Role of oxygen vacancy ordering and channel formation in tuning intercalation pseudocapacitance in Mo single-ion-implanted CeO2–x nanoflakes

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dc.contributor.authorZheng, XRen_AU
dc.contributor.authorMofarah, SSen_AU
dc.contributor.authorCen, Aen_AU
dc.contributor.authorCazorla, Cen_AU
dc.contributor.authorHaque, Een_AU
dc.contributor.authorChen, EYen_AU
dc.contributor.authorAtanacio, AJen_AU
dc.contributor.authorManohar, Men_AU
dc.contributor.authorVutukuri, Cen_AU
dc.contributor.authorAbraham, JLen_AU
dc.contributor.authorKoshy, Pen_AU
dc.contributor.authorSorrell, CCen_AU
dc.date.accessioned2022-05-05T06:56:28Zen_AU
dc.date.available2022-05-05T06:56:28Zen_AU
dc.date.issued2021-12-07en_AU
dc.date.statistics2022-04-20en_AU
dc.description.abstractMetal oxide pseudocapacitors are limited by low electrical and ionic conductivities. The present work integrates defect engineering and architectural design to exhibit, for the first time, intercalation pseudocapacitance in CeO2–x. An engineered chronoamperometric electrochemical deposition is used to synthesize 2D CeO2–x nanoflakes as thin as ∼12 nm. Through simultaneous regulation of intrinsic and extrinsic defect concentrations, charge transfer and charge–discharge kinetics with redox and intercalation capacitances together are optimized, where reduction increases the gravimetric capacitance by 77% to 583 F g–1, exceeding the theoretical capacitance (562 F g–1). Mo ion implantation and reduction processes increase the specific capacitance by 133%, while the capacitance retention increases from 89 to 95%. The role of ion-implanted Mo6+ is critical through its interstitial solid solubility, which is not to alter the energy band diagram but to facilitate the generation of electrons and to establish the midgap states for color centers, which facilitate electron transfer across the band gap, thus enhancing n-type semiconductivity. Critically, density functional theory simulations reveal, for the first time, that the reduction causes the formation of ordered oxygen vacancies that provide an atomic channel for ion intercalation. These channels enable intercalation pseudocapacitance but also increase electrical and ionic conductivities. In addition, the associated increased active site density enhances the redox such that the 10% of the Ce3+ available for redox (surface only) increases to 35% by oxygen vacancy channels. These findings are critical for any oxide system used for energy storage systems, as they offer both architectural design and structural engineering of materials to maximize the capacitance performance by achieving accumulative surface redox and intercalation-based redox reactions during the charge/discharge process. © 2021 American Chemical Societyen_AU
dc.description.sponsorshipAustralian Research Council (ARC Grant DP170104130)en_AU
dc.identifier.citationZheng, X., Mofarah, S. S., Cen, A., Cazorla, C., Haque, E., Chen, E. Y., Atanacio, A. J., Manohar, M., Vutukuri, C., Abraham, J. L., Koshy, P., & Sorrell, C. C. (2021). Role of oxygen vacancy ordering and channel formation in tuning intercalation pseudocapacitance in Mo single-ion-implanted CeO2–x nanoflakes. ACS Applied Materials & Interfaces, 13(50), 59820-59833. doi:10.1021/acsami.1c14484en_AU
dc.identifier.issn1944-8252en_AU
dc.identifier.issue50en_AU
dc.identifier.journaltitleACS Applied Materials & Interfacesen_AU
dc.identifier.pagination59820-59833en_AU
dc.identifier.urihttps://doi.org/10.1021/acsami.1c14484en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/13121en_AU
dc.identifier.volume13en_AU
dc.language.isoenen_AU
dc.publisherAmerican Chemical Societyen_AU
dc.subjectOxygenen_AU
dc.subjectDefectsen_AU
dc.subjectAtmospheric chemistryen_AU
dc.subjectSolidsen_AU
dc.subjectRedox reactionsen_AU
dc.subjectIon implantationen_AU
dc.subjectVacanciesen_AU
dc.titleRole of oxygen vacancy ordering and channel formation in tuning intercalation pseudocapacitance in Mo single-ion-implanted CeO2–x nanoflakesen_AU
dc.typeJournal Articleen_AU
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