Heterostructure Co2N-Ni3N/NF nanoarrays synthesized by in situ nitriding treatment for high‑performance supercapacitor

Transitional metal nitrides (TMNs) are regarded as comparatively promising electrode materials for supercapacitor due to the high electronic conductivity, good corrosion resistance and special electron structure. Herein, in this work a heterostructure Co 2 N-Ni 3 N nanosheets-nanowires arrays grown on Ni foam (NF) are designed and synthesized by a simple hydrothermal reaction and nitriding treatment. The prepared Co 2 N-Ni 3 N/NF nanoarrays has a high electrical conductivity, abundant surface active sites, charge transfer channels and the synergy effect between each component, which makes it exhibit outstanding electrochemical performance. Electrochemical test results revealed that the areal capacitance of Co 2 N-Ni 3 N/NF was 2.17 F cm −2 at 1 mA cm −2 using a three-electrode system in 1 M KOH. Meanwhile, when the current density increases to 20 mA cm −2 , it can still retain 62.21% of the original capacitance, suggesting a good rate capability. In addition, in two-electrode test with Co 2 N-Ni 3 N/NF as the positive electrode and activated carbon as the negative electrode, a maximum energy density of 145.65 μWh cm −2 is shown when the power density is 0.75 mW cm −2 . And it has 85.90% capacitance retention after 5000 cycles. • Unique Co 2 N-Ni 3 N nanoarray heterostructure was successfully synthesized. • Co 2 N-Ni 3 N/NF achieves an areal capacitance 2.17 F cm -2 at current density of 1 mA cm -2 . • The Co 2 N-Ni 3 N/NF // AC exhibits good electrochemical performance in two-electrode tests.