<p>The introduction of metal single atoms (SAs) into semiconductors can effectively optimize their electronic configuration and enhance their photocatalytic properties. Therefore, it is crucial to clarify the corresponding principles and photocatalytic mechanisms for efficient and sustainable photocatalytic water remediation systems. Herein, a promising Fe single-atom photocatalyst (Fe_SA-CN) is obtained by anchoring Fe SAs in graphitic carbon nitride using a simple calcination strategy. Characterization and experimental results indicate that the modification of Fe SAs not only introduces a doping energy level, but also changes the valence band position, which expands the light absorption range, enhances the reduction ability of photogenerated electrons, and improves the separation and transfer of photogenerated charge carriers. Subsequently, contaminants adsorbed on the Fe_SA-CN surface trigger their oxidation removal by h⁺, and the H₂O₂ generated via two-electron direct reductions is converted in situ into ·OH by self-Fenton reaction for the synergistic contaminant degradation. In summary, Fe_SA-CN offers a promising pathway for single-atom photocatalysts in water remediation because of outstanding contamination removal efficiency, adaptability, and stability.</p> Graphical abstract <p></p>