Synthesis of sulfur-doped nickel cobalt hydroxide nanostructures on stainless steel substrates by electrodeposition and their characteristics as supercapacitor electrodes

It has been widely recognized that the structure, composition, and morphology of materials determine their properties. Sulfur-doped nickel cobalt hydroxide (S-Ni_1−xCo_x(OH)₂) nanostructures were synthesized directly on the surface of stainless steel wire mesh via a one-step facile electrodeposition route. Comparative experiments have shown that the presence of thiourea can inhibit the reduction of nickel and cobalt ions, while promoting the formation of hydroxides and further sulfurization, thereby obtaining sulfur-doped nickel cobalt hydroxide nanostructures. The doping of sulfur has been found to improve the specific capacities of the monometallic hydroxides (Ni(OH)₂ and Co(OH)₂), while the synergistic effect between Ni and Co has a more pronounced impact on energy storage performance. In addition, the molar ratio of nickel to cobalt can affect the morphology of material. S-Ni_0.5Co_0.5(OH)₂ with a favorable morphology of nanosheet array, and porous structure exhibits the highest specific capacity, optimal rate performance, and improved cycling stability among the studied electrodes. In 1 M KOH electrolyte, the specific capacities of S-Ni_0.5Co_0.5(OH)₂ electrode at current densities of 1 and 10 A g⁻¹ are 488 and 275 C g⁻¹, respectively, and the capacity retention is 56.6% after 10,000 cycles at the current density of 10 A g⁻¹.