Construction of 3D CrN@nitrogen-doped carbon nanosheet arrays by reactive magnetron sputtering for the free-standing electrode of supercapacitor

Abstract

Owing to their favorable chemical stabilities and electronic conductivities, transition metal nitrides (TMNs) have been targeted as the potential electrode materials for the supercapacitors. Herein, 3D CrN@nitrogen-doped carbon nanosheet arrays (NCs) were successfully deposited on carbon paper (CP) by reactive magnetron sputtering method. The CrN@NCs@CP electrode exhibited satisfactory electrochemical properties: initially, the electrode showed a 132.1 mF cm−2 specific capacitance at 1.0 mA cm−2 current density; subsequently, the electrode demonstrated a 95.9% capacitance retention after 20 000 galvanostatic charge–discharge cycles at 5.0 mA cm−2 current density. The specific capacitance of the CrN@NCs@CP electrode was significantly higher than that of the CrN@CP electrode (4.1 mF cm−2 at 1.0 mA cm−2). Furthermore, the symmetric supercapacitor that incorporated two CrN@NCs@CP electrodes demonstrated 5.28 μWh cm−2 (2.7 Wh kg−1) energy density at 0.41 mW cm−2 power density. These findings exemplify the suitability of the 3D composite electrodes of TMNs for energy storage application.