Promoting practical photodegradation application potential of a Bi2WO6-based step-scheme heterojunction under outdoor natural sunlight irradiation

Abstract

The majority of current photodegradation experiments utilize high-energy xenon lamps as simulated sunlight, which ignores the changeable weather in nature. In this paper, we synthesize a flower-like Bi₂WO₆/CdS heterojunction via a surfactant assisted one-pot hydrothermal strategy. Owing to the suitable energy level match, an S-scheme charge transfer route is achieved in the composite, which possesses tremendous practical application potential in photocatalytic degradation. In an outdoor environment with cloudy weather, the obtained Bi₂WO₆/CdS S-scheme heterojunction exhibits superior tetracycline decomposition performance, with 67.12% degradation efficiency within 150 min, higher than those of pristine B₂WO₆ (64.15%) and CdS (19.62%). Bi₂WO₆/CdS also presents excellent photocatalytic activity in a large volume of tetracycline solution without magnetic stirring to simulate a motionless wastewater environment. After 4 cycles of the photodegradation test, little loss of tetracycline removal efficiency is observed for Bi₂WO₆/CdS, suggesting its strong durability. Moreover, the Bi₂WO₆/CdS composite also reveals favorable photodegradation ability toward various dye pollutants under real natural sunlight irradiation, with degradation efficiencies of 78.11%, 92.79%, and 95.96% for methyl orange, methylene blue, and rhodamine B after natural light irradiation for 80, 60 and 40 min, respectively. This work could provide a significant impact on the promotion of Bi₂WO₆-based photocatalysts into real-world applications of wastewater treatment.