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 CO2 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 CO2 in aqueous solution. (C) 2018 Elsevier Ltd. All rights reserved.