Characteristics of Titanate Nanotube and the States of the Confined Sodium Ions

Abstract

The titanate nanotubes (TNTs) prepared by the reaction of titanium dioxide (TiO2) with NaOH were treated with acid (HNO3) solutions of various concentrations and/or heat treated at different temperatures. The properties of the treated TNTs were investigated in relation to the photocatalytic activities. The state and the role of Na ions confined in the TNTs were analyzed by means of 23Na and 1H NMR spectroscopy. It was revealed that there exist two states of Na ions, i.e. strongly and weakly interacting with the TNT system. The Na ions strongly bound to the interlayer of TNT play an important role to stabilize the tube structure. On the other hand, Na ions weakly interacting with the surface of the TNT suppress the photocatalytic activity but can be easily removed by a weak acid treatment with 50 mM HNO3 solution to lead the optimum photocatalytic activity. In addition, the Na ions on the surface of the TNT interfere with the crystalline transition to anatase on calcinations. Although the photocatalytic activity of TNT has been believed to be lower than that of conventional TiO2 photocatalysts of nanoparticles, it was also found that TNT showed specifically high photocatalytic activities, even higher than P25 TiO2 (Degussa P25), for some cationic reactant such as trimethylamine.

Influence of solution chemistry on the removal of Ni(II) from aqueous solution to titanate nanotubes

“…Since the innovative work of Kasuga et al [9][10][11], titanate nanotubes (TNTs) have been of particular research interest for their potential application as hydrogen sensors, catalyst supports, ionexchange materials and superior sorbents due to their fascinating microstructures and excellent physicochemical properties [12]. In the past few years, various investigations have been conducted to study the adsorption potential of TNTs towards the removal of gas [13], organic dyes [14][15][16][17], Ag(I) [18], Pb(II) [18][19][20], Cu(II) [18,21] and As(V) [22].…”

First-principle calculations for electronic structure and bonding properties in layered Na2Ti3O7

“…In recent years, sodium trititanate (Na 2 Ti 3 O 7 ) has received considerable attention due to its potential technological applications in various fields such as ion exchangers [1], photocatalysts [1][2][3][4], electrodes for secondary batteries [5], bioactive ceramics [6] and sensors [7]. Generally, it can * E-mail: junshen@hit.edu.cn be synthesized by solid state reactions [8] from TiO 2 and Na 2 CO 3 or by sol-gel methods [9].…”

Low-temperature CO2 adsorption on alkali metal titanate nanotubes

“…Compared to K-Ti-NT, its Na analog showed higher adsorption capacity. The role of Na ions in Na-Ti-NT was investigated by Suetake et al (2008). There exist two states of Na ion in the Na-Ti-NT, strongly and weakly interacting with the titania nano tube (TNT) system (Suetake et al, 2008).…”

“…The role of Na ions in Na-Ti-NT was investigated by Suetake et al (2008). There exist two states of Na ion in the Na-Ti-NT, strongly and weakly interacting with the titania nano tube (TNT) system (Suetake et al, 2008). The Na ions that are strongly bound to the TNT interlayer play an important role in stabilizing the tube structure.…”