Methylene Blue as a Redox Additive in Electrolytes for Advanced Charcoal-Based Hybrid Supercapacitors

Methylene Blue as a Redox Additive in Electrolytes for Advanced Charcoal-Based Hybrid Supercapacitors | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Methylene Blue as a Redox Additive in Electrolytes for Advanced Charcoal-Based Hybrid Supercapacitors Van Nhat Nguyen, An-Giang Nguyen, Thi Viet Bac Phung, Phi Long Nguyen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7156238/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 06 Nov, 2025 Read the published version in Scientific Reports → Version 1 posted 10 You are reading this latest preprint version Abstract Carbon-based supercapacitor electrodes derived from biomass have recently garnered significant attention due to their low cost, natural abundance, and environmental sustainability. In this study, charcoal was pretreated using a simple ultrasonic method and was employed as the active electrode material in both three-electrode and symmetric supercapacitor configurations. To further enhance electrochemical performance, a sustainable and dual-functional strategy was implemented by introducing methylene blue, a redox-active additive, into an aqueous sodium chloride electrolyte. Structural and morphological characterizations revealed that charcoal possessed a highly porous architecture with preserved plant-based vascular channels, facilitating efficient electrolyte penetration and ion transport. Electrochemical analyses demonstrated that the incorporation of methylene blue significantly enhanced charge storage through a synergistic combination of electric double-layer capacitance and pseudocapacitive behavior. The optimal device, utilizing the MB35 electrolyte composition, delivered a high specific capacitance of 212.23 F g –1 at 0.5 A g –1 , an energy density of 15.34 Wh kg –1 at a power density of 350 W kg –1 , and excellent cycling stability, retaining 91.3% of its initial capacitance after 2000 cycles. This work presents a cost-effective route for fabricating high-performance biomass-derived supercapacitors while offering a novel approach for the reutilization of dye pollutants in sustainable energy storage applications. Physical sciences/Chemistry Physical sciences/Energy science and technology Physical sciences/Engineering Earth and environmental sciences/Environmental sciences Physical sciences/Materials science supercapacitors charcoal methylene blue redox electrolyte Full Text Additional Declarations No competing interests reported. Supplementary Files SupportingInformation.docx Cite Share Download PDF Status: Published Journal Publication published 06 Nov, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 08 Aug, 2025 Reviews received at journal 01 Aug, 2025 Reviews received at journal 30 Jul, 2025 Reviewers agreed at journal 28 Jul, 2025 Reviewers agreed at journal 26 Jul, 2025 Reviewers agreed at journal 25 Jul, 2025 Reviewers invited by journal 25 Jul, 2025 Editor assigned by journal 21 Jul, 2025 Submission checks completed at journal 19 Jul, 2025 First submitted to journal 18 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7156238","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":491201883,"identity":"807935a7-f82f-46bb-9613-942e13ca8d06","order_by":0,"name":"Van Nhat Nguyen","email":"","orcid":"","institution":"VinUniversity","correspondingAuthor":false,"prefix":"","firstName":"Van","middleName":"Nhat","lastName":"Nguyen","suffix":""},{"id":491201884,"identity":"93cd8639-f20d-400d-b013-d58846f04fa1","order_by":1,"name":"An-Giang Nguyen","email":"","orcid":"","institution":"VinUniversity","correspondingAuthor":false,"prefix":"","firstName":"An-Giang","middleName":"","lastName":"Nguyen","suffix":""},{"id":491201885,"identity":"194d16e0-078a-426e-bc09-b8594aacb1a7","order_by":2,"name":"Thi Viet Bac Phung","email":"","orcid":"","institution":"VinUniversity","correspondingAuthor":false,"prefix":"","firstName":"Thi","middleName":"Viet Bac","lastName":"Phung","suffix":""},{"id":491201886,"identity":"d11c5398-33b8-451d-9c01-f3b71e712f3b","order_by":3,"name":"Phi Long Nguyen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6ElEQVRIiWNgGAWjYBACPigtx8/A2ACkJYA4Ab8WNihtLNlAqpbEDQfgYoS0sPcefsG44w7j5hvJbY95d1gw8LPnGDDz7sCjhedcmgXjmWfMZjcS2415z0gwSPa8AWo5g0eLRI6ZAWPbYTazMwfbpHnbJBgMbuQYMM5sI6yFx7gHqsWeCC3GD4BaJAzYG6G2SOQYMHzEp4XnjBlDYtszA4njjW2Sc9skeCTOPCs4gE8LP3uP8YePbXfq+5vZn0m8bauT429P3vggEY8WsNsSGA7AeTwg4gAOpTDA/IGwmlEwCkbBKBjRAACCOEnUOSuxcQAAAABJRU5ErkJggg==","orcid":"","institution":"VinUniversity","correspondingAuthor":true,"prefix":"","firstName":"Phi","middleName":"Long","lastName":"Nguyen","suffix":""}],"badges":[],"createdAt":"2025-07-18 09:38:31","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7156238/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7156238/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-22861-y","type":"published","date":"2025-11-06T15:57:25+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":95564125,"identity":"5d30df15-af19-45d9-8b1a-148c22e2d9fd","added_by":"auto","created_at":"2025-11-10 16:08:08","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1270012,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7156238/v1_covered_18bebeb5-43d3-49f2-8fc1-673645e7d121.pdf"},{"id":87690557,"identity":"83a5d2a1-55ad-4b47-93fb-9ccf9a091356","added_by":"auto","created_at":"2025-07-28 04:22:10","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":609626,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-7156238/v1/0e67046769bebcd6c85e458d.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Methylene Blue as a Redox Additive in Electrolytes for Advanced Charcoal-Based Hybrid Supercapacitors","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"supercapacitors, charcoal, methylene blue, redox electrolyte","lastPublishedDoi":"10.21203/rs.3.rs-7156238/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7156238/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCarbon-based supercapacitor electrodes derived from biomass have recently garnered significant attention due to their low cost, natural abundance, and environmental sustainability. In this study, charcoal was pretreated using a simple ultrasonic method and was employed as the active electrode material in both three-electrode and symmetric supercapacitor configurations. To further enhance electrochemical performance, a sustainable and dual-functional strategy was implemented by introducing methylene blue, a redox-active additive, into an aqueous sodium chloride electrolyte. Structural and morphological characterizations revealed that charcoal possessed a highly porous architecture with preserved plant-based vascular channels, facilitating efficient electrolyte penetration and ion transport. Electrochemical analyses demonstrated that the incorporation of methylene blue significantly enhanced charge storage through a synergistic combination of electric double-layer capacitance and pseudocapacitive behavior. The optimal device, utilizing the MB35 electrolyte composition, delivered a high specific capacitance of 212.23 F g\u003csup\u003e\u0026ndash;1\u003c/sup\u003e at 0.5 A g\u003csup\u003e\u0026ndash;1\u003c/sup\u003e, an energy density of 15.34 Wh kg\u003csup\u003e\u0026ndash;1\u003c/sup\u003e at a power density of 350 W kg\u003csup\u003e\u0026ndash;1\u003c/sup\u003e, and excellent cycling stability, retaining 91.3% of its initial capacitance after 2000 cycles. 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