Enhancement of the electrochemical performance of Ni₃S₂-ZnS/carbon-coated TiN nanotube arrays through Au-ion beam sputtering

In this study, Au nanoparticles coating Ni₃S₂-ZnS/carbon-coated TiN nanotube arrays (Au@Ni₃S₂-ZnS/C-TiN NTAs) were fabricated through the controlled electrodeposition of vertical ZnS nanosheets and an ultra-thin Ni₃S₂ nanosheet layer onto the C-TiN NTAs of 3-dimensional bracket structure of C-TiN NTAs. Subsequently, Au nanoparticles were sputtered onto this structure. This careful structure design endowed the Au@Ni₃S₂-ZnS/C-TiN NTAs composite materials with additional active sites and improved capacitance and cycling stability properties. The Au nanoparticle coating led to an increase in sulfur vacancies, enhancing the accessibility and adsorption of OH⁻ ions, thus improving ions and electrons transport properties and consequently enhancing capacitive properties of the material. The cyclic stability of the Ni₃S₂-ZnS/C-TiN NTAs was substantially improved through performing Au-ion beam sputtering on its surface. Additionally, an aqueous asymmetric supercapacitor was assembled using an Au@Ni₃S₂-ZnS/C-TiN NTAs as the negative electrode and Au-coated ZnS/NF (nickel foam) as the positive electrode. The aqueous supercapacitor device exhibited a wide potential window voltage of 1.8 V, coupled with high energy density and cycling stability. As indicated by experimental results, the as-prepared Au@Ni₃S₂-ZnS/C-TiN NTAs present as a promising negative electrode material for asymmetric supercapacitors.