ZIF67衍生硫化钴/多孔碳复合催化剂的制备及其电催化性能

采用离子交换法与热处理相结合的方法,以ZIF67为前驱体,硫代乙酰胺为硫源,制备出硫化钴/多孔碳(CoS/C)复合催化材料,并探讨了硫化时间对复合催化剂的形貌、结构及其氧还原(ORR)性能的影响。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)、N2吸附-脱附测定仪、X射线光电子能谱分析(XPS)、拉曼光谱仪(Raman)和旋转圆盘电极(RDE)技术表征催化剂的物理特征和电催化性能。研究结果显示,在碱性条件下该复合催化剂具有与20%(w/w)的商业Pt/C催化剂相媲美的ORR活性,其半波电位仅比Pt/C催化剂低31 mV。随着硫化时间的增加,硫化钴颗粒逐渐增大,催化剂中碳材料的无序程度出现先减小后增大的趋势。在硫化时间为10 min时,复合催化剂在0.1 mol·L-1KOH中表现出良好的电催化活性,且在ORR过程中复合催化剂的平均转移电子数可达到3.72,接近于4,说明氧气在该催化剂表面发生的是四电子转移过程。

Preparation and Electrocatalytic Property of Cobalt Sulfide/Porous Carbon Composite Catalyst Derived from ZIF67

Cobalt sulfide/porous carbon (CoS/C) composite catalysts have been synthesized through combination of ion exchange method and heat treatment method with ZIF67 as precursor and thioacetamide as sulfur source. The effect of vulcanization time on the morphology, structure and oxygen reduction (ORR) performance of the composite catalyst were discussed. The morphology and structure of the composite catalyst were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N₂ adsorption-desorption measurement, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman) and rotating disk electrode (RDE) techniques. The results showed that the composite catalyst had the comparable ORR activity to commercial 20%(w/w) Pt/C catalyst in alkaline medium, and its half-wave potential was negative to the Pt/C catalyst only 31 mV. With the increase of vulcanization time, the cobalt sulfide particles gradually increased, and the degree of disorder of carbon materials in the catalyst first decreased and then increased. When the vulcanization time was 10 min, the composite catalyst showed the best ORR performance in alkaline medium (0.1 mol·L^-1 KOH). The average number of transferred electrons in the ORR process could reach 3.72, close to 4, indicating that the ORR was a four electronic transfer process on the surface of the catalyst.