Atomically dispersed rare earth dysprosium-nitrogen-carbon for boosting oxygen reduction reaction.

Transition metal-nitrogen-carbon (MNC) based on 3d metal atoms as promising non-precious metal catalysts have been extensively exploited for oxygen reduction reaction (ORR), but MNC with 4f rare earth metals have been largely ignored, most likely due to their large atomic radii that are difficult to coordinate with N dopants using conventional precursors. Herein, atomically dispersed dysprosium-nitrogen-carbon (DyNC) nanosheets were developed via the pyrolysis of anitrogen-containing chelate compound of 2, 4, 6-Tri (2-pyridyl) 1, 3, 5-triazine (TPTZ) ligand with Dy under the assistance of molten NaCl. The as-synthesized DyNC features specific moieties of single Dy atom coordinated by N and O as active sites for ORR, displaying excellent performance. The half-wave potentials of 0.77 V and 0.88 V in acidic and alkaline media respectively are superior to those of iron-nitrogen-carbon (FeNC) synthesized using the same method. Meanwhile, a practical zinc-air battery verifies the ORR activity of DyNC with a maximum power output of 216 mW cm, which is even better than the commercial platinum on carbon catalyst (Pt/C) under the same loading.In addition, theoretical calculations verify that compared to the classic FeN4 moiety,the DyN4O1 exhibits a lower overpotential of 0.570 V, demonstrating that it possesses more significant catalytic performance for ORR. This work provides the inspiration of developing non-precious metal electrocatalysts with atomic 4f rare earth metals for ORR.