S-scheme photocatalyst Mo2C/α-Fe2O3 with vacant oxygen for highly efficient tetracycline degradation in peroxymonosulfate-mediated photocatalytic system

To alleviate antibiotic problems in the aqueous environment, the integrated the photocatalysis/sulfatebased catalytic systems as a promising technology has received widespread attentions. In this work, a Sscheme heterojunctions Mo2C/alpha-Fe2O3 with oxygen vacancies (OVs) were prepared through a hydrothermal method and applied for tetracycline-TC degradation in peroxymonosulfate-mediated photocatalytic system. The results indicated that the 8%-Mo2C/alpha-Fe2O3 coupled with PMS/Vis conditions (Mo/Fe-2/PMS/Vis) presented the highest degradation efficiency and excellent repeatability, which could degrade 93% tetracycline-TC in 15 min and its kinetic constant (0.1404 min(-1)) was 4.9 and 4.0 times higher than that of Mo2C/PMS/Vis (0.0289 min(-1)) and alpha-Fe2O3/PMS/Vis system (0.0348 min(-1)), respectively. Mo2C with metallic Mo-0 was proved not only to enhance the light absorption but also to accelerate charge separation/transfer. Moreover, the exposed Mo/Fe active components were beneficial for the activation of peroxymonosulfate (PMS) and the abundant OVs played an essential role in the generation of non-radical O-1(2). Radical quenching experiment revealed that the generated active species participated in TC decomposition and their relative contribution order was: h(+) > O-1(2) > SO4 center dot- > center dot O-2(-) > center dot OH. The toxicity prediction reflected that the toxicity of most of degradation intermediates was lower than that of TC. Additionally, the underlying catalytic mechanism of this joint system and the TC degradation pathways were clarified in detail. This study demonstrates that constructing an integrated photocatlysis/sulfate-based catalytic system for water remediation is a feasible technology. (c) 2023 Elsevier B.V. All rights reserved.