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‐C3N4 under H2 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 molNaCl−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.

Enhanced Pseudo-Capacitance Process in Nanoarchitectural Layered Double Hydroxide Nanoarrays Hollow Nanocages for Improved Capacitive Deionization Performance

“…Further, the electrochemical impedance spectra (EIS) of C/ CoNi-LDH, CoNi-LDH, and S-CoNi-LDH were investigated to analyze their electrochemical resistance and ion diffusion behavior (Figure 3c and Table S4). As shown in Figure 3c, the EIS curves for all samples show a semicircle and a sloping straight line, which correspond to the charge transfer resistance (R ct ) and the Warburg diffusion resistance, 7,33,64 S12), consistent with the results with CV and GCD. Moreover, the C/CoNi-LDH electrode also exhibited excellent electrochemical cycling performance, the GCD curve kept the initial shape without clear changes after 1000 cycles at 1 A g −1 , and the average coulombic efficiency was maintained at 100% (Figure 3e).…”

“…Further, the electrochemical impedance spectra (EIS) of C/CoNi-LDH, CoNi-LDH, and S-CoNi-LDH were investigated to analyze their electrochemical resistance and ion diffusion behavior (Figure c and Table S4). As shown in Figure c, the EIS curves for all samples show a semicircle and a sloping straight line, which correspond to the charge transfer resistance ( R ct ) and the Warburg diffusion resistance, ,, respectively. C/CoNi-LDH shows a smaller semicircle than CoNi-LDH and S-CoNi-LDH, indicating that C/CoNi-LDH has the lowest charge transfer resistance.…”

Electrocapacitive Deionization: Mechanisms, Electrodes, and Cell Designs

“…For carbon-based electrode materials, carbon defects, including both intrinsic defects (holes, edges, vacancies, or topological defects) and external defects (heteroatoms doping), have been explored by DFT, which revealed that both intrinsic defects and external defects have higher adsorption energy, contributing to ion adsorption ability. [150][151][152] Recently, a dynamic DFT combined with a modified Poisson equation studied the dynamic adsorption of ions into charged nanopores. [153] The adsorption capacity and time are significantly relative to the overlapping electric potentials inside the micropores.…”

Rational fabrication strategies of freestanding/binder-free electrodes for efficient capacitive deionization

“…[33][34][35][36][37][38] Therefore, Faradaic materials have been rigorously adopted to ameliorate aforementioned limitations of carbon-based materials in the CDI community, triggered by the pioneering work of a desalination battery, hybrid CDI, and intercalation-based systems. [39][40][41] Although prosperous deployment of improved CDI dedicates on leveraging state-ofart electrode materials from tailoring carbon materials (e.g., porosity, 42 surface area, 43 and surface functionalization 44,45 ) to exploiting various Faradaic materials (e.g., metal oxides, [46][47][48] MXene, 49 transition metal dichalcogenides (TMDs), 50 carbon/Faradaic compositions, [51][52][53] and so on), the innovation in fabrication of electrodes for CDI is a substantial candidate. the innovation in fabrication of electrodes for CDI is a substantial candidate.…”

“…Until now, prosperous deployment of CDI mostly dedicates on leveraging state-of-the-art electrode materials ranging from tailoring carbon materials ( e.g. , porosity, 42 surface area, 43 and surface functionalization 44,45 ) to exploiting various Faradaic materials ( e.g. , metal oxides, 46–48 MXene, 49 transition metal dichalcogenides (TMDs), 50 carbon/Faradaic compositions, 51–53 and so on).…”