AgBr nanoparticle surface modified SnO₂ enhanced visible light catalytic performance: characterization, mechanism and...

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Developing efficient photocatalysts is crucial for addressing water pollution.
• Metal halide composites offer promising avenues for enhanced photocatalytic degradation.
• Tin oxide (SnO2) and silver bromide (AgBr) are key components in advanced oxidation processes.

Purpose of the Study:

• To synthesize and characterize SnO2-AgBr composites using a facile hydrothermal and in situ precipitation method.
• To evaluate the photocatalytic efficiency of the synthesized composites for the degradation of simulated organic wastewater.
• To elucidate the underlying Z-scheme mechanism and active species involved in the photocatalytic process.

Main Methods:

• Hydrothermal procedure and in situ precipitation for SnO2-AgBr composite synthesis.
• Characterization using techniques to assess dispersion, crystallinity, and purity.
• Photocatalytic degradation experiments with methyl orange (MO) and methylene blue (MG) under simulated conditions.
• First-order kinetic modeling and free radical trapping experiments to determine reaction kinetics and active species.

Main Results:

• SnO2-AgBr composites exhibited excellent dispersion, crystallinity, and purity.
• The SnO2-AgBr (1:1) composite showed the highest photocatalytic performance, degrading 96.71% of MO and 93.36% of MG in 150 minutes.
• Degradation efficiency increased with catalyst dosage, while humic acid showed varied effects; the composite demonstrated good pH stability.
• Hydroxyl radicals (·OH) and superoxide radicals (·O2⁻) were identified as primary active species, with holes (h⁺) as secondary.

Conclusions:

• The synthesized SnO2-AgBr (1:1) composite is a highly effective photocatalyst for organic wastewater treatment.
• A Z-scheme mechanism governs the photocatalytic activity, enhancing charge separation and utilization.
• This study provides novel insights into Z-scheme mechanisms and offers new strategies for photocatalysis in water pollution control.