Modified hydrothermal method for synthesizing titanium dioxide-decorated multiwalled carbon nanotube nanocomposites for the solar-driven photocatalytic degradation of dyes

Abstract

This study aimed to address the issue of rapid electron–hole recombination in photocatalysis by exploiting multi-phase TiO₂ decorated on multiwalled carbon nanotubes (MWCNTs) to improve the photocatalytic degradation of dyes. A simple and eco-friendly one-pot method was utilized to create the TiO₂/MWCNT nanostructure using glucose as both a structure-directing agent and a carbon source without requiring any prior covalent or non-covalent functionalization of the MWCNTs at 160 °C. Furthermore, it was found that the average width of the nanocomposites changed from 20 ± 1 and 42 ± 2 nm to 56 ± 3 nm, corresponding to MWCNT contents of 1.0, 2.0, and 3.0 (wt%), respectively. Specifically, TiO₂/MWCNTs with a low content of MWCNTs demonstrated enhanced performance for the photocatalytic degradation of dyes, with the bandgap of the nanocomposites decreasing to 2.5 eV with 1.0% MWCNTs and 2.4 eV with 2.0% MWCNTs. The TiO₂/MWCNT-1.0 catalyst demonstrated high photocatalytic efficiency for methylene blue (MB) degradation with a rate constant of 0.0051 min⁻¹. TiO₂/MWCNT-2.0 was more effective for rhodamine (RhB) degradation than pristine TiO₂, with a rate constant of 0.0065 min⁻¹ within 120 min of solar-light exposure. This novel modified approach can be used to synthesize nanocomposites simply and is potentially feasible for efficient dye degradation and beyond, offering a promising solution for water-pollution treatment.