Enhanced catalytic oxidation of 2,4-dichlorophenol via singlet oxygen dominated peroxymonosulfate activation on CoOOH@Bi2O3 composite

Cobalt oxyhydroxide (CoOOH) has been turned out to be a high-efficiency catalyst for peroxymonosulfate (PMS) activation. In this study, CoOOH was loaded on bismuth oxide (Bi 2 O 3 ) using a facile chemical precipitation process to improve its catalytic activity and stability. The result showed that the catalytic performance on the 2,4-dichlorophenol (2,4-DCP) degradation was significantly enhanced with only 11 wt% Bi 2 O 3 loading. The degradation rate in the CoOOH@Bi 2 O 3 /PMS system (0.2011 min −1 ) was nearly 6.0 times higher than that in the CoOOH/PMS system (0.0337 min −1 ). Furthermore, CoOOH@Bi 2 O 3 displayed better stability with less Co ions leaching (16.4% lower than CoOOH) in the PMS system. These phenomena were attributed to the Bi 2 O 3 loading which significantly increased the conductivity and specific surface area of the CoOOH@Bi 2 O 3 composite. Faster electron transfer facilitated the redox reaction of Co (III) / Co (II) and thus was more favorable for reactive oxygen species (ROS) generation. Meanwhile, larger specific surface area furnished more active sites for PMS activation. More importantly, there were both non-radical ( 1 O 2 ) and radicals (SO 4 − •, O 2 − •, and OH•) in the CoOOH@Bi 2 O 3 /PMS system and 1 O 2 was the dominant one. In general, this study provided a simple and practical strategy to enhance the catalytic activity and stability of cobalt oxyhydroxide in the PMS system.