Construction of surface micro-electric fields on common metal Fe/Mg co-doped g-C3N4 with surface acidification for synergistic activation of peroxymonosulfate

Developing low-cost, sustainable catalysts is critical to meet the green-transition goal in water treatments. Herein, a low-cost, common metal modified g-C3N4 material (FeMg-O-g-C3N4) was designed to improve electron mobility and peroxymonosulfate (PMS) utilization. Likewise, surface acidification of g-C3N4 has introduced extra porous structure, anchor sites for metals, and activate sites. This new catalyst free of expensive rare-earth metals creates numerous surface micro-electric fields through: 1) large difference in electronegativity for Fe (1.83) and Mg (1.31); 2) cation-π effect formed between metals and benzene-like ring structure of g-C3N4; and 3) added PMS and pollutant (tetracycline (TC)) as electron provider promoting the transfer of electrons to the electron-rich Fe sites. Both non-radical (1O2) and radical (surface-bound ·OH and SO4·−) pathways contribute to the pollutant degradation. Given the promising results and stability of the catalyst, this study opens new horizons to apply common metals over expensive, toxic rare metals in PMS-based water treatments.