Two-dimension on two-dimension growth: hierarchical NiMoN/Fe-doped NiN nanosheet array for overall water splitting.

Developing advanced electrocatalysts with low cost for electrocatalytic water splitting are highly desirable. Herein, we report the design of two-dimension on two-dimension growth of hierarchical NiMoN nanosheets on Fe-doped NiN nanosheets supported on Ni foam (NiMoN/Fe-NiN/NF) hydrothermal reaction and nitridation treatment. In the hierarchical structures, small NiMoN nanosheets were uniformly anchored on Fe-NiN nanosheets. Due to enhanced electron transfer between NiMoN and Fe-NiN, NiMoN/Fe-NiN/NF exhibits superior electrocatalytic activity for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). After stability tests for 50 h, NiMoN/Fe-NiN/NF exhibits negligible degradation of the current density for the OER (91% remain) and HER (95% remain), suggesting excellent stability. Owing to the outstanding performance, NiMoN/Fe-NiN/NF display a cell voltage of 1.54 V (10 mA cm) for electrocatalytic overall water splitting.