A Reverse‐Defect‐Engineering Strategy toward High Edge‐Nitrogen‐Doped Nanotube‐Like Carbon for High‐Capacity and Stable Sodium Ion Capture

Abstract Developing high‐performance defect‐rich carbon materials with abundant accessible active sites is exceedingly vital for electrochemical water desalination, but this still remains a significant challenge. Herein, a reverse‐defect‐engineering strategy is reported to synthesize high edge‐nitrogen‐doped nanotube‐like carbon through the annealing process of protonated g‐C 3 N 4 under H 2 atmosphere. The hydrogen bonds interaction between the proton and nitrogen atoms performs a crucial role in regulating nitrogen configurations. The nitrogen‐doped carbon obtained from HCl pretreatment (HCl‐NC) reduces the proportion of graphitic N and exhibits a high ratio of pyrrolic N to pyridinic N. Thus, the resulting synergetic structure of high edge‐type N and small graphitic carbon nanodomains ensures more accessible active sites and fast charge‐transfer kinetics simultaneously, contributing to high desalination capacity (100.3 mg g −1 at 1.2 V), fast time‐average specific adsorption rate (1.7 mg g −1 min −1 ), low energy consumption (82.9 kJ mol NaCl −1 ), and superior cyclic stability (no signs of performance decay after long‐term cycling). The Na + ‐intercalation mechanism and structure‐response relationship of HCl‐NC are revealed by the electrochemical quartz crystal microbalance with dissipation monitoring and density functional theory calculations, respectively. This study provides a novel idea to modulate the nanotube‐like, nitrogen‐containing configurations for engineering carbon nanomaterials for advanced electrochemical applications.