Defect engineered nickel oxide nanorods by low energy nitrogen ion exposure for supercapacitor applications

Abstract

This work presents a comprehensive study on the enhancement of electrochemical performance in nickel oxide (NiO) nanorods via 5 keV low-energy nitrogen ion (N⁺) irradiation. The thin films of nickel oxide nanorods were irradiated at four different ion fluences of 1 × 10¹⁶, 3 × 10¹⁶, 5 × 10¹⁶ and 7 × 10¹⁶ ions cm⁻². The ion irradiation induces surface modifications, including the formation of defects and oxygen vacancies, which significantly improve the nanorods’ surface activity and ion transport properties. Electrochemical analyses such as cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) confirm that the irradiated samples demonstrate superior specific and areal capacitance, enhanced rate capability, and improved cycling stability compared to pristine NiO. Structural and defect analyses through SRIM, IRADINA and TRI3DYN simulations further support the role of ion-induced modifications in boosting electrochemical behavior. These results highlight nitrogen ion irradiation as an effective technique for tailoring NiO nanostructures toward high-performance supercapacitor applications.