A general and controllable synthesis of ComSn (Co9S8, Co3S4, and Co1-xS) hierarchical microspheres with homogeneous phases

This work presents a facile and general solvothermal approach to prepare hierarchical cobalt sulfides (ComSn) microflowers, which are composed of curved nanosheets. The homogeneous phases of Co9S8, Co3S4 and Co1-xS could be obtained just by adjusting the molar ratio of cobalt acetate to thiourea. The structure and morphology of the as-prepared cobalt sulfides were investigated by powder X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM) and high-resolution TEM, X-ray photoelectron spectroscopy and N-2-sorption measurements. The possible growth process was discussed on the basis of time-dependent experimental results. The ComSn materials exhibited great electrocatalytic activities towards both oxygen reduction and oxygen evolution reactions, making them a kind of promising electrode materials for fuel cells and batteries.