In this study, we prepared a hydrothermal carbonation carbon (HTCC) coated with Fe3C nano-catalyst (Fe/C nano-catalyst) for water decontamination. We first fabricated HTCC via a hydrothermal carbonization process with abundant Fe3+ dopants, and the subsequent calcination transformed iron species into magnetic Fe3C nanoparticles. The Fe/C nano-catalyst was employed for activating peroxymonosulfate (PMS) and degrading phenolic pollutants. The Fe3C species significantly enhanced the activity of HTCC to generate reactive species, achieving 100 % phenol degradation in 30 min. Radical capture and electrochemical tests revealed that organic pollutant was oxidized via two pathways: sulfate radical oxidation and direct electron transfer pathway over the Fe/C nano-catalyst. The findings will inspire the development of green and high-performance purification system for organic wastewater treatment.