3D flower-like Ni–Co–S with high specific surface area for the electrocatalytic oxidation of methanol

The 3D flower-like Ni–Co–S was synthesized by a typical hydrothermal method in the presence of urea and thioacetamide. As comparison, the urchin-like Ni–Co–O was prepared in the absence of thioacetamide. The former processed higher electrocatalytic activity for methanol oxidation than the latter. Ni–Co–S exhibited the anodic peak current density of 19.23 mA/cm 2 for methanol oxidation, far higher than Ni–Co–O. It also showed the Tafel slopes of 57 mV/dec, much lower than Ni–Co–O. The BET results showed that the surface area and pore volume are 96.373 m 2 /g and 0.367 cm 3 /g for the flower-like Ni–Co–S, which is higher than 88.736 m 2 /g and 0.224 cm 3 /g for the urchin-like Ni–Co–O. As a result, the flower-like Ni–Co–S possessed more electroactive sites for methanol oxidation. The superhydrophobicity of the flower-like Ni–Co–S helps for the formation of micro air film on the surface of flower petals. Such a tri-phase interface of Ni–Co–S solid, reaction solution and air film may help for the electrocatalytic oxidation of Ni–Co–S toward methanol oxidation since the produced CO 2 can leave the surface of Ni–Co–S quickly and enter into solution phase due to the presence of air film and high solubility of CO 2 in aqueous solution.