs via the 2e − electron transfer process and not effectively via the 4e − process. Moreover, for ORR, the faster adsorption of O 2 molecules on the surface of the catalysts is a crucial step to obtain enhanced catalytic performance, and the logic behind the incorporation of the nitrogen in the carbon planes is to induce the polarization by generation of C(ς + ) and N(ς − ), which provides a convenient way for O 2 adsorption on catalyst.…”

Synthesis of graphitic-N and amino-N in nitrogen-doped carbon via a solution plasma process and exploration of their synergic effect for advanced oxygen reduction reaction

“…Also, the total nitrogen contents of in our catalyst are less than 3 at.% and comparatively lower than other N-doped carbon catalyst reported by previous studies. [29][30][31][32][33][34][35][36][37][38] The catalytic activity can be drastically improved by applying C-N precursors with higher nitrogen ratio, which should increase the total nitrogen content. Also, post-annealing under lower temperature (under 400 o C) could increase the crystallinity of amorphous carbon with limited evaporation of nitrogen content.…”

“…30 Also, Zheng et al revealed that pure pyridinic-N doped graphene catalysed twoelectron transfer process of ORR. 31 On the other hand, Wang et al proposed that graphitic-N atoms in the carbon matrix facilitated electron transfer from the carbon electronic bands to the anti-bonding orbital of O 2 . 32 Kim et al showed that the graphitic-N provided the most pronounced ORR activity improvement, especially in terms of current density.…”

Functionalized graphene-based materials for li-ion batteries : from anode to cathode

“…However, to date, this research field is still very young, and is only limited to theoretical calculations. [226][227][228] It could be very interesting to follow further pyridinic N configuration have rarely been reported, [229,230] let alone their applications in LIBs.…”