Ternary-structured graphite carbon nitride quantum dots/TiO2 nanotubes/3D SiO2 photonic crystals for enhanced dye photodegradation

Abstract

A ternary-structured photocatalyst of graphite carbon nitride quantum dot sensitized TiO₂ nanotubes (g-CNQDs/TNTs) on SiO₂ photonic crystals (PCs) was fabricated successfully to achieve higher photodegradation efficiency of dyes in wastewater. Hydrothermal compositing conditions of g-CNQDs/TNTs were optimized to be 160 °C for 20 h and with a loading ratio of 1 : 8 of g-CNQDs to TNTs. In addition, the effect of the photonic bandgap (PBG) of PCs on the photocatalytic activity was investigated. When the PBG of PCs was located near the absorption peak of g-CNQDs at 464 nm, the photodegradation performance of g-CNQDs/TNTs and g-CNQDs/TNTs/PCs was 2.14 times and 3.76 times higher than that of pristine TNTs, respectively. The synergistic effect of quantum dots and PCs contributes to suppressing the recombination of photo-generated carriers and enhancing light harvesting. This work provides a pathway for efficient pollutant degradation on multi-synergistic photocatalysts by constructing a ternary-structure.