Results and Discussion

Surfactant-Mediated Synthesis and Structural Characterization

The N-bridged MoS2/C heterostructures were synthesized via a surfactant-mediated strategy that combined precise coordination chemistry with an in situ conversion process (Fig. 1a). The synthesis begins with the confinement of a quaternary ammonium surfactant, cetyltrimethylammonium bromide (CTAB), within the dendritic mesopores of mesoporous SiO2 templates (designated as mSiO2@CTAB, Figs. S1 and S2). Subsequent introduction of molybdate anions induces electrostatic coordination with the positively charged quaternary ammonium headgroups, yielding mSiO2@CTAB-MoO_x_ composites. Notably, the mSiO2 template primarily acts as a nanoconfinement reactor rather than a rigid morphology-replication scaffold. During subsequent thermal treatment with thiourea, the MoO_x_ precursors are converted into MoS2 (Fig. S3), while the CTAB molecules undergo carbonization to form N-doped carbon layers. Concurrently, interfacial Mo–N bonds are formed between Mo species and nitrogen-containing carbon species, enabling intimate coupling between MoS2 and the carbon framework and guiding the formation of well-defined heterostructures. Meanwhile, the decomposition of surfactant species releases gaseous products, reconstructing the carbon framework and generating abundant mesopores throughout the composite.

Fig. 1: Synthesis and structural characterization of the MoS2–N–C heterostructures. a Schematic of the surfactant-mediated synthesis and formation of Mo–N-bridged carbon layers. b TG curves of mSiO2@CTAB under Ar and mSiO2@C in air, along with the DTG curve of mSiO2@C. c FESEM image, d TEM image, e HAADF image with corresponding elemental mapping, and f HRTEM image of MoS2–N–C700. g Schematic illustration of expanded interlayer spacing of MoS2 due to Mo–N bridging with N-doped carbon layer

To verify the carbon origin, mSiO2@CTAB was pyrolyzed under Ar atmosphere. A color change from white to black was observed, indicating the transformation of CTAB into amorphous carbon (Fig. S4). The carbonized product, named mSiO2@C, shows significant mass loss between 430 and 600 °C in thermogravimetric (TG) and differential TG (DTG) analyses (Fig. 1b), corresponding to the decomposition of CTAB-derived carbon species. The TG curve of mSiO2@CTAB under Ar shows gradual mass loss from 200 to 600 °C, primarily due to the decomposition of hexadecyl chains into carbon components. In contrast, pure CTAB exhibits a rapid decomposition even between 200 and 350 °C (Fig. S5), indicating that confinement within the mSiO2 framework enhances thermal stability and promotes carbon formation. Additionally, TG analysis of thiourea confirms its decomposition contributes additional carbonaceous species, which deposit onto the material to further stabilize the MoS2 structure (Fig. S6).

Field emission scanning electron microscopy (FESEM) images of the MoS2–N–C heterostructures reveal a porous architecture composed of interconnected irregular aggregates (Figs. 1c and S7). The seemingly fragmented morphology observed after template removal does not indicate structural collapse. Instead, it represents the expected porous inverse structure generated by hard-templating process. As the sulfurization temperature increases from 600 to 800 °C, the aggregates become progressively denser and the overall porosity gradually decreases, suggesting temperature-dependent densification of the carbon–MoS2 framework. Transmission electron microscopy (TEM) images of MoS2–N–C700 further confirm the porous and hierarchical structure and indicate a polycrystalline nature (Figs. 1d and S8). In contrast, commercial MoS2 exhibits a bulky morphology composed of heavily stacked multilayered domains (Fig. S9). Energy-dispersive X-ray spectroscopy (EDS) elemental mapping of MoS2–N–C700 reveals the uniform distribution of Mo, S, C, and N, confirming the nanoscale integration of nitrogen-doped carbon with MoS2 (Figs. 1e and S10). High-resolution TEM (HRTEM) image further reveals intimate contact between amorphous carbon layers and MoS2 nanodomains (Fig. 1f). The few-layered MoS2 displays an expanded interlayer spacing of 0.633 nm for MoS2, moderately larger than the 0.622 nm of commercial MoS2 (Fig. S11). This expansion confirms that the Mo–N bridging between the carbon layer and MoS2 creates a tensile effect, pulling Mo atoms toward the carbon side (Fig. 1g).

Interfacial Mo–N Bridging between MoS2 and Carbon Layers

X-ray diffraction (XRD) analysis was conducted to investigate the effect of sulfurization temperature on the crystallinity of MoS2–N–C heterostructures (Fig. 2a). All samples display distinct diffraction peaks of the 2H–MoS2 phase, confirming the formation of a thermodynamically stable hexagonal polymorph. The peaks at approximately 13.9°, 33.3°, 39.7°, and 58.6° are indexed to the (002), (100), (103), and (110) crystal planes of 2H–MoS2 (PDF#37-1492), respectively [25]. Notably, the (002) peak shifts toward lower diffraction angles compared with bulk MoS2, indicating an expanded interlayer spacing. This observation is consistent with the TEM results and suggests the modulation effect of carbon layers on the layered structure of MoS2. As the sulfurization temperature increases from 600 to 800 °C, the intensity and sharpness of the (002) peak gradually increase, indicating improved crystallinity. In contrast, commercial MoS2 exhibits a much stronger and sharper (002) reflection, characteristic of highly crystalline bulk MoS2 (Fig. S12).

Fig. 2: Compositional and chemical state analyses of the MoS2–N–C heterostructures synthesized at different sulfurization temperatures. a XRD patterns, b, c Raman spectra, d TG curves, e N2 absorption/desorption isotherms, f–i deconvoluted Mo 3d, S 2p, C 1s, and N 1s + Mo 3p XPS spectra, respectively

Raman spectroscopy further confirms the structural evolution of the MoS2–N–C heterostructures. As shown in Fig. 2b, two characteristic vibrational modes at 380.4 cm−1 (E12g) and 403.5 cm−1 (A1g) are observed, confirming the formation of few-layer 2H–MoS2. The intensities of both peaks increase with increasing sulfurization temperature, indicating enhanced crystallinity. In contrast, the D and G bands associated with the carbon component gradually weaken with increasing temperature. The corresponding decrease in the _I_D/_I_G ratio from 1.04 to 0.99 and 0.97 (Fig. 2c) suggests a reduction in defect density and an increase in graphitization degree of the carbon matrix. Meanwhile, the relative intensity variation between MoS2 and carbon bands indicates a progressive increase in the MoS2 fraction at higher temperatures (Fig. S13) [13].

TG analysis provides quantitative data on the MoS2 content in the MoS2–N–C heterostructures. MoS2–N–C600, MoS2–N–C700, and MoS2–N–C800 show weight retention values of 60.1%, 66.6%, and 73.6%, respectively, after calcination in air, corresponding to 66.8%, 74.1%, and 81.8% MoS2 content by weight (Fig. 2d). These results align with XRD and Raman analysis, indicating that higher sulfurization temperatures resulted in a higher MoS2 content in the heterostructures. The carbon component is derived from the in situ carbonization of the alkyl chains of CTAB surfactant and plays a crucial role in constructing the overall MoS2–N–C nanostructure. The carbon matrix primarily serves as a conductive and structural backbone, improving electrical conductivity and buffering the volume variation of MoS2 during cycling. Nitrogen adsorption–desorption isotherms confirm the presence of a well-defined mesoporous structure in all the materials, as indicated by type-IV isotherms (Figs. 2e and S14). The specific surface areas (SSAs) of MoS2–N–C600, MoS2–N–C700, and MoS2–N–C800 are 70.9, 112.9, and 90.9 m2 g−1, respectively. MoS2–N–C700 has the highest SSA with a most probable pore size of ~ 2.0 nm, which is favorable for Li+ diffusion and electrolyte accessibility.

X-ray photoelectron spectroscopy (XPS) was conducted to investigate the surface chemical states of these MoS2–N–C heterostructures (Fig. S15). The Mo 3_d_ spectra display two main peaks at 229.5 and 232.6 eV, corresponding to 3_d_3/2 and 3_d_1/2 signals of Mo4+ species in MoS2, along with two smaller peaks at 232.8 and 235.9 eV for Mo6+ species due to partial surface oxidation (Fig. 2f) [26]. The S 2_p_ spectra exhibit Mo–S bonds at 162.4 and 163.5 eV, C–S bonds at 164.1 and 165.2 eV, and oxidized sulfur species at 168.7 and 169.8 eV (Fig. 2g) [27, 28]. The relative proportion of Mo–S species increases with sulfurization temperature, consistent with Raman results (Table S1). The C 1_s_ spectra reveal three peaks at 284.8, 285.7, and 286.6 eV, attributed to C–C, C–N, and C–S bonds, respectively (Fig. 2h) [29]. The C–S species might come from the thiourea-derived carbon supports. As shown in the N 1_s_ spectra, four distinct peaks are observed at 397.6, 398.5, 399.8, and 401.3 eV, corresponding to Mo–N, pyridinic N, pyrrolic N, and graphitic N species, respectively (Fig. 2i) [30]. Notably, the presence of Mo–N bonding is further confirmed by the Fourier-transformed (FT) extended X-ray absorption fine structure (EXAFS) spectrum of Mo K-edge, which exhibits a characteristic first-shell scattering contribution associated with Mo–N coordination (Fig. S16) [25]. These results provide direct evidence for the nitrogen-bridged interfacial bonding between MoS2 and the carbon layer. Among the nitrogen configurations, pyridinic N and pyrrolic N are the dominant species, which are well known to introduce abundant structural defects and active sites within the carbon matrix, thereby enhancing pseudocapacitive contributions and facilitating Li+ diffusion. In contrast, graphitic N content increases with temperature, reflecting thermally driven conversion of less stable nitrogen species into more stable configurations, which contributes to improved electronic conductivity of the carbon framework (Table S2). The existence of C–N species in both the C 1_s_ and N 1_s_ spectra confirms the successful transformation of CTAB into an N-doped carbon layer, which was chemically linked to MoS2 via Mo–N bonds. To further verify the origin of Mo–N bonding, a nitrogen-free MoS2 control sample (denoted as Pristine MoS2) was synthesized under identical sulfurization conditions without CTAB-capped mSiO2 templates. This sample exhibits a bulk-like aggregated morphology without internal porosity (Fig. S17). More importantly, no N 1_s_ signal or Mo–N bonding is detected in XPS spectra (Fig. S18), confirming that the Mo–N bonds originate from the CTAB-derived N-doped carbon framework.

Electron paramagnetic resonance (EPR) spectra exhibit a weakening signal at g = 2.003 (Fig. S19), suggesting the existence of sulfur vacancies [15, 31]. These vacancies are likely associated with interfacial Mo–N coordination, which modulates the local electronic structure of MoS2 and alters the defect distribution. The gradual decrease in signal intensity with increasing temperature indicates that Mo–N coordination effectively tunes the electronic environment and stabilizes defect configurations within the heterostructure.

Electrochemical Performance for Lithium-Ion Batteries

The MoS2–N–C heterostructures were systematically evaluated as anode materials for lithium-ion batteries (LIBs) at the mass loading of 1.1–1.3 mg cm−2. As shown in Fig. 3a, the MoS2–N–C700 electrode delivers an initial discharge capacity of 539.2 mAh g−1 at 0.5 A g−1, and gradually increases to 625.9 mAh g−1 after 800 cycles, accompanied by nearly 100% Coulombic efficiency. This capacity increase indicates excellent structural reversibility without an increase in defect density (Fig. S20) but progressive activation of the porous structure and additional redox sites during cycling (Figs. S21 and S22). The integrity of the interfacial Mo–N bridges in MoS2–N–C700 is further confirmed by ex situ XPS analysis after cycling (Fig. S23). The cycling performance of MoS2–N–C700 surpasses that of most previously reported MoS2/C nanocomposites (Table S4). In contrast, the MoS2–N–C600 electrode maintains the lowest reversible capacity (~ 400 mAh g−1) throughout the cycling test (Fig. S24), while the MoS2–N–C800 electrode shows obvious capacity decay after 500 cycles (Fig. S25). These distinct electrochemical behaviors highlight the critical balance among MoS2 crystallinity, interfacial Mo–N coupling strength, and carbon framework integrity in achieving high-capacity and long-life cycling performance. The Mo–N bridges function as both efficient electron-transfer pathways and robust structural anchors that buffer volume changes during cycling. Their effectiveness strongly depends on the integrity of the carbon framework (Fig. 2d). Although MoS2–N–C600 possesses the highest carbon fraction (33.2 wt%), its insufficient MoS2 crystallization limits the formation of effective heterointerfaces. In contrast, MoS2–N–C700 achieves an optimized balance between carbon content (25.9 wt%) and interfacial Mo–N coupling, enabling both efficient charge transport and structural buffering. For MoS2–N–C800, despite its highly crystallinity, the substantially reduced carbon framework (18.2 wt%) weakens interfacial anchoring and structural stability, resulting in accelerated capacity fading during prolonged cycling.

Fig. 3: Electrochemical performance of the MoS2–N–C anodes for LIBs. a Cycling stability at 0.5 A g−1. b, c dQ/dV curves of MoS2–N–C700 and commercial MoS2 at different cycles. d First three CV curves at 0.1 mV s−1 and e first three GCD profiles at 0.1 A g−1 of MoS2–N–C700. f Rate capacities and g comparison of rate performances between MoS2–N–C700 and recently reported MoS2/C composites

In contrast, commercial MoS2 suffers from rapid capacity decay during the first 50 cycles, ultimately retaining only 282.8 mAh g−1 (44.6% retention) after 800 cycles. For comparison, a physical nitrogen-doped carbon and MoS2 hybrid (MoS2/NC) without interfacial Mo–N bridging was also prepared (more details in Supporting Information). MoS2/NC exhibits a much lower specific surface area (66.8 m2 g−1) than MoS2–N–C700 (112.9 m2 g−1) (Fig. S26) and lacks a well-defined porous structure (Fig. S27), demonstrating the advantage of the proposed synthetic strategy. As a result, MoS2/NC displays poor cycle stability with only 263.6 mAh g−1 (55.2% retention) after 150 cycles. These results highlight the significant role of interfacial Mo–N bridging in enhancing the cycling stability of MoS2. Moreover, the MoS2–N–C700 anode also displays decent cycling stability at 2 A g−1 for 1000 cycles (Fig. S28), with Coulombic efficiency close to 100% throughout cycling.

Differential capacity analysis (d_Q_/d_V_) further confirmed the superior reversibility of the MoS2–N–C electrodes. The MoS2–N–C700 anode shows highly overlapped redox peaks from the 2nd to the 800th cycle, indicating excellent structural stability and highly reversible phase transitions during cycling (Figs. 3b and S29). Conversely, both MoS2/NC and commercial MoS2 show significant redox peak shifting and intensity fading during cycling, suggesting progressive electrode polarization and irreversible structural degradation (Figs. 3c and S30).

Cyclic voltammetry (CV) tests were employed to gain further insights into the electrochemical reversibility and lithiation/delithiation mechanisms (Figs. 3d and S31). The first cathodic scan for MoS2–N–C700 shows a weak peak at ~ 0.90 V and a sharp reduction peak at ~ 0.43 V, corresponding to Li+ intercalation into MoS2 layers and the conversion of Li_x_MoS2 into metallic Mo and Li2S, respectively. Subsequent anodic scan displays two distinct oxidation peaks at ~ 1.59 and ~ 2.22 V, associated with the reformation of MoS2 from metallic Mo and the oxidation of Li2S to element sulfur, respectively [5, 32]. In the following cycles, the CV curves stabilize and exhibit two well-defined cathodic peaks at ~ 1.75 and ~ 1.28 V, attributed to the reduction of S to Li2S and the formation of LixMoS2, respectively, along with two stable anodic peaks consistent with the first cycle [33]. For MoS2/NC and commercial MoS2, a prominent peak occurs at ~ 0.90 V in the first cathodic sweep, suggesting typical Li+ intercalation into the MoS2 layers but lacking the stable and well-defined redox features observed for MoS2–N–C700 (Figs. S32 and S33). The anodic peak associated with Mo reoxidation is significantly suppressed, confirming inferior reversibility and structural instability. Among all samples, MoS2–N–C700 exhibits the highest specific capacity, with discharge and charge capacities of 1044.7 and 709.2 mAh g−1, respectively (Figs. 3e and S34, S35). MoS2–N–C700 exhibits an initial Coulombic efficiency of approximately 68% in LIB half-cells. The irreversible capacity loss is primarily attributed to solid–electrolyte interphase formation and surface defect-related Li+ trapping during the initial lithiation process, which is typical for porous nanostructured conversion/intercalation-type MoS2-based anodes.

The MoS2–N–C700 anode also demonstrates outstanding rate capability (Fig. 3f). It delivers reversible capacities of 709.2, 660.0, 590.6, 523.6, 444.8, and 326.8 mAh g−1 at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 A g−1, respectively. When the current density is returned to 0.1 A g−1, the capacity recovers to 788.4 mAh g−1, confirming excellent electrochemical reversibility and robust structural stability. Across all current densities, MoS2–N–C700 consistently outperforms its counterparts synthesized at other sulfurization temperatures. More importantly, its rate performance surpasses that of most previously reported MoS2/C nanocomposites [24, 29, 32, 34–39], highlighting the effectiveness of the interfacial Mo–N bridging strategy for constructing high-performance heterostructured electrodes (Fig. 3g). Notably, when the mass loading is increased to ~ 2.9 mg cm−2, MoS2–N–C700 maintains outstanding rate capability with reversible capacities comparable to those obtained at a lower mass loading (Fig. S36). It also exhibits stable cycling with a high capacity of ~ 600 mAh g−1 at 0.5 A g−1 over 120 cycles. In contrast, commercial MoS2 suffers from a dramatic capacity drop at high rates due to its poor intrinsic conductivity and structural vulnerability, with specific capacities of only 276.7 and 116.4 mAh g−1 at 2.0 and 5.0 A g−1, respectively (Fig. S37). Similarly, MoS2/NC exhibits inferior rate capability with specific capacities of only 406.1 and 241.5 mAh g−1 at 2.0 and 5.0 A g−1, respectively.

Structure Evolution During Long-Term Cycling

The morphological evolution of the electrodes during cycling was investigated. The pristine MoS2–N–C700 electrode exhibits a highly porous interconnected nanostructure composed of uniformly distributed nanoparticle agglomerates (Fig. 4a). In contrast, the pristine commercial MoS2 electrode consists of large micron-sized layered flakes with loose stacking and obvious interparticle gaps (Fig. 4b). During cycling, the MoS2–N–C700 electrode undergoes only slight morphological adjustment, while its porous framework remains largely preserved and the surface becomes more uniform. Such structural robustness effectively accommodates the repeated Li+ insertion/extraction processes and preserves electrode integrity. In contrast, the commercial MoS2 electrode experiences severe structural degradation even after the first cycle. The layered flakes become heavily stacked and distorted, and the originally well-defined flake boundaries gradually disappear due to pronounced exfoliation induced by Li+ intercalation. After five cycles, the structure collapses into aggregated fine particles, leading to serious deterioration of electrode integrity and cycling stability.

Fig. 4: Structure evolution and electrochemical behavior of the MoS2–N–C and commercial MoS2 anodes during cycling in LIBs. a1–a3 FESEM images of the pristine and post-cycled MoS2–N–C700 electrodes. b1–b3 FESEM images of the pristine and post-cycled commercial MoS2 electrode. c, d HRTEM images of the post-cycled MoS2–N–C700 electrodes. e Nyquist plots of the post-cycled MoS2–N–C700 and commercial MoS2 electrodes. f In situ XRD patterns and g enlarged contour plots of characteristic (002) and (100) peaks of MoS2–N–C700 during the first GCD cycle

HRTEM images further confirm the structural stability of the MoS2–N–C700 electrode. After five cycles, a uniform inorganic solid–electrolyte interphase (SEI) layer with a thickness of only a few nanometers is observed on the electrode surface (Fig. 4c). Clear lattice fringes with spacings of 0.274 and 0.285 nm are attributed to the (100) plane of MoS2 and (200) plane of Li2S, respectively, suggesting the coexistence of reversible conversion and intercalation processes. Even after 200 cycles, distinct diffraction patterns can still be indexed to Mo (200) and Li2S (311), with spacings of 0.201 and 0.172 nm, respectively, confirming the structural durability of the active material (Fig. 4d). XPS analysis of the MoS2–N–C700 electrode discharged to 0.01 V reveals a distinct Mo–N peak at 397.3 eV (Fig. S38), indicating that the interfacial coupling between Mo species and N-doped carbon framework remains intact even after deep conversion reactions.

Electrochemical impedance spectra (EIS) reveal that the MoS2–N–C700 electrode maintains significantly lower impedance than both commercial MoS2 and the MoS2/NC throughout cycling (Figs. 4e and S39–S41). Specifically, the MoS2–N–C700 electrode exhibits charge-transfer resistances (_R_ct) of 77.1 and 229.1 Ω after 5 and 200 cycles, respectively, whereas commercial MoS2 shows much higher values of 1605.0 and 312.2 Ω (Table S3). The MoS2/NC control sample shows a reduced _R_ct of 164.6 Ω, confirming that the introduction of a conductive carbon framework can improve charge transfer to some extent. However, in the absence of chemical interfacial bonding, the electronic interaction between MoS2 and carbon remains limited. These results further demonstrate that the N-bridged heterostructure not only stabilizes electrode morphology but also sustains efficient charge-transfer kinetics during long-term cycling, in stark contrast to the rapid degradation observed for commercial MoS2.

In situ XRD patterns were further employed to investigate the phase evolution of the MoS2–N–C700 electrode during the first GCD cycle (Fig. 4f). The contour color transition from red to blue corresponds to different charge/discharge states. As shown in the enlarged contour plots (Fig. 4g), during discharge, the (002) peak gradually shifts toward lower angles, indicating Li+ intercalation into the MoS2 interlayers and the associated expansion of interlayer spacing. During the subsequent charging process, the peak gradually shifts back to its original position, demonstrating highly reversible intercalation behavior. Meanwhile, the intensity of the (100) peak continuously decreases and eventually disappears during discharge, suggesting the conversion of MoS2 into metallic Mo and Li2S. During charging, the (002) peak reappears, confirming the excellent reversibility of the conversion reaction.

Lithium-Ion-Transport Kinetics Analysis

Galvanostatic intermittent titration technique (GITT) was employed to investigate the Li+ diffusion kinetics of the MoS2–N–C heterostructures (Fig. 5a). The calculated Li+ diffusion coefficients (_D_Li+) indicate that MoS2–N–C700 exhibits the highest diffusion coefficient, reaching up to 1.64 × 10–12 cm2 s−1, indicative of highly efficient ion-transport pathways (Fig. 5b). Among all MoS2–N–C heterostructures, MoS2–N–C700 consistently displays higher _D_Li+ values during both discharge and charge processes. CV measurements at various scan rates further confirm the superior electrochemical kinetics and reversibility of the MoS2–N–C materials, with well-defined and symmetric redox peaks (Fig. 5c). The corresponding log(i)–log(v) plots yield b-values of 0.83, 0.88, 0.85, and 0.87 for the four redox peaks of MoS2–N–C700, indicating a dominant pseudocapacitive charge-storage behavior (Fig. 5d) [40, 41]. The specific pseudocapacitive contribution increases with scan rate, reaching 64.9%, 75.3%, and 70.0% for MoS2–N–C600, MoS2–N–C700, and MoS2–N–C800, respectively, at 1.0 mV s−1 (Figs. 5e and S42–S44). In contrast, MoS2/NC exhibits a much lower value of 40.9% (Fig. S45) than MoS2–N–C700, highlighting the critical roles of the N-doped carbon matrix, interfacial Mo–N coupling, and porous architecture for fast pseudocapacitive Li+ storage. These results confirm the dominance of fast surface-controlled charge-transfer kinetics in the MoS2–N–C heterostructures.

Fig. 5: Electrochemical kinetic analysis of the MoS2–N–C anodes for LIBs. a GITT curves after five GCD cycles. b Li+ diffusion coefficients derived from GITT curves of MoS2–N–C600, MoS2–N–C700, and MoS2–N–C800. c CV curves at scan rates from 0.2 to 1.0 mV s−1, d linear fitting of the logarithmic relationship between peak current (log i) and scan rate (log v), e pseudocapacitive contribution at 1.0 mV s−1, f, g In situ EIS spectra during discharge and charge, and h DRT contour plot of charge-transfer process (Rct) during the 6th charge–discharge cycle of MoS2–N–C700 (the negative voltage represents the discharging process)

In situ EIS tests were conducted to investigate the dynamic electrochemical behavior of MoS2–N–C700 after activation at 0.1 A g−1 for five cycles (Figs. 5f, g and S46–S47). The _R_ct value gradually increases during discharging from 3.0 to 0.01 V, followed by a decrease during charging, ultimately reaching 47.3 Ω. Notably, a distinct change in the Nyquist plots appears at approximately 0.8 V during lithiation, corresponding to the formation of a robust SEI layer. Distribution of relaxation times (DRT) plots obtained from the in situ EIS data further corroborates this evolution process (Figs. 5h and S50–S52) [42]. Moreover, the _D_Li+ of MoS2–N–C700 reaches a peak value of 5.38 × 10–12 cm2 s−1 during cycling, surpassing that of the other counterparts. Such outstanding kinetic behavior is attributed to the synergistic structural features of the heterostructures, including nitrogen-doped carbon layers that accelerate electron transfer through interfacial Mo–N coupling, expanded layer spacings of MoS2 that facilitate rapid Li⁺ diffusion, and porous morphology that endows structural robustness.

To validate the generality of the surfactant-mediated strategy, it was further extended to the WS2 system. The XRD pattern of the as-synthesized WS2–N–C700 sample (Fig. S53) matches well with hexagonal WS2 (PDF#87-2417). Notably, the barely discernible (002) diffraction peak at about 14.5° indicates suppressed layer stacking, confirming the effective nanoconfinement imposed by the mSiO2 template. This is consistent with the structural characteristics observed in the MoS2 system. SEM analysis (Fig. S54) further reveals that the WS2–N–C700 sample exhibits a similar interconnected porous architecture to that of the MoS2–N–C700 heterostructures. When applied as an anode material for LIBs, the WS2–N–C700 electrode exhibits a reversible intercalation-conversion Li+ storage process and excellent cycling stability (Fig. S55). It delivers a reversible capacity of 539.7 mAh g−1 at 0.1 A g−1, exceeding the theoretical capacity of bulk WS2 (~ 432 mAh g−1). Furthermore, the electrode exhibits exceptional cycling stability at 0.5 A g−1, maintaining nearly 100% capacity retention after 300 cycles. These results collectively support that the proposed mesopore-confined, surfactant-mediated strategy can serve as a generalizable platform for synthesizing N-bridged LTMD/C heterostructures beyond MoS2.

Device-Level Lithium-Ion Supercapacitor Performance

Benefiting from the excellent structural stability and surface-controlled charge-storage behavior, MoS2–N–C700 emerges as a promising anode for high-performance lithium-ion supercapacitors (LISCs). A full device was constructed by using MoS2–N–C700 as the anode and commercial activated carbon (AC) as the cathode (Fig. 6a). The CV curves of the individual electrodes exhibit distinct electrochemical behaviors (Fig. 6b). The MoS2–N–C700 anode exhibits broad redox peaks associated with reversible faradaic reactions, while the AC cathode presents a nearly rectangular profile typical of electrical double-layer capacitive (EDLC) behavior [43, 44]. When assembled, the MoS2–N–C700//AC LISC exhibits a quasi-rectangular CV profile across a broad voltage window of 0.5–4.0 V, integrating both faradaic and capacitive processes (Fig. 6c). The operating voltage window of MoS2–N–C700//AC is carefully selected based on the stable potential ranges of both electrodes. Across scan rates from 0.5 to 20 mV s−1, the device retains its capacitive shape, highlighting its excellent reversibility and high-rate adaptability.

Fig. 6: Electrochemical evaluation of lithium-ion supercapacitor (LISC) assembled with the MoS2–N–C700 heterostructure anode and activated carbon (AC) cathode. a Schematic of the LISC configuration. b Operating windows of MoS2–N–C700 anode, AC cathode and MoS2–N–C700//AC device. c CV curves at different scan rates. d GCD curves at different current densities. e Specific capacitances of MoS2–N–C700//AC device at different current densities. f Ragone plot comparing the energy and power densities of MoS2–N–C700//AC device with reported transition-metal dichalcogenide (TMD)-based LISCs. g Cycling stability of the MoS2–N–C700//AC device at 1 A g−1, with the inset showing LED illumination. h GCD curves during the initial 10,000 s

The GCD curves of MoS2–N–C700//AC further confirm the capacitive nature, showing nearly symmetric triangular shapes with minimal iR drop across different current densities (Fig. 6d). The device delivers specific capacitances of 75.9, 64.7, 55.1, 48.6, and 41.7 F g−1 at current densities of 0.1, 0.2, 0.5, 1.0, and 2.0 A g−1, respectively, suggesting its outstanding rate capability (Fig. 6e). The energy and power outputs are assessed by a Ragone plot (Fig. 6f). The MoS2–N–C700//AC LISC delivers a high energy density of 175 Wh kg−1 at a power density of 129.2 W kg−1 and maintains 80.0 Wh kg−1 even at 3500 W kg−1. The energy density outperforms most reported transition-metal dichalcogenide (TMD)-based LISCs and traditional carbon-based anodes (Table S5) [26, 40, 45–50].

The device also possesses remarkable long-term cycling stability. At 1 A g−1, it retains 78.2% of its initial capacitance after 10,000 cycles, with an initial Coulombic efficiency of 81.1% (Fig. 6g). The ability to power an LED further verifies its stable energy output and practical applicability. Moreover, stable operation is maintained across the full voltage window (Fig. 6h). Overall, the MoS2–N–C heterostructure enables a LISC device that simultaneously achieves high energy density, superior power density, and outstanding durability, positioning it as a promising candidate for advanced energy storage applications.

The outstanding electrochemical performance originates from the rationally designed heterostructure. In this system, a surfactant-mediated synthesis strategy is employed to construct N-bridged MoS2/C heterostructures, in which the alkyl chains of CTAB undergo in situ carbonization to generate N-doped carbon layers. Meanwhile, CTAB decomposition releases gaseous species that reconstruct the carbon framework and produce abundant mesopores. More importantly, Mo–N bonds are formed at the MoS2/C interfaces, enabling strong interfacial coupling and stabilizing the integrated porous structure. The N-doped carbon matrix serves as a conductive and robust framework, facilitating electron transport and buffering volume variation of MoS2 during cycling. The MoS2 component functions as the primary active phase for Li+ storage. In parallel, the hierarchical porous architecture suppresses MoS2 restacking, exposes abundant active edge sites, enhances electrolyte accessibility, and accommodates structural strain during repeated cycling.