石墨烯负载四硫化三钴复合物氧还原催化剂的制备与性能

选取二氯化钴和硫脲为钴源和硫源,以自制的还原氧化石墨烯(rGO)为载体,采用回流法在乙二醇溶剂中一步合成出Co₃S₄/rGO复合物。利用X射线衍射、扫描电镜和拉曼光谱(Raman)等手段对催化剂进行结构与形貌表征。结果表明:Co₃S₄/rGO样品中生成了具有立方结构的Co₃S₄细小晶粒,生长在rGO上的Co₃S₄晶粒发生聚集,具有较好的分散性。Co₃S₄/rGO的拉曼谱图的峰强比(I_D/I_G)为0.92,Co₃S₄对石墨烯结构无明显影响,石墨烯起到载体作用。在0.5mol/L H₂SO_4电解液中,线扫伏安测试表明,Co₃S₄/rGO催化剂具有良好的氧还原催化性能,氧还原起始电位为0.75V(vs.RHE),在动力学电位区,Tafel斜率和传递系数分别为119.5mV和0.49,氧分子在Co₃S₄/rGO催化剂上按四电子机理直接还原成水。

Preparation and property of graphene supported Co3S4composite catalyst for oxygen reduction reaction

The Co₃S₄/rGO composite was synthesized in ethylene glycol solvent by refluxing method using home-made reductive graphene oxide(rGO)as carrier,and choosing cobalt dichloride and thiourea as cobalt source and sulfur source,respectively.The structure and morphology of the catalyst were characterized by XRD and ramam technique.The results shown that the Co₃S₄crystal particles with cubic structure were formed,the Co₃S₄grains grown on rGO gathered and had good dispersibility.The I_D/I_G of raman spectra of the samples was 0.92,Co₃S₄had no obvious effect on the structure of graphene and graphene acted as a carrier.In 0.5 mol/L H₂SO₄ electrolyte,the linear sweep voltammetric test shown that the Co₃S₄/rGO catalyst had good catalytic performance for oxygen reduction,and the open-circuit potential was 0.75 V(vs.NHE).In the kinetic potential region,the Tafel slope and transfer coefficient were 119.5 mV and 0.49,respectively.Oxygen molecules were directly reduced to water on the Co₃S₄/rGO catalyst according to the four-electron mechanism.