Interface electron transfer driven H2O2 activation over a MOF-derived Fe3O4-FeM/C cathode for efficient electro-Fenton degradation of tetracycline

Alloy catalysts have been recognized as one of the promising methodologies to modulate the electronic structure to generate ·OH. Although various alloy catalysts play an essential role in H 2 O 2 activation, systematic investigations conducted within a unified framework remain scarce. Here, three adjacent transition metals (Mn, Co, and Ni) were employed as dopants to construct a series of Fe 3 O 4 -FeM/C (M = Mn, Co and Ni) alloy catalysts, and their H 2 O 2 activation performance and underlying catalytic mechanisms were systematically investigated. Density functional theory analysis indicated that the alloy structure can form a built-in electric field within the catalyst, which can facilitate the migration of electrons from the catalyst interior to the exterior. Meanwhile, according to the bader charge analysis, the amount of charge transferred to the carbon shell follows the order: Mn (0.36 e − ) > Co (0.19 e − ) > Ni (0.01 e − ). This trend indicated that when Mn formed an alloy with Fe, it most effectively facilitated electron migration from the internal metal sites to the external carbon shell, thereby markedly enhancing the catalytic activation of H 2 O 2 . Therefore, the Fe 3 O 4 -FeM/C exhibited superior performance compared with the other electrodes, achieving a 92.0% degradation of tetracycline within 12 min. Furthermore, electron spin resonance tests combined with probe quantification verified that transition metals incorporation enhanced the production of ·OH species, among which the Mn-doped catalyst exhibited the most significant enhancement. This study elucidates the catalytic mechanism of alloy catalysts toward H 2 O 2 from an electronic transfer perspective, providing theoretical guidance for the reasonable design of highly active alloy catalysts.