Nano cocatalyst–catalytic system for boosting photothermal–photocatalytic water treatment enabled by visible LEDs

Abstract

Cocatalyst–catalytic system is rationally proposed in photothermal–photocatalytic water treatment. As the cocatalyst, multifunctional MoS₂ enhances the photothermal effect, pre-adsorption of pollutants, and electrochemical stimulation, while defect-rich flower-like BiOBr (FBBov) is promoted to degrade tetracycline antibiotics. Consequently, the cocatalyst-catalytic FBBov@MoS₂ (1 : 1) system achieves a rapid photothermal response and a remarkable catalytic activity under 5 W low-energy LED excitation. The tetracycline removal rate gets 72.3% via 45 min adsorption, reaching 95.9% after 90 min LED stimulation. For treating complicated river water, FBBov@MoS₂ (1 : 1) still displays excellent performance. Significantly, the application guidance of FBBov@MoS₂ (1 : 1) is proposed with statistical strategies and a “generalized equation” is developed to quantitatively evaluate the photothermal effect. Based on in situ thermal infrared imaging, electrochemical analysis, and ESR tests, the cocatalyst MoS₂ boosts the photothermal effect to accelerate photocatalysis and promotes the spatial separation of photogenerated carriers for an enhanced production of reactive oxygen species. This discovery provides a new strategy for a low-cost and energy-saving photocatalytic method to purify water.