Interface electron transfer driven H₂O₂ activation over a MOF-derived Fe₃O₄-FeM/C cathode for efficient...

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 H₂O₂ 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 Fe₃O₄-FeM/C (M = Mn, Co and Ni) alloy catalysts, and their H₂O₂ 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 H₂O₂. Therefore, the Fe₃O₄-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 H₂O₂ from an electronic transfer perspective, providing theoretical guidance for the reasonable design of highly active alloy catalysts.