Novel crystalline/amorphous heterophase Fe-Mn core-shell chains on-site generate hydrogen peroxide in aqueous solution

Hydrogen peroxide (H₂O₂) is a crucial eco-friendly oxidizer with increasing demand due to its wide range of applications. Activating O₂ with catalysts to generate H₂O₂ on-site offers a promising alternative to traditional production methods. Here, we design unique crystalline/amorphous heterophase Fe-Mn core-shell chains (ZVI-Mn) for efficient on-site generation of H₂O₂ and manipulation of subsequent H₂O₂ activation. The yield of H₂O₂ on-site produced by ZVI-Mn in water within 5 min was 103.7 mg·L^-1, which was much greater than that of zero-valent iron (ZVI) and amorphous Mn (A-Mn) (0 and 42.5 mg·L^-1). Raman and density functional theory (DFT) calculations confirmed that *OOH is the key species involved in the on-site generation of H₂O₂. Electrochemical tests confirmed the excellent electron-transferring ability, while electron paramagnetic resonance (EPR) revealed oxygen vacancy defects in the catalysts, which proved to be conducive to improving the catalytic activity of ZVI-Mn. Additionally, by regulating the pH of aqueous solution, ZVI-Mn can simultaneously achieve efficient on-site generation of H₂O₂ and in-situ removal of enrofloxacin from aqueous solution.