Enhanced electrochemical capacitance of titanium oxide nanoparticles using low-energy nitrogen ion irradiation

Abstract

In this study, we report a method for enhancing the charge storage capacity by attaching titanium oxide nanoparticles using an ion beam, stimulating the formation of surface imperfections. We synthesized titanium dioxide nanoparticles, using the planetary ball milling process, which were then coated onto a silicon substrate via the spin-coating technique. We then exposed the nanoparticles to different levels of ion fluence in a low-energy N⁺ ion beam with an energy of 5 keV. The samples containing pristine TiO₂ nanoparticles exhibited a specific capacitance of 3.5 F g⁻¹ when the current was normalized to 10 A g⁻¹. In contrast, the irradiated TiO₂ nanoparticles showed a specific capacitance of 5 F g⁻¹. The extensive empirical findings provide valuable insights into the enhanced ability of irradiated nanoparticles to retain electric charge. The irradiation sample maintained 90% of its capacitance after over 5000 measurement cycles. When exposed to high fluences of irradiation, the nanoparticles became fused at precise junction points, leading to the creation of tiny clusters. The increased ability to store electric charge observed in the irradiated samples can be attributed to different causes such as the creation of oxygen vacancies and the enlargement of the surface area as supported by TRI3DYN simulations.