Nanocube-size-dependent Fermi level positioning in Cu 2 O/TiO 2 S-scheme heterojunctions for optimized VOC photodegradation

Nanocube-size-dependent Fermi level positioning in Cu 2 O/TiO 2 S-scheme heterojunctions for optimized VOC photodegradation | 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 Research Article Nanocube-size-dependent Fermi level positioning in Cu 2 O/TiO 2 S-scheme heterojunctions for optimized VOC photodegradation Lu Liu, Hubdar Ali Maitlo, Younes Ahmadi, Ki-Hyun Kim This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9439402/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Precise control over interfacial energetics through nanoscale component engineering remains a key challenge in designing efficient heterojunction photocatalysts. This work demonstrates that the Fermi-level position of Cu 2 O—and consequently the interfacial electronic structure of Cu 2 O/TiO 2 S-scheme heterojunctions—can be directly tuned by varying Cu 2 O crystal size (edge lengths: 30, 55, and 315 nm). With a fixed 1 wt% loading, the heterojunction constructed from the smallest nanocubes (CT-30) achieves superior BTX oxidation efficiencies: 84.3% for benzene, 98.2% for toluene, and 94.1% for xylene, significantly outperforming pure TiO 2 , Cu 2 O, and the large-cube composite (CT-315). For toluene, this performance corresponds to an apparent quantum yield of 3.2% and a reaction rate of 6.04 µmol g⁻ 1 h⁻ 1 . Detailed electronic characterization shows that smaller Cu 2 O nanocubes have a more negative conduction band, enlarging the Fermi-level offset (ΔE F ) with TiO 2 . This strengthens the interfacial electric field, forming an efficient S-scheme photocatalysts that separates and preserves high-energy carriers. The retained electrons at the Cu 2 O conduction band (–0.79 V) drive abundant •O 2 ⁻/•OH generation, leading to complete BTX mineralization via intermediates to CO 2 /H 2 O. This work establishes size-mediated Fermi-level engineering as a key design principle for high-efficiency S-scheme photocatalysts. crystal size conduction band Fermi level heterojunction S-scheme photocatalysts Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 16 May, 2026 Reviews received at journal 15 May, 2026 Reviewers agreed at journal 14 May, 2026 Reviewers agreed at journal 07 May, 2026 Reviewers agreed at journal 06 May, 2026 Reviewers agreed at journal 06 May, 2026 Reviewers invited by journal 05 May, 2026 Editor assigned by journal 17 Apr, 2026 Submission checks completed at journal 17 Apr, 2026 First submitted to journal 16 Apr, 2026 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. We do this by developing innovative software and high quality services for the global research community. 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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-9439402","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":636549562,"identity":"944b0ee2-904e-4577-bc4f-aeee8dd29517","order_by":0,"name":"Lu Liu","email":"","orcid":"","institution":"Hanyang University","correspondingAuthor":false,"prefix":"","firstName":"Lu","middleName":"","lastName":"Liu","suffix":""},{"id":636549563,"identity":"3f9d4ceb-6a6d-45c3-a0fc-c1541aa9a9fd","order_by":1,"name":"Hubdar Ali Maitlo","email":"","orcid":"","institution":"Hanyang University","correspondingAuthor":false,"prefix":"","firstName":"Hubdar","middleName":"Ali","lastName":"Maitlo","suffix":""},{"id":636549564,"identity":"10dd02a1-a76b-4ec2-a739-30b343c475b6","order_by":2,"name":"Younes Ahmadi","email":"","orcid":"","institution":"Sonoma State University","correspondingAuthor":false,"prefix":"","firstName":"Younes","middleName":"","lastName":"Ahmadi","suffix":""},{"id":636549566,"identity":"faac66ee-ef49-4bf9-bddc-9723de06cf2d","order_by":3,"name":"Ki-Hyun Kim","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA80lEQVRIiWNgGAWjYBACCR7GBoYPBjYJSGJshLUwzihII0kLAwMzx4fDJGiR7DncupnB4Hwe/+wew88Fvxjk+RvY0j7g0yLN29h2u8DgdrHEnTPG0jP7GAxnHGA7PAOfFjl+xrbbMwxuJzbcyDGQ5u1hYNzAwN6M12FgLTwG5xLn38gx/g3UYk9QC9hhPAYHEjfcyDGT5vnBkLiBge0wXi2SPQfbbs4wSE7ceCOtzJq3QSJ5xmG2ZLxaJM6kP7vx4Y9d4rwbyZtv8/yxse1vbzPGqwUJcBgwMLZJAKOJWA0MDOwPGBj+EK98FIyCUTAKRg4AAO9wS/5Qu0ZaAAAAAElFTkSuQmCC","orcid":"","institution":"Hanyang University","correspondingAuthor":true,"prefix":"","firstName":"Ki-Hyun","middleName":"","lastName":"Kim","suffix":""}],"badges":[],"createdAt":"2026-04-16 14:23:54","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9439402/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9439402/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":109405337,"identity":"d3a9d49f-2d01-46fe-bc23-1cfdfc076821","added_by":"auto","created_at":"2026-05-17 13:17:10","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3397183,"visible":true,"origin":"","legend":"","description":"","filename":"260416TiO2Cu2OV24KH.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9439402/v1_covered_459126eb-bd60-4093-90a0-378970eeb868.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Nanocube-size-dependent Fermi level positioning in Cu 2 O/TiO 2 S-scheme heterojunctions for optimized VOC photodegradation","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"advanced-composites-and-hybrid-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"achm","sideBox":"Learn more about [Advanced Composites and Hybrid Materials](https://link.springer.com/journal/42114)","snPcode":"42114","submissionUrl":"https://submission.nature.com/new-submission/42114/3","title":"Advanced Composites and Hybrid Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"crystal size, conduction band, Fermi level, heterojunction, S-scheme photocatalysts","lastPublishedDoi":"10.21203/rs.3.rs-9439402/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9439402/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePrecise control over interfacial energetics through nanoscale component engineering remains a key challenge in designing efficient heterojunction photocatalysts. This work demonstrates that the Fermi-level position of Cu\u003csub\u003e2\u003c/sub\u003eO\u0026mdash;and consequently the interfacial electronic structure of Cu\u003csub\u003e2\u003c/sub\u003eO/TiO\u003csub\u003e2\u003c/sub\u003e S-scheme heterojunctions\u0026mdash;can be directly tuned by varying Cu\u003csub\u003e2\u003c/sub\u003eO crystal size (edge lengths: 30, 55, and 315 nm). With a fixed 1 wt% loading, the heterojunction constructed from the smallest nanocubes (CT-30) achieves superior BTX oxidation efficiencies: 84.3% for benzene, 98.2% for toluene, and 94.1% for xylene, significantly outperforming pure TiO\u003csub\u003e2\u003c/sub\u003e, Cu\u003csub\u003e2\u003c/sub\u003eO, and the large-cube composite (CT-315). For toluene, this performance corresponds to an apparent quantum yield of 3.2% and a reaction rate of 6.04 \u0026micro;mol g⁻\u003csup\u003e1\u003c/sup\u003e h⁻\u003csup\u003e1\u003c/sup\u003e. Detailed electronic characterization shows that smaller Cu\u003csub\u003e2\u003c/sub\u003eO nanocubes have a more negative conduction band, enlarging the Fermi-level offset (ΔE\u003csub\u003eF\u003c/sub\u003e) with TiO\u003csub\u003e2\u003c/sub\u003e. This strengthens the interfacial electric field, forming an efficient S-scheme photocatalysts that separates and preserves high-energy carriers. The retained electrons at the Cu\u003csub\u003e2\u003c/sub\u003eO conduction band (\u0026ndash;0.79 V) drive abundant \u0026bull;O\u003csub\u003e2\u003c/sub\u003e⁻/\u0026bull;OH generation, leading to complete BTX mineralization via intermediates to CO\u003csub\u003e2\u003c/sub\u003e/H\u003csub\u003e2\u003c/sub\u003eO. This work establishes size-mediated Fermi-level engineering as a key design principle for high-efficiency S-scheme photocatalysts.\u003c/p\u003e","manuscriptTitle":"Nanocube-size-dependent Fermi level positioning in Cu 2 O/TiO 2 S-scheme heterojunctions for optimized VOC photodegradation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-14 10:01:27","doi":"10.21203/rs.3.rs-9439402/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-16T16:39:30+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-15T19:57:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"291149486396445534033821949931086923505","date":"2026-05-14T14:07:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"271204946357829924618023957492800272985","date":"2026-05-08T03:30:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"9659408771326849071386552402168476001","date":"2026-05-06T14:23:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"36778755815287621064438556594039953322","date":"2026-05-06T08:48:33+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-05-06T03:19:33+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-17T10:52:10+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-17T10:24:51+00:00","index":"","fulltext":""},{"type":"submitted","content":"Advanced Composites and Hybrid Materials","date":"2026-04-16T14:07:51+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"advanced-composites-and-hybrid-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"achm","sideBox":"Learn more about [Advanced Composites and Hybrid Materials](https://link.springer.com/journal/42114)","snPcode":"42114","submissionUrl":"https://submission.nature.com/new-submission/42114/3","title":"Advanced Composites and Hybrid Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"be7d2474-821b-448c-b27a-2d47611c4452","owner":[],"postedDate":"May 14th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-16T16:39:30+00:00","index":14,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-15T19:57:18+00:00","index":13,"fulltext":""},{"type":"reviewerAgreed","content":"291149486396445534033821949931086923505","date":"2026-05-14T14:07:55+00:00","index":12,"fulltext":""},{"type":"reviewerAgreed","content":"271204946357829924618023957492800272985","date":"2026-05-08T03:30:12+00:00","index":11,"fulltext":""},{"type":"reviewerAgreed","content":"9659408771326849071386552402168476001","date":"2026-05-06T14:23:53+00:00","index":10,"fulltext":""},{"type":"reviewerAgreed","content":"36778755815287621064438556594039953322","date":"2026-05-06T08:48:33+00:00","index":9,"fulltext":""},{"type":"reviewersInvited","content":"5","date":"2026-05-06T03:19:33+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-14T10:01:28+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-14 10:01:27","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9439402","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9439402","identity":"rs-9439402","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}