Cobalt and chlorine co-doped nickel sulfide catalysts: impact of hydrothermal treatment duration on electrochemical activity and stability for ethylene glycol oxidation

This study investigates the electrochemical activity and stability of cobalt- and chlorine-co-doped nickel sulfide (Co,Cl–NiS) catalysts for ethylene glycol (EG) oxidation in alkaline media. The catalysts were synthesized directly on nickel foam using a one-step hydrothermal method with thiourea, sodium chloride, and cobalt nitrate precursors, with hydrothermal durations of 12, 18, and 24 h. The 12 h catalyst exhibited the highest peak current density (~210 mA cm⁻²) but showed limited stability (~67.7% retention after 1800 s). In contrast, the 24 h catalyst demonstrated lower activity (~180 mA cm⁻²) but improved stability (84.1% retention). The 18 h catalyst achieved comparable peak activity (~210 mA cm⁻²) while exhibiting the highest stability (86.1% retention), indicating an optimal balance between activity and durability. These results reveal a synthesis-duration-dependent activity–stability trade-off, with intermediate hydrothermal treatment producing the most balanced catalytic performance. This work highlights hydrothermal duration as a key parameter for tuning catalytic behavior in dual-doped NiS systems and provides a basis for further structural and mechanistic investigation.