Precise graphitic nitrogen-incorporation by electrochemical oxidation

Abstract

Graphitic nitrogen (graphitic-N) plays a very important role in energy conversion and environmental protection. Although various synthesis methods have been developed, complex devices and harsh conditions are often needed, causing difficulty in flexible regulation. Electrochemical approaches are attracting increasing attention due to their mild reaction conditions, controllability, and environmental compatibility. However, precisely incorporating graphitic-N remains a significant challenge. In this study, a synthesis strategy is designed that creates carbon single vacancies via electrochemical oxidation and then incorporates N radicals to construct graphitic-N. Graphite paper doped with exclusively graphitic-N was achieved by using ammonium ions as the nitrogen source. By integrating multiple operando electrochemical characterization techniques and density functional theory calculations, the crucial regulation parameters were clarified, and the proposed doping mechanism was validated. Hydroxyl radicals generated from electrochemical water dissociation performed three functions: involving the formation of (i) carbon single vacancies and (ii) adjacent oxygen-containing functional groups, and (iii) activation of ammonium ions into N radicals. Ketones exhibited better thermodynamic behavior than hydroxyl species when assembling N radicals into carbon single vacancies. The findings offer both experimental and theoretical foundations for a deeper understanding of the structure–property relationships of graphitic-N and broaden the application prospects of graphitic-N-doped materials.