An interfacial carbonization strategy was rationally designed to synthesize ultrathin 2D carbon nanosheets with uniformly dispersed Fe dopants, using FeCl3 and oleic acid as precursors. The resulting FeCl3@C achieves an outstanding perfluorooctanoic acid (PFOA) adsorption capacity of 695.23 mg g-1 and exceptionally rapid kinetics of 7148.30 g mg-1 h-1.