In this work, nitrogen-doped carbon nanoshell structure with the encased Fe-0/Fe3C nanoparticles (Fe@NC) was synthesized with a solvent-free method via direct carbonizing the ground mixture of dicyandiamide and ferric chloride hexahydrate. The morphology, structure, and surface properties of as-synthesized Fe@NC were characterized systematically, and the removal performance of Fe@NC towards U(VI) was studied in detail. The results manifested that the Fe@NC possessed large surface area (127.0 m(2)/g) with mesoporosity and the encapsulated Fe-0/Fe3C nanoparticles were concentrated at the tip of N-doped carbon nanotubes. Moreover, the Fe@NC hybrid material exhibited the maximum removal capacities of 0.85 and 0.44 mg/m(2) at pH 4.5 and 1.5, respectively. The mechanism of U(VI) removal by the Fe@NC was attributed to the synergistic effects of adsorption via nitrogen/oxygen-containing groups and redox reaction between Fe-0/Fe2+ and U(VI). (C) 2020 Elsevier Inc. All rights reserved.