More reactive oxygen species generation facilitated by highly dispersed bimodal gold nanoparticle on the surface of Bi2WO6 for enhanced photocatalytic degradation of ofloxacin in water

An essential strategy to eliminate emerging contamination in water is to initiate more reactive oxygen species (ROS) in the catalytic systems. 0.14 wt.% Au loaded Bi2WO6 (Bi2WO6/Au-400 degrees C) was fabricated after 400 degrees C annealing with the assistance of glutathione for Au atom anchoring and stabilization on Bi2WO6 surface. Bimodal Au size distribution of highly dispersed small size clusters (0.5 +/- 0.1 nm) and large size nanoparticles (6.3 +/- 1.0 nm) simultaneously existed on Bi2WO6 nanosheets in Bi2WO6/Au400 degrees C, which were verified through high resolution transmission electron microscopy (HR-TEM). 95% of ofloxacin (OFX) was degraded over Bi2WO6/Au-400 degrees C in 180 min under visible light irradiation with a reaction constant of 24.5 x 10(-3) min(-1), which showed 3.0 and 2.5-fold enhancement compared with bare Bi2WO6 and unimodal Bi2WO6/Au-500 degrees C (annealed at 500 degrees C, Au NPs (8.6 +/- 1.0 nm)), respectively. The enhanced catalytic activity originated from the additional ROS production that initiated by photoinduced electron transported from small Au clusters to large Au NPs through the conduction band of Bi2WO6. Moreover, it still maintained a good stability after five cycling performance and the total cost of 10 g Bi2WO6/Au-400 degrees C was estimated to be 6.78 $. Lower-content of bimodal Au NPs decorated Bi2WO6 catalyst possesses high efficiency to degrade pollutant and lower cost, which provides a promising alternative in practical environmental remediation by photocatalysis. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The Bi2WO6/Au-400 degrees C catalyst, with a bimodal distribution of small size clusters and large nanoparticles, showed a significantly enhanced catalytic activity in degrading OFX under visible light irradiation. This enhancement was attributed to the additional ROS production initiated by photoinduced electron transfer between small Au clusters and large Au NPs. Moreover, the catalyst demonstrated good stability after repeated cycling tests and a relatively low total cost, making it a promising alternative for practical environmental remediation through photocatalysis.