Refractory Metal Oxide–Doped Titanate Nanotubes: Synthesis and Photocatalytic Activity under UV/Visible Light Range

Min-Sang Kim,Tohru Sekino,Hyun-Joo Choi,Se-Hoon Kim,Young-Do Kim

doi:10.3390/catal11080987

Abstract

This study synthesized refractory metal-oxide-doped titanate nanotubes (TNTs) using a hydrothermal process and investigated their photocatalytic activity under ultraviolet and visible light irradiation. Refractory metal doping ions such as Mo6+ and W6+ can be supplied from molybdenum oxide and tungsten oxide sources. The refractory metal-doped TNT may act as an electron trap or enhance the adsorption capacity, which increases the number of active sites and promotes separation efficiency.

Highlights

A photocatalyst is a substance that promotes a chemical reaction through photochemical reactions from external light energy
Among the various materials with photocatalytic properties, TiO2 is believed to be the most promising because of the (i) high photocatalytic activity stemming from its wide band gap, (ii) low cost owing to its natural abundance and nontoxicity, and (iii) long-term stability stemming from its chemical stability [5]
Without revealing the presence of any oxides; H2 Tin O2n+1 or Nax H2-x Tin O2n+1 (n = 3, 4) is known to be formed in pure titanate nanotubes (TNTs) fabricated by an alkaline hydrothermal method [15]

Summary

Introduction

A photocatalyst is a substance that promotes a chemical reaction through photochemical reactions from external light energy. Hydrothermal methods, first reported by Kasuga et al [7,14], are preferable because of their simple and cost-effective setup, environmental friendliness, and high reactivity, which are suitable for large-scale production. Despite such advantages, the practical applications of TiO2 as photocatalysts are extremely limited because of its poor absorption capability under the visible light range (>400 nm), which originates from its intrinsically large energy band gap and low quantum yield caused by the rapid recombination of photo-generated electrons and holes [21,22]. Several TiO2 modification studies have been proposed, including composites with TiO2 and other semiconductors with low band gap energy [23,24], metal-ion-doped TiO2 using transition metals [25], and non-metal-doped TiO2 [26,27]

Methods

Results

Conclusion