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

Preparation and property of graphene supported Co_(3)S_(4)composite catalyst for oxygen reduction reaction

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Co_(3)S_(4)/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:Co_(3)S_(4)/rGO样品中生成了具有立方结构的Co_(3)S_(4)细小晶粒,生长在rGO上的Co_(3)S_(4)晶粒发生聚集,具有较好的分散性。Co_(3)S_(4)/rGO的拉曼谱图的峰强比(I_(D)/I_(G))为0.92,Co_(3)S_(4)对石墨烯结构无明显影响,石墨烯起到载体作用。在0.5mol/L H_(2)SO_4电解液中,线扫伏安测试表明,Co_(3)S_(4)/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Co_(3)S_(4)/rGO催化剂上按四电子机理直接还原成水。

The Co_(3)S_(4)/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 Co_(3)S_(4)crystal particles with cubic structure were formed,the Co_(3)S_(4)grains grown on rGO gathered and had good dispersibility.The I_(D)/I_(G) of raman spectra of the samples was 0.92,Co_(3)S_(4)had no obvious effect on the structure of graphene and graphene acted as a carrier.In 0.5 mol/L H_(2)SO_(4) electrolyte,the linear sweep voltammetric test shown that the Co_(3)S_(4)/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 Co_(3)S_(4)/rGO catalyst according to the four-electron mechanism.