Defect induced improved capacitive performance of MnS incorporated MoO3 nanocomposite for supercapacitor electrodes in aqueous electrolytes

Mizanur Rahaman; Mehedi Hasan Prince; Saif Mahmud Bijoy; Zakaria Siddiquee; Muhammad Rakibul Islam

doi:10.1371/journal.pone.0349019

Abstract

Electrode materials play a crucial role in improving supercapacitor performance. In this work, MnS nanoparticles were incorporated into MoO₃ to form a MoO₃/MnS nanocomposite via hydrothermal synthesis, and the capacitive performance of the resulting supercapacitor electrodes was evaluated. Their electrochemical performances were studied in conjunction with KCl and Na₂SO₄ electrolytes. The generation of MoO₃/MnS nanocomposite was confirmed by XRD analysis and HR-TEM imaging. It is found that the MnS nanoparticles altered the morphology of MoO₃ from nanobelts to nanofibers and produced a defective, rough surface. The defective surface expanded the interlayer distance from 0.396 nm to 0.421 nm. In both ionic electrolytes, the MoO₃/MnS composite demonstrated higher capacitive performance than the pristine MoO₃. At 0.3 A g^-1 current density, the estimated specific capacitance of MoO₃/MnS was 387 F g^-1 and 335 F g^-1 in KCl and Na₂SO₄ electrolytes, respectively. In the symmetric two-electrode system, the MoO₃/MnS shows a specific capacitance of 297 F g⁻¹ at 1 A g⁻¹, with an energy density of 33.37 Wh kg⁻¹ and a power density of 450 W kg⁻¹. The MoO₃/MnS nanocomposite provides excellent 90% retention after 1000 continuous charging-discharging cyclic. The enhancement of electrochemical performance is attributed to the large surface area, defective morphology, and broader interlayer distance. This system bridges the gap between traditional batteries and capacitors, offering a unique approach to producing supercapacitor electrodes.

Citation: Rahaman M, Prince MH, Bijoy SM, Siddiquee Z, Islam MR (2026) Defect induced improved capacitive performance of MnS incorporated MoO₃ nanocomposite for supercapacitor electrodes in aqueous electrolytes. PLoS One 21(5): e0349019. https://doi.org/10.1371/journal.pone.0349019

Editor: Latha Marasamy, Universidad Autónoma de Querétaro: Universidad Autonoma de Queretaro, MEXICO

Received: December 10, 2025; Accepted: April 22, 2026; Published: May 18, 2026

Copyright: © 2026 Rahaman et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: The authors (MR and MRI) gratefully acknowledge the financial support from the Ministry of Education, Government of Bangladesh, under grant 37.20.0000.004.33.020.23(Part-5). MRI also gratefully acknowledges the financial support from the Basic Research Grant provided by the Bangladesh University of Engineering and Technology No. songtha/R-60/Re-6714(06.03.2024). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: no competing interest.

1 Introduction‌‌

The rapid advancement of human civilization and technology in recent times has been largely driven by the widespread use of fossil fuels. The burning of fossil fuels harms our environment and is being depleted rapidly. The use of sustainable energy, such as sunlight and wind, requires reliable energy storage. Electrical energy can be stored either electrochemically in batteries or electrostatically in capacitors. Batteries have ~50–200 Wh/kg energy density and low (~1–1000 W/kg) power density, while electrostatic capacitors have energy densities less than 0.1Wh/kg and power densities over 5000 W/kg [1]. The gap between batteries and capacitors has been partially bridged by supercapacitors, which are currently used in power conditioning and electric transportation. Supercapacitors offer notable advantages such as long cyclic life, relatively fast charge and discharge, and high-power density, which makes a bridge between batteries and capacitors [2,3]. Generally, electrode materials play a significant role in enhancing the performance of supercapacitors [4–7].

Transition-metal oxides such as molybdenum trioxide (MoO₃) have gained significant interest as electrodes due to their high theoretical capacitance (1,005 C/g), exceptional cation accommodation efficiency, favorable charge transfer ability, and semiconducting properties [8–10]. MoO₃ has three different polymorphs. Among them, α-MoO₃ is remarkably important due to its structural anisotropy and the alternating stack of MoO₆ octahedra double layer bound by the Van Der Waals force along the [001] direction [11]. However, MoO₃ is prone to structural instability, has poor electrical conductivity, and limited rate capacity that reduces the electrode’s electrochemical properties for supercapacitor applications [12]. The electrochemical performance of MoO₃ can be improved by enhancing its electrical conductivity, surface area, and interlayer spacing.

The incorporation of nanostructured materials is an efficient approach for improving the capacitance of the oxide-based materials. The incorporation enhances surface area, improves conductivity, expands interlayer distance, and generates electrochemically active sites — all of which help achieve better capacitive performance. [4] Several studies have been performed on the supercapacitor applications of MoO₃-based nanocomposites. Zhou et al. fabricated an Ag-decorated MoO₃ nanocomposite for a supercapacitor electrode in a liquid phase method [13]. They achieved the highest specific capacitance of 225 F g^-1 and 71.1% cyclic stability with 8% Ag content in the Ag@MoO₃ nanocomposite. Capacitive performance and cyclic stability may not fully reflect the stability of a supercapacitor electrode. Imran et al. used the hydrothermal method to produce intertwined porous MoO₃–MWCNT nanocomposites [14]. The measured specific capacitance is 210 F g⁻¹at the lowest scan rate, 5 mV s⁻¹. At the lowest scan rate, ion diffusion is very slow, resulting in a longer time to complete the full cycle. Sadananda et al. grew ZnO nanoparticles on MoO₃ via the solid-state impregnation-calcination method [15]. This nanocomposite is combined with carbon black, yielding a specific capacitance of 280 F g^–1 at a current density of 1 A g^–1. In this work, the carbon black modifies the nanocomposites’ original capacitance.

Recently, MnS nanoparticles gained considerable attention due to their high theoretical capacitance, strong redox reactions, charge transfer kinetics, and higher electronic conductivity (3.2 × 10³ S cm⁻¹) compared to their oxide counterparts [16]. Nanostructured MnS demonstrates high ionic penetration and intercalation–deintercalation properties, contributing to the electrochemical stability of supercapacitors. Moreover, when combined with other materials, MnS shows improved performance [17]. The polymorph structure of MnS plays a vital role in improving the electrochemical performance of MoO₃ [18]. Moreover, MoO₃/MoS₂ binary nanocomposites have shown significantly high specific capacitance and cycling stability [19]. Another recent study on MoO₃/MoS₂ nanocomposite electrode has demonstrated ultrahigh capacity and excellent rate performance, highlighting the advantages of such hybrid structures for pseudocapacitive energy storage [20]. Other research has also studied morphology and defect-controlled α- [20] MoO3 structures, showing that morphologies with higher surface area and defect sites can significantly improve charge storage capacity [21]. Beyond MoO₃/MoS₂ systems, various metal sulfide-modified MoO₃ composites, including bimetallic sulfide/oxide heterostructures, have been shown to enhance electrical conductivity and charge transport, providing a promising strategy to overcome the inherently low conductivity of pure MoO₃ [22]. Although reports on MoO3/MnS nanocomposites specifically for supercapacitors are limited, results from related metal sulfide and MoO3/metal sulfide systems suggest that forming heterostructures and introducing defects may enhance electrochemical performance. Several MoO₃-sulfide-based systems have been explored for electrochemical energy storage, reports on MnS-incorporated MoO₃ nanobelts synthesized via hydrothermal processing and systematic evaluations in different aqueous electrolytes are lacking. In particular, the role of MnS-induced defects in enhancing the capacitive performance of MoO₃ has not yet been comprehensively investigated.

In this study, we used a facile hydrothermal approach to synthesize MoO₃ nanobelts and MoO₃/MnS nanocomposites and studied their structural, morphological, and electrochemical properties. The hydrothermal process was chosen because it produced approximately 85–90% of the final product relative to the precursor mass. Repeated batches prepared under identical conditions demonstrated consistent phase purity and electrochemical performance, indicating reliable batch-to-batch reproducibility. The incorporation of MnS drastically changed the morphology of the MoO₃ nanobelts to nanofibers, generating defects and pores. The defective porous morphology increases the specific surface area, number of active sites, thereby enhances the nanocomposite’s electrochemical properties. The nanocomposite shows specific capacitances of 387 F g^-1 and 335 F g^-1 at current density 0.3 Ag^-1 in 0.5M KCl and 0.5M Na₂SO₄ electrolytes, respectively. These results demonstrate remarkable enhancement of the capacitive performance of MoO₃/MnS nanocomposite thus opening a new way for improving supercapacitor electrodes.

2 Experimental section

2.1 Synthesis of MoO₃, MnS and MoO₃/MnS nanocomposites

For the hydrothermal synthesis of MoO₃ nanobelts and MnS nanoparticles, the precursors, Sodium Molybdate (Na₂MoO₄.2H₂O) and Hydrochloric Acid (HCl), Manganese (II) chloride tetra-hydrate (MnCl₂.4H₂O), and Hydrazine hydrate (N₂H₄), were purchased from Merck, India.

Initially, 0.08 M Na₂MoO₄.2H₂O was dissolved in 120 ml of DI water and stirred. After that, HCl (~3 ml) was added dropwise, the pH was maintained at 1, and the solution was stirred for 30 minutes to form a homogeneous solution. The mix was subsequently moved to a Teflon-lined autoclave, heated for 24 hours at 150 °C, and allowed to cool to room temperature. Following centrifugation, the yield was cleaned more than three times with ethanol and DI water to eliminate impurities. First, a specific amount of MnCl₂· 4H₂O and C₂H₅NS was combined in 120 mL of DI water, stirred for 1 hour. The past solution was merged with hydrazine hydrate (N₂H₄), and the mixture was agitated for 2 hours to form a homogeneous solution. The solution was then transferred to the autoclave and heated to 180 °C for 24 hours. The precipitate was washed several times with ethanol and DI water and dried at 60 °C for 3 h on a hot plate to obtain the MnS nanoparticles.

To prepare the MnS-incorporated MoO₃ nanocomposite, first, 5 wt% MnS nanoparticles were dissolved in 50 mL DI water and sonicated for 1 hour. Then it was mixed with 70 mL of a MoO₃ precursor solution and stirred for 30 minutes. The solution was heated in the autoclave to 150° C for 24 hours, then cooled to room temperature. Finally, the resulting MoO₃/MnS nanocomposite was washed numerous times and dried at 60 °C.

2.2 Characterization

The surface morphology of MoO₃ and MoO₃/MnS was examined by a field emission scanning electron microscope (JSM 7600, JEOL) and a transmission electron microscope (JEM 2100 F, JEOL). For the structural analysis, X-ray diffraction (XRD) patterns of the samples were obtained by utilizing an X-ray diffractometer (PANalytical Empyrean) equipped with a Cu-Kα X-ray source (λCuKα = 1.54278 Å). The electrodes’ electrochemical behavior was tested using a CS310 (Cortest, China) workstation in standard three-electrode configurations with a modified graphite working electrode, an Ag/AgCl reference electrode, and a platinum counter electrode plate. 0.5 M Na₂SO₄ and 0.5 M KCl aqueous ionic electrolytes were used in a voltage window. For the working electrodes, polyvinyl alcohol (C₂H₄O) and dimethyl sulfoxide (C₂H₆OS) solvents were mixed with the electrode materials. Afterwards, these mixed solutions were put uniformly (0.3 mg active mass loading) via drop casting on the surface of modified graphite electrode and dried 30 min at 60 °C.

3 Results and discussion

3.1 Morphological analysis

Fig 1(a) shows the FE-SEM image of MoO₃ nanobelts formed after hydrothermal reaction with 200–300 nm diameters and 5–10 μm lengths. The inset of Fig 1 (a) shows FE-SEM image of MnS nanoparticles. The MoO₃ nanobelts aggregate because of their large surface energy and surface tension, which minimizes their specific surface area [23]. After incorporation of MnS nanoparticles, the morphology of MoO₃ changed from nanobelts to nanofibers, as shown in Fig 1(b). By using ImageJ software, the measured nanofibers diameter is 30–40 nm. The MnS nanoparticles shrink to the width of the MoO₃ belts, resulting in an increase of specific surface area that improves the capacitive performance. The MnS nanoparticles are randomly distributed in the MoO₃ medium, creating a rough surface and numerous pores in MoO₃. Such rough and porous morphology of the MoO₃/MnS nanocomposites significantly increases the specific surface area, therefore, supplies more electrochemically active sites, which can accommodate the volume expansion [24]. This enhances the overall capacitive performance of MnS injected MoO₃ nanocomposites. Due to this unique morphology, the impedance of the material greatly reduces and provides rapid charge transportation, thereby enhancing capacitance [25].

Download:

Fig 1. Images of MoO₃ nanobelts and MoO₃/MnS nanocomposites.

(a) FE-SEM images of MoO₃ nanobelts; (b) FE-SEM images of MoO₃/MnS nanocomposites; (c) TEM images of MoO₃ nanobelts; (d) TEM images of MoO₃/MnS nanocomposites.

https://doi.org/10.1371/journal.pone.0349019.g001

Fig 1 (c, d) shows TEM micrographs of MoO₃ nanobelts and MoO₃/MnS nanocomposites. From TEM micrographs, it is evident that MoO₃ forms nanobelts that connect with one another. In the case of MoO₃/MnS nanocomposites, it is evident that the nanobelts break down, producing rich, porous nanofibers with defects.

Fig 2 demonstrates HR-TEM images of MoO₃ and the MoO₃/MnS nanocomposite, with clearly visible lattice fringes.

Download:

Fig 2. HR-TEM images of (a) pristine MoO₃ nanobelts, (b) MnS-incorporated MoO₃ (MoO₃/MnS) nanocomposites.

https://doi.org/10.1371/journal.pone.0349019.g002

The irregular lattice fringes and distorted lattice planes suggest the presence of defect related structural distortion in the nanocomposite [26]. The measured interlayer spacing of MoO₃ nanobelts was 0.396 nm, which is consistent with previous experimental results. After the incorporation of MnS nanoparticles, the interlayer spacing of the nanocomposite has increased to 0.421 nm. The observed increase in interlayer spacing is primarily due to defect formation induced by MnS incorporation. In addition, local lattice strain and interfacial distortion at the MoO₃/MnS heterojunctions may also contribute to the lattice expansion. Such combined structural effects facilitate shortened diffusion pathways and may enhance ion accessibility within the electrode material [27]. The increased interlayer distance enhances the material’s stability and reduces charge collapse between layers. Meanwhile, the pores of the nanocomposite accumulate more ions and potentially act as channels for prompt transportation [28]. While any spectroscopic techniques such as XPS, Raman, or EPR could enable quantitative analysis of defect states, the present conclusions are based on qualitative structural and diffraction evidence.

3.2 Structural analysis

The crystal structure of MoO₃ and MoO₃/MnS was investigated by X-ray diffraction (XRD), as shown in Fig 3.

Download:

Fig 3. X.ray diffraction pattern of (a) MoO₃/MnS nanocomposite and (b) MoO₃.

https://doi.org/10.1371/journal.pone.0349019.g003

The diffraction pattern of MoO₃ in Fig 3(b) displays sharp, well-defined peaks, which are characteristic of a highly crystalline material. The diffraction peaks at 12.7°, 23.3°, 25.7°, 27.4°, and 39.0° correspond to the (020), (110), (040), (021), and (060) planes of orthorhombic (Pbnm space group) MoO₃ (JCPDS card No. 35–0609), respectively [29]. The prominent peak at 25.7° indicates anisotropic growth along the (004) plane during the synthesis process [30]. The sharp peaks suggest relatively large crystallite sizes. The diffraction peaks of MnS match the JCPDS card number 06–0518, corresponding to cubic α-MnS with a rock-salt structure (S1 Fig). The relatively weak MnS peaks may be attributed to their low weight fraction and uniform dispersion within the MoO₃ matrix. The XRD pattern of the MoO₃/MnS nanocomposite in Fig 3(a) shows notable differences. While some of the original peaks of MoO₃ are retained, additional peaks of MnS appear, confirming the successful formation of MoO₃/MnS nanocomposite. The characteristic peaks of MnS, at and can be assigned to the (111) and (220) cubic MnS, respectively. The coexistence of the MoO₃ and MnS peaks in the nanocomposite’s XRD pattern indicates that the two phases remain separate and that no new phase is forming. In addition, some MoO₃ peaks are eliminated in the nanocomposite after incorporation of MnS, indicating increased disorder in MoO₃ [31]. MnS particles embedded within or at the grain boundaries of MoO₃ may introduce defects that reduce the material’s overall crystalline, leading to missing XRD peaks [32]. The MoO₃ peaks in the nanocomposite’s XRD pattern are broader and slightly shifted compared to those in the pure MoO₃ sample. The disappearance and broadening of certain MoO₃ diffraction peaks in the MoO₃/MnS nanocomposite may be attributed to reduced crystallite size, defects, and lattice distortion induced by MnS incorporation, as confirmed by HR-TEM (Fig 2). The Scherrer equation for crystallite size estimation was not applied, as its underlying assumptions are not fully valid for this defective nanocomposite system. Moreover, the peak shift to higher angles may be attributed to the introduction of compressive strain in MoO₃.

Although direct elemental mapping by STEM-EDS was not performed in this study, the incorporation of MnS is supported by XRD, which is also consistent with the morphological transformation observed in TEM, and defect-induced lattice distortion in HR-TEM. Given the low MnS loading (5 wt%), MnS is expected to be finely dispersed within the MoO₃ matrix.

3.3 Electrochemical analysis

Cyclic voltammetry (CV) measurement was performed to investigate the charge storage mechanisms in the synthesized MoO₃ and MoO₃/MnS nanocomposite. The CV curves were recorded at a 40 mV s^-1 scan rate, as shown in Fig 4 (a-b). It is observed that the area enclosed within the CV curves is higher for MoO₃/MnS nanocomposite than pure MoO₃ for both 0.5 M Na₂SO₄, and 0.5 M KCl electrolytes. In case of the 0.5 M Na₂SO₄, the area for MoO₃ is , while the MoO₃/MnS nanocomposite exhibits a larger area of . Similarly, in 0.5 M KCl, the areas are and for MoO₃ and MoO₃/MnS, respectively. This increase in the enclosed area for the MoO₃/MnS nanocomposite indicates an enhancement in specific capacitance compared to pure MoO₃, signifying its superior charge storage capability [30]. The area under the CV curves, is noticeably greater when KCl is used as the electrolyte compared to Na₂SO₄. This may be due to the smaller ionic radius and higher mobility of K⁺ ions in KCl, which enhance charge storage and ion transport within the electrode structure, as observed in previous studies [33].

Download:

Fig 4. CV curves at 40 mVs^-1 scan rate for MoO₃ (a) and MoO₃/MnS (b); Galvanostatic Charge Discharge (GCD) curves with constant current density 0.3 Ag^-1 in three three-electrode system of (c) MoO₃/MnS in Na₂SO₄, (d) MoO₃/MnS in KCl.

https://doi.org/10.1371/journal.pone.0349019.g004

For the MoO₃ sample, the CV curves in both electrolytes exhibit a quasi-rectangular shape, suggesting that its charge storage mechanism is influenced by a combination of double-layer capacitance (EDLC) and pseudo-capacitive processes [34]. In contrast, the MoO₃/MnS nanocomposite shows a more noticeable deviation from the rectangular shape, especially in the 0.5 M KCl electrolyte. From the CV analysis (i = aνᵇ), the b value is 0.78 that indicates the contributions of both capacitive and diffusion controlled. This indicates the dominant contribution is faradaic pseudo-capacitive charge storage [5]. In the absorption/desorption reaction mechanism, alkali cations (Na⁺ and K⁺) are adsorbed and desorbed into the electrode/electrolyte interface, as illustrated below:

Here, M⁺ represents the Na⁺ and K⁺ present in two different electrolytes. In the intercalation mechanism, cations are intercalated into and then extracted from the electrode material. This process involves a reversible structural change, which contributes to the faradaic charge storage.

The intercalation mechanism can be represented as:

The improvement in the specific capacitance of the MoO₃/MnS nanocomposite can be attributed to several factors. The nanocomposite defective porous morphology with increased surface area, as evident from the SEM images Fig 1(a-b), may facilitate better electrolyte piercing and ion movement, thereby enhancing the charge storage capabilities [35]. Additionally, the incorporation of MnS not only improves electrical conductivity but also provides more active sites for redox reactions, which are crucial for pseudo-capacitance. However, MnS does not serve as the dominant pseudocapacitive phase; rather, it acts as a conductive, defect-inducing component that modifies the MoO₃ lattice, facilitating enhanced ion diffusion and charge transport.

Fig 4 (c-d) shows the galvanostatic charging curves of MoO₃ and MoO₃/MnS electrodes at different electrolytes at a constant 0.3 Ag^-1 current density. The discharging time of the MoO₃/MnS is much longer than that of the MoO₃ electrode [15]. These indicate improvement in charge storage capacity, as shown in the CV curve. The specific capacitance (Cs) from GCD (Galvanostatic Charge Discharge) curves could be determined by applying the following formula, where I = discharge current, Δt = discharging time, ΔV = potential window, and m = deposited mass of working electrode. The specific capacitances of MoO₃ in Na₂SO₄ and KCl electrolytes are estimated to be 285 F g^-1 and 243 F g^-1, respectively. After inserting the MnS nanoparticles, the MoO₃/MnS electrode exhibits higher specific capacitance in both electrolytes, and the values are 335 F g^-1 in Na₂SO₄ and 387 F g^-1 in KCl. The specific capacitance is enhanced due to the porous morphology and the surface defects.

S2b Fig shows the GCD curve of the MoO₃/MnS electrode in the symmetric two-electrode system, where the specific capacitance is 297 F g⁻¹, the energy density is 33.37 W h kg⁻¹, and the power density is 450 W kg⁻¹. In addition, the nanocomposite exhibits higher capacitance in KCl electrolyte than in Na₂SO₄ electrolyte. Generally, K⁺ ions have higher molar conductivity than Na⁺, which easily migrates into the electrode/electrolyte surface [36]. In case of Na₂SO₄, the anion will reduce the mobility of Na⁺ cation, thus making the electrochemical process less effective. Additionally, the K⁺ ions have a lower hydration radius that also helps to increase overall capacitance of the nanocomposite [37].

Electrochemical impedance spectroscopy is another measurement to characterize the electrode materials. From Fig 5(a) exhibits the Nyquist spectra of MoO₃ and MoO₃/MnS nanocomposite. In the Warburg region, the MoO₃/MnS curve is stepper than MoO₃ which indicates MoO₃/MnS has low Warburg resistance. The decreased Warburg resistance expedites ion transport and improves capacitive performance.

Download:

Fig 5. Electrochemical impedance spectra of (a) MoO₃ and MoO₃/MnS and (b) Cyclic stability of MoO₃/MnS nanocomposite in KCl solution.

https://doi.org/10.1371/journal.pone.0349019.g005

Cyclic stability is another critical measurement to characterize supercapacitors. Fig 5(b) shows the cyclic stability of MoO₃/MnS electrode for 4000 charging-discharging cycles. The MoO₃/MnS electrode exhibits 87% cyclic stability. The enhancement of the nanocomposite’s cyclic stability suggests that the electrode shows a higher specific capacitance as observed for metal sulfide base nanocomposites [38].The common electrochemical activation energy in electrochemistry is the cause of this phenomenon and indicates excellent stability of the novel MoO₃/MnS.

To summarize, MnS is incorporated into MoO₃ nanobelts via a two-step hydrothermal method. The hydrothermal process employed in this study is facile and cost-effective. Its high yield and consistent batch reproducibility at the laboratory scale indicate significant potential for future scale-up and industrial application. The diffraction analysis confirmed the successful formation of MoO₃ nanobelts and MoO₃/MnS nanocomposite. The incorporated MnS nanoparticles produced defective porous nanofibers and expanded the inter layer spacing. These distinctive features allow ions to move promptly between their interfaces, providing effective charge storage. The MoO₃/MnS nanocomposite shows 387 F g^-1 and 335 Fg^-1 specific capacitances in KCl and Na₂SO₄ electrolytes, respectively. The power density of the nanocomposite is 450 W kg⁻¹ with an energy density of 33.37 W h kg⁻¹.The defective porous structure of MoO₃/MnS obtained by this simple technique provides an efficient way to produce high quality supercapacitor electrodes for energy storage applications.

Supporting information

S1 Fig. X-ray diffraction pattern of MnS nanoparticles.

https://doi.org/10.1371/journal.pone.0349019.s001

(DOCX)

S2 Fig. CV curve of MoO₃/MnS (a), and GCD curve of MoO₃/MnS nanocomposite (b) at two electrode system.

https://doi.org/10.1371/journal.pone.0349019.s002

(DOCX)

S1 File. All relevant data‌‌.

https://doi.org/10.1371/journal.pone.0349019.s003

(DOCX)

Acknowledgments

The authors also acknowledge Professor Dr. Antal Jákli for correcting the manuscript and checking the validity of the data.

References

1. Chu YS, Lister TE, Cullen WG, You H, Nagy Z. Basic Research Needs for Electrical Energy Storage: Report of the Basic Energy Sciences Workshop on Electrical Energy Storage. http://www.sc.doe.gov/bes/reports/files/EES_rpt.pdf
2. He X, Zhang X. A comprehensive review of supercapacitors: Properties, electrodes, electrolytes and thermal management systems based on phase change materials. Journal of Energy Storage. 2022;56:106023.
- View Article
- Google Scholar
3. Chatterjee DP, Nandi AK. A review on the recent advances in hybrid supercapacitors. Royal Society of Chemistry. 2021.
- View Article
- Google Scholar
4. Rahaman M, Islam MR, Islam MR. Improved electrochemical performance of defect-induced supercapacitor electrodes based on MnS-incorporated MnO2 nanorods. Nanoscale Adv. 2024;6(16):4103–10. pmid:39114155
- View Article
- PubMed/NCBI
- Google Scholar
5. Islam MS, Hoque SM, Rahaman M, Islam MR, Irfan A, Sharif A. Superior cyclic stability and capacitive performance of cation- and water molecule-preintercalated δ-MnO2/h-WO3 nanostructures as supercapacitor electrodes. ACS Omega. 2024;9(9):10680–93.
- View Article
- Google Scholar
6. Parfomak PW. CRS Report for Congress Energy Storage for Power Grids and Electric Transportation: A Technology Assessment. 2012. https:\\www.crs.gov
- View Article
- Google Scholar
7. Zhang S, Pan N. Supercapacitors performance evaluation. 2015.
- View Article
- Google Scholar
8. Kim H-S, Cook JB, Lin H, Ko JS, Tolbert SH, Ozolins V, et al. Oxygen vacancies enhance pseudocapacitive charge storage properties of MoO3-x. Nat Mater. 2017;16(4):454–60. pmid:27918566
- View Article
- PubMed/NCBI
- Google Scholar
9. Fathi S, Aslibeiki B, Torkamani R. Oxytetracycline photodegradation by transition metals doped ZnO nanorods. Journal of Water and Environmental Nanotechnology. 2023;8(3):254–66.
- View Article
- Google Scholar
10. Kalantar-zadeh K, Tang J, Wang M, Wang KL, Shailos A, Galatsis K, et al. Synthesis of nanometre-thick MoO3 sheets. Nanoscale. 2010;2(3):429–33. pmid:20644828
- View Article
- PubMed/NCBI
- Google Scholar
11. Nieto-Pinero E, et al. Building nanoplatelet α-MoO3 films: A high quality crystal anisotropic 2D material for integration. Appl Surf Sci. 2024;672:160871.
- View Article
- Google Scholar
12. Jia Y, Ma Y. Advances in MoO3-based supercapacitors for electrochemical energy storage. Journal of Energy Storage. 2024;85:111103.
- View Article
- Google Scholar
13. Zhou C. A facile route to synthesize Ag decorated MoO3 nanocomposite for symmetric supercapacitor. Ceram Int. 2020;46(10):15385–91.
- View Article
- Google Scholar
14. Shakir I, Shahid M, Cherevko S, Chung C-H, Kang DJ. Ultrahigh-energy and stable supercapacitors based on intertwined porous MoO3–MWCNT nanocomposites. Electrochimica Acta. 2011;58:76–80.
- View Article
- Google Scholar
15. Muduli S, Pati SK, Swain S, Martha SK. MoO3@ZnO Nanocomposite as an Efficient Anode Material for Supercapacitors: A Cost Effective Synthesis Approach. Energy Fuels. 2021;35(20):16850–9.
- View Article
- Google Scholar
16. Rajagopal R, Ryu K-S. Synthesis of MnO2 nanostructures with MnS-deposits for high performance supercapacitor electrodes. New J Chem. 2019;43(33):12987–3000.
- View Article
- Google Scholar
17. Jia Y, Lin Y, Ma Y, Shi W. Hierarchical MnS2-MoS2 nanotubes with efficient electrochemical performance for energy storage. Materials & Design. 2018;160:1071–9.
- View Article
- Google Scholar
18. Pei Y, Liu C, Han Z, Neale ZG, Qian W, Xiong S, et al. Revealing the impacts of metastable structure on the electrochemical properties: The case of MnS. Journal of Power Sources. 2019;431:75–83.
- View Article
- Google Scholar
19. Kaur J, Sharma S, Chand P, Arya A, Sharma A. MoO3/MoS2 based nanocomposite electrodes with ultrahigh performance and excellent cyclic stability for supercapacitor application. Materials Science and Engineering: B. 2025;314.
- View Article
- Google Scholar
20. Abdel-Aty AAR, Awad MM, Kanoun O, Khalil ASG. Morphology-engineered α-MoO3 nanostructures via MoS2 transformation for high-performance supercapacitors. Mater Adv. 2025.
- View Article
- Google Scholar
21. Luo L, Dai J, Xia L, Wang X, Xie H, Tang Z, et al. An ultra-thin interlayer bimetallic sulfide for enhancing electrons transport of supercapacitor electrode. Journal of Energy Storage. 2022;55:105528.
- View Article
- Google Scholar
22. Sonapatel, Udayabhanu, Nandeesh KN, Prashantha K. Recent advances on metal sulfides as next-generation electrodes for supercapacitor energy storage: A holistic review. Next Materials. 2025;9:101103.
- View Article
- Google Scholar
23. Wang ZL. Functional oxide nanobelts: materials, properties and potential applications in nanosystems and biotechnology. Annu Rev Phys Chem. 2004.
- View Article
- Google Scholar
24. Hu X, Zhang W, Liu X, Mei Y, Huang Y. Nanostructured Mo-based electrode materials for electrochemical energy storage. Royal Society of Chemistry. 2015.
- View Article
- Google Scholar
25. Chen S, Xing W, Duan J, Hu X, Qiao SZ. Nanostructured morphology control for efficient supercapacitor electrodes. J Mater Chem A. 2013;1(9):2941–54.
- View Article
- Google Scholar
26. Huang X, Zhao Z, Chen Y, Chiu C-Y, Ruan L, Liu Y, et al. High density catalytic hot spots in ultrafine wavy nanowires. Nano Lett. 2014;14(7):3887–94. pmid:24873775
- View Article
- PubMed/NCBI
- Google Scholar
27. Yang H, Wu N. Ionic conductivity and ion transport mechanisms of solid‐state lithium‐ion battery electrolytes: A review. Energy Science & Engineering. 2022;10(5):1643–71.
- View Article
- Google Scholar
28. Liu T, Zhou Z, Guo Y, Guo D, Liu G. Block copolymer derived uniform mesopores enable ultrafast electron and ion transport at high mass loadings. Nature Communications. 2019;10(1).
- View Article
- Google Scholar
29. Yan H, Song P, Zhang S, Zhang J, Yang Z, Wang Q. Au nanoparticles modified MoO3 nanosheets with their enhanced properties for gas sensing. Sensors and Actuators B: Chemical. 2016;236:201–7.
- View Article
- Google Scholar
30. Fang L, Shu Y, Wang A, Zhang T. Green synthesis and characterization of anisotropic uniform single-crystal α-MoO3 nanostructures. Journal of Physical Chemistry C. 2007;111(6):2401–8.
- View Article
- Google Scholar
31. Edelson D, Kuck VJ, Lum RM, Scalco E, Starnes WH Jr, Kaufman S. Anomalous behavior of molybdenum oxide as a fire retardant for polyvinyl chloride. Combustion and Flame. 1980;38:271–83.
- View Article
- Google Scholar
32. Teh LP, Setiabudi HD, Sidik SM, Annuar NHR, Jalil AA. Synergic role of platinum (Pt) and molybdenum trioxide (MoO3) promoted HBEA zeolite towards n-heptane isomerization. Mater Chem Phys. 2021;263:124406.
- View Article
- Google Scholar
33. Zhu J, Xu Y, Wang J, Lin J, Sun X, Mao S. The effect of various electrolyte cations on electrochemical performance of polypyrrole/RGO based supercapacitors. Phys Chem Chem Phys. 2015;17(43):28666–73. pmid:26444443
- View Article
- PubMed/NCBI
- Google Scholar
34. Niu C, Han G, Song H, Yuan S, Hou W. Intercalation pseudo-capacitance behavior of few-layered molybdenum sulfide in various electrolytes. J Colloid Interface Sci. 2020;561:117–26. pmid:31812858
- View Article
- PubMed/NCBI
- Google Scholar
35. Liang Y, Zhang W, Wu D, Ni QQ, Zhang MQ. Interface engineering of carbon-based nanocomposites for advanced electrochemical energy storage. 2018.
- View Article
- Google Scholar
36. Shao TL. Recent research on strategies to improve ion conduction in alkali metal-ion batteries. 2019.
- View Article
- Google Scholar
37. Oraon R, De Adhikari A, Tiwari SK, Nayak GC. Enhanced Specific Capacitance of Self-Assembled Three-Dimensional Carbon Nanotube/Layered Silicate/Polyaniline Hybrid Sandwiched Nanocomposite for Supercapacitor Applications. ACS Sustainable Chem Eng. 2016;4(3):1392–403.
- View Article
- Google Scholar
38. Hou J, Shao Y, Ellis MW, Moore RB, Yi B. Graphene-based electrochemical energy conversion and storage: Fuel cells, supercapacitors and lithium ion batteries. 2011.
- View Article
- Google Scholar

[ref1] 1. Chu YS, Lister TE, Cullen WG, You H, Nagy Z. Basic Research Needs for Electrical Energy Storage: Report of the Basic Energy Sciences Workshop on Electrical Energy Storage. http://www.sc.doe.gov/bes/reports/files/EES_rpt.pdf

[ref2] 2. He X, Zhang X. A comprehensive review of supercapacitors: Properties, electrodes, electrolytes and thermal management systems based on phase change materials. Journal of Energy Storage. 2022;56:106023.
View Article
Google Scholar

[3] View Article

[4] Google Scholar

[ref3] 3. Chatterjee DP, Nandi AK. A review on the recent advances in hybrid supercapacitors. Royal Society of Chemistry. 2021.
View Article
Google Scholar

[6] View Article

[7] Google Scholar

[ref4] 4. Rahaman M, Islam MR, Islam MR. Improved electrochemical performance of defect-induced supercapacitor electrodes based on MnS-incorporated MnO2 nanorods. Nanoscale Adv. 2024;6(16):4103–10. pmid:39114155
View Article
PubMed/NCBI
Google Scholar

[9] View Article

[10] PubMed/NCBI

[11] Google Scholar

[ref5] 5. Islam MS, Hoque SM, Rahaman M, Islam MR, Irfan A, Sharif A. Superior cyclic stability and capacitive performance of cation- and water molecule-preintercalated δ-MnO2/h-WO3 nanostructures as supercapacitor electrodes. ACS Omega. 2024;9(9):10680–93.
View Article
Google Scholar

[13] View Article

[14] Google Scholar

[ref6] 6. Parfomak PW. CRS Report for Congress Energy Storage for Power Grids and Electric Transportation: A Technology Assessment. 2012. https:\\www.crs.gov
View Article
Google Scholar

[16] View Article

[17] Google Scholar

[ref7] 7. Zhang S, Pan N. Supercapacitors performance evaluation. 2015.
View Article
Google Scholar

[19] View Article

[20] Google Scholar

[ref8] 8. Kim H-S, Cook JB, Lin H, Ko JS, Tolbert SH, Ozolins V, et al. Oxygen vacancies enhance pseudocapacitive charge storage properties of MoO3-x. Nat Mater. 2017;16(4):454–60. pmid:27918566
View Article
PubMed/NCBI
Google Scholar

[22] View Article

[23] PubMed/NCBI

[24] Google Scholar

[ref9] 9. Fathi S, Aslibeiki B, Torkamani R. Oxytetracycline photodegradation by transition metals doped ZnO nanorods. Journal of Water and Environmental Nanotechnology. 2023;8(3):254–66.
View Article
Google Scholar

[26] View Article

[27] Google Scholar

[ref10] 10. Kalantar-zadeh K, Tang J, Wang M, Wang KL, Shailos A, Galatsis K, et al. Synthesis of nanometre-thick MoO3 sheets. Nanoscale. 2010;2(3):429–33. pmid:20644828
View Article
PubMed/NCBI
Google Scholar

[29] View Article

[30] PubMed/NCBI

[31] Google Scholar

[ref11] 11. Nieto-Pinero E, et al. Building nanoplatelet α-MoO3 films: A high quality crystal anisotropic 2D material for integration. Appl Surf Sci. 2024;672:160871.
View Article
Google Scholar

[33] View Article

[34] Google Scholar

[ref12] 12. Jia Y, Ma Y. Advances in MoO3-based supercapacitors for electrochemical energy storage. Journal of Energy Storage. 2024;85:111103.
View Article
Google Scholar

[36] View Article

[37] Google Scholar

[ref13] 13. Zhou C. A facile route to synthesize Ag decorated MoO3 nanocomposite for symmetric supercapacitor. Ceram Int. 2020;46(10):15385–91.
View Article
Google Scholar

[39] View Article

[40] Google Scholar

[ref14] 14. Shakir I, Shahid M, Cherevko S, Chung C-H, Kang DJ. Ultrahigh-energy and stable supercapacitors based on intertwined porous MoO3–MWCNT nanocomposites. Electrochimica Acta. 2011;58:76–80.
View Article
Google Scholar

[42] View Article

[43] Google Scholar

[ref15] 15. Muduli S, Pati SK, Swain S, Martha SK. MoO3@ZnO Nanocomposite as an Efficient Anode Material for Supercapacitors: A Cost Effective Synthesis Approach. Energy Fuels. 2021;35(20):16850–9.
View Article
Google Scholar

[45] View Article

[46] Google Scholar

[ref16] 16. Rajagopal R, Ryu K-S. Synthesis of MnO2 nanostructures with MnS-deposits for high performance supercapacitor electrodes. New J Chem. 2019;43(33):12987–3000.
View Article
Google Scholar

[48] View Article

[49] Google Scholar

[ref17] 17. Jia Y, Lin Y, Ma Y, Shi W. Hierarchical MnS2-MoS2 nanotubes with efficient electrochemical performance for energy storage. Materials & Design. 2018;160:1071–9.
View Article
Google Scholar

[51] View Article

[52] Google Scholar

[ref18] 18. Pei Y, Liu C, Han Z, Neale ZG, Qian W, Xiong S, et al. Revealing the impacts of metastable structure on the electrochemical properties: The case of MnS. Journal of Power Sources. 2019;431:75–83.
View Article
Google Scholar

[54] View Article

[55] Google Scholar

[ref19] 19. Kaur J, Sharma S, Chand P, Arya A, Sharma A. MoO3/MoS2 based nanocomposite electrodes with ultrahigh performance and excellent cyclic stability for supercapacitor application. Materials Science and Engineering: B. 2025;314.
View Article
Google Scholar

[57] View Article

[58] Google Scholar

[ref20] 20. Abdel-Aty AAR, Awad MM, Kanoun O, Khalil ASG. Morphology-engineered α-MoO3 nanostructures via MoS2 transformation for high-performance supercapacitors. Mater Adv. 2025.
View Article
Google Scholar

[60] View Article

[61] Google Scholar

[ref21] 21. Luo L, Dai J, Xia L, Wang X, Xie H, Tang Z, et al. An ultra-thin interlayer bimetallic sulfide for enhancing electrons transport of supercapacitor electrode. Journal of Energy Storage. 2022;55:105528.
View Article
Google Scholar

[63] View Article

[64] Google Scholar

[ref22] 22. Sonapatel, Udayabhanu, Nandeesh KN, Prashantha K. Recent advances on metal sulfides as next-generation electrodes for supercapacitor energy storage: A holistic review. Next Materials. 2025;9:101103.
View Article
Google Scholar

[66] View Article

[67] Google Scholar

[ref23] 23. Wang ZL. Functional oxide nanobelts: materials, properties and potential applications in nanosystems and biotechnology. Annu Rev Phys Chem. 2004.
View Article
Google Scholar

[69] View Article

[70] Google Scholar

[ref24] 24. Hu X, Zhang W, Liu X, Mei Y, Huang Y. Nanostructured Mo-based electrode materials for electrochemical energy storage. Royal Society of Chemistry. 2015.
View Article
Google Scholar

[72] View Article

[73] Google Scholar

[ref25] 25. Chen S, Xing W, Duan J, Hu X, Qiao SZ. Nanostructured morphology control for efficient supercapacitor electrodes. J Mater Chem A. 2013;1(9):2941–54.
View Article
Google Scholar

[75] View Article

[76] Google Scholar

[ref26] 26. Huang X, Zhao Z, Chen Y, Chiu C-Y, Ruan L, Liu Y, et al. High density catalytic hot spots in ultrafine wavy nanowires. Nano Lett. 2014;14(7):3887–94. pmid:24873775
View Article
PubMed/NCBI
Google Scholar

[78] View Article

[79] PubMed/NCBI

[80] Google Scholar

[ref27] 27. Yang H, Wu N. Ionic conductivity and ion transport mechanisms of solid‐state lithium‐ion battery electrolytes: A review. Energy Science & Engineering. 2022;10(5):1643–71.
View Article
Google Scholar

[82] View Article

[83] Google Scholar

[ref28] 28. Liu T, Zhou Z, Guo Y, Guo D, Liu G. Block copolymer derived uniform mesopores enable ultrafast electron and ion transport at high mass loadings. Nature Communications. 2019;10(1).
View Article
Google Scholar

[85] View Article

[86] Google Scholar

[ref29] 29. Yan H, Song P, Zhang S, Zhang J, Yang Z, Wang Q. Au nanoparticles modified MoO3 nanosheets with their enhanced properties for gas sensing. Sensors and Actuators B: Chemical. 2016;236:201–7.
View Article
Google Scholar

[88] View Article

[89] Google Scholar

[ref30] 30. Fang L, Shu Y, Wang A, Zhang T. Green synthesis and characterization of anisotropic uniform single-crystal α-MoO3 nanostructures. Journal of Physical Chemistry C. 2007;111(6):2401–8.
View Article
Google Scholar

[91] View Article

[92] Google Scholar

[ref31] 31. Edelson D, Kuck VJ, Lum RM, Scalco E, Starnes WH Jr, Kaufman S. Anomalous behavior of molybdenum oxide as a fire retardant for polyvinyl chloride. Combustion and Flame. 1980;38:271–83.
View Article
Google Scholar

[94] View Article

[95] Google Scholar

[ref32] 32. Teh LP, Setiabudi HD, Sidik SM, Annuar NHR, Jalil AA. Synergic role of platinum (Pt) and molybdenum trioxide (MoO3) promoted HBEA zeolite towards n-heptane isomerization. Mater Chem Phys. 2021;263:124406.
View Article
Google Scholar

[97] View Article

[98] Google Scholar

[ref33] 33. Zhu J, Xu Y, Wang J, Lin J, Sun X, Mao S. The effect of various electrolyte cations on electrochemical performance of polypyrrole/RGO based supercapacitors. Phys Chem Chem Phys. 2015;17(43):28666–73. pmid:26444443
View Article
PubMed/NCBI
Google Scholar

[100] View Article

[101] PubMed/NCBI

[102] Google Scholar

[ref34] 34. Niu C, Han G, Song H, Yuan S, Hou W. Intercalation pseudo-capacitance behavior of few-layered molybdenum sulfide in various electrolytes. J Colloid Interface Sci. 2020;561:117–26. pmid:31812858
View Article
PubMed/NCBI
Google Scholar

[104] View Article

[105] PubMed/NCBI

[106] Google Scholar

[ref35] 35. Liang Y, Zhang W, Wu D, Ni QQ, Zhang MQ. Interface engineering of carbon-based nanocomposites for advanced electrochemical energy storage. 2018.
View Article
Google Scholar

[108] View Article

[109] Google Scholar

[ref36] 36. Shao TL. Recent research on strategies to improve ion conduction in alkali metal-ion batteries. 2019.
View Article
Google Scholar

[111] View Article

[112] Google Scholar

[ref37] 37. Oraon R, De Adhikari A, Tiwari SK, Nayak GC. Enhanced Specific Capacitance of Self-Assembled Three-Dimensional Carbon Nanotube/Layered Silicate/Polyaniline Hybrid Sandwiched Nanocomposite for Supercapacitor Applications. ACS Sustainable Chem Eng. 2016;4(3):1392–403.
View Article
Google Scholar

[114] View Article

[115] Google Scholar

[ref38] 38. Hou J, Shao Y, Ellis MW, Moore RB, Yi B. Graphene-based electrochemical energy conversion and storage: Fuel cells, supercapacitors and lithium ion batteries. 2011.
View Article
Google Scholar

[117] View Article

[118] Google Scholar

Figures

Abstract

1 Introduction‌‌

2 Experimental section

2.1 Synthesis of MoO3, MnS and MoO3/MnS nanocomposites

2.2 Characterization

3 Results and discussion

3.1 Morphological analysis

3.2 Structural analysis

3.3 Electrochemical analysis

Supporting information

S1 Fig. X-ray diffraction pattern of MnS nanoparticles.

S2 Fig. CV curve of MoO3/MnS (a), and GCD curve of MoO3/MnS nanocomposite (b) at two electrode system.

S1 File. All relevant data‌‌.

Acknowledgments

References

2.1 Synthesis of MoO₃, MnS and MoO₃/MnS nanocomposites

S2 Fig. CV curve of MoO₃/MnS (a), and GCD curve of MoO₃/MnS nanocomposite (b) at two electrode system.