Charge accumulation and polarization in titanium dioxide electrodes
2006 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 110, no 37, 18286-18290 p.Article in journal (Refereed) Published
Nanocrystalline TiO2 electrodes were studied spectroelectrochemically by observing the simultaneous relaxation of the current and absorbance after applying a voltage step. The absorbance behaved differently in two time regimes: (1) ionic polarization in the oxide electrode, in which charged ions, such as Ti3+ sites and/or interstitial Ti4+ sites, move in response to the applied electric field, and ( 2) the diffusion of Li+ ions into the TiO2. These two behaviors were analyzed with equivalent circuit models. Li+ ions reduce the resistance of the TiO2 by similar to 90%, increase the capacitance by similar to 350%, and decrease the inductance by similar to 30%. Voltage cycling produces a buildup of intercalated Li+ ions, lessening the electrode's response to the potential step, and causing it to become a more efficient inductor. The potential distribution in the nanoparticles is described by using a dielectric model in which roughly half the applied potential is dropped across the interface with a Li+-ion-ontaining electrolyte.
Place, publisher, year, edition, pages
2006. Vol. 110, no 37, 18286-18290 p.
IdentifiersURN: urn:nbn:se:uu:diva-155115DOI: 10.1021/jp0616664ISI: 000240496500037OAI: oai:DiVA.org:uu-155115DiVA: diva2:423932