Interfacial Engineering of Two-Dimensional MoN/MoO 2 Heterostructure Nanosheets as a Bifunctional Electrocatalyst for Overall Water Splitting.

It is still a challenge to realize the dream of a hydrogen-based economy using a robust catalyst for overall water splitting. Here, we introduce two-dimensional MoN/MoO 2 heterostructure nanosheets using nickel foam as a substrate for water splitting. The heterojunction formation was achieved through the partial nitriding of a Mo-based precursor to MoN in the annealing process under NH 3 environment. The heterogeneous interface between MoN and MoO 2 as active sites is supposed to improve the surface reaction kinetics and electronic conductivity. Therefore, an excellent performance is achieved when MoN/MoO 2 is employed as both cathode and anode electrocatalysts; the corresponding cell voltages are 1.57 and 1.84 V at 10 and 100 mA cm -2 in 1 M KOH, respectively. The promising bifunctional catalytic performance of our catalyst opens up a new way for efficient electrochemical water splitting.