Unraveling the generation mechanism of singlet oxygen in Bi2WxMo1-xO6 solid solution and roles in photocatalytic degradation of gaseous toluene under visible-light irradiation

Photocatalytic degradation volatile organic compounds (VOCs) represent an appealing strategy since the inexhaustible solar energy and facile reaction condition. In this work, a flower-like microsphere Bi 2 W x Mo 1-x O 6 solid solution photocatalysts with abundant oxygen vacancies (OVs) were prepared via HTAB-assisted hydrothermal method. The mole ratio of W and Mo atoms were regulated by adjusting the stoichiometric ratio of their precursor. The optimized Bi 2 W 0.25 Mo 0.75 O 6 presented outstanding photocatalytic performance with 96.8% of toluene degradation rate after 180 min of irradiation under visible light (>420 nm), which was 13.76 times higher than that of pure Bi 2 MoO 6 and 10.32 times higher than that of pure Bi 2 WO 6 , respectively. The enhanced photocatalytic activity of Bi 2 W 0.25 Mo 0.75 O 6 was attributed to the optimized band structure and efficient separation efficiency of carriers as well as the participation of singlet oxygen ( 1 O 2 ) radicals. Free radical trap experiments and electron spin resonance investigations revealed that 1 O 2 , hydroxyl radical, and holes were the predominated reactive oxygen species (ROSs) in toluene degradation. Meanwhile, the generation of 1 O 2 was related to abundant OVs of Bi 2 W 0.25 Mo 0.75 O 6 solid solution. This work suggested that solid solution with abundant OVs was an effective photocatalyst to improve the VOCs degradation activity under visible-light irradiation.