Sustainable production of MnO₂/activated carbon hybrid electrodes from pomegranate peels for efficient energy storage

Abstract

To meet the enhanced demand for renewable energy sources, high-performance and sustainable energy storage devices are needed. In this study, KOH activation and the controlled redox deposition of MnO₂ at different mass loadings (10, 25, and 40 wt.%) were used to synthesize biomass-based activated carbon (AC) and hybrid AC/MnO₂ electrodes from pomegranate peel biomass. The porous structure of the uniformly distributed MnO₂ nanoparticles was confirmed by detailed structural analysis using field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET) analysis, and X-ray diffraction (XRD) techniques. Electrochemical analysis was performed using a three-electrode system with 1M Na₂SO₄ as the electrolyte. The results showed that the AC/MnO₂-25 electrode possessed the highest electrochemical response with a specific capacitance of 394 Fg⁻¹ at 1 Ag⁻¹, along with good rate capability and low internal resistance. Even after 5000 cycles, the capacitance retention was 94.5%. The results confirmed a good electrochemical response with a Coulombic efficiency of approximately 98%. The enhanced electrochemical response was due to the combination of high-surface-area activated carbon with MnO₂ nanoparticles, which contributes to electric double-layer capacitance and pseudocapacitance. The results confirmed the suitability of pomegranate peel biomass as a sustainable source of biomass to produce high-performance electrode materials for the fabrication of high-performance supercapacitor devices.

Keywords

activated carbon / pomegranate peel / MnO₂ hybrid electrodes / supercapacitors / sustainable energy storage

References

[1] Shaheen S (2025) Hybrid ZnO-MnO₂ nanomaterials for glucose detection: A review of recent progress . Biol Clin Sci Res J 6: 119-130. https://doi.org/10.54112/bcsrj.v6i5.1769

[2] Sanderbrandes L, Turek T (2024) Investigation of nickel-based gas diffusion electrodes for implementation in a hybrid alkaline water electrolysis cell. ECS Meet Abstr MA2024-02: 2140. https://doi.org/10.1149/MA2024-02282140mtgabs

[3] Ahmer MF, Ullah Q, Uddin MK (2024) Magnetic metal oxide assisted conducting polymer nanocomposites as eco-friendly electrode materials for supercapacitor applications: A review. J Polym Eng 45: 1-41. https://doi.org/10.1515/polyeng-2024-0101

[4] Patel A, Patel SK, Singh RS, et al. (2024) Review on recent advancements in the role of electrolytes and electrode materials on supercapacitor performances. Discover Nano 19: 188. https://doi.org/10.1186/s11671-024-04053-1

[5] Thomas SA, Cherusseri J, Rajendran DN (2024) Nickel disulfide (NiS₂): A sustainable low-cost electrode material for high-performance supercapacitors . Energy Technol 12: 2400138. https://doi.org/10.1002/ente.202400138

[6] Jiang Y, Liu J (2019) Definitions of pseudocapacitive materials: A brief review. Energy Environ Mater 2: 30-37. https://doi.org/10.1002/eem2.12028

[7] Fang G, Zhou J, Pan A, et al. (2018) Recent advances in aqueous zinc-ion batteries. ACS Energy Lett 3: 2480-2501. https://doi.org/10.1021/acsenergylett.8b01426

[8] Dubal DP, Chodankar NR, Kim DH, et al. (2018) Towards flexible solid-state supercapacitors for smart and wearable electronics. Chem Soc Rev 47: 2065-2129. https://doi.org/10.1039/C7CS00505A

[9] Zhao C, Yang J, Zhang Y, et al. (2025) Hierarchically pore-optimized wood-derived thick carbon electrodes with in-situ grown BCN nanotubes for high-performance supercapacitors. Carbon 243: 120520. https://doi.org/10.1016/j.carbon.2025.120520

[10] Zhang Y, Sheng L, Zhao C, et al. (2025) Tailored biomass-derived porous carbon with dual-activator for high-mass-loading supercapacitors with enhanced rate capabilities. J Energy Storage 136: 118601. https://doi.org/10.1016/j.est.2025.118601

[11] Zuo W, Li R, Zhou C, et al. (2017) Battery-supercapacitor hybrid devices: recent progress and future prospects. Adv Sci 4: 1600539. https://doi.org/10.1002/advs.201600539

[12] Borenstein A, Hanna O, Attias R, et al. (2017) Carbon-based composite materials for supercapacitor electrodes: A review. J Mater Chem A 5: 12653-12672. https://doi.org/10.1039/C7TA00863E

[13] Manimekala T, Sivasubramanian R, Dar MA, et al. (2025) Crafting the architecture of biomass-derived activated carbon via electrochemical insights for supercapacitors: A review. RSC Adv 15: 2490-2522. https://doi.org/10.1039/D4RA07682F

[14] Hegde SS, Bhat BR (2024) Sustainable energy storage: Mangifera indica leaf waste-derived activated carbon for long-life, high-performance supercapacitors. RSC Adv 14: 8028-8038. https://doi.org/10.1039/D3RA08910J

[15] Rajasekaran SJ, Grace AN, Jacob G, et al. (2023) Investigation of different aqueous electrolytes for biomass-derived activated carbon-based supercapacitors. Catalysts 13: 286. https://doi.org/10.3390/catal13020286

[16] Hepsiba P, Rajkumar S, Elanthamilan E, et al. (2022) Biomass-derived porous activated carbon from anacardium occidentale shell as electrode material for supercapacitors. New J Chem 46: 8863-8873. https://doi.org/10.1039/D2NJ01041K

[17] Rajesh M, Manikandan R, Park S, et al. (2020) Pinecone biomass-derived activated carbon: The potential electrode material for the development of symmetric and asymmetric supercapacitors. Int J Energy Res 44: 8591-8605. https://doi.org/10.1002/er.5548

[18] George NS, Jose LM, Aravind A (2022) Review on transition metal oxides and their composites for energy storage application. In: Stevic Z (Ed.), Updates on Supercapacitors, London: IntechOpen, Chapter 4. https://doi.org/10.5772/intechopen.108781

[19] Naresh V, Lee N (2021) A review on biosensors and recent development of nanostructured materials-enabled biosensors. Sensors 21: 1109. https://doi.org/10.3390/s21041109

[20] Zhang P, Li W (2020) Microwave-assisted synthesis of CuO/MnO₂ nanocomposites for supercapacitor application . Micro Nano Lett 15: 938-942. https://doi.org/10.1049/mnl.2020.0400

[21] Tarcan R, Todor-Boer O, Petrovai I, et al. (2020) Reduced graphene oxide today. J Mater Chem C 8: 1198-1224. https://doi.org/10.1039/C9TC04916A

[22] Najib S, Erdem E (2019) Current progress achieved in novel materials for supercapacitor electrodes: mini review. Nanoscale Adv 1: 2817-2827. https://doi.org/10.1039/C9NA00345B

[23] Sevilla M, Mokaya R (2014) Energy storage applications of activated carbons: Supercapacitors and hydrogen storage. Energy Environ Sci 7: 1250-1280. https://doi.org/10.1039/C3EE43525C

[24] Wang J, Kaskel S (2012) KOH activation of carbon-based materials for energy storage. J Mater Chem 22: 23710-23725. https://doi.org/10.1039/c2jm34066f

[25] Saini S, Chand P, Joshi A (2021) Biomass derived carbon for supercapacitor applications: Review. J Energy Storage 39: 102646. https://doi.org/10.1016/j.est.2021.102646

[26] Lee YS, Selvaraj AR, Rajendiran R, et al. (2023) Synthesis of biomass-derived porous activated carbon (Pac) sheets and 1d manganese oxide (MnO₂) composite towards the asymmetric supercapacitors . Preprint. https://doi.org/10.2139/ssrn.4672170

[27] Zhang P, Wu Yh, Sun Hr, et al. (2021) MnO₂/carbon nanocomposite based on silkworm excrement for high-performance supercapacitors . Int J Miner Metall Mater 28: 1735-1744. https://doi.org/10.1007/s12613-021-2272-8

[28] Chung HY, Chang HM, Wang CP (2024) Manganese oxide-doped hierarchical porous carbon derived from tea leaf waste for high-performance supercapacitors. Int J Mol Sci 25: 10884. https://doi.org/10.3390/ijms252010884

[29] Choi J, Wixson T, Worsley A, et al. (2021) Pomegranate: an eco-friendly source for energy storage devices. Surf Coat Technol 421: 127405. https://doi.org/10.1016/j.surfcoat.2021.127405

[30] Saka C, Yardım Y, Genel İ (2025) Ammonia-treated biomass carbon for efficient charge storage: role of nitrogen doping in capacitance enhancement. J Electroanal Chem, 119427. https://doi.org/10.1016/j.jelechem.2025.119427

[31] Nazhipkyzy M, Kurmanbayeva G, Seitkazinova A, et al. (2024) Activated carbon derived from cucumber peel for use as a supercapacitor electrode material. Nanomaterials 14: 686. https://doi.org/10.3390/nano14080686

[32] Li G, Li Y, Chen X, et al. (2022) One step synthesis of N, P co-doped hierarchical porous carbon nanosheets derived from pomelo peel for high performance supercapacitors. J Colloid Interface Sci 605: 71-81. https://doi.org/10.1016/j.jcis.2021.07.065.