High H 2 sensing performance in hydrogen trititanate-derived TiO 2

Abstract

Two types of H 2Ti 3O 7 powders were prepared by ion exchange and hydrothermal methods, and the H 2 sensing properties of the H 2Ti 3O 7-derived TiO 2 sensors were examined. In the ion exchange method, Na 2Ti 3O 7 was first synthesized via a solid-state reaction, and H 2Ti 3O 7 was obtained from Na +/H + exchange on Na 2Ti 3O 7. H 2Ti 3O 7 was also prepared via a hydrothermal reaction of TiO 2 powder in a NaOH solution. The morphology, size, and phase evolution of H 2Ti 3O 7 were found to be strongly dependent on the preparation methods. The TiO 2 sensors fabricated by the H 2Ti 3O 7 powders calcined at 700 °C (ion exchanged) exhibited an excellent gas response ( S = 30,000) to 1.0% H 2/N 2 at 500 °C, which was three orders of magnitude higher than that of the hydrothermally synthesized powder and commercial anatase powder even though its specific surface area was smaller. The higher H 2 gas response in the TiO 2 sensor derived from the ion exchanged H 2Ti 3O 7 is discussed in terms of the metastable β-TiO 2 and anatase phases.