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Voids in walls of mesoporous TiO2 anatase nanotubes by controlled formation and annihilation of protonated titanium vacancies

Abstract

Amorphous TiO2 nanotubes (TNTs) grown anodically on Ti metal in aqueous electrolytes show a crystallization behaviour strongly dependent on the atmosphere used during annealing at high temperature. In wet oxidizing conditions, the amorphous TNTs walls transform into relatively large and well crystallized anatase-like domains permeated by prismatic voids. On the other hand, crystallization of the amorphous nanotubes under dry reducing conditions induces nanocrystalline aggregates that do not show prismatic voids and exhibit different electronic properties. Supported by density functional theory calculations, it is argued that the formation or absence of voids can be understood in terms of formation and condensation of protonated titanium vacancies. Tunable morphology through defect chemical engineering as such, enables TNTs with increased surface area and catalytic activity, which find potential application in supercapacitors, sensors, photocatalysis, photoelectrochemistry, and dye-sensitized solar cells.

Category

Academic article

Language

English

Author(s)

  • Marit Norderhaug Getz
  • Athanasios Eleftherios Chatzitakis
  • Xin Liu
  • Patricia Almeida Carvalho
  • Tor Svendsen Bjørheim
  • Truls Eivind Norby

Affiliation

  • SINTEF Industry / Sustainable Energy Technology
  • University of Oslo

Year

2020

Published in

Materials Chemistry and Physics

ISSN

0254-0584

Volume

239

View this publication at Norwegian Research Information Repository