Enhanced electrocatalytic activity of sulfur and tungsten co-doped nickel hydroxide nanosheets for urea oxidation

Ni(OH)2 is regarded as one of the most promising electrocatalyst candidates for urea oxidation reaction due to its structural diversity and low cost, however the inferior electrocatalytic activity severely limits its application. Herein, tungsten and sulfur species are successively doped into Ni(OH)2 nanosheets (S,W-Ni(OH)2) and synergistically promote the electrocatalytic activity towards urea electro-oxidation. Compared with Ni(OH)2 without doping or Ni(OH)2 doping with only one species, S,W-Ni(OH)2 exhibits faster reaction kinetic, larger ECSA, smaller charge transfer and urea adsorption resistance, which should guarantee the enhanced electrocatalytic activity. Potential dependent impedance measurements indicate that tungsten doping can prevent the electrocatalyst from being poisoned and sulfur doping will further enhance the charge transfer and urea adsorption ability. Therefore, simultaneously introducing sulfur and tungsten species into Ni(OH)2 should offer a promising way for designing efficient Ni-based electrocatalysts towards urea electro-oxidation.