Two-dimension on two-dimension growth: hierarchical Ni 0.2 Mo 0.8 N/Fe-doped Ni 3 N 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 Ni 0.2 Mo 0.8 N nanosheets on Fe-doped Ni 3 N nanosheets supported on Ni foam (Ni 0.2 Mo 0.8 N/Fe-Ni 3 N/NF) via hydrothermal reaction and nitridation treatment. In the hierarchical structures, small Ni 0.2 Mo 0.8 N nanosheets were uniformly anchored on Fe-Ni 3 N nanosheets. Due to enhanced electron transfer between Ni 0.2 Mo 0.8 N and Fe-Ni 3 N, Ni 0.2 Mo 0.8 N/Fe-Ni 3 N/NF exhibits superior electrocatalytic activity for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). After stability tests for 50 h, Ni 0.2 Mo 0.8 N/Fe-Ni 3 N/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, Ni 0.2 Mo 0.8 N/Fe-Ni 3 N/NF display a cell voltage of 1.54 V (10 mA cm -2 ) for electrocatalytic overall water splitting.