Enhancement of iron cycling in Fenton-like catalysis by MoO2-C: Carbon-mediated efficient electron transport

In this study, the charge transfer capability of MoO2 materials was significantly improved by introducing carbon materials in situ. The resulting MoO2-C material could accelerate the Fe(III)/Fe(II) redox cycle and promote the continuous generation of reactive oxygen species in Fenton-like system. The results suggested that MoO2-C exhibited significant co-catalytic activity against a variety of pollutants. Meanwhile, the mechanisms behind the Fe(III)/Fe(II) cycle and reactive oxygen species generation were clarified. Analysis indicated that the incorporation of carbon material provided a reduction active site for the reduction of Fe(III) to Fe(II) on the surface of molybdenum oxide, and also reduced the thermodynamic energy barrier associated with Fe(III) reduction. Furthermore, quenching experiments and electron paramagnetic resonance (EPR) technology demonstrated that hydroxyl radicals (∙OH) and singlet oxygen (1O2) rapidly degrade the target pollutants. Fe(II) was verified as the primary component responsible for peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation. Additionally, the main generation pathway for 1O2 differed between the MoO2-C/Fe(III)/PDS and MoO2-C/Fe(III)/PMS systems. This study provides a new strategy to improve the iron reduction properties of metal oxide materials.