N-CQDs accelerating surface charge transfer of Bi4O5I2 hollow nanotubes with broad spectrum photocatalytic activity

Abstract

Novel N-doped carbon quantum dots (N-CQDs) modified Bi4O5I2 hollow nanotubes photocatalysts have been prepared for the first time. Bi4O5I2 nanomaterials with hollow nanotube structure were designed to shorten the charge carriers’ migration distance from bulk phase to surface while the N-CQDs was modified to accelerate the surface charge transfer. Multiple characterization methods have been applied to explore the phase structure, elemental composition, optical absorption properties and photocatalytic performance of as-prepared N-CQDs/Bi4O5I2 composites. The N-CQDs/Bi4O5I2-0.2 composite showed higher photocatalytic activity for the removal of bisphenol A than pure Bi4O5I2 hollow nanotube under UV light, visible light, light above 580 nm, which exhibited the broad spectrum photocatalytic activity. ESR analysis demonstrated the N-CQDs modification can tune the concentration of reactive oxygen species (•OH and •O2−). Combined with free radical trapping experiment results, hole, •OH and •O2− were demonstrated to be the main active species and synergistically promoted the enhancement of photocatalytic activity for N-CQDs/Bi4O5I2 composite.