title: Modulation of Crystal Surface and Lattice by Doping: Achieving Ultrafast Metal-Ion Insertion in Anatase TiO2.
abstract: We report that an ultrafast kinetics of reversible metal-ion insertion can be realized in anatase titanium dioxide (TiO2). Niobium ions (Nb5+) were carefully chosen to dope and drive anatase TiO2into very thin nanosheets standing perpendicularly onto transparent conductive electrode (TCE) and simultaneously construct TiO2with an ion-conducting surface together with expanded ion diffusion channels, which enabled ultrafast metal ions to diffuse across the electrolyte/solid interface and into the bulk of TiO2. To demonstrate the superior metal-ion insertion rate, the electrochromic features induced by ion intercalation were examined, which exhibited the best color switching speed of 4.82 s for coloration and 0.91 s for bleaching among all reported nanosized TiO2devices. When performed as the anode for the secondary battery, the modified TiO2was capable to deliver a highly reversible capacity of 61.2 mAh/g at an ultrahigh specific current rate of 60 C (10.2 A/g). This fast metal-ion insertion behavior was systematically investigated by the well-controlled electrochemical approaches, which quantitatively revealed both the enhanced surface kinetics and bulk ion diffusion rate. Our study could provide a facile methodology to modulate the ion diffusion kinetics for metal oxides.
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University , Block N1.2, 62 Nanyang Drive, Singapore 637459, Singapore.
authors.forename: Hsin-Yi
authors.initials: HY
authors.lastname: Wang
authors.affiliation: TUM CREATE , 1 CREATE Way, #10-02 CREATE Tower, Singapore 138602, Singapore.
authors.forename: Han-Yi
authors.initials: HY
authors.lastname: Chen
authors.affiliation: National Synchrotron Radiation Research Center , Hsinchu 300, Taiwan, Republic of China.
authors.forename: Ying-Ya
authors.initials: YY
authors.lastname: Hsu
authors.affiliation: School of Chemistry, Faculty of Science, Agriculture and Engineering, Bedson Building, Newcastle University , Newcastle upon Tyne NE1 7RU, United Kingdom.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Stimming
authors.affiliation: Department of Chemisty, National Taiwan University , Taipei 106, Taiwan, Republic of China.
authors.forename: Hao Ming
authors.initials: HM
authors.lastname: Chen
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University , Block N1.2, 62 Nanyang Drive, Singapore 637459, Singapore.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
keywords: TiO2 nanosheets; doping modulation; lattice expansion; metal-ion diffusion; surface kinetics