Enhancement of Electron Transfer Between Fe/Mn Promotes Efficient Activation of Peroxomonosulfate by FeMn-NBC

Bimetallic catalysts can effectively enhance the catalytic degradation efficiency of peroxymonosulfate (PMS), which is usually attributed to the enhancement of electron transfer, but currently, there is no clear explanation of the mechanism of how the electron transfer is enhanced. A nitrogen-doped Fe/Mn composite biochar (FeMn-NBC) was co-constructed by hydrothermal synthesis and high-temperature calcination. The FeMn-NBC activated PMS more efficiently than the monometallic one due to the enhanced electron transfer between Fe and Mn. The FeMn-NBC/PMS system activated PMS with Mn as the active center, and the high oxidation state of Mn4+promoted the acceleration of the PMS adsorption of the generation of Mn2+/Mn3+. This gaining effect accelerated the electron cycling between Fe2+/Fe3+and Mn2+/Mn3+/Mn4+, which enhanced the PMS catalysis to generate free radicals (•OH, SO4•−and •O2−) and non-radicals (1O2) for the efficient degradation of diisobutyl phthalate (DIBP). Benefiting from this gaining effect, the degradation rate of DIBP by the FeMn-NBC/PMS system was increased by 2.43 and 3.38 times compared to Fe-NBC and Mn-NBC. The bimetallic-enhanced electron transfer mechanism proposed in this study facilitated the development of efficient catalysts for more efficient and selective removal of organic pollutants.