FeNi3–FeNi3N – a high-performance catalyst for overall water splitting

The design and development of non-precious metal catalysts with high activity and stability for overall water splitting remains a major challenge. Herein, lamellar FeNi3N incorporated by FeNi3 is synthesized via thermal ammonolysis. The abundance of hollow sites in this FeNi3–FeNi3N heterostructure significantly enhances the intrinsic activity towards hydrogen evolution reaction, while the heterostructure also offers high electrochemical active surface area for oxygen evolution reaction. FeNi3–FeNi3N enables a lower overpotential for both hydrogen and oxygen evolution electrocatalysis in alkaline media. When FeNi3–FeNi3N is employed as a bifunctional material for overall water splitting, it shows a cell voltage of only 1.5 V at 10 mA cm−2 and offers stable performance for up to 48 h at current densities of ∼40 mA cm−2.