Influence of the sodium/proton replacement on the structural, morphological and photocatalytic properties of titanate nanotubes

TL;DR

This study investigates how sodium/proton exchange affects the structure, optical properties, and photocatalytic efficiency of titanate nanotubes, revealing that protonated forms exhibit enhanced photocatalytic activity despite lower dye adsorption.

Contribution

It provides a detailed analysis of how sodium/proton replacement alters titanate nanotubes' properties and their photocatalytic performance, introducing a controllable synthesis method and comparative insights.

Findings

Protonated nanotubes have a lower band gap (~2.81 eV) than sodium-rich ones (~3.27 eV).

Protonated nanotubes show superior photocatalytic degradation of rhodamine 6G.

Sodium content influences optical behavior and dye adsorption capacity.

Abstract

Titanate nanotubes (TNT) with different sodium contents have been synthesised using a hydrothermal approach and a swift and highly controllable post-washing processes. The influence of the sodium/proton replacement on the structural and morphological characteristics of the prepared materials was analysed. Different optical behaviour was observed depending on the Na+/H+ samples' content. A band gap energy of 3.27\pm0.03 eV was estimated for the material with higher sodium content while a value of 2.81\pm0.02 eV was inferred for the most protonated material, which therefore exhibits an absorption edge in the near visible region. The point of zero charge of the materials was determined and the influence of the sodium content on the adsorption of both cationic and anionic organic dyes was studied. The photocatalytic performance of the TNT samples was evaluated in the rhodamine 6G degradation process. Best photodegradation results were obtained when using the most protonated material as catalyst, although this material has shown the lowest R6G adsorption capability.