Regulating band structure, charge transfer and separation, oxygen adsorption and activation by surface ion...

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Photocatalytic efficiency enhancement is crucial for environmental applications.
• Bismuth oxycarbonate (BOC) nanotubes show promise but require improved performance.
• Surface modification strategies are explored to boost photocatalytic activity.

Purpose of the Study:

• To investigate the effect of surface halogenation (Cl and I) on BOC nanotubes.
• To enhance the photocatalytic efficiency of BOC nanotubes for pollutant degradation.
• To understand the mechanism behind the improved photocatalytic activity.

Main Methods:

• Synthesis of BOC nanotubes modified with Cl and I via hydrothermal treatment.
• Characterization using X-ray diffraction (XRD), EDX, and X-ray photoelectron spectroscopy (XPS).
• Density functional theory (DFT) calculations to analyze electronic structure and surface properties.
• Photocatalytic degradation experiments using rhodamine B (RhB) under UV irradiation.

Main Results:

• Cl and I chemically adsorb onto the BOC surface without lattice doping.
• Surface modification slightly broadens light absorption and significantly enhances photoelectron migration and carrier separation.
• DFT calculations confirm adjusted band structure and surface charge distribution favoring O2 adsorption and electron trapping.
• Degradation ratios of RhB over 150-Cl-BOC (94%) and 150-I-BOC (85%) were 4.2 and 3.7 times higher than pristine BOC (18%).

Conclusions:

• Surface halogenation of BOC nanotubes is an effective strategy to improve photocatalytic activity.
• Enhanced activity is attributed to improved carrier separation and formation of reactive oxygen species (•O2−).
• This simple modification offers a promising route for developing advanced environmental photocatalysts.